Tacking Angles

[mackinac]

Can anyone suggest what optimum tacking angles are for a P-35 in moderate wind? I noticed last weekend that I could not tack within 90 degrees. I think I have excess headstay sag, but I hate to tighten up the rig needlessly.

[Matt]

As the wind increases the tack angles get broader. There are a couple of affects that could be taking place while you are Tacking.

Make sure that your Center Board is down a bit. if it is in the up position then the boat will spin downwind and increase your angle

Also sheet out your main a little bit. As you finish the tack the boat is a little stalled. With the main trimmed in the boat has a hard time "getting on its feat" sort of speak. This will push your boat sideways and then down as you accelerate.

Also look at the amount of weather helm that you have. If in light conditions the boat has a tendency to round up then you have weather helm.. To fix this tighten your headstay, this will move the center of effort farther forward

Just some thoughts
Matt

[mackinac]

Thanks for the reply Matt. Assume I do all that, and have the rig adjusted properly, etc. Then, after I get the boat footing after I come out of a tack, what do you think an optimum "tacking angle" in moderate winds would be , (i.e. the included angle between the port/starboard tacks).

I'm thinking 90 degress for an older full keel boat, but I don't really know. Got any ideas?

[What promted this question is that last fall a Beneteau 36.7 did a total "horozon job" on me. He must have been pointing 15 degrees higher and going twice as fast. I realize he is modern Farr designed, 7 foot draft, SA/D = 20++, but it still got me thinking about optimizing my set up and trying to do the best I can.]

I think I might install a backstay adjuster - probably a Wichard wheel.

[Matt]

I did some investigating into the comparison of those two boats (Beneteau 36.7 and the Pearson 35). There are some obvious differences. While the narrower 35 should track upwind better the 36.7 has a much greater sail plan. The upwind sail plan on the 36.7 is larger therefore it can track straighter faster. Creating the horixon job.

Pearson 35 Sail area is 550 sq Ft
Beneteau 36.7 sail area is 657 sq ft with a jib

The Beneteau 36.7 also has a longer LWL at 30' opposed to the 25 of a pearson 35.

Also the keel design is very important. A deeper keel will tack (pivot) faster than a shoal or full keel. On the pearson there is more lateral resistance to move throught the water so it takes longer to tack.

The ability to point up wind is a direct relationship to the sail plan and the skipper. Flat, new sails will point higher than old roller furling ones. Also while racing the Skippers sole job it to make the boats go fast. When I race upwind I look at the luff of the jib and the water ahead of the boat for about 50 yards. Looking anywhere else is slow. There should be other people on the boat to look around. Another ting is to get rig of extra weight.

Now the Beneteau 36.7 has a PHRF rating of about 95 the Pearson rates about 175 big difference. If you are worried aout the horizon effect my suggestion would be to get in front and cover the other boats. Slow boats can win races but they have to be smarter.

Next time I am out in moderate wind I'll get some angle measurments and let you know what I get.

Cheers,
Matt