SHig's Pram Build Thread

[SHigSpeed]

Okay, well here goes. I need some place to document the process. From beginning to (hopefully) end. Who knows, I may pour 6 months into this and end up buying one, or maybe just sticking to inflatables? :)

Anyway, so far I've had my hands and tape on a Redwood boat. I'm hoping to get some time with a Metalhead this weekend, and others if the PramFest 2010 comes together as planned.

I've drafted up something close and a few revisions and made 1:12 scale paper models. Here're some photos so far...

http://farm5.static.flickr.com/4093/4769973121_cae46d2bd3.jpg
http://farm5.static.flickr.com/4081/4770611124_7f5138f2f1.jpg
http://farm5.static.flickr.com/4136/4770614358_9e1b3d6c13.jpg
http://farm5.static.flickr.com/4140/4770615910_6baaafdf56.jpg
http://farm5.static.flickr.com/4096/4769977787_9e3147cdf4.jpg
http://farm5.static.flickr.com/4121/4769979191_e7289f5355.jpg
http://farm5.static.flickr.com/4096/4770620152_306f89e60f.jpg
http://farm5.static.flickr.com/4123/4769982083_172ef7def3.jpg

As of now, I'm thinking I'll be doing some sort of Carbon/Glass/Kevlar composite with maybe thin plywood or foam core. Single seater, car topper, target weight of 40 lbs. Haven't done the math on the areas yet, but I think that I may be able to go lower while having the required rigidity and strength. We'll see.

I want to be able to row stillwater easily but outright speed isn't necessary. Stand with better than average stability, and be able to run some small moving water. Maybe a small electric or gas motor.

Some rocker but not so much as to sacrifice standing stability. If it doesn't glide on the river as well as a "mini-drifter" I'll live with that. Flat bottom for ease of build and stability, kevlar bottom for durability.

Does anyone out there build a high tech composite pram? I can't possibly be the first nutcase to consider it right? I know Spring Creek makes a fiberglass/kevlar jobber, but isn't it at its core a chopper gun "plus"? Not feather light by any means...

Anyway, feel free to chime it. Follow along. Point fingers and laugh. Just don't tell my wife about this or her suspicions of my madness will be confirmed and I'll never get to go fishing again! :)

_SHig

[Bill Kiene semi-retired]

Very exciting.......

Ray Jensen of Endure Boats in Medford, OR mocked up my 17' jet boat hull first about a foot long from aluminum. It was pretty cool.....

[Scott V]

Let me know if you want an extra hand in building Shig, I would like to learn how to build one myself. Because if you don't teach me you know I will be asking for one.

I know I have plans for a plywood boat somewhere, I will look for them and if I find them I will get a copy made and give you a set.

[Jgoding]

Good luck Shig. Reminds me of the boat we made in highschool physics class out of cardboard and paper maché coating. We molded the front using a paper maché molding from our canoe and built on from there. Put on a nice enamel paint and a parafin wax coating on the bottom/sides and it floated all afternoon and we almost took the speed contest. It held two people easily.

[Black Cloud]

SHig, here is the one I built with 1/4" mahogany marine ply. I used an epoxy kevlar on the bottom.

James

[SHigSpeed]

Oh damn that's pretty! So how does she handle? Coming out for Prama-Palooza this Saturday?

What would you like to do differently next time?

What's it weigh?

How's standing and casting?

The coating on the bottom - is it the Duplicolor stuff? Or actual fabric and epoxy?

Thanks for the input! :)

_SHig

[Black Cloud]

The next one I build will have more of a flat bottom and the sides will be 2" higher, mainly so the seat won't be so low. The coating is called COAT-IT from Tap Plastics. Weight is about 75lbs, 8'x4', fits in the bed of a truck. Unfortunatly, I can't make it this weekend, we have the Putah Creek Fundraiser. Next year this one might be raffled at the event.

James

[SHigSpeed]

The next one I build will have more of a flat bottom and the sides will be 2" higher, mainly so the seat won't be so low. The coating is called COAT-IT from Tap Plastics. Weight is about 75lbs, 8'x4', fits in the bed of a truck. Unfortunatly, I can't make it this weekend, we have the Putah Creek Fundraiser. Next year this one might be raffled at the event.

James

Hmm... So the raised flat floor makes you squat more than sit?

Do you have plans picked out for the next boat already?

That'll make some raffle winner VERY happy...

_SHig

[jbird]

That is a really nice looking pram!

[Gulicemo]

That wood pram makes me want to clean out the garage and quit work... Very nice!

[Hairstacker]

Man, I agree, that's a beauty! :cool:

[SHigSpeed]

Man, I agree, that's a beauty! :cool:

For sure! There's something to be said about a nice stained wood classic. Sort of like a 'boo rod. That said, I'm going tech on this one. Maybe I'll go old school when I build me a cane stick years from now...

_SHig

[Randy B]

Scott,

I really like the lines of the model you mocked up, and the flat, slightly rockered floor/bottom. Looks like it'll row easy and motor well.

[pgw]

As a former builder (and maintenance man) of a wooden El Toro sailboat (Boy Scout Merit Badge Project in 1964) I have to say that I don't miss the wooden boat.

I have a Redwood Welding 8' drifter (really 7' 7") and after a TPL and a couple of Valcos, it's the best I've had.

One thing I observed in Black Cloud's beauty that I wish I had in the drifter (that I suggest you consider for your project) is the drain hole in the stern.

Your pattern appears to mimic the Redwood drifter with one exception and that is the oarlock mounts that are 3 inches higher than the gunwales (like the extensions on Black Cloud's)...I wish the ones on mine were a little higher (at least 2") to keep the oars off my knees...I have 2" spacers that I added to the oarlocks on my Clackacraft drift boat that now go back and forth between it and the Redwood Little Drifter.

Have fun..."Happpy Hand Tools"

Paul

[michaeln]

I know Spring Creek makes a fiberglass/kevlar jobber, but isn't it at its core a chopper gun "plus"?

Dunno what that means, but the Spring Creek prams are hand laid, not chopper gun.


Not feather light by any means...

The Stillwater Classic "Lite" is 59lbs. Remember that those boats have full USCG flotation, sturdy solid oak gunwales and a pedestal swivel seat built-in and included in that weight.

[SHigSpeed]

Dunno what that means, but the Spring Creek prams are hand laid, not chopper gun.



The Stillwater Classic "Lite" is 59lbs. Remember that those boats have full USCG flotation, sturdy solid oak gunwales and a pedestal swivel seat built-in and included in that weight.

Hand laid can mean fabric and glue over chopper though. Does SC use any sort of core material? Or perhaps a thick roving or mat between fabric? Because fabric alone would make for a thinner, flexy layup. Thick enough to be rigid would be heavier.

On your Hopper II can you guess how thick the walls were? Did they have plywood/foam/anything embedded in the 'glass?

59 lbs ain't bad, but it's not a feather - though the seat probably weighs 5 pounds alone.

I like all the "if I were to do things different" comments BTW. Keep 'em coming!

So, does anyone stand on the seat bench? Folding boat seat that much better than sitting on a flotation throw?

_SHig

[pgw]

So, does anyone stand on the seat bench? Folding boat seat that much better than sitting on a flotation throw?

_SHig

At 6-4/255, my center of gravity would be over 5' above the waterline (and the balance point) if I stood on the bench of the Redwood Welding Drifter...my mom fed all the dumb babies to the hogs when their bones were still soft...so I am disinclined to stand on the bench for any reason.

