Wooden Boat People
By McKenzieDriftBoat.com
Dorf's Wooden Drift Boat
I just found this Forum the past week and was pleased to see all the interesting discussions. I have previously (2006) built and launched a 16 ft. Peterborough Stripper from Tom Moore's original Canoecraft. The Bear Mountain Boats Forum was a wealth of information, as I had not built anything from wood that was expected to float, in water. The stripper was a lot of fun to build.
About a year later I discovered/purchased Roger Fletcher's book and decided to make a go of it and build a drift boat. Last April I laid out all the framing on poster board full scale. I am a retired Mfg. Engineer with 41 yrs in the Machine tool and Automotive Industry with lots of hrs. Hanging over a drafting table. After making the decision to build I spent many hours deciding materials, features etc.
I have 210 BF of White Ash from a couple of trees infected with the Emerald Ash Bore (big issue in Mid-Mich). So the framing is Ash (3/4" x 3.00"). I finished the last one in December. I just need to coat them with epoxy (been waiting for 60 degree temps). The frames are constructed using Half-lap joints. I discussed this in 2011 with Jim Watson of Gougeon Brothers and he offered their services in testing the joint strength (they have a MTS Tensile Test Machine w/ 100K Load Cell). I just received the results and test pieces a couple of weeks ago and will post them soon in this discussion. (I need to figure out how to post pictures here.)
The Stem blank is solid Ash. I just finished the transom a couple of weeks ago. It was made from African mahogany. The sides are going to be 1/4 x 7/8" WRC w/bead & cove. I have a couple of planks left over from the canoe. The sides will be encapsulated in 6 oz. glass and West System 105-207 Epoxy prior to being fastened to the frame. The bottom of the boat will be "cold molded" ash at 1/4 x 2 1/4" in two layers one oriented Fore Aft and the other 90 degrees to the first. Planning to add graphite to epoxy on the bottom.
Next work is to build a strong back and begin assembling the framing. Am looking foreword to your comments and assistance.
Thanks for being here.
phil w. (Dorf)
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Replies to This Discussion
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Permalink Reply by Phillip Westendorf on
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Well It hasn't been a productive last two weeks. Hadn't much time to devote to the boat. I got back into it today and took three steps back. I Was fitting the second Starboard Chine Log and the Port Log popped at frame station eight. I had to really tweak the Starboard one it to get it to the stem and the frames didn't hold as I hoped they would. Five minutes later the Starboard Chine Log it popped too. Cracked right at a the screw hole in the last frame and followed the grain, same as the first one did. Back to the drawing board! The scarf joint I used to add a new end held. The break was within an inch of the scarf.
Port Side:
Starboard Side:
Shows Scarf Line just above the break:
I think we'll have to be more selective of the grain for this end of the Chine Logs and consider heating or even steaming them on a fixture prior to fitting them. The Port Log had been fitted to the frames and stem for the last two weeks, I figured it had taken a set. The stress was too much, eh.
Gotta keep going!
phil w
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Permalink Reply by Rick Newman on
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Phil, what a bummer! I feel your pain. The first chine log didn't appear to have bad run out at all. In the Oregon "style" boats there is a debate between having a floating chine log which is only fastened to the plywood skin and not to any of the frames. The non-floating chine log has a 1 1/2" screw through the skin into the frames. I realize that since your plywood is attached after the chine log is installed it would be difficult to hold your chine log in place without screws into the frame members.
I wonder if a combination floating / non-floating would work? It is my understanding that the majority of the strength in a driftboat comes from the fact that the skin is a stressed member. Does there have to be a fastener at each frame? What about every other frame or every third frame? Are you planning on using screws through the skin every 2.5 to 3" into the chine log. That's the method that Greg Tatman suggests in his instruction manual. I don't remember how frequently he suggests that screws should be installed in the outer chine log.
I'm not familiar with the construction details of your boat's design. I look forward to see how they differ. Press on and keep us informed. Sorry to hear about your bad luck.
Rick Newman
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Phil, I saw this wood product a few days ago. Maybe it would work for you. http://www.flutedbeams.com/discovery/bendingslideshow.html
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Rick,
Thanks for the reply. I went to the web site you suggested, sounds interesting, but awful an expensive way to go.
I think I'll try steaming the Chine Log Ends (about 4-5 ft.) and mounting it to the stem prior to holding it to station 8 & 9 with clamps or screws. The stem end has a more severe bend, so I'll start there this time. I know now the exact length and end configuration of both logs so I am hoping the wood will "hold"coming from this direction. When I made the ash log blanks I made enough for four logs. The bends from the transom to Frame # 7 seems be holding alright with screws but I'll take your suggestion and add them only where necessary.
Another option is to steam a few 1/8" pieces and laminate them. Then attach it to the frames and let it Dry in place, epoxy it together and then scarf it to the aft piece. A lot of work, especially making a parallelegram shape, but very doable.
The frame/logs will be a solid structural member. The sides will be 1/4" x 7/8" bead and cove cedar strips. I plan on stripping each side complete with permanent attachment to the frames, after I glass both the inside and outside and then re-attach it "whole" . I am not sure yet how to best attach the Sides to the framing. The bottom will be cold molded with 1/4" thick strips. Not sure what width they'll be but I have lots of time to figure it out, eh.
Having comments, opinons and assistance for others with similar experiences sure helps keep the confidence up.
More to come,
Dorf
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Phil, so you are going to strip it. Wow, you have picked a hard way to build your boat. My hat's off to you. You do like a challenge. You're in a whole new area than I've ever experienced, however you have built your canoe strip style.
