GROCO Bronze Thru-Hull Installation Tool

The GROCO bronze thru-hull installation tool allows one installer to hold a standard GROCO thru-hull fitting in position from inside the boat while the seacock or locknut is threaded onto it. The stepped tool fits through the thru-hull and gives a temporary way to pull the fitting firmly against the hull during assembly.

A monofilament line can be tied to the tool's eye and passed through the prepared hull opening, allowing the installer to draw the caulked thru-hull flange into place from inside the vessel. This method reduces the need for a second person outside the hull and helps keep the fitting seated while the internal hardware is started.

Confirm that the tool supports the thru-hull size being installed and follow GROCO procedures for hole preparation, bedding compound, seacock or locknut engagement, and final tightening. The tool is an installation aid rather than a permanent plumbing component. Inspect the completed thru-hull for proper seating and watertight sealing before launch. Find more in our marine plumbing.

• The tool helps hold the external fitting while internal hardware is threaded into place.
• The eye and temporary line provide controlled positioning from inside the boat.
• The stepped body accommodates multiple standard GROCO thru-hull fittings.
• The installer can control the fitting from the interior side of the hull.