I do stand up on the deck (which some may call the floor) when necessary to see fish when I fish lakes but have never found it necessary to stand for casting...I installed a swiveling folding seat on the bench (slides on and off)...can still use "just" the floatation cushion if necessary but having the backrest/support provided by the seat...priceless!

Paul

[michaeln]

When I had my Hopper II I seldom stood up to cast.

My main reason to stand up in that pram was to pee into a bottle. I didn't feel comfortable standing anywhere but dead center in the boat, and I can't really count on being able to pee accurately and forcefully enough to get it all past the gunwale, so I kept a (large mouth) plastic bottle in the battery compartment and would pee into that, then dump it and rinse it.

Maybe TMI, but I keep reading about people standing in prams, and peeing out of them, and at least on the Hopper II, I was never really comfortable doing either.

[SHigSpeed]

As a former builder (and maintenance man) of a wooden El Toro sailboat (Boy Scout Merit Badge Project in 1964) I have to say that I don't miss the wooden boat.

I have a Redwood Welding 8' drifter (really 7' 7") and after a TPL and a couple of Valcos, it's the best I've had.

One thing I observed in Black Cloud's beauty that I wish I had in the drifter (that I suggest you consider for your project) is the drain hole in the stern.

Your pattern appears to mimic the Redwood drifter with one exception and that is the oarlock mounts that are 3 inches higher than the gunwales (like the extensions on Black Cloud's)...I wish the ones on mine were a little higher (at least 2") to keep the oars off my knees...I have 2" spacers that I added to the oarlocks on my Clackacraft drift boat that now go back and forth between it and the Redwood Little Drifter.

Have fun..."Happpy Hand Tools"

Paul

Early on I had considered the El Toro type shape, but the flat bottom is really where I want to be. My current plans are based on general dimensions of the Redwood, though I've heard that the Metalhead is more stable. You say you like the Drifter better than the Valco huh? Lots of guys love the Valco.

At current, I'm taking the Redwood and widening the bow, and removing some rocker. I'm going to use the seat fore and aft bulkheads to add rigidity to the sides and bottom vs. hanging the seat from the walls alone. Tying in the three sides REALLY minimize deflection and twist. This is rediculously clear from my paper models. The nose is still floppy but a flotation chamber, stiffening ribs, and some gusseting will address that.

I'll make sure to verify the ergonomics of rowing based on the geometry of my pontoon frame.

Why the drain hole? Can't you just tip it up on end and drain it? Can't utilize this while on the water right?

Thanks for the input!

_SHig

[k.hanley]

Shig it's cool to see the models you're making. This is fun to watch you develop your project.


James that is some f-i-n-e boat building you have there! Beautiful. Thanks for sharing the pics.
Cheers, Ken

[michaeln]

Why the drain hole? Can't you just tip it up on end and drain it?

No drain hole in the Spring Creek prams. I kept a large sponge in the battery compartment under the seat to remove the water that accumulates in the boat during the day, and the remainder would get drained out when I put it on the rack on my car.

Besides, if you have a drain hole it is only a matter of time until you do what every boater with a boat that has a drain plug does eventually... launch the boat having forgotten to put the plug in. :oops:

[Scott V]

I see no need for a drain hole, it is just another thing to have to remember to do before I go fishing. Plus it is another place that can leak.

[wjorg]

Early on I had considered the El Toro type shape, but the flat bottom is really where I want to be. My current plans are based on general dimensions of the Redwood, though I've heard that the Metalhead is more stable. You say you like the Drifter better than the Valco huh? Lots of guys love the Valco.




Metalhead is significantly more stable than the Redwood welding and valco.

[SHigSpeed]

Metalhead is significantly more stable than the Redwood welding and valco.

What about the design of the Metalhead contributes to this stability?

Thanks!

_SHig

[wjorg]

I suppose you could always have a good design and load the boat wrong with the weight you have in it.

When Ive seen guys in the valcos, they didnt seem to want to stand much.

The RW rocker seemed to contribute to a stern close to the water when a guy stood and especially when he reached down to pull the anchor with a fish on. The cut out handles are a death trap.

Metalhead seems not to tilt stern down as much, even with the full rocker design. The flat bottom was the "cats meow," hence how I told you one could "lean out of the corner and piss out of it." : )

[Black Cloud]

The swivel seat is used when I use the electric motor. The drain plug isn't necessary, the first pram I built didn't have one, you just tip it over. Standing isn't necessary for casting , I just like the idea I can stretch my legs and take a leak. I also have flotation chambers in the two boxes front and back.

James

www.fisharslonga.com

[SHigSpeed]

The swivel seat is used when I use the electric motor. The drain plug isn't necessary, the first pram I built didn't have one, you just tip it over. Standing isn't necessary for casting , I just like the idea I can stretch my legs and take a leak. I also have flotation chambers in the two boxes front and back.

James

www.fisharslonga.com

Hey James,

How did you decide where to put your seat? It seems a bit far forward compared to other designs. Is that where the plans showed it (if you used plans)? I'm wondering because it's far from the transom and the motor tiller and seems like when sitting and casting the center of weight is a bit more forward than the center of buoyancy. I guess with a 60 lb battery and 30 lb motor all the way back it may balance things out nicely...

_SHig

[SHigSpeed]

I suppose you could always have a good design and load the boat wrong with the weight you have in it.

When Ive seen guys in the valcos, they didnt seem to want to stand much.

The RW rocker seemed to contribute to a stern close to the water when a guy stood and especially when he reached down to pull the anchor with a fish on. The cut out handles are a death trap.

Metalhead seems not to tilt stern down as much, even with the full rocker design. The flat bottom was the "cats meow," hence how I told you one could "lean out of the corner and piss out of it." : )

I did notice from the photos that the side height of the MH boats was higher in the rear with less rear rocker. That's what I've incorporated in my design. No handle cutouts either! I'm sure the high stern of the RW boat would help in rivers rowing backwards in the current, but that's not a high priority for me.

_SHig

[Black Cloud]

SHig , the plans for my pram is called sabotina, same as the el toro,a small sailboat. I modified a few things but the seat is where it was called for.

[Ed Wahl]

I guess I'm the exception here. I spend more time standing on the seat of my Metalhead than I do the floor. I'm pretty active while fishing, constantly looking in the water and in all directions for clues as to where the fish are. On the seat I can cast in any direction quickly and get a bit more distance out when I need to.

Lucky it wasn't Mom's job to feed the hogs. :)

Ed

[SHigSpeed]

I guess I'm the exception here. I spend more time standing on the seat of my Metalhead than I do the floor. I'm pretty active while fishing, constantly looking in the water and in all directions for clues as to where the fish are. On the seat I can cast in any direction quickly and get a bit more distance out when I need to.

Lucky it wasn't Mom's job to feed the hogs. :)

Ed

Watching you fish was why I asked about standing on the seat in the first place! I'm drawing a 12" wide bench for now but wider would make for a more rigid boat at a minuscule increase in weight.

Any thoughts on this?

_SHig

[michaeln]

Any thoughts on this?

Include a good PFD in your plans. ;-)

[Ed Wahl]

Include a good PFD in your plans. ;-)

I've seen Shig stand up on his pontoon, a pram will be a walk in the park.

A tradeoff for that kind of stability, I think, is the weight It's pretty heavy.

I wouldn't mind trying that in one of these guys' sissy prams, just to compare.

BAM!

Ed

[SHigSpeed]

I've seen Shig stand up on his pontoon, a pram will be a walk in the park.

