SIB repair/improvement

minisponger · 11 April 2019, 07:37

Hello all once again!
I find myself in need of repairing the wooden floor in my old Avon s250, but I have some different options.
The first is to use proper marine ply and using the floor I already have as a template, bit of varnish and carpet and away I go.
The second is to use exterior ply and just make sure it’s very well sealed.
The third is to use some thinner exterior ply but then giving it a decent layer of fibre glass and epoxy resin to keep the strength but make it lighter.

Currently the floor doesn’t really fit well, it falls off the Step on the transom if i go any distance at speed, so I’ll need to make it slightly longer but i’m Tempted to cut a template to make the floor out of 1 solid piece rather than the current 2 sections. Is there any reason this would stop the boat working as well? Does it need that little bit of flex? And would exterior ply do the job as well as marine considering exterior is about £20 a sheet compared to marine weighing in at £70?
Thanks in advance!
Sam

jeffstevens763@g · 11 April 2019, 08:02

personally i would keep it original with good quality marine ply i two pieces as it was designed and varnish with good quality stuff OMO

beamishken · 11 April 2019, 16:25

Id go with a decent exterior ply and varnish well. Marine ply is intended for use below the waterline and is certified hardwood with no defects exterior ply uses the same waterproof glue but less expensive veneers and may contain the odd defect but once sealed it will be fine for many years. In any case you can renew it 4 times before your up to the cost of 1 marine ply floor.
I'd imagine the floor is in two pieces to make it pack up small but if you don't need it to pack small and it will install in 1 piece then I dont see a problem with that

jeffstevens763@g · 11 April 2019, 17:27

Marine ply has more veneers than exterior ply ideal in the floor application where strength and flex is needed any voids in exterior ply is a week point. With marine ply made to a standard that has a better finish grade AA both sides less work to prep and finish well worth the extra dosh IMO

minisponger · 11 April 2019, 17:36

Quote:

Originally Posted by jeffstevens763@g

Marine ply has more veneers than exterior ply ideal in the floor application where strength and flex is needed any voids in exterior ply is a week point. With marine ply made to a standard that has a better finish grade AA both sides less work to prep and finish well worth the extra dosh IMO

But if I were to glass the whole panel would it give me the extra strength I need for much less cost? I’m not planning on any heavy use, I’m definitely a fair weather boater so it won’t need to take much of a battering...

beamishken · 11 April 2019, 18:07

Quote:

Originally Posted by minisponger

But if I were to glass the whole panel would it give me the extra strength I need for much less cost? I’m not planning on any heavy use, I’m definitely a fair weather boater so it won’t need to take much of a battering...

My pal builds wooden rowing boats which he hires out he uses marine ply for below waterline and exterior above, for your purpose exterior will be fine wether you glass or not

jeffstevens763@g · 11 April 2019, 19:27

Quote:

Originally Posted by minisponger

But if I were to glass the whole panel would it give me the extra strength I need for much less cost? I’m not planning on any heavy use, I’m definitely a fair weather boater so it won’t need to take much of a battering...

If you glass it you add rigidity and risk of splinter if it breaks plus you add weight and it would need to be flow coated to seal it you can epoxy but that discolours over time the cost then is mounting, the edge would be very hard to glass over at that thickness and keep a shape required with the potential of puncture if it splinters. your floor is under a lot of strain with quite big gaps only supported by the keel and just under the tubes and the transom floor.
My Ali floored boat moves on the joints and flexes in the bow with the last two boards being plywood as is all Ali floors that I know of.
Having done a lot of this recently I would if I was you look at the cost difference if you glass it on the cheaper ply. one other thing you need to prime the wood before glassing or it won't adhere especially under flexing more cost.my bet is if you cost out there might be very little difference but a lot less work if you go marine ply.