Transom rebuild

LRM2 · Post by **LRM2** » Thu Jun 24, 2021 10:23 pm

Hi all,
New San Juan 21 Mark I owner here. Sometime in my boat's 50 year life, someone decided that an open transom would be a good idea. While that's perhaps debatable, what is very clear is that they didn't execute the design very well. So I will be rebuilding to its original shape. Two pictures show how the transom looked when I brought it home. Then one from the inside - it's a little hard to tell, but there is some plywood backing up the transom held in place with spray foam. I'll be tearing it down to bare fiberglass and rebuilding from there.
As you can see from the second and third pictures, the top of the transom on this boat was basically flat. From what I can tell, all the SJ21s have a curved-top transom. In some pictures, it seems to be just an inch or two, and in others, maybe three or four. Might be that some are taken with wide angle lenses. Maybe more pronounced on the Mark II, but still curved on the Mark I. Is that correct? If so, how high is the center of the curve compared to the ends?
Thanks for any insight!
Lewis

Steve · Post by **Steve** » Sun Jun 27, 2021 2:43 pm

It can take a long time for a rush of water over the gunnels into the cockpit to drain. And water in the cabin can bring these boats down - because there's not nearly enough buoyancy. So maybe the open transom is a worthwhile safety feature. The only issue might be objections should you enter a one-design regatta.

LRM2 · Post by **LRM2** » Sun Jun 27, 2021 8:46 pm

Thanks, Steve. Interesting point, and leads me to another question: how is the cockpit drain(s) supposed to be plumbed? I guess I should ask that in a new post with a new subject.
But I do like the classic look of the SJ 21, and want to restore the transom to as close to original as I can. I'm hoping that some kind soul will run a straightedge across their transom and tell me how high the center of the curve is.

kingtoros · Post by **kingtoros** » Tue Jun 29, 2021 11:46 pm

I just saw one on the Fleet 1 forum: http://www.sj21fleet1forums.org/viewtop ... =2&t=13148

LRM2 · Post by **LRM2** » Sun Nov 14, 2021 11:10 pm

After spending a few months on other things, I have been working on the transom rebuild recently. The first shot shows the top of the transom layed up with 6 layers of 6mm plywood and the section that had been removed by the previous owner backed up with 6mm ply. The second shot shows one more layer of 6mm ply across the top of the transom and another section of 6mm ply filling in the removed section. Also all the paint and original yellow gelcoat sanded away down to bare fiberglass. Next up is a couple of layers of 1708 biaxial cloth/mat. I've been lucky with the weather and should be able to get the transom rebuild done before it gets too cold to work outside.
Once the transom is structurally sound, the plan is to put a big pin (3/4 inch threaded rod) in the middle of it, and a matching one in the bow. I'll use those as pivot points to hang the boat and flip it. That should be fun!

LRM2 · Post by **LRM2** » Sun Nov 14, 2021 11:11 pm

Second pic didn't show up in previous post.

kuriti · Post by **kuriti** » Wed Nov 17, 2021 2:53 pm

Lookin good!

LRM2 · Post by **LRM2** » Tue Nov 23, 2021 8:53 pm

Two layers of epoxy and 1708 glass is done. Starting to look like a real boat! A lot more sanding, fairing, etc. to do, but the basic structure of the transom is complete.