A tradeoff for that kind of stability, I think, is the weight It's pretty heavy.

I wouldn't mind trying that in one of these guys' sissy prams, just to compare.

BAM!

Ed

<lol> BAM!

As for standing on the 'toon seat, that was neither easy nor fun. I was just jealous of you catching all the fish and I couldn't see fish for $#!+! I almost bailed more than once...

So the mere inertia of the mini-battleship prevents any heaving eh? I don't buy it! :P

PFD - probably a good idea. Will at least have the throw cushing and I already own (but rarely - no, never - use) an inflatable belt unit. Will definitely sport that one on any river that I might float but stillwater? Not sure...

_SHig

[wjorg]

Ed, the stability comes from the design. The weight is from the thicker aluminium preventing punctures. The weight also comes from the reinforcement pieces they incorporated to prevent oil canning. You boat was 1 of 6 or 7 before he "got it right," fron what I understand. Unfortunately, your and my boats are heavy.

My friends pram is MH design with no rocker, 45 pounds, no oil canning, you can fight a 50 pound salmon in damn near the corner of the boat. But you can stab it with a pencil its so thin. Cant have it all in one pram.

[Ed Wahl]

I don't think I'd give up the weight, I do love having the ability to run it up on the rocks and step out without worrying about a puncture.

Like you said, everythings a tradeoff.

Ed

[SHigSpeed]

My friends pram is MH design with no rocker, 45 pounds, no oil canning, you can fight a 50 pound salmon in damn near the corner of the boat. But you can stab it with a pencil its so thin. Cant have it all in one pram.

So this thing is flat bottom front to back and side to side? Like the SC Hopper II? Interesting...

_SHig

[michaeln]

So this thing is flat bottom front to back and side to side? Like the SC Hopper II?

Huh? The Hopper II isn't flat with no rocker. It's not extreme, but there is definitely some rocker:

http://michaelnel.smugmug.com/Boats/Spring-Creek-Hopper-II-Pram/pramside/682019638_y3gqo-L.jpg

[SHigSpeed]

Huh? The Hopper II isn't flat with no rocker. It's not extreme, but there is definitely some rocker:

http://michaelnel.smugmug.com/Boats/Spring-Creek-Hopper-II-Pram/pramside/682019638_y3gqo-L.jpg

You're right, there is some curvature there. Definitely minor compared to a lot of boats out there. Loaded on the water I'm guessing neither end stays above the waterline?

_SHig

[michaeln]

Loaded on the water I'm guessing neither end stays above the waterline?

I don't know, but I suspect that is a function of the load in the boat and how it is distributed. With my fat butt in the boat and the gear I carried, the gunwales were barely above the waterline. :D

[SHigSpeed]

I have a Redwood Welding 8' drifter (really 7' 7") and after a TPL and a couple of Valcos, it's the best I've had.

Paul

Hey Paul,

The Valco is pretty much a short Jonboat right? Flat length and width with a pickup in the front?

How did this boat handle differently from the MH? Is it relatively narrow? Was standing an issue in it?

Thanks!

_SHig

[pgw]

Hey Paul,

The Valco is pretty much a short Jonboat right? Flat length and width with a pickup in the front?

How did this boat handle differently from the MH? Is it relatively narrow? Was standing an issue in it?

Thanks!

_SHig

I had a 10' (that was stolen) and a 12' Valco jonboat...the primary use was for duck hunting in salt ponds around SF Bay and fishing on Fall River. The Valcos did well in those applications but were heavy (100+ for the 10' and 130 for the 12'). The bottom width of these guys, 44 inches or so, made them stable for casting and shooting...a 33# thrust minKota electric moter would almost get the 10' version up on step but they were pigs to row and acted like big sails in the wind.

Nothing but good with the TPL except that the 8' model I had only provided about 2" of freeboard with me, motor, gear...it found a home when I went to the larger 10" Valco.

My Redwood Welding drifter provides greater freeboard than the TPL, is slightly narrower than both the TPL and the Valcos, and does have the tapered bow (like an El Toro) but there's not angles to the bottom like the El Torro, just the rocker. It rows like a racing shell and the 33# MinKota has more thrust (and speed) than the boat needs.

When I fish in the drifter, I have my 14# anchor on an extended mount on the bow (to my back) and the second, 12# anchor on a cam-cleat mounted on a corner of the stern. I've never had an issue with the stern dipping down when landing fish (Lakes, tidal area on coastal rivers, or flowing rivers (Yuba, Russian, Trinity) or pulling the anchor...bow down first and up last if I use both...usually on lakes. I attach an empty plastic bleach bottle to the end of the bow anchor line when I fish the coastal rivers for steelhead/salmon and rather than pull the anchor to follow a fish downsteam to fight it, I slip the line, and after the fight, return to the floating bottle, re-secure the anchor line. and start over...pram tactics 101.

Paul

[SHigSpeed]

I had a 10' (that was stolen) and a 12' Valco jonboat...the primary use was for duck hunting in salt ponds around SF Bay and fishing on Fall River. The Valcos did well in those applications but were heavy (100+ for the 10' and 130 for the 12'). The bottom width of these guys, 44 inches or so, made them stable for casting and shooting...a 33# thrust minKota electric moter would almost get the 10' version up on step but they were pigs to row and acted like big sails in the wind.

Nothing but good with the TPL except that the 8' model I had only provided about 2" of freeboard with me, motor, gear...it found a home when I went to the larger 10" Valco.

My Redwood Welding drifter provides greater freeboard than the TPL, is slightly narrower than both the TPL and the Valcos, and does have the tapered bow (like an El Toro) but there's not angles to the bottom like the El Torro, just the rocker. It rows like a racing shell and the 33# MinKota has more thrust (and speed) than the boat needs.

When I fish in the drifter, I have my 14# anchor on an extended mount on the bow (to my back) and the second, 12# anchor on a cam-cleat mounted on a corner of the stern. I've never had an issue with the stern dipping down when landing fish (Lakes, tidal area on coastal rivers, or flowing rivers (Yuba, Russian, Trinity) or pulling the anchor...bow down first and up last if I use both...usually on lakes. I attach an empty plastic bleach bottle to the end of the bow anchor line when I fish the coastal rivers for steelhead/salmon and rather than pull the anchor to follow a fish downsteam to fight it, I slip the line, and after the fight, return to the floating bottle, re-secure the anchor line. and start over...pram tactics 101.

Paul

Ouch! 100# for a 10' aluminum. Probably bulletproof though. Good to know that 44" of width will do the job. I think my drawings so far have about that or a skosh more...

2" of freeboard on the TPL!? You must tote a lot of stuff. I'm a bit surprised that the Redwood gives you more freeboard than the TPL. No issues with the handle cutouts acting as swamping faucets huh? I guess the anchor sequence is key to safety there. I do like the idea of the throwaway front anchor. Can't have a "captured" pulley to make that play - have to remember this point... How do you control the boat chasing fish?!

Great insights, again.

_SHig

[michaeln]

Can't have a "captured" pulley to make that play


Use the Pocket Puller davits. They allow you to insert the line through the side, and they work great. I had them front and rear on my Hopper II.

