As previously published in


Emergency portlight covers
Holding the water out when a port breaks at sea
by Jamie Harris


According to the pilot charts of the central and north Pacific Ocean, the incidence of gales during late July and August on the preferred sailing route from Hanalei Bay, Kauai, to San Francisco is less than 5 percent. It's even lower in May on the trade wind route from California to Hilo. Still, while planning a summer cruise to Hawaii, the possibility, no matter how small, of a full gale at sea focused my attention on the size of my boat's cabin portlights and other coastal-cruising design features.

My good old Spencer 35, Onrust (Dutch word meaning "unrest"), is a classic CCA-design, one of the mid-1960s vintage solid fiberglass cruisers with moderate overhangs, a long keel, and sweet sea motion. I had every confidence in her capability to make a summer cruise from San Francisco to Hawaii and back. However, her raised doghouse has bigger windows than I think ideal for an ocean passage. The four main cabin ports measure almost 40 inches in length and 12 inches in height. Having one of them break at sea was not a pleasant prospect. Yet I didn't want to mar the cabin sides with permanent armor of some kind. What to do?

"I wanted something very inexpensive, easy to store aboard, and quick to mount from inside the cabin -- assuming that if conditions were bad enough to break a window, I wouldn't want to do a lot of work on deck..."

I decided to construct emergency portlight covers that could be installed over the frame in case a port were broken. The Pacific Cup Yacht Club, sponsors of the biennial Pacific Cup race to Hawaii from San Francisco, endorses this solution but does not provide any details for building covers.

For my Hawaii cruise in the summer of 2006, I wanted something very inexpensive, easy to store aboard, and quick to mount from inside the cabin -- assuming that if conditions were bad enough to break a window, I wouldn't want to do a lot of work on deck, particularly a job requiring both hands to install nuts and bolts.

Installed from inside

My design was for a solid 1/2-inch-thick plywood port cover that could be installed and locked into place through a broken window from inside the cabin and tightened up enough against the exterior of the cabin side to provide a watertight seal. (The windows are mounted in standard aluminum frames, more or less flush with the exterior of the cabin side.)

First I bought a 4- x 4-foot square of high quality 1/2-inch plywood. I selected cabinet-quality birch ply. With the extra layers, it is quite stiff. After measuring twice, I cut rectangular covers 1 1/2 inch larger on each dimension than the exterior edge of the window frames. I figured that two would be sufficient and, while I was at it, I made two smaller ones to fit over the head compartment ports as well. I beveled the corners and edges to create smooth edges and then put on four coats of polyurethane varnish for waterproofing, paying special attention to soak a lot into the edges of the plywood. I then cut a 1-inch by 2-inch teak board into clamping pieces. To create a more even clamped pressure on the large covers, I made two clamps for each of the covers but concluded that one would do for the small head port covers (13 inches by 6 1/2 inches). These clamping battens are 3 inches longer than the maximum vertical dimension of the windows in order to have good purchase on the inside of the window frame and cabin wall. I drilled 1/4-inch holes through the clamp and the cover to take 3-inch long stainless-steel bolts, washers, and wingnuts: two in the large ones and one in the small ones. Then I installed rubber hatch gasket material around the inside edge of each board where it will contact the cabin side.

Not a problem

I did not have to deal with a broken window on my passage to Hawaii, but if one had broken, I would have levered the cover board out through the broken window, while holding on to the clamp boards from inside the cabin. Then I would have pulled the cover into place, overlapping the edges of the window frame, and tightened the wingnuts to pull the clamps against the inside frame and draw the board up against the gasket tightly. (Note: have a plan for removing or drilling through the remains of the broken port lens. –Eds.)

Jamie's emergency portlight replacements can be mounted and clamped from inside the cabin, eliminating the need to go on deck just when the weather is at its worst.

The hole for the bolt in the head port covers is off-center to account for a vertical aluminum framing piece in the middle of the window frame that supports the fixed side of the half opening port. In the case of the head windows, unless the frame were broken along with the windows, I would have had to go on deck to install them. The vertical frame piece in the head ports would prevent passing the cover out from inside. On the other hand, these windows are so small that breakage seemed unlikely.

The total cost of this solution was less than $55 for the plywood, hardware, and varnish. I cut the clamp boards from my garage supply of miscellaneous teak scraps that came with the boat when I bought her four years ago.

I stored the covers with the bolts removed so they could lie flat together under the forepeak. These were emergency supplies I hoped never to have to use, but when the sea kicked up at night on my voyage, I worried less about what might happen if one of those big windows cracked.

The author:

Jamie Harris bought Onrust, a Spencer 35 in the spring of 2003. After sailing her in San Francisco Bay for three years, he crossed to Hawaii in the summer of 2006.