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Install A Solar Vent

A solar vent is a great addition to any boat that has any sort of below deck area.

Solar vent

A solar vent requires no external power, the vent will ensure air circulation and help prevent the formation of mold and mildew, especially when the boat is left closed up for extended periods. Some vents can run in either direction so it's often possible to fit two, one to draw air into the space and another to extract further enhancing efficiency. This is an easy project that almost anyone with a basic set of tools can achieve, although you may need to purchase a hole saw of the correct size. Carefully read any instructions that come with your particular model before starting the installation as they may differ slightly from those shown in the photographs.

The vent I installed was a 4-1/2-inch Marinco model purchased from West Marine.

Tape sheet of plastic under hatch

Photos: Stacey-Nedrow-Wigmore

Tip

Tape a bag or sheet of plastic under the hatch before starting to catch any dust or debris.

Tech Support

Degree of Difficulty: Easy

Materials:

  • Solar vent
  • Silicone sealant or butyl tape
  • Masking tape

Tools:

  • Hole saw
  • Drill
  • Screwdriver
  • Sandpaper

Cost: $200

Masking tape outside surface

Step 1: Start by sticking masking tape to the outside surface, center section of the hatch as this helps prevent chipping of the polycarbonate hatch panel when cutting through with the hole saw.

Marking the center point

Step 2: Mark the center point by drawing across the diagonals and noting where the lines cross. Check your measurements carefully, a vent positioned off-center will stick out like a sore thumb.

Drilling through lexan

Step 3: Position the pilot bit of the hole saw on the center mark. You may find a punch helpful. Carefully drill through the Lexan using a slow speed. You’ll likely need a plug-in drill as rechargeables often lack sufficient power. You may also need to periodically reverse the hole saw to allow it to cool and prevent the Lexan from melting in the teeth.

Test fit of outer mounting

Step 4: After removing the tape, test fit the outer mounting flange into the drilled hole. Drill for the mounting bolts or screws using a drill of the correct size; the size is often given in the vent installation instructions.

Apply bead of sealant

Step 5: Apply a bead of sealant to the underside of the mounting flange, or use butyl tape as I have here, before affixing the top flange with screws. Don't overtighten the screws or you risk cracking the Lexan.

Cleaning off excess sealant

Step 6: Press the flange into place, and clean off any excess sealant or tape using a scraper followed by a suitable solvent.

Install solar vent in place

Step 7: Install the solar vent in place by screwing it into the mounting flange. Note that this particular vent has a neoprene gasket as an additional measure to prevent water intrusion.

Screw on inner trim ring

Step 8: Screw on the inner trim ring from inside the cabin, noting that unlike the outer ring, this one has a neoprene gasket in place of any kind of sealant.

Completed solar vent

Step 9: The completed job showing the gap below the "mushroom" where the air is vented from below decks.

Mark Corke

A marine surveyor, and holder of RYA Yachtmaster Ocean certification, Mark has built five boats himself — power and sail. He was senior editor of Sail magazine's hands-on "Boatworks" publication, worked for the BBC, written four DIY books, skippered two round-the-world yachts, and holds the Guinness World Record for the fastest there-and-back crossing of the English Channel, in a kayak! He and his wife have a Grand Banks 32.