[pgw]

How do you control the boat chasing fish?!_SHig

Short Answer: follow the fish

Long answer (Pram Tactics 101): Regardless of the current in the tidal situation, the area is usually "fairly" wide open...I already have the stern facing downstream (the bow anchor is what was holding the boat in the current) and as the fish runs, pressure against the fish (moving the rod from side to side) usually results in the fish pulling away from the direction of the rod...gather line back & land the fish and use the stern anchor if necessary (not a good option since dropping the stern anchor can create interesting activity if your rod pressure can't keep the fish away from the anchor line)...self preservation is a key factor, there may be a time that you have to put the rod in a holder, hope the fish stays connected, and pull on the oars to set the boat's drift to miss something before you finish the fight.

Paul

ps-in most tidal situations, quite a few boats are in the line-up, slipping the anchor to move downstream prevents your fish from snagging the other fishermans' lines or screwing up their drifts.

[Phil Synhorst]

Watching you fish was why I asked about standing on the seat in the first place! I'm drawing a 12" wide bench for now but wider would make for a more rigid boat at a minuscule increase in weight.

Any thoughts on this?

_SHig

Scott, I stand on my seat without any stability problems. However, I do wish it was a few inches wider. I'll measure it tomorrow, and let you know it's width.

I'm thinking of making a removable deck; span from seat to stern. I think there is a definite advantage in that extra foot of elevation.

[SHigSpeed]

Scott, I stand on my seat without any stability problems. However, I do wish it was a few inches wider. I'll measure it tomorrow, and let you know it's width.

I'm thinking of making a removable deck; span from seat to stern. I think there is a definite advantage in that extra foot of elevation.

Cool, thanks! What kind of boat do you have?

_SHig

[Phil Synhorst]

It's an Outback, 10ft., Kevlar/Glass hull. The bow is shaped more like a Tri-hull boat, not like the traditional prams.

[pgw]

It's an Outback, 10ft., Kevlar/Glass hull. The bow is shaped more like a Tri-hull boat, not like the traditional prams.

The Outback boats have the same Tri-hull design as the old TPL...I think Brian (Outback) was using the same mold (may have obtained it from TPL in 1988).

Paul

[Hibbygibi]

Was your 10' Valco a three bench model or two? I have a 2 bench that weighs all of 80lbs and is perfect for the Fall and small lakes. Easy for one man to handle.


The Valcos did well in those applications but were heavy (100+ for the 10' and 130 for the 12'). The bottom width of these guys, 44 inches or so, made them stable for casting and shooting...a 33# thrust minKota electric moter would almost get the 10' version up on step but they were pigs to row and acted like big sails in the wind.
Paul

[Phil Synhorst]

Scott, finally got around to measuring the seat. It's 10in., nice enough to stand on, but 12-14in. would be better(imho).

[pgw]

Was your 10' Valco a three bench model or two? I have a 2 bench that weighs all of 80lbs and is perfect for the Fall and small lakes. Easy for one man to handle.

My 10' Valco had 2 bench seats...I guess it felt heavier because it had to go on top of my Toyota FJ-40...the rack was 7' from the ground.

Paul

[michaeln]

One thing I really liked about the Hopper II was the pedestal seat. No having to step over a bench seat, and with the swivel "tractor" type seat you could rotate it to any direction.

It was also nice to be able to stow the battery under the seat, (putting that weight right in the middle of the boat), and there was an enclosed channel to route the trolling motor wires (6 gauge!) back to the transom, with a HD quick disconnect.

Very well thought-out design.

[SHigSpeed]

Scott, finally got around to measuring the seat. It's 10in., nice enough to stand on, but 12-14in. would be better(imho).

Cool, thanks! Ed's is nearly 16" wide an is plenty wide.

_SHig

[SHigSpeed]

Okay, some updates after pondering Ed's boat. I think I may understand why some people say that the Redwood is a dunking ready to happen.

I guess the common failure on the Redwood is if you lean too far forwards to pull an anchor or make the mistake of stepping into the bow area too far (or at all depending on who you ask) the ass end comes up and water rushes over the bow. The grab holes that sacrifice a couple of inches of freeboard don't help either. At any rate, if you look at a Redwood, the tallest part of the boat is pretty much dead center, under the rower's seat, and the rocker is somewhat "peaked" about this point.

Check this photo out for clarification:

http://farm5.static.flickr.com/4078/4784628370_1f34c85d84_o_d.jpg

Add to this fact that the boat does narrow up quite a bit to the front so it offers less buoyancy than the rear. While this is probably fine if you sit on the seat the whole time, if you put any weight fore of this point, hellloooo teeter-totter.

Compare to the Metalhead:

http://farm5.static.flickr.com/4097/4781369704_fbd1321d56.jpg

There is no pronouced teeter-totter point under the rower's seat. There's still stem to stern rocker, but more gentle from the stern 2/3 of the way forward, and only then does it kick up the rest of the way. Both boats have similar kick-up distances front and back, but the rate at which the kick happens is the difference. There's more freeboard ahead of the seat, and though it too tapers to the bow (as seen from above) in similar dims to the Redwood, this extra buoyancy will help fight the nosedive.

Back to my origami/kirigami.

Earlier boat - Notice how the rocker is a very smooth transition stem to stern with a bit of change in rate right at the rower's seat. No real "kick" anywhere, very, well, rocking horse.

http://farm5.static.flickr.com/4123/4769982083_172ef7def3.jpg

Here's my most recent model. I've done a couple of tweaks since the above version. This next one has a wider seat, less "trapezoid" in the bow, and more trapezoid in the stern to help boost width a skosh to about 54". Floor width hasn't changed since the first iteration and matches both the RW and MH at about 44" at its widest point. Side height is at max about 14".

You may notice that I've chosen not to match the narrower bow of both MH and RW by going with a 24" floor width at the front vs. about 19" for both other boats. I feel that the added width won't affect rowing or river capability much if at all but will add to safety and stability.

http://farm5.static.flickr.com/4115/4784600938_6df5a2e013.jpg


http://farm5.static.flickr.com/4095/4784598400_071664e291.jpg

http://farm5.static.flickr.com/4075/4783963745_a57a9b4826.jpg

http://farm5.static.flickr.com/4138/4783949713_b521e35d60.jpg

You'll also notice that I continued the more gradual rocker from the rear of the boat further fore and then added more more quickly to give a later kick-up. I may not be totally satisfied with the total amount of kick up as the MH and RW have about 8" of front kick and this one is more like 6", though with the wider front end and more buoyancy it will even it out a bit. My goal is to have the entire bow of the boat out of the water under all normal operation (standing anywhere on the seat rearwards, rowing, motoring, anchored river and lake, etc).

I'm feeling I'm getting closer.

As always, all input and questions are welcomed! :)

_SHig

[SHigSpeed]

One more thing...

I think I'm not getting the front kick up I want because of a concession to simplicity in the pattern. Check out the CAD so far...

http://farm5.static.flickr.com/4123/4784748956_df6e41119d.jpg

You'll notice the sides have a straight edge to it. Due to the bow out of the sides the profile as built will have a slight banana to it. BUT, to get the extra kick up of the front without doing creative widening to the front half of the boat (if I squish out the walls of my models, the ends kick up due to the geometry so I COULD take advantage of this but then it'll look odd and over-wide).

I may have to suck it up and add a curve to the front end of the top and follow this with more curvature to the bottom edge to maintain side height profile.

This will add to the sexy driftboat profile but will it add performance? Not sure...

