Hello all.  I wanted to introduce myself and start things right off with getting some opinions.

I have built furniture and done framing in the past, but this will be my first boat build.  I chose the 17' (Finishes under 17', most likely around 16'6") Chinook from Spira Intl.  Being my first boat build I have done as much research as I could with what is available online.  When I found this site I was blown away!  There is more info here than about 90% of what's online.  With that said it got me asking questions about the bill of materials on the Chinook.  I talked to Jeff at Spira and he cleared up some fastener issues, but after looking at so many of your projects I have come to the conclusion that although the Chinook is well engineered it may be "over" engineered.  I have questions and would love to entertain comments on my thoughts about lightening up some of the materials.  The plans call for for 5/4 x 4 for frames, and 1/2 ply for all panels.  I would like to go as light as possible on all materials, but I would like to hear from you experts first.

I float mostly western Oregon rivers... The McKenzie, Siuslaw, Alsea, Lake creek, etc... And none of (for the most part) the stretches I would be floating have anything that could be considered a "rapid" with any classification.

I look forward to your opinions and much discussion!

Thanks so much,

Jordan

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Jordan:
Welcome- you will get many inputs and comments from the forum. If you have built furniture, framed you will have no problems. Furniture makers work to the nearest 1/64" inch, framers to the nearest 1/8" and boatbuilders to the nearest boat. My DB was 16'6" on centerline(17'+ around the gunwales)- stitch and glue with short glued in ribs. The plans called for 3/8" sides and 1/2" bottom(with the option of a 1/4" added) All of marine grade Douglas Fir. You can't find any good DF plywood around here anymore. If you are not going to run really big rapids - like the Grand Canyon,Green, etc I think 3/8" and 1/2" would be fine. The 5/4x4 ribs seem to be a little beefy to me but I have never built a truly framed boat- except for a little skiff. AJ,Randy and others will give you better advice.
Good Luck
Welcome to the forum... I spent months searching the internet for drift boat plans, then some how lucked up on this fine website. I wanted a traditional framed drift boat... as many of the members here have built. I first bought the Sp. plans as you did, then found another set of plans that were exactly what I was looking for. I'll send you a message...
Jordan, While I am not one of the experts here, I am a former furniture builder who just last spring finished my first build with no big problems; the only major differences being many more miters and the need to work with glass/kevlar and epoxy (neither of which is a big deal).
I built from Roger Fletcher's book (the 16' DE with transom). I used 1/4" sides and 5/8" bottom. Being from the East, I don't float many huge rapids - But, I really like the more hefty bottom, as you can still take some pretty hard hits from time to time even in class 2-type water. I think anything less than 1/2 on the bottom would be skimpy (though the addition of a sacrificial skid plate may be a possibility). You can also save some weight based on how much you glass and epoxy - I only did the outside and oiled the interior - though the number of layers of glass and epoxy also matters. Second, I know the furnishings can add quite a bit as well. I have pretty heavy duty seats, sliding seat rails, and a substantial floor board system. While these are all removable, I could have probably cut down and saved some weight.
One last thought, in addition to the water you intend to float, it probably also matters how you intend to load the boat, lots of people, gear, maybe a motor on the transom (I have a 3/4" transom for a small kicker), etc.. These loads will also play a role in the flexing of the frame - the plywood, like in a house, probably does a good bit to stiffen the frame - thus thinner wood = more flexing. While all boats flex to some degree, I would believe that too much may be a bad thing in the long run. Keep us all posted on the build. J.G.
Hey Jordan,
Welcome!
Most of us use 1/4" for the sides and 1/2" for the bottom. As for the frames I use 1x4 cvg fir (actually 3/4"x3-1/2"). you can also use 1x6 and get both side frames from one piece but 1x4 is usually cheaper than half the cost of 1x6.
My personal boat actually has 3/8 acx for the bottom with glass. You could also plane the 3/4" down to 5/8" to save a little weight.
Mike
Welcome - Good choice of plans - everyone I have talked with who has built one of his boats were very happy with the results. I have built one of Spira's boats and went with a/c exterior plywood from the local lumberyard. 3/8 on the sides and 1/2 on the bottom. I used 1 x 4 spruce for my ribs and 1x 6 for the keelson. In hind site I wish I would have went with 1/4 on the sides so as to lighten up a bit. Not running any big rapids so the chines and bottom mostly take all the hits. I have pictures of my build at http://picasaweb.google.com/southedisto/DriftBoatBuild?feat=directlink
but with you being a furniture builder you will likely be a lot more detailed oriented than myself.

Make sure to post your progress.
Bryan

Your boat turned out well! I like the plans from Spira. I have confidence that by melding design characteristics I will be able to lighten the boats materials yet keep structural integrity. Now, to actually put words to practice. I will keep everyone posted with pictures!
If you will be floating rivers in the North West there is a chance that the more trips you make the more you will be willing to go on more difficult runs. Light is not everything. I would recommend staying with solid materials over going light if there is any chance at all that you might one day make a run on something class IV. Even class III runs can cause damage.

I have built with 3/8 plywood on the bottom. With kevlar it can be ok but kevlar is expensive. I think 1/2 inch on the bottom will give you a more durable boat in the long run. As others have said, 1/4 inch is standard on the sides. Even 3/8 will be difficult to bend around on the sides.


As for 5/4 frame stock that does seem kind of heavy. I don't build farmed boats so I am sure others will have a recommendation on the thickness of the frame stock.

No matter what you decide your wooden boat will be far lighter than any commercial molded fiberglass boat and it will last a life time.

If you really want light, then composites are an option but then it's not wood and wood boats are the best looking crafts on the river.

Take you time and enjoy the process. While I always look forward getting a new boat on the water, when they are done I always want to start building another. I think building is even more fun the rowing.

L
L

I agree totally with the possibility that I may run heavier waters at some point. I agree also that the bottom should be and will be 1/2 or greater (dependent on coating, shoe, etc...). I really appreciate all the tips! You hit the nail on the head with calling out the 5/4 stock for frames. I have already gone with 1x4 CVG fir for the frames and 1x3 for ribs.

Thanks again

Jordan

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