screw on deck!

regatta · #1 (**permalink**) 10-31-2011

Hello!
Any suggestion how to bedding and sealed stuff in deck with screws!??
Please help!
Cheers

paulk · #2 (**permalink**) 10-31-2011

We've had poor results with screws in a cored deck, even with 3M 4200 bedding. Through-bolting (with the same bedding compound) seems to work better, along with the appropriate backing plates or washers, to spread the loads. Pilot holes for screws are invariably drilled too small, leading to expanding cracks when the screws are driven. The screws have nothing but the thin exterior layer of fiberglass (1-2mm. if that) to grip, since the end-grain balsa has no holding strength. They therefore pull out, or crack the fiberglass beyond the bedding, which allows moisture to enter the deck, which then begins to delaminate. The Gougeon brothers (West System guys) suggest creating an oversize hole, filling it with thickened epoxy, and inserting a waxed (so it can be unscrewed) screw into the liquid epoxy until it hardens. THEN attach your fitting.

CalebD · #3 (**permalink**) 10-31-2011

Damn! I'm screwed. I thought this was a different discussion of a screw on deck.
(couldn't resist)

Basta amigo Regatta!
In addition to the helpful suggestions of paulk I can only add that I am quite happy using Butyl tape as a bedding compound for deck fittings attached with screws/bolts or whatever.
Need Butyl Tape ?? Photo Gallery by Compass Marine at pbase.com
The same website has a tutorial about through deck fasteners and how to deal with this:
Sealing Deck Penetrations to Prevent Core Rot Photo Gallery by Compass Marine at pbase.com

I hope your English is good.
Welcome.

xymotic · #4 (**permalink**) 11-01-2011

West 610 is AWESOME for this.

Quote:

Originally Posted by paulk

We've had poor results with screws in a cored deck, even with 3M 4200 bedding. Through-bolting (with the same bedding compound) seems to work better, along with the appropriate backing plates or washers, to spread the loads. Pilot holes for screws are invariably drilled too small, leading to expanding cracks when the screws are driven. The screws have nothing but the thin exterior layer of fiberglass (1-2mm. if that) to grip, since the end-grain balsa has no holding strength. They therefore pull out, or crack the fiberglass beyond the bedding, which allows moisture to enter the deck, which then begins to delaminate. The Gougeon brothers (West System guys) suggest creating an oversize hole, filling it with thickened epoxy, and inserting a waxed (so it can be unscrewed) screw into the liquid epoxy until it hardens. THEN attach your fitting.

CorvetteGuy · #5 (**permalink**) 11-01-2011

There is a bunch of good thread using bytle tape

serenespeed · #6 (**permalink**) 11-01-2011

What are you trying to do?

dillybar · #7 (**permalink**) 11-02-2011

Whatever method you choose Regattta, etiquette demands you do it at least 1000 yards from other boats ... at least in daylight.

regatta · #8 (**permalink**) 11-03-2011

Hello1
Thanks to everyone reply my question,
I sealed with butyl all the brought bold screw as plain in many websites, but I saw many confusion in sealed screw only for this reason i ask because i have no clear in my mind how to do.
wich product to use? how to do at best?
this is the problem!