Fixing into GRP

[ChiPete]

Hi All,

I'm a new member, new boat and first post.

We've recently taken delivery of our new Beneteau Oceanis 323 (we business-cased having kids vs having a yacht and you know which won!).

I want to fit a halyard bag in the cockpit, however, I'm a tad concerned about drilling and fixing screws into the GRP. When I fitted a shock cord loop in the heads to hold the loo brush container to the bulkhead, it seemed the eyes were about to strip out the drilled holes.

Could anyone advise the best way to drill and fix screws into the GRP?

Thanks for any assistance in advance.
Pete

 

[Graham66]

Ensure that the pilot hole is the same size as the shank of the screw and lubricate (tallow, beeswax)the fastening before insertion

 

[srp]

Self tappers and grp are not a particularly happy combination (in my view). I prefer to through-bolt anything that is likely to get pulled about, though that probably doesn't apply to a halyard bag.
Alternatives to self tappers might be Bighead fasteners bonded on to the grp, or even a strip of hardwood or tufnol bonded on (with Sikaflex), into which you can screw a self tapper.

 

[johnalison]

Although self-tappers are not ideal, they should be adequate for this application. I fitted winch-handle pockets last year, with bungee-tensioners and they are as firm as anything. If the glass is thin, then bolting would certainly be better.

 

[captainslarty]

Agree, self tappers are fine for most unstressed items.. problem is - most modern caravans are a tad thin on the grp leading to problems.. if its a properly built boat /forums/images/graemlins/wink.gif .. then it will work fine.. just fitted well over a hundred self tappers to the cabin top (Dual layer balsa cored) from underneath of course ...) ... dont even need to pilot drill them.. just clearance in the wood cladding.

dont over tighten, if thin grp drill a pilot hole.. if gel coated, drill a pilot hole too.

 

[VicS]

[ QUOTE ]
fix screws into the GRP

[/ QUOTE ] If you are using self tappers drill a clearance hole though the gel coat to minimise chipping and a generous sized pilot hole for the screw. That means if you are using 4mm (no8 gauge) screws and a typical set of drill bits a 4.5mm hole through the gel coat and a 3.2mm pilot hole or even 3.5mm if the grp is thick. I also like to put the screw in with a little epoxy adhesive (but not if some lubricant has been used)
If you have access to a more comprehensive set of drill bits then maybe don't make the clearance hole quite as much as 4.5mm and make the pilot hole 3.3 or 3.4mm.

I think if I was using larger screws than 4mm/no8 I would consider tapping a hole for a machine screw say M5 or M6. I'd still put them in with a dab of epoxy though.

 

[Chris_G]

How about double sided self adhesive velcro ? No holes and if it doesn't work you can always go back to trad. screws. Anyone tried it ?
C.

 

[Sneds]

SWMBO swears buy it!
And blue tac for ratling doors etc!

 

[Haven't-a-Clue]

I've used 'No more Nails' tape for quite a few items on board 'cos I hate drilling holes (strange I know!) and if left for 24 hours before using, sticks like 5h1t to a blanket, or the 3M sticky hooks are very good, too.

 

[ChiPete]

Thanks to all of you for the replies, much appreciated.

Good call re the velcro and No More Nails; I think I'll try that first to avoid turning the boat into Swiss cheese. Strangely, my SWMBO also swears by it (when not swearing at me!).

Thanks also for the steers re the drilling of the holes. If I need to go down this route, that's great advice.

Right, I'm off to give it a go!

Cheers,
Pete

 

[VicS]

Too late i guess but what about Evostik "Serious Stuff" "sticks almost anything to anything"

http://www.bostik.co.uk/corpweb/p2.nsf/3...dElemFormat=jpg

 

[ChiPete]

Not at all VicS, that stuff looks good as well. The question I have about Evostick and NMN is: is it waterproof? I get the impression that the manufacturers claim huge bonding abilities.....so long as it's dry.
Didn't manage to do the job today; no velcro emporiums open on a Sunday!
Cheers,
Pete

 

[VicS]

[ QUOTE ]
is it waterproof

[/ QUOTE ] Ordinary Evostik Impact and Timebond are AFAIK but it does not say so on the website. Serious stuff is and it says so. Wet grab is and can even be used on wet surfaces. Evostik Liquid Nails comes in intreior and exterior formulations. Presumably the exterior one is water proof.

"No more nails " comes in several versions The "exterior" one and the "all weather" one are weather proof.

But hey you've heard of Google as well! /forums/images/graemlins/grin.gif