_SHig

[michaeln]

I cropped and leveled and flipped this image so you could see the Hopper II profile easily and it looks to me like it's pretty close to what you are coming around to in your models.

http://michaelnel.smugmug.com/Other/Michaels-Junkbox/4783949713b521e35d60/931306386_xNwnA-L.jpg

http://michaelnel.smugmug.com/Other/Michaels-Junkbox/hopperprofile/931301789_icVMX-L-1.jpg

The Hopper II still has less rocker in the bow, and that may have a lot to do with its stability when you move around in the boat.

[SHigSpeed]

I cropped and leveled and flipped this image so you could see the Hopper II profile easily and it looks to me like it's pretty close to what you are coming around to in your models.

http://michaelnel.smugmug.com/Other/Michaels-Junkbox/4783949713b521e35d60/931306386_xNwnA-L.jpg

http://michaelnel.smugmug.com/Other/Michaels-Junkbox/hopperprofile/931301789_icVMX-L-1.jpg

The Hopper II still has less rocker in the bow, and that may have a lot to do with its stability when you move around in the boat.

I know that the Hopper II is a rock, and for sure the nearly flat bottom can be credited (or to blame, depneding...). That said, if I'm headed to Hoppertown, it's not on purpose! :) If anything it's closer to the Stillwater Classic than the Hopper.

I wouldn't want to try to make the Hopper work in moving water, and that's definitely on the priority list for my design.

BTW, now that you've had your pontube for a while, can you comment on how the fishing experience compares to using the Hopper? Other than the transportation and storage issues, would you say that the pram was a better fit for what you do, or is the NFO everything you want and need?

_SHig

[michaeln]

I wouldn't want to try to make the Hopper work in moving water, and that's definitely on the priority list for my design.

Jim specifically designed the Hopper II for use on Class I and II rivers. Are you planning on doing serious whitewater with your pram?


BTW, now that you've had your pontube for a while, can you comment on how the fishing experience compares to using the Hopper? Other than the transportation and storage issues, would you say that the pram was a better fit for what you do, or is the NFO everything you want and need?

If I lived in a place with a garage or side yard out in the suburbs and I had a truck and a trailer for the pram, I would MUCH rather have the pram. I liked having the trolling motor, I liked not having to wear waders or deal with fins. I liked the higher seated position in the pram, and I liked that I could more easily carry more stuff in the pram.

But, that's not the world I live in right now, and in *my* real world, the Rampage is clearly the better choice for me. As far as 'toons go, there isn't any other one I would rather have, especially the framed ones.

Strangely, in rough water the Rampage feels much safer to me. It's 10 1/2 feet long and wider than the pram, and most of the flotation is farther away from the centerline of the vessel, aiding stability. It's also rated to carry 1300 pounds, against the pram's 375 lb rating. With my svelte self pushing 280 nekkid and then adding two anchors, dry bags, tackle, etc. to the Hopper II, I was using up a LOT of that 375 lbs rating (and freeboard).

If I had that truck and trailer setup I spoke of above, I would probably get a 14' Gregor or Klamath semi-V welded aluminum boat and skip the pram idea altogether.

[SHigSpeed]

Jim specifically designed the Hopper II for use on Class I and II rivers. Are you planning on doing serious whitewater with your pram?


No whitewater for me. With the heavy walls, ample flotation, and high sides, I can see how the Hopper may go downstream safely, but I'm more interested in being able to move across and up on the oars as easily as possible. I may be wrong, but with the blunt nose on that thing I gotta think that the flow would win without a lot of work or a motor.





If I lived in a place with a garage or side yard out in the suburbs and I had a truck and a trailer for the pram, I would MUCH rather have the pram. I liked having the trolling motor, I liked not having to wear waders or deal with fins. I liked the higher seated position in the pram, and I liked that I could more easily carry more stuff in the pram.

But, that's not the world I live in right now, and in *my* real world, the Rampage is clearly the better choice for me. As far as 'toons go, there isn't any other one I would rather have, especially the framed ones.

Strangely, in rough water the Rampage feels much safer to me. It's 10 1/2 feet long and wider than the pram, and most of the flotation is farther away from the centerline of the vessel, aiding stability. It's also rated to carry 1300 pounds, against the pram's 375 lb rating. With my svelte self pushing 280 nekkid and then adding two anchors, dry bags, tackle, etc. to the Hopper II, I was using up a LOT of that 375 lbs rating (and freeboard).

If I had that truck and trailer setup I spoke of above, I would probably get a 14' Gregor or Klamath semi-V welded aluminum boat and skip the pram idea altogether.

Heh... 280 nekkid. The ID plate on the Metalhead shows a max capacity of 200 lbs so I guess that rules it out for you? :)

Thanks for the feedback on craft of choice. I don't have a lot of space at my place, but if the thing fits on the roof of the car and travels light, a pram can be made to work in my real world. I love tube fishing, but then again I loved being high and dry and flinging far. The rowing certainly took a toll on my arms though. Gotta alternate the arm and legs workouts! (Pram/tube/pram/tube...). That or get a motor. ;)

_SHig

[Reno Flytyer]

Get a motor Shig. As for your arms, I've seen better arms on a snake! ;o)

Having some background in mechanical illustration, I appreciate your approach to this pram project.

Buzz me when you get a Frenchman Jones.

RFT

[gene goss]

I brought 8ft.TPL 29 years ago, with a little modifying, i could hang a 7 1/2 hp sears 2 stroke (37lbs) off the back, the TPL would come up on plain (20mph)....i would face the front of the boat and use my body english to turn the boat. The seat board could be removed so i could lay down in the bottom of the boat, and sleep in it. The TPL is a very stable boat, you could walk around in the boat, and not be afraid of turning it over. With out a motor i could row a couple of miles. I still have 7ft. of the TPL (i cut a foot off the back, so it would fit inside my asto van), and it still row's, and has stablitity.

Shig if your going to put a outboard motor or a trolling motor on the back, you need to know how much weight you can hang off the end. If your going to row this boat, you don't need a trolling motor, and a pram with a little bigger outboard motor, you could cover a lot of water. There's a group of guys that fish Davis Lake, and they have small prams with big motors, and they have no problems fishing the whole north end of the lake in a day.

[Scott V]

I wanna put a 225 hp mercury outboard on mine Shig. Oh yeah and wings too so I can fly it.

[wjorg]

I have a Metalhead with a 350 pound rating. I have put both a 42 lb trolling motor and 3.5 outboard on mine with no real issues. Just realize when you open the outboard throttle your pram may do a wheelie. If you hit something floating in the water with the bow up at "higher" speeds its game over. Im thinking about getting a heavy plate to offset that, but it just adds more weight to the boat. Its not really an issue because I never really should be going fast with gunwales that are less than a foot out of the water....

I can stand in the metalhead and cruise at least at 5-10 mph while im running the outboard looking in the water. But Im used to jet boats in shallow streams at higher speeds, so this is a step down. I have the full rocker boat with an "aftermarket" keel and it seems to handle pretty nicely....

The most stable pram Ive been in had a flat bottom, no rocker to the stern. No keel, thin aluminum...and no oil canning.

[SHigSpeed]

Get a motor Shig. As for your arms, I've seen better arms on a snake! ;o)


<lol> You should have seen me back in the day when I was scooping ice cream by night and throwing newspapers before biking to the river before dawn. Can you say "fiddler crab"? I'd've probably rowed in circles!


I wanna put a 225 hp mercury outboard on mine Shig. Oh yeah and wings too so I can fly it.

I'll get right on that!


The most stable pram Ive been in had a flat bottom, no rocker to the stern. No keel, thin aluminum...and no oil canning.

So the front had a kick up, but from 1/3 beam forward it was flat? Like a jonboat?

