JEM Watercraft

OK got the problems with the stiff back sorted out. I changed the way I was trying to mount them. I found a straight 2x4x14 and cut it to fit between the Bow and Stern and then cut a hole in the forms to run them over the stiff back.





This seemed to work a whole better than the way I was trying to do it. i was trying to build an individual stand for each form and it just was not working for me. it did not take long with this method and I had all of the forms on the stiff back. At this point they are not leveled or fastened. I am going to use wood wedges to level all of the forms before screwing them to the stiff back. I also built several stands down the length of the stiff back to stop any swaying or sagging.

Darrells,
Is just my eyeballs or is station #8 or is that #9 a little out of plumb?
Bob

Yea they are. All of the stations are just sitting there now. Nothing has been leveled or fastened down.

What is nice about the way you ran the strong back through the forms is that you can flip the whole boat leaving the strong back in. That way you don't have to worry about removing the hull from the forms and worry about it deforming while not on the forms. It also makes it easier to get a more exact fit of the deck to the hull along the sheer line.

That's a good point. I'd be tempted to create a 2x16 from plywood. Make it in a box beam shape to ensure no twisting.

I like the box beam method like Matt suggested.

The first strong back I built was for a kayak I designed for myself for small waters (which was a lesson for me to leave the designing to the pros). The strong back was made out of 3 layers of 5/8 inch particle board glued and screwed together. Its very dimensionally stable. It was eleven feet long by 1 7/8” x 4”. It also weighed close to 5000 pounds. At least that is what it felt like. Positives: it was nice and straight and didn't sag. Negatives: Heavy. I still have it in case I ever decide to build another smaller boat. I don't have the heart to bust it up and trash it.




I recently built a 17 foot strong back out of 1/2 inch plywood in the form of a box beam using glue and staples to hold it together. This was for a canoe for which I have had the forms for many years, and finally decided to use them. Its for an 18 1/2 footer that will be used for my family of 5. After starting the stripping last summer and being nowhere near done, I wish I would have bought the Sasquatch 18-5 . It has very similar lines. But, I had already invested in the materials several years ago and had all the forms, so I figured I may as well use them. I'm one of those people who has to finish something once they start it. Especially if there was a financial investment in it. Besides, I needed to get the materials out of the garage so I can build my Sabalo.

Here is the cross section of a piece I cut off. You can see I missed a couple of staples.



Here is the full length



I pounded a nail into the center of the SB on each end and tightened a piece of braided fishing line between to make a perfectly straight centerline and to be sure there was no curvature to the SB. Then, I lined the centerline of each form up on this string line being careful not to move it. Its not a good photo at all. I also screwed the supporting structures to the floor of my back deck after lining everything up so things can't get bumped out of line by my two boys.



It will bend side to side some over the 17 foot length, but doesn't sag. I think it would be hard to find any material that wouldn't flex over that length. I also supported it in 5 different points over the 17 feet. It is much lighter than solid wood. Particle board in particular.

Of course the canoe will be on the back burner once I get the Sabalo plans I ordered.

Sorry, If got too detailed and hijacked your thread, I didn't mean to go off on a tangent.

I really like the box beam method. It's gonna have to wait till the next build. No way I'm tearing it all aprt and starting over.

Darrells wrote:I really like the box beam method. It's gonna have to wait till the next build. No way I'm tearing it all aprt and starting over.

oh come...don't be a chicken!

I wouldn't start over either. I think the way you have it looks great. I was just throwing the info out there for when you do your strip built Okwata 15-26 or Freedom 18 . You will need a much longer strong back then.

I got all of the forms leveled and secured to the strongback today. I have a question for ya'll. Is redwood good to build with? I was given enough today for atleast a couple of boats.