Hello Everyone,

 

My name is Guy and this is my first post in this forum.  I am here because I want to build a wooden drift boat and, undoubtedly, I will occasionally need advice of the pool of experts and experienced drift boat builders on this forum.

 

In preparation for this project I have read and studied three books: Drift Boats and River Dories by R. L. Fletcher, Boatbuilding with Plywood by G. L. Witt, and Covering Wooden Boats with Fiberglass by A. H. Vaitses.  I have also developed my own set of construction plans based off of the "Original McKenzie Double-Ender with Transom" in Fletcher's book.  I used and MS Excel spreadsheet to calculate all of the dimensions, cut angles, compound angles, and bevel angles of all frame components and I used Pilot3D software to calculate the as-cut dimensions of the plywood sides and bottom.  At this point I am pretty comfortable with the mechanics of construction and I think that I am just about ready to start purchasing lumber.

 

Presently, I plan to use Meranti Hydro-Tek plywood; 1/4-in. on the sides and 1/2-in. on the bottom.  I found plenty of places to purchase these materials, but they are all far away from Idaho Falls, Idaho, and as a result shipping costs more than the materials.  Are any of you aware of a business within a few hundred miles of Idaho Falls that sells this plywood?  I have a few requests in to the local lumber companies, but I have yet to talk with someone who has heard of this material before.

 

I also plan to use Port Orford Cedar (CVG) for the straight frame sections and White Oak (quater sawn) for the bent frame sections (chine logs and sheer rails).

 

Thank you, Guy

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It sounds like you are ready to roll Guy.  Best of luck and post often.

Give World Panel a call.  If you can find a few more people in your area that also need some plywood then you might be able to get a deal on shipping.

Thank you Randy.

I have a feeling that I'm going this one alone.

At least until it's time to go fishing.  ; )

You have already put in much more advance prep time than I did, which will pay off, I'm sure. I used a Hankinson design from Glen-L. Like many plans I hear, they don't provide many of the key angles and dimensions, but rather you size up as you go. The hardest part for me, undoubtedly, was getting the chines and sheers to be absolutely co-planar for applying the sides and bottom. I had a roughly 30 deg bevel to account for the slope of the sides, but when you bend the rail onto the form, it is a compound bend which introduces some twist to the piece. If you get a great plane between chine and sheer, the rest is easy. Part of the problem may have been with the transom and bow angles, for which I didn't have good dimensions. by the way, when they say "get a tractor-style rowers seat" from Hyde or somebody, do yourself a favor and get an actual short back tractor seat. cheaper and more comfortable.

Short story - built boat, looks good, have taken it out 3 times and hooked some big steelhead and a bunch of trout. And Everybody on the river including some of the guides I know goes nuts over the thing. Keep me posted.

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Thank you Dave.  That is a great point about the "compound bend" of the sheer rails, chine logs, and chine caps.  (I think) The layout of the as-cut dimensions of the side panels should give you an idea of the severity of this problem.  For example, if the as-cut edges of the gunwale-edge and chine-edge of the side panels are relatively straight, then the effects of the compound bends should be mimimized.  On the other hand, if there is significant curvature to the cuts of the gunwale-edges and/or chine-edges, then you might see more of a problem with keeping the surfaces of the bent lumber flush with the side panels.  I will study my plans carefully for this effect.

 

That is a great looking boat.  You should be proud of that!

Welcome Guy.  Can I make a little recommendation- Use AB fir in 1/2" or 5/8 on your bottom, versus the Hydrotek.  I feel it is a bit tougher wood for a boat bottom.  Also, use flat sawn oak for those curved sections.

Thank you Dave.  That is an excellent point about the quater sawn white oak.  That is probably a much stiffer cut and may not bend the way you would expect it to.  The straight sawn white oak should be much more pliable and bend in a more predictable way.  Good catch Dave!

 

It turns out that I can get the AB Grade Marine Douglas Fir locally.  My plan is to glass and paint the outside of the hull (dark green) and leave the interior an all wood finish.  I just might wind up using the Douglas Fir and use the A-face toward the inside.

I used vertical grain doug fir for most of the chines, sheers, (I snapped a few) and floor battens - the grain really looks good in epoxy - and mahogany for the inner sheer because a) my widebody design caused me to keep snapping sheers and that mahogany bends like nobody's business and b) I wanted the contrast when you look down the gunwhales. It looks great.  For panels, I used 3/8 on the sides and 5/8 on the bottom.  Also, the hankinson design has no ribs on the interior except for the side storage compartments amidships. clean look. easy to move around in for oafs like me.

 

 

I agree with this Dave.  That is the way we build also.

Today's discussions have really made me think about how I need to approached my boat design.

What I did was take an existing set of profile and plan dimensions of the sheer and chine and rescale them to what I wanted (slightly longer, wider, and taller).  I then added some additional frame members and made the frames equidistant to each other.  Then I calculated the as-cut dimensions of the side panels and, low and behold, the gunwale-edges and chine-edges of the side panels are not perfectly straight.  This would have given me the "compound bend" problem that Dave pointed out in his post.

What I need to do is revisit the design, but this time begin with the as-cut dimensions of the side panels (forcing them to have straight gunwale and chine edges) and let the profile and plan dimensions of the sheer and chine fall into place accordingly.  Then I can calculate the frame dimensions for the resulting proportions.

In other words, begin the design with side panels whoes as-cut dimensions have straight edges along the gunwale-edges and chine-edges.  This prevents the sheer rails, chine logs, and chine caps from developing any "compound bends" when applied and they should lay flat along the surfaces of the side panels.

Then the degrees of freedom of the design are accomodated in the dimensions of the frame elements.

Guy - we have much in common, both are in Idaho Falls and starting our first boat. I am only 1 - 2 steps ahead of you. I am building from a custom set of plans i made combined from a Don Hill 16' and plans for a Honky Dory I purchased from Sandy at Montana Riverboats. I am stretching my boat to 18' (gunnel) and building a 56" bottom for it. I am currently waiting for my bottom scarph joints to set up and then I will start wrapping my sides around my temp. frames. (I am building a stitch & glue). If you would like to get together and go over plans, feel free to send me email at flyguy688@live.com. I would be great to have someone local to bounce ideas around with.

Greg

That's awesome Greg.  I will get in contact with you.

I have been waffling on the width of the boat.  Do I stay under 48 in. or do I go with the wider bottom and have a center-length scarf?  I do want a boat that holds three comfortably; as in front, center, and back.  So I am leaning toward a center-line length of 17 ft.

I've considered stitch & glue, but I really like the look of the traditional framed drift boats.  The stich & glue construction should certainly produce a lighter boat.

I am still working on finalizing my design spreadsheet.  The basic calculation strategy is this...

1) specify the as-cut 2D dimensions of the side panels (with straight sheer and chine edges)

2) specify the maximum bottom width

3) specify the minimum transom width

4) mathematically bend a vertical side panel around a horizontal Catenary curve

5) mathematically rotate the bent side panel off vertical through centerline until stem face is vertical

6) translate resulting coordinate system into standard construction coordinate system

7) define profile and plan views of the sheer and chine

8) specify number of frame elements

9) calculate the as-cut dimensions of the frame elements.

Hopefully, I will get this part of the project wrapped up this weekend.

Guy, I am intrigued by your design spreadsheet idea. How will you develop items 4 and 5? How will you translate the coordinate systems?

Overall I just want to learn more about your process. I am guessing that perhaps you have an engineering background?

As always it is very informative to see the approaches that people take to develop their boats.

Rick Newman

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