Hmmm...

_SHig

[OceanSunfish]

I had a 10' (that was stolen) and a 12' Valco jonboat...the primary use was for duck hunting in salt ponds around SF Bay and fishing on Fall River. The Valcos did well in those applications but were heavy (100+ for the 10' and 130 for the 12'). The bottom width of these guys, 44 inches or so, made them stable for casting and shooting...a 33# thrust minKota electric moter would almost get the 10' version up on step but they were pigs to row and acted like big sails in the wind.

Nothing but good with the TPL except that the 8' model I had only provided about 2" of freeboard with me, motor, gear...it found a home when I went to the larger 10" Valco.

My Redwood Welding drifter provides greater freeboard than the TPL, is slightly narrower than both the TPL and the Valcos, and does have the tapered bow (like an El Toro) but there's not angles to the bottom like the El Torro, just the rocker. It rows like a racing shell and the 33# MinKota has more thrust (and speed) than the boat needs.

When I fish in the drifter, I have my 14# anchor on an extended mount on the bow (to my back) and the second, 12# anchor on a cam-cleat mounted on a corner of the stern. I've never had an issue with the stern dipping down when landing fish (Lakes, tidal area on coastal rivers, or flowing rivers (Yuba, Russian, Trinity) or pulling the anchor...bow down first and up last if I use both...usually on lakes. I attach an empty plastic bleach bottle to the end of the bow anchor line when I fish the coastal rivers for steelhead/salmon and rather than pull the anchor to follow a fish downsteam to fight it, I slip the line, and after the fight, return to the floating bottle, re-secure the anchor line. and start over...pram tactics 101.

Paul

I understand the process of using the bleach bottle, but I'm wondering how you attach the bottle to the anchor line and let it slip through the bow anchor pulley ? The bow pulley system on the RWs have a small plastic wheel where only the anchor line fits through....

Just curious...

Thanks.

[SHigSpeed]

I understand the process of using the bleach bottle, but I'm wondering how you attach the bottle to the anchor line and let it slip through the bow anchor pulley ? The bow pulley system on the RWs have a small plastic wheel where only the anchor line fits through....

Just curious...

Thanks.

My guess is that his had a non-captured pulley wheel, otherwise you could put the bleach bottle outside the cage, and run a doubled line through the pulley, though that wouldn't be very easy to use. It'd work though, so if released, the loop would run out, and the whole system would separate.

_SHig

[pgw]

My guess is that his had a non-captured pulley wheel, otherwise you could put the bleach bottle outside the cage, and run a doubled line through the pulley, though that wouldn't be very easy to use. It'd work though, so if released, the loop would run out, and the whole system would separate.

_SHig

That's it, I have the same extended anchor/pocket puller that's on the RW pram for sale in the photo you posted.

Paul

[wjorg]

Youll look like a bum with a bleach bottle and not half as cool as Schaadt, go get some red and white floats from West Marine.

BTW, if you throw the line overboard with a float on a crowded river, and someone else's fish get lost in your floating anchor line, you're in for it. I really only use the float as a backup plan to prevent loosing $150 in quality rope and anchor. Just haul the damn anchor when you go after a fish.

[pgw]

Youll look like a bum with a bleach bottle and not half as cool as Schaadt, go get some red and white floats from West Marine.

BTW, if you throw the line overboard with a float on a crowded river, and someone else's fish get lost in your floating anchor line, you're in for it. I really only use the float as a backup plan to prevent loosing $150 in quality rope and anchor. Just haul the damn anchor when you go after a fish.

a) I'm cheap, the bleach bottle is less expensive than a float from West Marine, and
b) In the crowded rivers I've fish where a majority of the fishermen in prams (either slip the anchor or pull it) leave the line up to drift downstream to fight fish, other fishermen's fish don't seem to get tangled in drifting anchor lines any more than they do in the anchor lines of fishermen who remain the line up and continue to fish.

Paul

[wjorg]

Im sorry, my mouth filter didnt work. Sorry Paul. Didnt mean to offend, I used a Gallon Crystal Geyser
bottle before I got the float(cheaper elsewhere). I had one guys salmon wrap my floating anchor line and was thoroughly chastised, I guess I should have said that.

-Walter

[pgw]

Im sorry, my mouth filter didnt work. Sorry Paul. Didnt mean to offend,-Walter

No offense taken...we're both providing examples of what we've seen, heard, & done...the customs of a line up (wading or floating) seem to evolve and change according to the personality (read: mob rule) of the group of fishermen who frequent the river...I've heard, "stay out of the line up until you get invited to fish with us", "don't get beween Tom & Dick, that's Harry's spot" (regardless of whether or not Harry is even there), "we only fish sinking shooting head's with Amnesia here, take your floating line and indicator up/downstream", "hey, they usually eat with the other end" (result of a foul hooked steelhead or salmon that tears up everybody's water), and my favorites (which can really screw you up if you're expecting the opposite), "don't just stand there, take a step (or move your boat) downsteam after a couple of casts, we rotate through the hole and restart at the top...don't crowd me, I'm fishing here, I don't have to move, I was here first"

Petri Heil,

Paul

[michaeln]

Ran across this pram build thread, thought you might get some ideas there:

http://forum.flybc.ca/index.php?showtopic=16784

[SHigSpeed]

Ran across this pram build thread, thought you might get some ideas there:

http://forum.flybc.ca/index.php?showtopic=16784

Cool! I have his current build bookmarked on my toolbar:

http://www.bcfishingreports.com/forums/threads/15791-jims-pram-build.../page2?

Thanks for the heads up!

_SHig

[SHigSpeed]

BTW, the "wheelbarrow pram" here"

http://www.bcfishingreports.com/forums/threads/15791-jims-pram-build.../page2?

is COOL!

I think I'll have to design in a wheel set and oar clamps to allow this sort of setup.

_SHig

[Phil Synhorst]

Out of curiosity, I checked out those threads on Flybc. The guys first project was pretty cool, all the extra/detailed work he put in payed off.:thumbsup:

[SHigSpeed]

More tinkering...

I wanted to tweak a bit to get the nose up a skosh more so instead of messing with the side profiles, I tried to widen the bow more, which would in turn tip up the nose in response. To do this I made the seat pretty much the same width on the leading and trailing edges (vs tapering narrower towards the front).

http://farm5.static.flickr.com/4075/4806464184_4ca91b53d5_z_d.jpg

I ended up with 4.31 above. As you can see, the shape of the top edge of the boat now doesn't match the floor shape. It did make the bow kick up, but it's disfigured and ugly. I tried a halfway setup between the nicely shaped 4.3 and 4.31 (4.32) and it is better, but still not "right".

http://farm5.static.flickr.com/4078/4806462582_f49f05b2ca_z_d.jpg

You can see above the evolution. Maybe you can see what I meant by the shape from above of 4.3 being "right".

So, back to the drawing board. What I decided on next was to go back to the proper seat taper idea, but widen the top of the stern a bit while keeping the bow the same. This should relieve some "warp" out back, while increasing it up front. I'd hoped this would cause the front tip up that I was looking for while allowing me to keep the matching floor/rim shapes. I also increased the freeboard an inch "just to be on the safe side".

