The water is too polluted up there for my liking and the winds
too unreliable. Then, there's the people of whom Bobsprit is
a good example. I would have to be crazy to go up there by
choice.

The reason I would probably beat you in a race from Key
Largo to Marathon is local knowledge (shortcuts, etc.) and
unless there was enough wind for you to reach hull speed
I would beat your boat because mine goes faster in lighter
winds. Yours has too much drag from propellers and
the extra wetted surface of two hulls. Also, I can hang
proportionately more sail area than you can.


"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message ...
"Simple Simon" wrote in message
...
If you ever get up the nerve again to motor down the Ditch to
Key West give me a shout when you get near Key Largo.

I'll race you to Marathon and no motors allowed. You will
be sooooo far behind.


That is such a pathetic challenge - its hard to see how you could keep up with me for 5
minutes.

For starters, my SA/disp is over 20, while yours is about 14.25. This predicts the speed,
as a percentage of hullspeed, for a given wind. Meanwhile, my hull speed (not that I'm
constrained by it, as you are) is about 8 knots. Your hull speed is about 6.3 knots.

I don't have the Polar diagram for either boat, but lets try to do a VPP-like prediction,
based on published data and tables. In a 14 knot breeze, a sail generates 0.02 HP per
square foot. For you, that's 6 HP, or 1040 pounds/hp; for me that 10.8, which is 815
pounds/hp. This means (using a table) that you'll move at about 1.05 times the sqrt of
your waterline, or 1.05x4.7 or 4.9 knots. My boat, on the other hand, will be at 1.14 x
sqrt(WL), or 6.7 knots, or 36 percent faster. I'm not even considering that my boat goes
faster than the table predicts, because of the very narrow effective beam of the
individual hulls.

Your boat will get to its 6.3 knot hull speed at some point around 20 knots breeze - at
which time I'll be flying away at 10+ knots. At low speed, in a 10 knot wind you'll be at
4.5 knots; I'll be at 6.2 knots. BTW, these number are fairly good predictors - I'm a tad
slower than the 10 knot wind prediction, a tad faster than the 14 knot. This makes sense,
since at low speed the wetted surface affects me more than a normal boat; at higher speed
I have less wave making resistance.

You can talk about your 130 jib, but I have one too. Or your chute, but I have a new
asymm. How about your main, is it a 3 year old modern full batten main or a blown out old
bag?

Do you have any chance? In light air anything can happen. And you certainly have local
knowledge. Short tacking up a narrow channel would not be pleasant for me. Upwind, the
margin might be a bit closer, though your shoal draft keel doesn't help you much. But on
a relatively open course, in any wind over, say 8 knots, I'll be going 35% faster than
you, or more. The last time I went by your mooring I was doing 8-9 knots, and averaged
that for the entire day.

Frankly, unless there's a dramatic change in my life, I don't think I'll get my boat down
there again for a few more years (though I may be driving by at Christmas). Why don't you
bring your fine bluewater craft up here next Summer?

-jeff www.sv-loki.com
"The sea was angry that day, my friend. Like an old man trying to send back soup at the
deli."