I have installed many plugs over the years.
For exterior work I usually use "Weldwood" plastic resin glue.
This is a two part glue mixed with water. It can also be cleaned up with water, before it cures.
Resorcinol glue is a fine glue also, water proof and can be cleaned up with water. However it always leaves a destinctive colored glue line, sort of a deep maroon, which some find undesireable.
Another good glue is urea. From what I've been told it is made partially from bovine urine, hence urea. This is a two part glue, one part powder, one part liquid. It used to be used extensively in the furniture industry. Can be cleaned up with water as well.
The advantage of urea and plastic resin glues is the color of the glue line. It pretty much disappears in woods such as teak and mahagony. Its light tan color is even disguised very well in blond woods such as ash and oak.
For cutting plugs and drilling screw and plugs holes, the Fuller company makes a line of tapered drill bits, countersinks and plug cutters.
The countersinks and plug cutters are matched so that the plugs produced by the cutter are an exact fit for the respective countersink.
The tapered bits are expensive but only needed for standard tapered shank wood screws.
In most applications on fiberglass boats SS sheet metal screws are used. For these use a standard straight bit.
i.e. #10 screw use a 5/32" bit and a #7 Fuller countersink. The #7 countersink has a pilot hole for the 5/32" bit and produces a 3/8" plug hole.
i.e. #8 screw use a 1/8" bit and I think a #8 Fuller countersink. The #8 countersink has a pilot hole for the 1/8" bit and produces a 3/8" plug hole.
Both the plug cutters and countersinks can be resharpened, carefully. For the average boater a set will last a lifetime.
As I remember Home Depot sells the Fuller products. You can also find them at many of the online woodworking tool sites.
Happy plugging,
Fred B.
