Transom Construction

gaff · Post by **gaff** » Sun Nov 13, 2011 10:45 am

Having glued up the mahogany for the transom, I am cutting the inside oak cleats.

I do not have a piece of oak wide enough for the center piece and was thinking of gluing up a 6" with two 3" on each side.

Will edge gluing be sufficient? Or do I need something stronger. I will use plenty of screws when attaching to mahogany.

Here is a picture of the transom so far.

https://app.photorocket.com/galleries/e ... a94741c346

The top needs trimming.

Thanks

Steve[/img]

Phill Blank · Post by **Phill Blank** » Sun Nov 13, 2011 11:35 am

Steve,

I would suggest adding some dowels or biscuts to the joints for added strength. I am not sure if I would trust the edge glued joint only for the support.
You could also screw thru from the back to strengthen the joint instead of the dowels or you could use both. The screws being on the back side would not be visable when installed.

Good Luck,

Phill

gaff · Post by **gaff** » Sun Nov 13, 2011 2:07 pm

Phill

Thanks for the reply. I am going to biscut them or maybe a spline.

Steve

gaff · Post by **gaff** » Sat Dec 03, 2011 11:23 am

I milled the cleats for the transom of the runabout I am restoring.

Here is a link:

https://app.photorocket.com/galleries/e ... 7de79a47a1

I was thinking of counter sinking and plugging the screw holes. I know that is not how it was done when it was built. I like the clean look though.

Any thoughts?

Thanks

Steve

thegammas · Post by **thegammas** » Sat Dec 03, 2011 2:55 pm

Looks great! I say countersink and plug - I too like the cleaner look and unless you are going to take the boat to some judged event where details like that matter, no need to worry about those details. Or something like that.

gaff · Post by **gaff** » Sun Dec 04, 2011 4:15 pm

Thanks Peter

Still not sure how I will screw the cleats on.

I am building this transom based on what was in the boat when I got it.

The original transom was replaced at some point with mahogany plywood. I am not sure if the cleat design is original. Maybe someone has an old picture of what the original transom would have looked like.

Anyway, it just seems kind of flimsy, particularly the top cleats where they meet the motor board.

I am considering two additional cleats, see attached photo. Like the rest of the cleats, they would be splined to adjoining cleats.

https://app.photorocket.com/galleries/e ... dbd27c06f3

Any advice or suggested is appreciated.

Thanks

Steve

LancerBoy · Post by **LancerBoy** » Mon Dec 05, 2011 10:29 am

A Thompson boat like this would typically have three transom knees (I assume this is what you have been calling "cleats"). One was oriented vertically at the boat's centerline and went from transom to the top of the keelson (does your boat have a keelson on top of the ribs?). The other two went from each inwale to transom and were horizontally oriented.

Andreas

gaff · Post by **gaff** » Mon Dec 05, 2011 11:55 am

Andreas

Thanks for the reply.

I am familiar with the three knees you mentioned.

The cleats are what Thompson refers to in their 1949 brochure on page 4. It describes the transom as "built up with cleats to make the strongest transom possible" . These are the pieces screwed flat to the inside surface of the transom (motor board and other pieces).

As I mentioned earlier, this boat was restored previously with a mahogany plywood transom instead of solid wood. It makes me wonder if the cleat arrangement on the rebuilt transom was true to the original.

Here are some photos of the transom and cleat layout. I have gone back with the same configuration as when I received it. If you advance to the next photo, this is something I am considering as well.

https://app.photorocket.com/galleries/e ... 7de79a47a1

I guess I would be interested if anyone knows for sure what the cleat configuration was on a boat like this.

Thanks

Steve

Phill Blank · Post by **Phill Blank** » Mon Dec 05, 2011 12:33 pm

Steve,

This is the transom on my 14 foot Super Deluxe Runabout. This is a deeper of the two styles of the 14 foot hull so the transom has the double cut down to the standard 15" transom height.

Hope this gives your some idea. Unfortunately I do not have my 12 footer here so am not able to get photos of that transom. If I think of it the next time I am up north and if I can get thru the snow to the upper garage I will take photos of that transom.

Good Luck,

Phill

gaff · Post by **gaff** » Mon Dec 05, 2011 1:24 pm

Phill

Thanks for the reply and the photo.

I recently saw a picture of a 12' Thompson owned by Bill & Mary Hermanson.

This boat is almost identical to the one I am restoring. I am not sure if anyone knows Bill and Mary or how I might contact them to see if they might have a photo to share. Their boat is all original.

The link to their boat is:

http://www.mnlakesmaritime.org/events_boatshow_2010.cfm

Thanks again Phill.

Steve

LancerBoy · Post by **LancerBoy** » Tue Dec 06, 2011 8:27 am

I found pictures of a 1940s TVT 14 ft. Runabout I once owned. The transom is exactly the same as Phill's photo above. I will not scan it.

I conclude that Phill's transom is pretty much how Thompson built 'em on the strip-built hulls in the 1940s and 1950s.

Andreas

thompsondockside.com

Transom Construction

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