Jonathan Ganz wrote:
I'm not sure what you mean about leaving a tapered area
around the hole. Why would this give it better bonding?


Wally wrote:
Feather the edge so it looks like a shallow countersink. It'll give a
greater surface area for adhesive to bond to, and, if you're filling the
space with something solid, make it large and feather it to match. The
instructions on tins of car body filler give an idea of the shape.

It also gives a better, rougher bonding surface, also IMHO exposing raw
threads of the old laminate, you can bond directly to the cloth.


Simple Simon wrote:

The proper way to patch a thru-hull hole in a GRP hull is
with polyesther resin and not epoxy resin.

Malarkey. Epoxy will form a stronger bond to polyester than polyester will
bond to itself. Furthermore, unless the surface is just right it is
difficult to get polyester to form a secondary bond (ie, bonding to an
already cured surface). Polyester is affected by temperature & humidity more
than polyester. Epoxy has a longer shelf life than polyester and is less
sensitive to mix ratio.

In short, there are many reasons why it's smart to use epoxy rather than
polyester resin.



The hole should be tapered in a radius of approximately
four times the radius of the hole itself.

Malarkey again.

The taper should be between 4:1 to 12:1 by thickness, the diameter of the
hole has nothing to do with it.

Fresh Breezes- Doug King