Help me out here, you have the engineering background. Doesn't the "skin" of a strip built vessel have the majority of the strength? What part will internal frame members play? In strip built canoes like yours the "frame" is only temporary.
What do you plan to do where the chine meets the bottom? Will you have a chine? You're doing a double ender so you don't need to worry about a transom if I remember correctly. Are you doing a traditional cold molded bottom consisting of two layers running at 45 degrees to the length of the hull and perpendicular to each other with a final layer running parallel to the length? Should be exceedingly strong!
I can hardly wait to see further details of your build. Once again my hat is off to you, your build will absolutely be one of a kind!
Rick Newman
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Rick,
I guess I am a glutton for punishment. As much as I enjoy fishing, and I really do, I enjoy the challenge of creating things with wood. My engineering background includes spending the better part of ten years as a special assembly machine designer. I get a kick out of designing and building simple things that work. But the truth be known, I sold my alum. river fishing boat two years ago and I have been experiencing withdrawal from not enjoying the rush of the water by the boat. The canoe is fine for trout fishing, but not for the big guys, Salmon & Steelies on the larger rivers, here in Michigan.
The canoes strength and stiffness comes from the composite hull, Inwales, Outwales and thwarts. I am trying to use the elements of the canoe to create the drift boat. There are lots of beautiful drift boats made from plywood and I guess i could do it too, but I really am enjoying the opportunity to use materials i have on hand. I guess It has challenged me more than I figured.
The sides and bottom will be made using the framing as a mold, glassed both sides and then re-attached to the framing permanently.
Watching, reading Guy’s post on this forum has been very timely and helpful. I am still considering the best way to attach the sides permanently to the framing without screws. Guy’s recent comment of considering using 5200 for his chine logs has got me thinking. I still like epoxy though, great invention!
I do have a transom; I like Woody H’s double ender with a transom for looks and the additional room. To me it’s a “more traditional” looking McKenzie. If you look at my pictures of April 13 (page 2) you can see the transom. I have made it from African Mahogany, as some of the other elements will be Mahogany also. Need to add some color!
I appreciate your questions and suggestions, they keep me thinking and I am an admitted rookie at boat building. You experience and that of others here is why I am on this forum.
Keep the cards and letters coming,
Phil w.
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Permalink Reply by Randy Dersham on
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Phillip, your chine log is significantly larger than a normal McKenzie. I think one way to solve your problem is by splitting the chine log to half as thick. Install one and then install the other. Use epoxy to glue them to each other and make a lamination. it will be super strong when finished and epoxy impregnated when complete.
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Randy,
Thanks for your idea I like it! It'll work. The chines were planned to be only 3/4" wide x 1.00" tall. Problems in making and fitting them to the frames caused them to grow. should have addressed the problem by modifing the frames that needed it and kept them as planned. Oh well, that's experience, eh.
Thanks,
phil w.
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Today I sorted through the wood pile and found a board with better looking grain and made a couple of new chine logs. I made them 1/2 the thickness as Randy suggested. It was necessary to scarf them to obtain the necessary length. That should not be a problem, it hasn't bit me yet (knock-on-wood).
The plan is to mount them tomorrow using S.S. Screws and epoxy. Assuming it goes well, I'll pull the screws in a few days and replace them with Trunnels (Rick's suggestion a few days ago). If all goes well I'd like to mount the outer half of the chine logs with epoxy without any screws. Kinda like adding Outwales with a bunch of c-clamps, etc. If this doesn't work you guys on Oregon & points West will see a big light in the Eastern Sky. It'll be the framing going up on smoke. I played with the thinner stock before scarfing them and it was significantly more flexable than the previous ones. Should work! I really like the idea of eliminating the screws too.
More to come,
phil w.
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Phil, good luck with the next few steps. I hope that the only glow that I see in the sky will be the rising sun!
Rick
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YES! I finally have two whole Chine Logs fitted in place.
Thanks again Randy for the idea. It was just what the Dr. ordered.
I cut the new logs at 7/16" thick and fit them to the framing. They are screwed with # 8 x 3/4 wood screws. Tomorrow I 'll epoxy them to the framing with thickened epoxy and pull the screws after the epoxy is set-up (4-6 hrs.). I plan to pull the screws and replace them with 1/4" dia Trunnels (dowels). If I can find a friend with a wood lathe I can use I'll make them tapered, 1/4" to 3/16" by 1.00" Lg. Don't have Black Locust for the
Trunnels, yet. I'll probably make them from the same Ash as the Chine Logs.I plugged the screw holes from the last set of logs with QuickWood Epoxy, two of which I had to insert a plug. I used a plug cutter to make 3/8" Ash plugs, drilled them out (broken screws) and glued them in with West system's G5 Epoxy. Put a plug of QuickWood behind the plugs to fill the gap created from the drill points. After a couple of hours everything was fine. The QuickWood hardens in 60 minutes and is workable. I've used it a lot in wood carvings. Nice stuff to have in the tool box. The new screw holes location and angle were moved as to not connect to the plugged holes. The Quick Wood isn't suitable for structural applications. It's basically just a filler.
After the logs are complete we'll make the Outer Logs and fit them to the Inner Log, Framing and Stem/Transom. I clamped a piece of wood in place at the transom end to get an idea of what it'll look like.
When this phase is complete it should look pretty good and no screws. Gotta love it, eh!
Keep your stick on the Ice, Go Kings!
phil w.
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Permalink Reply by Guy Fredrickson on
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Good job Phil! I'm glad to see it.
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