Correct way to fix fittings through the deck

[Nostrodamus]

Now you are showing your age and I am showing mine by knowing who you are talking about.
I have to do the same this week so i would welcome any suggestions.

 

[Dill et Bound]

The way to hold the filler in place is either.
Tape up a piece of thin ply with sellotape, two or times bigger than the patch and prop in place from below.
Self tap a piece of thin alloy plate, which you can wax, and fill the self tap holes later when your plug has cured

But either way , all you are effectively doing is stopping the compression when you eventually tighten the bolts.
The method does nt actually improve the strength or load bearing of the composite.

For that you need a backing plate, or a stiffener of some sort..

Good luck with your jobs, I am sure that they will turn out just fine..

Watch the cold temperature for curing.

And any air bubbles when you pour in from above, the air needs to escape as you slowly pour in.

 

[FairweatherDave]

I have quite a few of these holes to fill , some bionic tape would be seriously helpful rather than props or self-tappers......
But with certain sticky overhead DIY jobs like plastering I would have thought my initial approach from underneath with well thickened epoxy might work, but what do the experienced ones say?
And my question inserted into this thread was about not disturbing the fitting whilst refreshing the fixing bolt and making it water tight. Any advice there very welcome.
Apologies if that sounds disrespectful to the last poster, who is experienced, what I mean is I presume my underneath route should work too I hope ... there is more than one way to do the job or am I wrong?....
Certainly I will be finding out.

 

[Dill et Bound]

No problem..
I am sure an epoxy paste mix would be fine pushed up in from underneath..

Spread the paste out thin on your mixing board..
Disperses heat, extends working time..

Take advice on what to use as a thickener, so as not to weaken the mix, or use Epoxy putty..

The pouring in from the top was just a method that I read into the post..

Good luck... Dont get too stuck in!!!!:encouragement:

 

[Len Ingalls]

Use masking tape-the beige colored original stuff.Painters blue or green masking tape probably won't hold. Wipe GRP with acetone first.
You can use a small piece of waxed paper or plastic film first,if you like.Epoxy will not stick to it & leaves a nice smooth finish.

Don't use silicone on a boat.Use butyl tape(as used for auto windshields)for bedding components to deck.Stays flexible & removeable for 40+ yrs.Less messy than caulk type bedding compounds,& no rush to get all bolts tight before it sets up,cause it doesn't.Apply butyl,tighten bolts/screws & you're done.Trim off any squeeze out with a plastic scraper,knife-whatever & whenever-it doesn't set up.

In your case,you are bedding to a teak deck.Use a small plastic funnel to pour epoxy thru bolt holes til level with GRP deck top.No sense in filling teak-you're just going to drill it back out,& drill bit will try to run off into teak.
Chamfer holes in teak to allow butyl to form an "o-ring" around bolt. Don't use spacers between component & teak.That would reduce the bearing surface of deck/component interface,& make it wobbly-weakening it & flexing the sealant-causing future leak potential.

Inject Sikaflex,or other cartridge bedding compound,into holes thru teak deck.This will help stop water UNDER a leaky teak deck from following the bolts down & dripping in cabin.

The timber hatch things you speak of-no need to remove,if you are satisfied they are well bedded to deck.Follow same proceedure-run epoxy down thru them,Sikaflex the bolt holes.

You must use substantial backing plates for the frame you are installing,to spread load over large area of deck.Possibly,they should be thru bolted to deck also.using same epoxy methods.A square foot of surface would not be unreasonable,each side.These can be made out of 3/4 plywood,but I would tend toward 1/4" alum. plate,or 1/2" "Starboard"(solid PVC,etc).

Cheers/Len

 

[FairweatherDave]

I think I will be doing both methods depending on which hole it is, and use different ratios of thickener accordingly. Probably will be forming a plug and then topping up with runny mix later on with a syringe.

 

[FairweatherDave]

Thanks Len, of course! masking tape will hold. Will study your post later but I am summoned next door!