November 5, 2013

The question of seaworthiness

NO MATTER HOW SMALL a sailboat we may own, we all like to think she’s seaworthy.  There’s a bit of Walter Mitty in all of us that likes to take it for granted that if the worst came to the worst, and we had to flee from a devastated country, our sailboat would be capable of taking us across oceans until we found a safe haven.

But what really makes a boat seaworthy?  Well, a seaworthy boat is one that is:

— Able to recover from the inverted position without serious damage to her hull, deck, rig, rudder, or interior, and without taking on substantial amounts of water.

— Strong enough to look after herself while hove-to or lying ahull.

— Seakindly: that is, free of violent, extravagant, jerky rolling and pounding.

— Well balanced, docile on the helm, and easily handled under sail at all times.

— Agile downwind, to maneuver out of the way of plunging breakers.

— Habitable, that is, able to carry ample crew, with good headroom and comfort, plus water and supplies, for extended periods.

— Able to beat to windward, or at least hold her ground, in all but the heaviest conditions.

— Capable of good average speeds on long passages.

Well, that’s the theory. But the truth is that no boat can fulfill all these requirements to perfection, since many are mutually exclusive. For instance, the long keel that allows a boat to hold her course well also makes her less maneuverable. The widely-spread-out sail plan that helps balance the helm also makes her less efficient to windward.

Everything in boat design is  a matter of trade-offs. One desirable feature must be sacrificed for another. But the most successful designs spring from a kind of mysterious resonance that occurs when sacrifices, judiciously made, add up to a net gain.

One last point remains to be made, and that is that seaworthiness also includes the skill of the crew and their experience with that particular boat.  Many an unseaworthy old bucket has made it to the safety of port because her skipper and crew knew and understood her foibles, and how to nurse her through a storm.

Today’s Thought
My soul is full of longing
For the secret of the sea,
And the heart of the great ocean
Sends a thrilling pulse through me.
— Longfellow, The Secret of the Sea

“Mom, is it true what they told us at Sunday school, that people come from dust and go back to dust?”
“Yes, dear, that’s right. But what makes you ask?”
“I just looked under the fridge, and someone is either coming or going.”

 (Drop by every Monday, Wednesday, Friday for a new Mainly about Boats column.)


SailFarLiveFree said...

Very clear and concise post on seaworthiness, John. Well done! So how do you come out on the catamaran debate, since they don't typically meet your first criteria of being able to recover from the inverted position?

John Vigor said...

Well, the likelihood of a multihull's capsizing is small if she is in the right places at the right times, but of course it can and does happen.

The idea of positioning a fixed float at the mast top to prevent a full capsize has never been universally accepted, and although some multihulls may be able to regain their feet by flooding one hull or inflating a special masthead float, I'd say there were two requirements I'd like to see.

Firstly, since most multihulls won't sink, even if completely inverted, they should always carry an EPIRB or PLB to attract rescuers.

Secondly, they should have an escape hatch in the bottom of the boat or somewhere where the crew can gain access to the surface without having to dive through a dangerous tangle of lines and rigging.

If not a ready-made hatch, then a marked position and the tools needed to cut a hatch in an emergency.

John V.