Pram Design Help Wanted/Needed!

Hi All!

I'm wanting to build a ~10pram for hunting with my dog 'round lake/marsh margins and for  crossing the river and mellow water anchoring and fishing.  I weigh 220#; dog=100#; gear 50-100#.  So, I'm looking for something to safely float ~400-450#.

I'm thinking that I need a compromise.. neither a river runner, 'nor a long distance racer.  I just want to paddle/row ~100-200yrds to get where I and others can't go with waders.

This is modeled so that the wide transom is headed downstream, when drifting; or when rowing somewhere, the narrow transom it headed in the direction of travel.

I first modeled a Hudson Springs Pram:  http://www.duckworksbbs.com/plans/messer/hudson_springs/index.htm

I modified it by raking back both transoms, for river use.  I then widened the sides and freehand cut a bottom out and created the sides and transoms to fit.

I don't know how to use the FreeShip software.  I might figure out Hull.  But I need some sound advice on how to modify what I have.  I've attached pics.

1"=1'   So the bottom=8", or 8' long;  Bottom is 45" wide;  Narrow transom is 27" at bottom;  Wide transom is 40" at bottom;  Beam is~ 66";  Transom top to top is 9'10.5"; Sides are ~18-19" actual height/width and just shy of 10' long.

There's some rocker in this, but not much.  I'm thinking I could easily narrow the narrow transom some and a touch on the wide transom.  I'm thinking that this is way overbuilt for the weight I've given above.

Could I go narrower than 45" overall?  I've seen prams from 38.5" to 48" wide.  Could I go a little shorter on the side height?   I'm really open to all ideas!

Many thanks!   Ken

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Permalink Reply by Ken Shindledecker on November 4, 2013 at 11:02am

This is a lot like what I'm looking for,, but maybe more substantial than I want:  

http://fishingwithjay.wordpress.com/2010/07/03/jay-nicholas-koffler...

Permalink Reply by John Weston on November 4, 2013 at 3:01pm

that's a aluminum pram. very nice boat. I am not sure where Brads pram came from. I do know he widen it 6" full width. I drew up the boat but I did change some of dimentions on to suit my preference.

I am a fan of Dave Z's boats and like his drifter a lot. can't wait to see what he has done to the new design of it. should be a lot better. I like his pickup pram and have redone some of the mesurements of it to better it for what I need. when I start to build it it will be done in nylon and WRC frame. I build kayaks in SoF so want to do that to this pram. it will also be powered by a stern paddle wheel and oars when needed. should be very light. anyways, that is all I can tell you about the prams I mention. I would either follow thru with the model you did and make it what you want or look hard at Brads pram. look forward to what you decide.

JW

Permalink Reply by Ken Shindledecker on November 4, 2013 at 3:10pm

I narrowed the top of the wide transom a bit and it took out some of the rocker on that end.  I could have also widened the bottom of it a bit.  But it has a nice little rise on that end, which would help reduce the chance of hitting a rock with the leading edge.  I think I'll do a little to the narrow transom, as well.

Koffler originally made a narrow transomed pram, but enough people asked for it to be wider, that he offers both:  http://www.kofflerboats.com/white-water-prams/

Permalink Reply by John Weston on November 4, 2013 at 4:33pm

Ken, he makes nice boats. if I had the money I would go down and have one custom made but since I am just a poor old dude on SS, I got to make my own, which is ok with me. so on that note, GET TO BUILDIN. lets see what ya come up with.

JW

Permalink Reply by Ken Shindledecker on November 4, 2013 at 4:37pm

Koffler is probably the preferred boat here, in driftboat country.  I like the sound of wood on water.... But, they do take a lot of extra care!    Oh,, don't know if I'll get the garage straightened up this winter... plus, it's pretty cold out there.  If I do epoxy, I'll need diff. weather.  Still lots of planning and scheming to do.  This'll be my first build.

Permalink Reply by tungsten on November 4, 2013 at 4:44pm

Very nice!!  What's the max angle/flare on the sides?---somewhere around 30 in the middle then steeper as it goes for an aft.

Is this mainly for river running?------yes but also for small lakes.teh sheer is fairly flat so it fits on my roof rack without hitting the cab.

Does this have a lot of rocker?-----3" in the bow and 8" in the stern.

Is that a 48" bottom?------ yes,with about 30" of that being flat,the first build was so tippy that I wanted a stable place to stand.Works well and still turns very easy.

What is the actual width of the side panels?----The height is what you mean yes? 20"I have 17" of sheer.

One layer of glass, or two?----one.

Is that weight, including the internal structures you have there, or basic hull------ just the plywood,=1/4 ply= 1lb/sq/ft with one on ea side  6 oz woven with weave filled,  you have to add fillet,seam tape ,paint ,gunnels and epoxy for tape.100 grams of 6" 12 oz 45/45 tape needs 125 grams of goo to wet it out.

Permalink Reply by Ken Shindledecker on November 4, 2013 at 4:49pm

Thanks!  Where did you put the flat spot?... Did you have to dish the side panels to do that?

Permalink Reply by tungsten on November 4, 2013 at 6:04pm

You can see the flat spot in the pic,look at the fillet,it starts by the front seat pole and ends about the middle of the bench.

No I didn't dish the sides.

 

I did a mock up first with 1/8 hard board to see if I liked it first.You can see the flat spot a little better here.

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Permalink Reply by Ken Shindledecker on November 4, 2013 at 8:31pm

That's a neat idea!!  Did you use little blocks of wood to screw the board to?

And, does it row well on flat water?

Permalink Reply by tungsten on November 5, 2013 at 5:41am

Yes little blocks to hold sides to floor,the mock up helped design the end transoms.I first did sides and bottom then played with spreaders to adjust rocker.Once I was happy I had templates to use.

 

And yes rows and tracks quite well.I have a 50lb bow mount elec. motor that pulles me around.

 

 

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Permalink Reply by Ken Shindledecker on November 5, 2013 at 9:52am

This looks like a serious fishing boat!!  Do you think my I could go smaller, for just dragging to the marsh edge and for gentle drift/anchor for summer steelhead, I could go smaller and lighter?...  Some guys do a single-man 8'er,, but that's too small.  I really like what you've made!!  A few people out there trying to convince me that a pram is a crazy idea,, so it's nice to share things like your pics!  Did you center the flat spot under your center of mass?   Thanks again!...  Ken

Permalink Reply by tungsten on November 5, 2013 at 11:03am

I took most of my design by just looking at other drift boats,i just removed a bit from the front and back to get the length I wanted.

Small narrow boats are OK once your in,its the getting in and out that's tricky.

Make yourself a model that will float,then use Guys formula to scale down you and your dogs weight.Guys a great fella just ask him for the calculations.

 

Heres my boat with 500lbs in it,i used 1/6 scale.

 

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