Topic : Suitable wood for thwart reinforcement

I currently own Maid of Ply 3525 and sail it up at Bass in the Lake District. Due to the short courses I have taken out the steel hoop and replaced it with a rear mainsheet arrangment similar to a RS200. The downside of this is that i need to do some repair work to the thrwart to prevent local damage due to the removal of the support. There is a 20mm by 25mm spar that runs under the thwart that need replacing as it us not adequate now the hoop is gone.  

Do any of the members know of good wood type for this work and suppliers that can supply this in relatively small quantities if I cannot get it locally. The boat is a wooden boat mae primarily of plywood.

Kind regards

John Reekie

Posted: 20/02/2013 10:55:47
By: John Reekie
John, I would be very suprised if the hoop formed any kind of structural reinforcment to the thwart, in fact it is more likely to be the otherway round.

I should think your thward is made of mahogany if you feel you need to reinforce it and I always get mine deliveresd from Robbins Timber in Bristol, however they will charge the same delivery regardless of the amount.

Posted: 20/02/2013 11:44:03
By: Jez3719
Thanks for that. The hoop provided a vertical support to the thwart and the thwart had a stringer underneath which was notched out to take the hoop. The result of removing the hoop is that the thwart has been bending and cracked the stringer underneath due to crew sitting down. This has not raised itself before as the hoop bolted to the stringer was acting as a vertical brace off the floor/frame of the boat.

I am looking at Douglas Fir as it seems that it may be suitable for the stringer. The thwart is marine ply and is fine if the stringer is replaced underneath.

Posted: 21/02/2013 00:20:09
By: John Reekie
I have never seen a thwart made of Ply before but I may be wrong. It may have been built without one and been added later to provide a seat.

The crew should not be sitting on it anyway, maybe that is your answer!! I have no history of the biat and so can't answer why it is like this and I have not worked with Douglas Fir before, but it sounds heavy?!

Maybe someone with some knowledge of the boat could shed some light?

Posted: 21/02/2013 09:10:49
By: Jez3719
I would just epoxy in an offcut of carbon tube (a broken pole, or get a bit of tube of the internet). You are only looking for some compression resistance. I have never seen a hoop being used for structural reasons, but I guess that there is no reason why it shouldn't be.

Posted: 21/02/2013 09:50:23
By: Andy Hay - Business as Usual
A lot of boats with painted insides have plywood thwarts. If its not on show it don't need to be pretty!

Posted: 21/02/2013 19:21:59
By: Chris M - 3744
I think I will stick to wood to match the general design of the boat. I think it would be a little bit poor form to not respect its era.

Posted: 22/02/2013 08:29:39
By: John Reekie
My old Boat 3550 was built 3 boats later by Rowsell and had a painted inside but the thwart was still mahogany.

Maybe a lesson learnt???

Posted: 22/02/2013 08:57:02
By: Jez3719
Might the boat's name give a clue as to what it was made from, especially as it's not intended to be used for beam strength? Can't beat a nice bit of wood though.

Posted: 22/02/2013 15:54:58
By: K.M.
I'd say it's more likely to have been specified to save weight. That's also assuming Rowsell's finished that boat, I thought Tony Lock did.

Posted: 22/02/2013 18:52:18
By: Chris M - 3744
Thinking about this, if the stringer uderneath the thwart has been nothced to take the hoop, the hoop must have had a fair bit of rake on it. That being the case, the thwart will tend to sit on top of the hoop tube, so when the crew sits on the thwart it can't flex down as the hoop is in the way.

The hoop was never intended to do this, but it's a useful side effect especially as the structural element (the stringer) has been compromised to fit the hoop.

In terms of a repair i would have thought doubling up the stringer in the area where the hoop was should be sufficant. I don't see any need to go all the way across the boat.

Posted: 22/02/2013 19:17:43
By: Chris M - 3744
So, Chris M, you are now Chris M 3744!  Santa has been good to you!

Andrew still 3511

Posted: 23/02/2013 21:00:56
By: Andrew M


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