Portlights leak. On a passage, the windward side of the boat is constantly pelted with spray and the occasionnal wave. It's a law of nature that a sizeable portion of that water slams against the portlights. It's a law of portlights that they must find a way to usher the water into the previously dry, secure sanctum of the cabin.

Portlights have three major weaknessess: first, they require cutting a very large hole in the side of a boat; second, the hole must be larger than the portlight to allow installation which requires some quantity of marine caulk be used to close the insuing gap; third, most portlights open, all but guaranteeing that they'll let water into the boat, whether opened or closed. There's not much a boat owner can do about the first problem - the hole was likely there when you bought the boat, unless you're building it yourself, in which case you're on your own. However, the two remaining problems can be mitigated with some careful planning, skill and large, equal portions of marine caulking, silicone sealant, and luck.

Unfortunately, I've not yet done the second bit myself, so I can't honestly offer any useful advice on that particular point. I won't rebed the portlights in Good Omens until the new trunksides are installed. Do you know why we're installing new trunksides: portlight leaks. However, I do have some small measure of experience with the third, and most insidious of the three problems.

It would seem logical that when a window is closed, especially one designed to reside in a boat and presumably surrounded by hostile water, it should keep all manner of things from entering through it. Through experience, the weathered yachtie knows this is not the case. Even if the portlight is installed and bedded properly it often continues to leak, especially when a particularly egregious wave slams into the side of the boat. Little dribbles of water creep into the cabin between the portlight's window and its bronze or stainless steel frame. The keys to keeping this from happening on your boat are good, solid gasket material, the right quantity of silicone sealant, and lots of pressure.

Before you can install a new gasket, you must remove the old. Removal of all the old gasket and adhesive is absolutely imperative. If you don't get all the old, nasty adhesive out of the gasket channel, you're begging water to enter your boat. Scrape until the gasket channel gleams like new and then, if you're not deathly afraid of acetone, dab a bit of the nasty stuff onto a cloth rag and wipe it through the channel for good measure.

The material used to create the gasket between the window and the portlight frame must be solid. Hollow material is more prone to leaks as it degrades and wears tiny holes through its surface. Only use the solid gasket material. If you don't beleive me, believe Mark Perry at Quality Yacht Services - he knows. The gasket material must be carefully sized so that it's not too large nor too small; not by 1/16 of an inch.

Once the gasket has been fitted to ensure it is the appropriate size, place it aside and reach for a nice, fresh tube of silicone sealant - preferably clear. Liberally apply the silicone sealant to the gasket channel; this is not the time for frugality, really goop it on. Once the entire channel is covered with silicone, use your finger, preferably covered by a nice latex glove, to form the silicone into a smooth concave bed of equal thickness. When you have a nice silicone bed inside the gasket channel, you should also have a few large, icky globs of excess silicone everywhere else. Clean up the excess silicone with a rag before proceeding.

Before the bed of silicone has a chance to contemplate its existence, push the gasket material into the gasket track. This will likely produce more gobs of silicone sealant, but cleaning that mess is better than cleaning the water off your saloon floor. Once the gasket is pressed firmly into its channel, atop its bed of silicone sealant, close the portlight window and dog it down as tightly as possible. Once the window is closed and tighted, tighten it a little more.

More silicone should ooze out during the dogging phase; clean it up with a rag and let the portlight sit for at least twenty four hours. Don't even chance to look at it until a full day has passed.

If you follow these simple steps you should have good solid portlight gaskets ready to take on the most egregious water attacks. Of course, they might still leak, but you'll always carry a warm feeling of satisfaction from a job well done.

Besides, we've already agreed that boat's leak.