Replacing timber floor in Yacht....

[shanan]

Hi again.

I have removed the floor in my boat to repair wood rot and damage in the bilge.

It will soon be time to refit the floor and I need some advice and pointers on the best way to do a couple of things.

1. The floor was made up of plywood and on top of this plywood was the decorative lined timber (teak I think).
Like you see in many yachts - this is laid in line with the boat from bow to stern (if that makes sense) and each strip of the timber is separated by silicon (usually in white to contrast with that varnished timber). See picture attached.

I really need advice on what adhesive to use when I put this decorative flooring back down on the plywood base. The previous adhesive stuck well, however it was also weak enough to allow me to remove each strip of wood (using chisels and patient work etc) without destroying the wood strips. Never know if I will need to remove them again, so was hoping for something permanent, but not impossible to remove.

Adhesive suggestions?

2. On the same subject - when these strips are layed back down, I will need to apply silicon between each strip. Is there a particular way of applying the silicon? I have an applicator gun, however how to you fair the silicon once you apply it? Does a putty knife (or something similar) do the job? Or does it just pull the silicon back out as you try to level it off? Do I just use a wet finger to smooth it down?
S'cuse my ignorance, however I have never used silicon before and did not want to make a mess. Wanted it done properly the first time to avoid removing possible mess from the newly varnished floor.

Thanks!

[journeyman Mick]

shanan
see if you can get a copy of the sikaflex product manual. It has pretty complete instructions for a laid deck.

Mick

[STEPHEN MILLER]

Use epoxy like west system to glue them down then sikaflex marine sealant adhesive in between strips, sikaflex is also clean up with turps and can be painted over with west system etc.

[Ecca]

Shanan,
Silicon belongs in guttering and bathrooms. Sikaflex, or similar is what you need for caulking between the planks and as I was told and have since successfully tried can be over filled in the joints and then sanded with an orbital sander resulting in a perfectly flush joint. You can bed the planks in 3m 5200 or fix with epoxy
regards Ecca:cool:

[shanan]

Thanks heaps for the info guys.

[Boatmik]

Hi again.


2. On the same subject - when these strips are layed back down, I will need to apply silicon between each strip. Is there a particular way of applying the silicon? I have an applicator gun, however how to you fair the silicon once you apply it? Does a putty knife (or something similar) do the job? Or does it just pull the silicon back out as you try to level it off? Do I just use a wet finger to smooth it down?
S'cuse my ignorance, however I have never used silicon before and did not want to make a mess. Wanted it done properly the first time to avoid removing possible mess from the newly varnished floor.

Thanks!
There are two tricks to sikaflexing between strips.

Use the Sika Primer - it improves the bond strength to the timber for a permanent job. You can get away without it often, but it changes the situation from a fairly strong bond to a hugely strong bond (you'll know this if you have ever removed a window where the primer has been used - BAAAAD idea in that application - windows have to be replaced from time to time so don't use the primer)
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The second thing to know takes a little bit of explaining

It's quite common for the strips to be left natural without varnish.

Gives good footing and looks nice, providing you clean it from time to time.

If it is not sealed and the teak veneers are relatively thick (4mm and up) it is common to run a tape along the bottom of the gap so the sika will only stick to the teak and not the ply substrate (the ply deck).

The reason is that the teak will change dimensions as it gains and loses moisture. This will stretch and squeeze the sika during the drying and soaking cycles of use.
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Where the Sika is stuck only to the teak strips there is perhaps a 6mm gapa and if the Teak expands and contracts a mm the Sika is only being asked to stretch plus or minus 15 percent - it can cope easily.
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However if it is stuck to the substrate there is much less than 6mm between adjacent bonded surfaces. The sika bonded to the substrate is immediatly adjacent to the sika bonded to the edge of the teak strip.

So one mm of movement down near the corner where the teak meets the substrate may mean you are asking the Sika to stretch 100, 200 or 300 percent.

The end result is that the sika starts tearing in the bottom corner and with repeated drying and wetting cycles the tear will proceed slowly up the face of the teak until the sika tears away from the teak on one side of the gap.

Difficult to repair too - you can only rip it all out and start again.

So use release tape to prevent the teak sticking to the substrate. Sika sell "special tape - or you can just use a narrow plastic tape - it doesn't need to be permanent - its only purpose is to make sure the bond between the sika and substrate is not strong so the sika will tear away from he substrate and not the sides of the teak planks/veneers
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Best Regards
Michael Storer

[Boatmik]

Hi again.

I have removed the floor in my boat to repair wood rot and damage in the bilge.

It will soon be time to refit the floor and I need some advice and pointers on the best way to do a couple of things.

1. The floor was made up of plywood and on top of this plywood was the decorative lined timber (teak I think).
Like you see in many yachts - this is laid in line with the boat from bow to stern (if that makes sense) and each strip of the timber is separated by silicon (usually in white to contrast with that varnished timber). See picture attached.

I really need advice on what adhesive to use when I put this decorative flooring back down on the plywood base. The previous adhesive stuck well, however it was also weak enough to allow me to remove each strip of wood (using chisels and patient work etc) without destroying the wood strips. Never know if I will need to remove them again, so was hoping for something permanent, but not impossible to remove.

Adhesive suggestions?

2. On the same subject - when these strips are layed back down, I will need to apply silicon between each strip. Is there a particular way of applying the silicon? I have an applicator gun, however how to you fair the silicon once you apply it? Does a putty knife (or something similar) do the job? Or does it just pull the silicon back out as you try to level it off? Do I just use a wet finger to smooth it down?
S'cuse my ignorance, however I have never used silicon before and did not want to make a mess. Wanted it done properly the first time to avoid removing possible mess from the newly varnished floor.

Thanks!

Use epoxy to hold the veneers down.

The normal thing is to slightly overfill the gaps then sand the top surface of the whole shebang down flush. The veneers do need to be a minimum of about 4mm - gives you enough meat to get stuck into it. Maybe 3mm is OK if you are careful.

If the veneers are less than 3mm it is common to use veneers of a contrasting timber between the teak strips instead.

Others may be able to contribute more than me on what they have found succesful.

Best Regards
Michael Storer

[journeyman Mick]

We used to prime the edges of the boards with everdure - especially important for white beech because it's so greasy, still fairly important for teak as it's a bit oily too. Never used the proper primer, the bloke I was working for had done 100s of decks and always used everdure. The sika for the seams (can't remember the number but I think the suffix was DC) is fairly stiff stuff and best applied with a pneumatic caulking gun, partly to make it easy on yourself and partly to get a nice even flow. This cuts down on the amount of sanding that needs to be done later.

Very Important Make sure the deck has been shaded for a few hours prior to caulking and that it will be shaded for a few hours afterwards. Otherwise the caulking bubbles which means you'll end up with caulking that looks like an aero bar after it's been sanded.

Mick

[Boatmik]

We used to prime the edges of the boards with everdure - especially important for white beech because it's so greasy, still fairly important for teak as it's a bit oily too.

Never used the proper primer,

Mick

Mick is probably quite right here.

I have heard of all sorts of different things being used as a primer - one example is the hardener component of two pot paint - just used by itself.

I hesitate to recommend it though because I have had no experience.

If I was doing a small job I would consider using Everdure though - the Sika primer is ludicrously expensive and has a limited shelf life when opened

If I was doing a big job I would probably stick with the manufacturers directions. At least you can call em up if you have problems and they may take some of the responsibility.

Maybe you'll agree with Mick when you see the price of the primer!!!

Boatmik