The actual thru-hull? Or the sea cock? Mine are all Forespar Marelon...
http://www.forespar.com/marelon-marine-boat-plumbing.shtml
Mark
Hi all, about to haul and replace all thru hulls. Questions I have:
1) Use marine grade plywood for backing plates or is some other material worth considering?
2) As far as adhering the backing plate to the hull, I am thinking either polyester resin or 3m 5200. Thoughts?
Thank you,
David
I would personally use something like G10 composite material but epoxy-saturated marine plywood is commonly used and works fine. Bed it against the hull with poly($) or epoxy ($$) mush. While 5200 is certainly a good adhesive, it is just not the best product for this application IMHO.
One source for backing plates that is both free (usually) and also a great example of recycling is to get some frp scrap pieces from your local boat repair facility. If they are parting out an old hull, use the laminate to cut out backing plate circles.
(Besides being a thrifty guy in general, that's why I never toss out frp cutouts from old projects where a port or instrument was added to any of my boats. )
Regards,
Loren
Loren, much thanks for the info. I'm planning to use Marelon sea cocks that have the three screw holes to help secure it to the backing plate. It looks like the G10 only comes in 1/2" thickness. Any on how to secure this style of seacock to the G10 backing plate?
Also, can you please describe the poly resin mush you speak of? I'm guess fiberglass cloth won't really be of any value in securing the backing plate to the hull right?
Sorry to keep dragging this thread on... It looks like these two materials are essentially the same, just the FR4 is more flame/moisture resistant? So either one of these would do?
http://www.ebay.com/itm/G10-Phenolic-Sheet-1-2-x-11-7-8-x-11-7-8-/201306217204
http://www.eplastics.com/G10-FR4-glass-epoxy-sheet