The thing to be avoided is taking on large amounts of water by shipping a sea. Waves contain a great deal of water, and some or all of it coming on board may find its way inside. A great deal of water traveling along at some speed represents a great deal of force, and this force may damage your vessel. The same people who groan under the weight of a 10-gallon jerry can of water pretend to be surprised when big, fast-moving seas bend heavy stainless-steel stanchions.
You can avoid shipping a head sea by steering carefully and by slowing down your vessel. It's amazing how much small differences in speed make in a head sea. To avoid shipping a sea over the stern of your vessel-getting pooped, they call it-you can steer carefully or round up and take them on the bow. As long as you keep a big breaking sea astern, however, there is always danger of getting pooped. The ultimate weapon for dealing with dangerous breakers at sea is the parachute sea anchor. Your best chance of keeping the water out of your vessel in survival conditions is to lie to such an anchor. With a little luck, always a factor in seamanship, its vortex will keep the seas from breaking onboard.
Though shipping a sea is certainly to be avoided, it need not be a disaster if your vessel is decked, has a watertight cockpit, and has its deck openings strongly sealed. It's good for deck openings to be as near the centerline as possible. The more deck openings, the harder to keep the water out.
The worst thing the sea can do is turn your vessel upside down. A wave may roll it right down on its beam ends and on over. Or one may lift its stern so high that its bow digs in, the boat trips on it and does a somersault, with a half-twist thrown in or not, as the case may be. Pitchpoling is the all-too-descriptive term used.
Shipping a sea in an open boat, a half-decked boat, or a boat with an open cockpit is something else again. It is A Very Good Thing, of course, if such vessels can remain afloat even though full of water. As long as your vessel stays afloat, stay with it. Your greatest chance of saving lives is to save your vessel. When that proves impossible, and your vessel sinks, then it is A Very Good Thing to have a life raft or dinghy to climb into. That gives you another tiny vessel out of which to try to keep the water. If you don't have such a vessel, you at least ought to have something that will float for a long time. Amen.
The book The Elements of Seamanship, from which this article has been condensed, is available from The Gestalt Journal Press, Box 990, Highland, NY 12528-0990, email@example.com.