Here's what it is now:

http://farm5.static.flickr.com/4101/4805847501_5611144df8_z_d.jpg
http://farm5.static.flickr.com/4102/4805842695_610f42817f_z_d.jpg
http://farm5.static.flickr.com/4121/4805845881_7b064a9b68_z_d.jpg
http://farm5.static.flickr.com/4082/4806471922_c73c75a225_z_d.jpg

Well that's a bit more like it. The rim/floor shapes are back in harmony, the nose is tipped up higher, but the rear is too. I'd like the bottom from the stern to the point where the radius changes at the 1/3 beam mark to be more flat. Also, the extra freeboard has killed a bit of the sporty look (low sides, less wind reisistance, etc.)

Next? I'll add some radius (flatten out the curve) to the back 2/3 of the sides while at the same time compensating by reducing the angle at the stern end which will whittle down the freeboard at the midway of the boat which will take out some rear rocker. I'll try it first without touching the front radius, but if I need to I may shorten the bow plate and move the curve up along with it.

BTW, don't ask me why I jumped from 4.32 to 4.5. I don't have a good answer... :)

So let's review:

http://farm5.static.flickr.com/4123/4769982083_172ef7def3_z_d.jpg
http://farm5.static.flickr.com/4138/4783949713_b521e35d60_z_d.jpg
http://farm5.static.flickr.com/4095/4783952063_1369a3252a_z_d.jpg
http://farm5.static.flickr.com/4141/4784599592_08249b0e13_z_d.jpg
http://farm5.static.flickr.com/4082/4806471922_c73c75a225_z_d.jpg


More on the flip...

_SHig

[SHigSpeed]

Okay, so now I'm starting to get into the construction planning. I plotted out the areas of the bow, stern, floor, and the three sides of the seat. Pretty much all the built up stuff not including reinforcements and whatnot.

I've been crunching the numbers on weights of things like plywood, aluminum, and structural core foam and have built a program to calculate the weight based on these dims and thicknesses.

For example, if I built the entire thing of just 0.060" aluminum, the it'd weigh 48.3 pounds before any gunwale reinforcements, gussets, oarlocks, or anchor pulleys.

All 1/4" ply before any fiberglassing is 32.2 lbs. If I do a 1/4" ply floor and 1/8" ply sides? 25.3 lbs before glass. Again, no gunwales, gussets, etc.

Now next is where it gets interesting... Since I want to do carbon/kevlar/glass, I can save a lot of weight by using a structural foam core in place of the aluminum or plywood. This stuff varies in weight but a standard material is about 5 lbs per cubic foot. Crunch the numbers on the whole boat in 1/4" 5lb foam and... 5.98 lbs! Of course this is before the epoxy and reinforcement.

So, the whole boat is about 74.3 ft^2, but two sides = 148.6 ft^2. A particular carbon cloth is 0.0403 lb/ft^2. If you say 4 layers (lays up to about a mm or 0.040" or so depending on vacuum bagging or not), that'd be just under 600 ft^2 of fabric, or 24 lbs. Epoxy weighs about 8 lbs a gallon, and a rule of thumb is 1:1 by weight of epoxy to fiber so I'll need 3 gallons of epoxy.

So were talking about 54 lbs!? Not too light. Looks like I'll have to sharpen the pencil. I can probably get away with fewer layers on the seat, and maybe fewer layers on the inside of the boat, and fewer on the sides as well. Kevlar weighs less per thickness than carbon, is tougher, but not as rigid. I'll use at least one layer of that on the bottom, and maybe one layer on the inside of the floor (in place of or on top of the carbon?). Realistically? Maybe reduce the weight of the string and glue by 33%? That'd make it come in at 31 lbs of string and glue, 6 lbs of foam, and a few pounds of hardware. Under 40 lbs, and right around what I wanted. Now i need to decide if this is realistic or not...

Anyone have any real world experience with this? Surfboard building? Other crazy engineer types?

_SHig

[michaeln]

Heh... your thread is already longer than that BC guy's whole pram build thread. :D

[SHigSpeed]

Heh... your thread is already longer than that BC guy's whole pram build thread. :D

Gotta have someplace to think out loud while I re-invent the wheel! :)

Now I need to dig up the contact info of one of my engineering school buddies who actually worked in the biz to get a sanity check.

_SHig

[SHigSpeed]

Houston, we have some problems...

<lol> Just breaking the gravitational pull of Earth and the probe is already hurtling off course!

Maybe not so bad... Found a bug in my calcs, in a good way. I doubled the area of one side panel, then doubled it again. Turns out total area is more like 57 square feet. Or 6.396 square yards. Doubled for inner and outer skins it's 12.792 square yards.

Now looking online for some prices for cloth, I've found that 50" wide 9 oz (per square yard) fabric is around $30 per yard (50" wide by 36" length cut). This 9 oz fabric generally lays out to 0.014" per layer, so my 0.040" first run test would require 3 layers. Total of 38.376 yards of 36" wide material, but since the material is 50" wide, then I'll need at BEST 27.6 yards which works out to be about $830! Now I won't be able to use 100% of all the fabric so I'll need to order more than just 27.6 yards.

So 38.376 yards at 9 oz. a yard is 21.6 lbs, double that for epoxy and now the boat weighs 43.2 lbs pre-Jenny Craig. Not bad.

Still, a bit more than I was expecting. I'm finding other sources that may be able to sell the cloth for a touch less, and again, I'll further optimize the layup thicknesses depending on stress concentrations etc.

If I can go 2 layers for 0.028" each side, that'd be awesome - 28.5 lbs. Add 6 lbs for core, another 5 for hardware, I'm in under 40.

Still, an all 18 gauge aluminum boat will weigh less than 35 lbs without bracing. My 8" pontoon weighs 48#. Maybe I should just build a 60# aluminum boat and be done with it??

Hmm...

_SHig

[pgw]

Gotta have someplace to think out loud while I re-invent the wheel! :)

Now I need to dig up the contact info of one of my engineering school buddies who actually worked in the biz to get a sanity check.

_SHig

This pesky R&D stuff is what causes the price of $75 worth of materials to turn into a $700 fly rod...design changes, material variables, trial & error...fun stuff.

The lightweight "core" material instead of plywood is interesting...this is going to be an interesting project to see progress.

Paul

[michaeln]

It's becoming pretty clear why quality commercially-made prams like Koflers and Spring Creeks command the prices they do.

[SHigSpeed]

This pesky R&D stuff is what causes the price of $75 worth of materials to turn into a $700 fly rod...design changes, material variables, trial & error...fun stuff.

The lightweight "core" material instead of plywood is interesting...this is going to be an interesting project to see progress.

Paul

Heh... Except with this boat we're talking POUNDS of carbon fiber costing $900 versus an ounce or two of carbon selling for $700. ;)

The core is standard racecar/satellite/military/aircraft tech. In all composite parts it's the skin that's takes the stress so anything between the skins is there just to keep the layers separated. In engineering parlance, it's to increase the part's "moment of inertia".

_SHig

[SHigSpeed]

Update for today:

Went back to the drawing board a bit and took some rocker out of the back half.

Before (Rev 4.5)

http://farm5.static.flickr.com/4082/4806471922_c73c75a225_z_d.jpg

After (Rev 4.6)

http://farm5.static.flickr.com/4137/4811274744_856255fbd0_z_d.jpg
http://farm5.static.flickr.com/4139/4811275796_cb7f2c7c51_z_d.jpg
http://farm5.static.flickr.com/4078/4810653657_5a7150d1b8_z_d.jpg
http://farm5.static.flickr.com/4114/4810653923_afe34956cf_z_d.jpg

So the change in the side profile at the rear did the job. More flat in the second 2/3 of the boat, plenty of kick-up up front. Seat width contour is still "right" to keep the plan view rim to floor in harmony.

