Water Tight Conduit

Jeff and Anne have been doing a complete rebuild of s/v Pilgrim, a project which is way too large to qualify as a "small" boat project. Nevertheless, I thought you'd be interested in seeing how they created a water tite plumbing conduit under their icebox - it's a good example of fiberglass work:

Rainy, cool weather has delayed dropping Pilgrim’s rudder and forced me inside.  Fortunately a small portable heater maintains a comfortable working temperature inside the boat.

Like the original construction we plan to have multiple bilge pump discharge hoses, a propane line, and likely a couple electrical wires running under the ice box.  Now that we have fiber glassed close the gaps under the wall between ice box and the engine, any possible leaks from the hoses or spills in the cockpit locker could collect under the ice box.  My initial solution was to drill a couple limber (drain) holes along the base of the wall separating the engine and the ice box.  This solution had the downside of again allowing hot air from the engine access to the underside of the ice box.   A more elegant solution would be to create a water tight conduit between the cockpit locker and area under the stove.

Initially I looked for a large diameter PVC or fiberglass pipe to cut in half and glass down to the hull.  This search proved fruitless, but in my scrounging around I discovered some scrap pieces of 1” thick fiberglass paneling with a foam core.  Ok… the conduit will be square.

Creating templates for the conduit side walls.

The conduit began as so many custom fabrications do… by using luan plywood strips and a glue gun to create a template.  The templates of the 3” tall side walls were then transferred to the fiberglass panel.

Transferring the side wall template to the 1" thick fiberglass panel.

The more I worked with the 1” paneling the more I realize how ideal it is for this application.  The foam will add to the insulation. The strength of this stuff when laid up with heavy mat will add structurally to the hull.

Ready to tab side walls to hull and adjacent bulkheads.

After test fitting the side walls and cutting 1708 cloth tabbing, I glassed them down.  To minimize the risk of chafing hoses, I added a nice fillet along the inside corners.

Test fitting the top section.

Once the side walls cured, I was able to lay out the top section.

Beveling  the long edges along the top to allow the fiberglass cloth to smoothly lie over the corner.  After filling any gaps with thickened epoxy, I laid a single piece of 1708 cloth across the top ad down the sides.

Fiberglass work on conduit complete.

Once all the epoxy had cured, I sanded down any rough edges.

Conduit complete.

The outside dimensions of the conduit look large, but it incorporates one inch of foam insulation.

More images and notes from this on-going project as available in the Ice Box Rebuild Photo Album.