November 24, 2013

What's hidden under water

IT HAS ALWAYS SEEMED a little strange to me that one of the most important parts of a sailboat is usually totally hidden from view. When you look at a traditional cruising sailboat in the water you can’t see what’s below the waterline: that fairly deep keel that extends a long way fore and aft.  Neither can you see what what’s hanging from the bottom of a racing boat, or a modern cruising boat, that deep narrow keel that looks more like an airplane wing than part of a seagoing yacht.

Those people who know boats will have a good idea of what’s under water, of course. Just looking at the shape of the hull will tell them what to expect. But people who are new to the sea won’t know that a long, full keel will make a boat act very differently from one that has a small fin keel.

There are many people who will tell you that a fin keel means speed, while a full, old-fashioned keel means slow going and bad pointing; but the late Bill Crealock, a well respected yacht designer, once told me:  “A racing boat accelerates quicker, but there’s no reason why cruising hulls can’t be just as fast over long distances.”  And indeed, his words were proven when one of his best-known cruising designs, the Westsail 32, came first in class in the regular race across the Pacific from San Francisco to Hawaii.

Few boats are built with traditional keels these days, and some modern cruising designs have evolved keels that are neither fish nor fowl. They’re a compromise between the efficiency of a fin keel and the directional stability provided by a full-length keel.

To help restore the lost tracking ability that is such an advantage in long-distance cruising, they often have a skeg built on the after-end of the hull, to which the rudder is attached. The shortened keel is marginally more efficient in hydrodynamic terms, but the steering is quite a lot more tiring in terms of short-handed amateur crews, particularly the popular mom-and-pop teams.

There seems to be nothing terribly wrong with this compromise arrangement, apart from its propensity to snag stray ropes and lobster pots on the skeg and unprotected propeller, but sometimes you have to wonder whether it’s really necessary to depart from the traditional full-blooded cruising design that served so well for so many years.

The Westsail 32 I mentioned above is an offshoot of the double-ended Colin Archer type, for example—a Scandinavian lifeboat and pilot vessel.  Their ability to tow two fishing boats off a lee shore in a gale was legendary.

And I can never help smiling when I hear people say fin keels are faster.  If 5 knots is slow, is 6 knots fast?  Aren’t they both slow? Cruising is primarily about safety and dependability, comfort, and seakindliness. Although much faster speeds can be useful in avoiding bad weather, cruising is not primarily about speed. That’s what airplanes are for.

Today’s Thought
There  is more to life than increasing its speed.
— Mahatma Gandhi

“Still got your horse?”
“Nah, he was too polite for me.”
“Yeah, every time we came to a jump he insisted that I go first.”

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


Team Giddyup said...

John, I find this a very traditional way to see cruising boats. The way we saw things before buying our boat. As I'm sure you have seen too, we have heard and seen all types of boat designs experiencing safety issues.

We love sailing, and being able to sail at reasonable speeds when the wind is under 10 kts (rather than motor as many of the traditional boats seem to do) is huge for us. At the end, it is know your boat and try to keep the needle in the green... - Carol Dupuis

SailFarLiveFree said...

Great perspective, as usual John. Your closing paragraph sums it up nicely by comparing 5 knots to 6 knots. But over a 1,000 mile passage, that 1 knot difference adds up. Sailboats, like every choice, are a trade-off. Coincidentally, here's what Bob Perry recently wrote about keel designs.

Anonymous said...

Whenever you see a list of "blue water" boats it is always overpopulated with full keels. I understand and appreciate it but some of the most beautiful (yes beautiful) underwater profiles I ever saw were older designs where it looked like the designer took a full keel and cut away bits fore and aft. One of the best examples is the Contest 33. It has a cutaway forefoot, a skeg on the rudder and another skeg instead of a strut for the prop shaft. She has a good turn of speed, points pretty AND is a great sea boat. The Contessa 32, Rival 32 and Seafarer 31 are similar and all seem to have found that sweet balance you mentioned in an earlier post.
Don P