Thing is, I'm not yet convinced it was a step in the right direction. The proportions are now a bit nose-heavy. It looks like a rock steady standing platform behind the seat, but the front looks like a Viking landing craft! :)

Also, thinking more about the materials and cost, though not really coming close to a decision yet. Considering a Kevlar/glass bottom for ruggedness, and with the right core it should still be plenty rigid for ease of standing and keeping the boat's shape. Then for the sides I can use thin carbon for rigidity where impact resistance isn't as important. I've also been mulling a hybrid glass/Kevlar bottom mated to aluminum sides for simplicity of build. Weight, OTOH, will take a hit.

Oh well, fun's fun.

_SHig

[Bill Kiene semi-retired]

I see lots of folks in Australia building their own aluminum boats.

[SHigSpeed]

I see lots of folks in Australia building their own aluminum boats.

Have any links Bill?

_SHig

[SHigSpeed]

Revision for today:

Rev 4.7 - Tried to keep the flatter rear rocker, reduce the height of and balance the front.

http://farm5.static.flickr.com/4094/4813990999_fb15c81510_z_d.jpg
http://farm5.static.flickr.com/4138/4813993273_c8bfa62339_z_d.jpg
http://farm5.static.flickr.com/4136/4814613154_8936291e6b_z_d.jpg
http://farm5.static.flickr.com/4123/4813991755_1d8cd2dea9_z_d.jpg

Hmmm... Well, the changes did what I wanted them to do.

Maybe I'll extend the stern wall down an inch more and even out the remaining slope towards the back a bit without losing the bottom profile...

BTW, after doing more research on Kevlar, I think I'm done with using it. Too much of a PITA to fabricate, and it's not the silver bullet for a wear material. Repair is tough because it fuzzies up and doesn't sand well. I think I'll stick to old fashioned glass for much of the bottom panel now to save a bit of cash and gain some ruggedness over carbon.

More to come, of course...

_SHig

[SHigSpeed]

Today's update:

Feeling REALLY good about this one.

http://farm5.static.flickr.com/4134/4820350838_f425345359_z_d.jpg
http://farm5.static.flickr.com/4123/4820353354_a047606b38_z_d.jpg
http://farm5.static.flickr.com/4118/4820352108_b82fc28065_z_d.jpg

Was:

http://farm5.static.flickr.com/4094/4813990999_fb15c81510_z_d.jpg

As you can see, a very minor change. Extended the stern panel down another inch and basically flattened out the rear a tad more giving the back half an even flatter profile. Also give more freeboard and slight side kickup from the seat rearward.

Don't see much else at the moment to tweak. Will make a few more models of this version to see if anything jumps out.

_SHig

[SHigSpeed]

More playing...

Found a sweet freeware program to help in the design process. It's called Carlson's Hull Design. Google it.

I took scaled dims on my most recent kirigami model and plugged the numbers into hulldesign and was able to use it to figure out what kind of freeboard and displacement to expect at differing loads.

Below is at "just me" case, and then "me and a ton of stuff" case:

http://farm5.static.flickr.com/4117/4825373599_501a9f2f25_b_d.jpg

And for fun rendered in 3D:

http://farm5.static.flickr.com/4134/4825982612_808a18ee34_z_d.jpg

There are a few other really cool hull design packages out there, one in particular that's really well thought out and sophisticated, though it's a HUGE step up in learning curve over the pretty simple Carlson's.

Looks like I have plenty of buoyancy, I just wish I could plug in load position and get the resultant pitch and heel.

_SHig

[wjorg]

I think we need a new website just for Shigs pram building thread...

[michaeln]

I think we need a new website just for Shigs pram building thread...

http://www.analysisparalysis.org/shigpram.htm

[SHigSpeed]

http://www.analysisparalysis.org/shigpram.htm

Bwahahahaha! For sure... But the fun is in the process. I'll might never get the damn thing wet if I do end up finishing the project...

_SHig

[Blueracer]

Is that 200 pounds with the minimal gear you would have?

[SHigSpeed]

Is that 200 pounds with the minimal gear you would have?

Me sopping wet and 3 rods and lunch plus oars is probably 190.

_SHig

[fishngy]

Found this fine example in Monterey Bay this past week. It looks simple and not over analized. I bet if flies with the 5hp outboard! I also think no Cad program was used! Later, Bill


http://i259.photobucket.com/albums/hh319/fishngy/IMG_0443.jpg

[michaeln]

You sure that isn't a motorized catbox?

[SHigSpeed]

Found this fine example in Monterey Bay this past week. It looks simple and not over analized. I bet if flies with the 5hp outboard! I also think no Cad program was used! Later, Bill


http://i259.photobucket.com/albums/hh319/fishngy/IMG_0443.jpg

Awesome!! But I'll bet that weighs more than 50 lbs and I'd NEVER embarrass my car by putting that on top.

Love to see that milk carton on the open ocean.

_SHig

[SHigSpeed]

Kind of a big jump in design philosophy this time. I've been noticing that the revs I've been working on have had some "tortured" side panels near the bow. Basically, the sides SHOULD for ease of build be a simple contour, but due to the geometry there was a bit or twist or warp up at the bow tip.

One thing I've been contemplating for a while was to change up the floor layout a bit. To this point, I haven't changed the shape of the floor at all. Basically it was a curved sides all the way from stem to stern. I've been noticing on other prams I've been researching that there's curve in the center to create the bowed out shape, but the runs up to the ends are more straight. I think that the continued curve up to the bow is what caused the approach angle of the sides to be such that a twist was needed to mate to the bow plate. In order to have done away with the torture on my last model I would've had to have either tapered the bow plate narrower at the top than at the waterline edge (which would look odd) or stand the plate up more and reduce the angle at the fronts of the sides (which would kill a bit of the sporty profile and the anchor rope overhang).

SO, I modeled the fronts and back side edges of the floor as straight lines connected by one single arc between the two.

Result? No torture, maybe a TINY amount at the stern plate, but it could be assembly tolerances that induced it in my kirigami model.

Before:

http://farm5.static.flickr.com/4134/4820350838_f425345359_z_d.jpg

Now:

http://farm5.static.flickr.com/4128/4833409686_45c2770eb7_z_d.jpg

Slightly less plan view area and therefore buoyancy, but it's probably negligible. A bit more reduction in front buoyancy vs. rear so I'd be less tempted to jump in the bow on a lark, but it may row easier as a result? It'll certainly be easier to build with more straight lines! :)

More photos:

http://farm5.static.flickr.com/4154/4832808767_b272b1a758_z_d.jpg
http://farm5.static.flickr.com/4103/4832808159_050f64fee8_z_d.jpg
http://farm5.static.flickr.com/4091/4832807597_db38207df8_z_d.jpg
http://farm5.static.flickr.com/4111/4832805319_bf8b3bcbea_z_d.jpg
http://farm5.static.flickr.com/4088/4833412074_036b312a76_z_d.jpg
http://farm5.static.flickr.com/4112/4833410210_52e4b390f1_z_d.jpg

I'll rework the 3D and flotation models next and gather the new areas for calculating materials. Not a huge difference, maybe a reduction of a couple percent of area is probably all.

I'll play with it in the tub and see if I find anything else to tweak (just kidding about the tub - DO NOT IMAGINE ME NAKED IN A TUB PLAYING WITH PAPER PRAMS!)

Punked!

Hahahhahahahaha...

_SHig