Ply floor - one piece or four?

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111KAB

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Further to my first post .... see

http://www.ybw.com/forums/showflat.php/Cat/0/Number/1959911/an/0/page/6

I have now (with a great deal of difficulty - see extent of tools!) removed the rotten ply floor in the boat. Now to start the re-building starting with some 10mm external quality ply.

Does this need to be one sheet (for integrity) or can I fit in sections which could possibly be removable so I can get at the area under the 'floor'? Hope this makes sense .... I will edit and post a pic of the area now the ply has been removed.

ply.jpg


Thanks again everybody.
 
[ QUOTE ]
You need marine ply. Exteria is not good enough. Make it so you can get under it for fixing and adding things.

[/ QUOTE ]

Reason I included previous post was that ALL who replied said exterior quality ply ok and not worth going to expense of marine so ??? Intend both treating and applying protective finish to ply used. Does anyone have definitive answer re type of ply to use? THANKS
 
I understand the main difference between the two is that standard ply is manufactured using a water-based adhesive, which means it will readily delaminate if used in damp conditions.

Marine ply is manufactured using water resistant adhesive.

P'raps forumite and renowned timber-shaper Jason/Cuchilo could confirm this ?
 
I am no expert but I would have thought that exterior ply is acceptable provided it is treated with several coatings of epoxy and then coats of varnish. Obviously marine ply best but cost would be much higher.

Sectioned floor must be better than 1 piece from the viewpoint of access and maintenance.
 
agreed, marine ply, and best to seal the ends with epoxy to prevent water getting inside the layers.

Certainly, being able to break up the floor into parts will help with e.g. bilge cleaning, running cable, retrieving specs, phones, change, etc, but it might be worth looking at a similar boat to see how the sections are separated, and held down. Sometimes it's with screws, sometimes with small pieces of wood that turn through 90degs. The last thing you want when bouncing around at any sort of speed is chunks of floor to start floating up and down.

If the wood is the final surface, you might find antislip paint or sand to be useful.

Looks as if you are making good progress, anyway. /forums/images/graemlins/grin.gif
 
Talk with Robbins timber in Bristol. They know it from A to Z. I'd definitely seal the edges or put an edging rail on the floor. You'll be getting quite a lot of spray inboard, honestly !

Robbins
 
if you decide to go one piece, then jigsaw some rectangular holes with nice rounded corners, and fix battens underneath so that the bit you've cut out can rest on top as a hatch cover for access to the bilge.
 
I would go for sections of marine ply with some sort of sealant over it all (especially the edges)
Marine ply because it does not use water based glue
seal the edges so the wood does not have any water ingression
sections rather than a single sheet so you can lift pieces (especially at either end) rather than the lot
 
I would go for either one piece or if difficult to fit, in two pieces BUT with say two or more removable 'hatches' to get at the bilge etc as mentioned earlier. And use marine ply with well sealed edges as mentioned. Fit more wooden bearers under the ply to make the floor nice and firm.
 
Depends how long you want it to last - exterior ply won't last as long as marine ply as it is not certain to be free of voids and water will find its way in eventually causing it to delaminate.
 
OK, case in point. I had new seats made for my fly bridge, about six years ago. The vinyl is still perfect, but the ply bases have rotted, tearing the vinyl when it came adrift from the brackets. I suspect they used none marine ply, so has created about a £600 expence.
 
Thanks sarabande for the link. OK so I've decided to go for marine 9mm ply and require a single sheet 2440 x 1220 mm - does anyone know a West Midlands supplier? I will incorporate a couple of hatches and protect all the edges. Going to cut a hardboard template first to make sure of exact fit. THANKS
 
you'll get better information on ply on the classic boat forum.

If you are going to pay more for 'marine' ply, specify '1088', not only does the 1088 spec define the glue but also there will be no voids in the layers.
 
You are not thinking straight!!!
You have gone to all the effort of taking out the old floor and fitting a new one and you plan to use a softwood plywood!!!
You MUST use proper marine plywood!
Someone suggested coating the cheap stuff with several coats of epoxy!!! If you are going to do all that why not just use cardboard!
Joking apart - you really must use the real thing - I have tried useing the cheap stuff and it looks great for a season then it all starts to go wrong as it starts to delaminate and rot.
Good luck!
 
The point of the original suggestions was to do with the relative cost of the ply and the boat/project. A sheet of 1/2" (15mm) marine ply is around £100 which could go a long way to fix up other areas of the boat.

Yes, of course outdoor ply will rot in a few years in a boat like this, but replacing a sheet that you can pick up at B&Q every few years may be more acceptable than sourcing £100 of specialist plywood.

At the end of the day, it depends on a) how much you want to spend doing up a 'free' boat, and b) how long you intend to keep it.

The bill so far could look like:
Morse/Teleflex steering: £100
Trailer bearings & bits: £100 (more if it's braked)
Vinyl & foam: £100-200 depending on what needs doing
Engine and controls: £???

Then the inmates here will doubtless add:

VHF: £150
Flares: £50
PB1/2 course: £???
Liferaft: £500
EPIRB: £250
Radar/plotter: £2000
Toaster: £12.99
Gennie: £200
etc etc
 
Wiggo - you have hit the nail on the head!

Anyway I've found a 8' x 4' sheet of 9mm marine ply at a local timber merchants for £35 so may as well go with this as the equivalent size of B & Q External hardwood veneer ply was £16.
In the fullness of time I'll start asking questions re the steering and engine - perhaps at that stage my newbie vocab will be sprinkled with the odd technical term!
Trailer refurb completed - 3 new tyres + bearings + jockey wheel + Hammerite + trailer board = £186
Vinyl seating looks like coming in around £120

Oh I've done my PB2 by the way - thats where/when I got the 'bug'

Think the real questions will come when I try and find a s/h engine.

Thanks all for your help.
 
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