Scarf joined planks

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Scarf joined planks

Postby JoeCB » Fri Apr 21, 2006 7:34 pm

While sanding down all the old bottom paint on the 57' Sea Lancer I was on the lookout for any sign of bottom plank scarf joint seperation :?: (ref.Capt'n Dan's post) . Close observation shows no indication of any kind of a joint. That's good news, either the joint is still tight or there never was one. Is it possible that some of these boats were built with long enough plywood to do a one piece garboard plank?
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Postby a j r » Sun Apr 23, 2006 6:09 am

Ho Joe, as far as I know, both Thompson Bros. Boat and Cruisers, Inc. bought full length plywood mill direct up until the early 1960s. They, of course, paid a premium for it. About 1962 Roy & Grant Thompson established a corporation called "R & G Engineering" to make their own long length plywood by means of scarfing regular 4' x 8" plywood into longer lengths. They sold the plywood to Cruisers, Inc., Thompson Bros. Boat, and maybe T & T Boats, Inc. Other boat builders may also have bought this plywood (Carver and Dunphy come to mind).

I assume they would have used resorcinol adhesive, as Unit Structures, Inc at Peshtigo was using this adhesive. Unit was right next door to Thompson in Peshtigo and until 01 Aug. 1962 half her stock was owned by Thompson family members. Roy and Grant were intimately familiar with Unit's operations (my dad was V.P. & Chief Engineer at Unit at that time). So I make the assumption that reorcinol was utilized.

This plywood scarf cutting and press equipment was purchased by my dad about 1972 and he still has it sitting in one of his storage sheds in Peshtigo.

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Thanks

Postby JoeCB » Sun Apr 23, 2006 2:24 pm

Thanks Andreas, another prompt, authoritive and informative reply. That explains the lack of any evidance of a scarf joint... I can rest easier now as I'm pounding out across the breakers on Lake Huron.
ps. I still have fond memories of the Sentinal Structures tour you hosted during the inaugural Rally in 02'.
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Postby JSC » Sun Apr 23, 2006 8:29 pm

Joe - I also read with interest Txcapt's account of joint separation. I'm just finishing painting the bottom of my '57 Offshore. I have been amazed at the number of "patches" in the garplanks - there must be at least a dozen. Started me wondering about the "life expectancy" of these patches. It also started me thinking about how deep Lk Washington is. I think I'll put it in the back of my mind - and keep the life jackets at hand! - Jeff
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Postby a j r » Mon Apr 24, 2006 4:20 am

Thanks for the nice words Joe. Correct spelling is S-e-n-t-i-n-e-l. NO a.

www.sentinelstructures.com

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Postby a j r » Fri May 12, 2006 4:45 am

I have been working on a 1959 Thompson Bros. (Peshtigo) Sea Lancer that I recently obtained. There are scarf joints in the plywood planking!

There definately are glued scarf joints in the planks above the waterline. I cannot tell if there are scarfs in the garboard and other planks below the waterline. The hull has been fiberglassed and there is paint in the bilge. Therefore it's impossible to see if there are scarfs or not.

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