[Rhodes22-list] Bow Chocks

[sprocket80]

The whole exercise of over drilling and filling the hole with epoxy (in cored decks) then re-drilling to the diameter of the screw is to seal the deck coring completely. Bedding compound eventually shrinks, wears, gets exposed to the elements, etc., and fails. Especially on chocks and chain plates which are also put under heavy mechanical loads. Squirting bedding compound into the holes and spreading it under the fixture offers little barrier to water intrusion into the core once it has failed, especially since the screw is going to push almost all of it out of the hole and into the cabin. Boat owners should re-bed the deck hardware every few seasons or so but often only find out the bedding compound has failed is when they feel a soft spot in the deck and the core is already failing.

Countersinking the hole (getting a clean cut with a countersink bit--NOT drill bit) accomplishes two jobs. First the flat underside of the fitting is going to force the compound into the countetsunk hole and around the fastener. Forcing it into a narrowing beveled hole is going to create a tighter plugging effect of the compound. Second, it removes a stress point of the screw against the edge of the gelcoat skin. Bedding compound should not completely harden and remain somewhat pliable. A fitting like a chock which gets lateral loading, is going to want to move by some small amount. With a straight drilled hole, the screw is going be in direct contact with and put stress on the edge of the skin around the hole. And as Dennis pointed out, we all know what stress does to the gelcoat.

Todd T




-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Graham Stewart
Sent: Monday, April 08, 2013 10:29 AM
To: 'The Rhodes 22 Email List'
Subject: Re: [Rhodes22-list] Bow Chocks

Rummy is probably right. There is no wood core in the edge that can rot
anyway and the fibreglass is quite thick there. So that would not be a
concern. If you decide to do that I would countersink slightly the screw
holes in the gel coat and bed the chock carefully as you will otherwise
probably get spider cracks in the gel coat around the screws over time.

Graham Stewart

-> snipped

_____________________________________________

To subscribe/unsubscribe go to
http://www.rhodes22.org/mailman/listinfo/rhodes22-list

For the list Charter and help with using the mailing list and archives go
to http://www.rhodes22.org/list
_____________________________________________


_____________________________________________

To subscribe/unsubscribe go to http://www.rhodes22.org/mailman/listinfo/rhodes22-list

For the list Charter and help with using the mailing list and archives go to http://www.rhodes22.org/list
_____________________________________________