How Do You Fill-In Unused Through-Hull Holes?

[rrobar]

Hi Gang,

Although most of the reference books detail how to install a new through-hull and seacock, no one mentions how to fill in unused bolt holes when replacing a seacock with a new one -or even the larger hole when eliminating the through-hull alltogether.

How do you safely fill in bolt holes in a fiberglass hull? Just filling with thickened epoxy doesn''t seem strong enough.

Thanks in advance for your advice!
lisa & randy
salem, ma

[Jeff_H]

You seem to be asking two separate questions. The first is how to remove a thruhull and fill the hole and the second is how to fill a smaller bolt hole in the hull. With the larger hole from a seacock I prefer to grind out a large tapered (8:1) area from both the interior and exterior of the hull and build up multiple layers of epoxy and cloth from both sides. I have nor problem with using thickened and reinforced epoxy as a core between the inner and outer cloth lay-ups on a really thick or cored hull.

For a bolt hole sized hole I would fill it with thickened epoxy and then grind a small dimple and cover the hole with a layer of cloth and epoxy. The cloth increases the tensile stength of the repair and prevents shrinkage from causing a leak into the inner laminate.

Jeff

[JEFryar]

You are right. You really need to reconstruct the area with layers of glass mat. With the fear of someone accusing me of owning stock in the company... The West System manual on fiberglass repair and maintenance and repair has guided me through several repairs. I picked up a free copy at West Marine.
Good luck
JEF