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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I managed to get back into mounting more frames to the strong back this week. The boat is starting to take shape and I am getting a feeling for what it is going to take to fit in the Chine Logs and the Inside Shear Rails. I’ve cut the notches for them but getting them bent and fitted into the frames is going to be a real challenge with my goal of no screws. It’s going to take a few Labats to get in the right frame of mind, eh.
Here’s a couple of pictures of the progress to date.
Frames 1 through 6 & transom are positioned.
More to come.
Dorf
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Finally got back to work this week. Too many distractions. I have the remaining frames mounted to the strong back and yesterday mounted the Stem (took a couple of tries) I had to lay it out full scale on posterbaoard to get angles & dimensions where they should be.
Today I cut the chine Logs from Cherrywood. and scarfed them together. The scarfing Jig (8:1 Ratio) is shown below and the glueing Jig also. Will be starting the fitting of the Logs to the framing this next week.
More to come,
Dorf.
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Well I just took one step forward and two back.
I spent three days making the chine logs and fitting the first one Tuesday to the Transom and the nine frames. With only the fit-up to the Stem to go, I was going to put it off till Wednesday morning. Thinking I was doing myself a favor I took a piece of rope and made a couple of wraps on the end just beyond the point of contact to the Stem and tied it off to the strong back to establish a nice curve. Was looking good until about five minutes later I heard a loud crack. Sounded like a 44 mag going off next to my head. The Cherrywood Log split between Frame 1 and 2. Wasn't a happy moment!
Here's the result.
So back to the planer.
I scrapped the cherrywood and made a new set of Chine Logs today from Ash. Going to find another use for the Cherrywood that's not structural. It is some fine looking wood but I don't trust it in a stressed application.
Managed to get one piece scarfed together. So we'll be back at fitting it up in the morning. Was hoping to get the two logs fastened to the frames before the weekend, oh well, "Ce la Vie".
More to come,
Dorf.
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Managed to dry fit the new Ash chine log on the Port side of the boat today. It's starting to look like a boat! It had a single coat of epoxy prior to fitting it. I plan on removing it and adding a second coat prior to re-mounting and epoxying it permanently. I have the second one fitted from the transom to No. 2 Frame with only No. 1 to go and the Stem. I Didn't get a chance to take any pictures. Will post them after the second one is complete.
Dorf.
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Permalink Reply by Rick Newman on
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Dorf, how are you holding the chine logs in place without screws? I am intrigued by your build and the no screw philosophy. After installing only one of my chine logs in my Tatman boat I view your strong back with envy. Steve Steele, the gentleman who had the beautiful but unfinished boats still uses his father's "jig" as one of his friends called it. I am assuming that it is a combination of a strongback with some additional support members used to hold the frames in place, making it easier to install chine logs and such. If a person chose to build the same boat repeatedly I can see a distinct advantage. I have been busy doing woodwork, electrical and plumbing but not a lick of work on my boat. Got to take advantage of the availability of work when I can get it. Keep up the good work.
Rick Newman
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Rick,
I am sorry to admit I had to use screws to hold the logs to the frames. Try as I might, I couldn't get the logs to stay where it should go. Had problems too with the Cherry wood Log. After I passed the mid point (frame 5) the log just wouldn't hold in position no matter what I tried. I made custom blocks for each frame to allow the clamps to pull in the correct angle to seat the log in the frame. So out of frustration I went out and purchased No. 8 x 1 1/2 SS Screws. Even with the screws and clamps either side of the screw I had one heck of a time getting them pulled tight.
I had added material to the Cherry wood logs to cover-up the problems with a couple of frames pre-cut notches. Rookie mistake I guess. The planned Logs were a parallelogram, .75"x 1.00" @ 25 degree angle. The heavier log (.875 x 1.125") required a lot more effort to seat them and the additional framing supports are holding them in position well. After the second log is in completely in place we’ll see how true to form the framing ends up. It broke where the grain was somewhat distressed between frame No. 2 and 1. Had to scarf a new end on it yesterday.
I am thinking maybe of epoxying the logs in place with West System’s Six-10 thickened epoxy and after 24-48 hrs seeing if I can pull the screws. Not sure how that might work? Maybe I can re-drill the screw holes and glue in a dowel to replace the screw.
Been asking myself, why not just leave the screws in and plug them. Took a few Molson Canadians and some Jim Beam to contemplate this issue over the last couple of weeks. Could use some discussion on this one. Like you, Rick there are other home projects taking up my time and leaving only scraps of time to work on the boat.
Duh!
Dorf
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Dorf, how about some trunnels or wedged trunnels? Then you could remove the screws which would be replaced with trunnels and some hard black locust wedges. No screws, just good OLD wood joinery, no wood sickness either from metal. Worth a try.
Rick Newman
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Rick,
The screws I have used are No. 8 x 1 1/2" lg. If I make Trunnels (dowels) to replace the screws they'd be only about 7/32" dia. Might be a little tough making them fit. The frames are only 3/4" wide and I am not too sure how centered they are in the frames, but I think I'll give it a try. I like the idea! We cut down a Black Locust tree at the Children;s Zoo where I work part time, lots of free wood, eh.
Thanks,
phil w.
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Phil, sorry I didn't see your post until now. How big would they have to be in order to hold the chine logs in place? In some senses a screw is essentially a wedge. It just follows a circular path rather than being driven in.
Why does it have to be a screw? Have you considers silicon bronze ring shank nails. Much smaller hole and still lots of holding power.
It would be an unusual thing to find when someone opened up your driftboat in fifty years. It follows with your concept of no screws. Since your chine logs have both broken maybe there is a Japanese wood joinery technique that might help too.
Good luck!
Rick
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Permalink Reply by Lawrence E. Long on
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Dorf: Been converting a utility trailer to a boat trailer so am a little late to the game here.Grain runout- no matter the species will get you every time on a piece under bending stress. The grain runout in your photo predicted the failure. Better to have it happen in the shop than on the middle fork of the Salmon. If you don't have any luck with the second log " fitting " you might consider using band clamps- the 1'x10' cheapie jobs. I don't think the log really has to be a hardwood have you considered cutting some new ones from spruce/fir. They might bend a lot better and getting a long piece could eliminate scarfs. The real strength of the hull comes from the PW attached to the frames. I would look at fitting new logs(with good runout) before epoxying/ screwing the log to the frame.
Randy,AJ,Hanson will have better advice about chine logs. Good Luck
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Lawrence, Thanks for the reply. I made a second pair of logs from Ash and the first is still there in place holding good with the screws. About the only thing I didn't use to hold it in place was the band clamps. I have several of them and didn't think of them, duh! I used them frequently when building my stripper to hold the strips tight to the frame mold. It worked well too.
If I paid better attention to the grain in the first place I wouldn’t have had as many problems. I blame it on my inexperience with dealing with wood quality. The Cherry wood I had isn't as clear as it needed to be for this application. The scarf joints are holding fine. I have an accurate jig and clamping fixtures to hold them in place to minimize variation.
I've been applying Titebond II to the bonding surfaces and letting it soak into the cut ends for a few minutes. I then apply a second light coating to one of the surfaces just prior to clamping them together. So far I have not had a glued joint failure.
The Outwales at the Bow and Stern on the stripper were stressed almost as much as the logs on this boat. If this doesn’t work I'll go after some Doug Fir or Spruce. I have a good source of lumber here in Michigan, L.L. Johnson Lumber Mfg. Co. (http://www.theworkbench.com/) but it's not cheap, but what isn’t.
I appreciate your comments, thanks.
Phil w.
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