What Speed Is Considered Good Performance?

[Lease]

Ah, we are talking about different things.

If someone asks me; "how fast does the boat go?" I think in terms of speed upwind.

Fun to debate though, so;

Maximum displacement speed is the speed at which a displacement hull will move through the water in displacement mode. I use this notion as a marker for the approximate goal to achieve when working upwind. As very few boats have the length/beam/ballast/sail/bouyancy ratios to plane upwind, then displacement speed seems reasonable to use from my point of view.

The equation turns pear shaped when a boat is off the wind. Hull shape and other considerations then determine how fast the boat will go in a given wind/sea state. Boats with less rocker tend to plane more easily than boats with more rocker for example. Once a boat is on the plane, then its maximum theoretical speed is limited only by the amount of wetted surface area and the power applied. Ergo, 90hp on a Mac = 25 knots (or thereabouts).

Therefore it seems to me that what Gerr postulates is the maximum displacement speed that the hull will achieve before it is planing. It then becomes a planing threshold, or transitional speed. I really don't think that the Mac has the goods to get anywhere near this speed when working to windward however, and so would pretty much dismiss it in that context.

The question then becomes, is the Mac capable of going faster than 8 knots (and therefore planing) on its fastest point of sail?

Don't know - haven't been there. I do have some doubts when running on a beam, or square reach, because the righting moment just isn't there to sail the boat properly in fresh breezes (though Beene's trapeze efforts would have revealed some interesting data, but I can't find a reference to speed in his posts) on these points of sail. DDW with a square kite in a big breeze would be interesting though, and I would think that sometime, somewhere, someone has had a real 'ride' on a Mac in these conditions.

[Zoran]

I have no idea are we planning or not, and I do not want to start that discussion. The best I ever achieved in my X was 7.6 kt close hauled for about 25 minutes, I had to furl in my jib on my way back and I still had 8.2kt running. The other time I achieved 9.6kt on broad reach for about 2 hours. In both situations I had a bit too much sails and a reefing point between the existing one and full sail would be ideal. Setup was full furling jib, and full standard main.

Zoran

[eric3a]

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[tlperrine]

I have never had luck pushing my boat beyond 8 MPH. I have been in many wind conditions on lakes here in Colorado. This boat just doesn't seem to go fast for me. I wish I knew how to get more boatspeed out of it. I wish I had a good answer for faster speed. Any ideas out there?
Thanks, Terry

[Kevin]

Terry,

Just to be clear, you are talking under sail, right? Something around 8 mph under sail on a lake with no current to assist isn't bad in my opinion. For lake sailing I was happy when I got an honest 6 mph for a good run. On the river delta 6 could be doing real good.

Now with the motor, that's a whole nother game.

Kevin

[johnnyonspot]

I'm happy with 2 mph, just so long as I am sailing.....