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 13, 2013 at 3:31pm

Thanks, Rick!

So,, 6mm x 8= 48mm=4.8cm;  6x12=72mm=7.2cm

1inch = 2.54 cm, so at least a good 2"-3"

If I use the MDO that JW suggests, do I also seal that, before painting?

Permalink Reply by John Weston on November 13, 2013 at 3:47pm

Ken, yes an no. mostly just primer and paint. this stuff is waterproof. as you learned it's for sign painting. you could seal it with expoxy then prime an paint but most just prime and paint. 1/4" is hard to fine so maybe 3/8. if so then I would put 3/8 on the whole boat, if you can find a source near you. or go with a marine grade in 1/4. I haven't worked with it for a long time. I think there is a place near me where I can get it, will have to check when I get ready to build, hopefully a rapid Robert 14'.

I only build sea kayaks, I suppose you could fish out of one, I have never done it. I like something a lot more stable an roomier to fish out of. hope this all helps.

yes I would seal with epoxy on all the end grains to seal that. yes, 6" on the front. from base line up to bottom of front end. not sure if 1/2 will bend but 3/8 will.

JW

Permalink Reply by Ken Shindledecker on November 13, 2013 at 4:06pm

Thank you!!  Troy2000 from boatbuildingdesign.net built a canoe with 1/4" bottom... I know you recommended 1/4".. Do you think 3/8", for this narrow of a boat and a coat of Coat-It on the bottom would be good,, or should I stick with the 1/2"?

Here's his nice series on building a flat bottom canoe:

http://www.boatdesign.net/forums/wooden-boat-building-restoration/b...

I'll check into other sources of marine plywood and their weights.  A 4x8 sheet of meranti was only 'bout $50-some.

Now that I have all this info, I can really be thinking/planning and understand what I'm reading elsewhere.

Thank you all again!....  Ken

Oh,, if you cut the stern off that Rapid Robert and put a transom back there and widen it a bit, you'll have a nice surfing nose pointed upstream.  Koffler has gone from making narrow transomed drift prams to wider backed ones... they make both, still.

Permalink Reply by John Weston on November 13, 2013 at 5:58pm

Ken, I like 3/8 for bottoms unless I am building a fast speed boat then it's 1/2 or up to 1". just depends on how fast the boat is designed for. for what you are wanting I would go either 1/4 or 3/8. just depends on if you use floorboards or not. if so go 1/4 if not go 3/8. your not going to be running into rocks and all so go with the lightest ply you feel ok with. any ply you go with I would seal all end grains and glass the seams. as far as sealing the rest I would oil both inside and out and paint with a oil base paint.

If I build the Robert I will not change a thing on it's design. that boat will be just right for what I want to do with it here in the Puget Sound area and can run class 2 rivers. it's an all around boat. build a model of what ya want before you do anything else. that is the best way to go.

JW

Permalink Reply by Ken Shindledecker on November 16, 2013 at 8:33am

Yes, the RR IS a pretty boat and most capable.

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