tacking angles

Dixie, the good news is I’m seeing a lot of consistency in your sail trim. Remember that your wind fly is measuring apparent wind which is forward of where the true wind is. Subtracting your compass headings (you can also measure this with a protractor off your plots.) will give you your tacking angle. Remember also, that your swing keel boat isn’t the most efficient and the simple C22 standing rigging won’t allow for the tightest of sheeting angles. You can work to see if you can “dial in” your boat. Start experimenting with mast rake as more rake induces more weather helm and gets you pointing better. Then go on to stay tension, fairlead car position etc. You will also need to look at your boat speeds while you’re doing this to make sure you are not sacrificing VMG for tacking angle. In the FWIW department my C34 is in the neighborhood of a hundred degrees.

Thanks guys, I'm getting some great info here. I'll definitely use the compass and a little math to get my "real" tacking angles next time, both port and starboard.

Now speaking of tension, may I stray just a little? I recently bought a Loos gauge, and tensioned the shrouds and stays according to North Sails' guide. While I was pleased to see that my "by ear" tensioning had at least been quite consistent, I had them a fair amount tighter than North recommends. And now when I sail, I see a little slack in the leeward stays. Is this normal?? I had not expected it.

Incidentally, this change in shroud tension happened in between the two sail days shown above. It didn't seem to make any change in the angles, which I just used a protractor on, and they seem to average about 60 degrees, which is at least better than I thought.

Dixie, you are well on your way… Most sailors don’t really think about tacking angles, VMG and the like. They think that those of us who do are “nuts” to wrangle the last tenth (or is it the last half) knot out of our boats. I just like to sail well…

Standing rigging: What you did using the North guide was to static tune your boat. The next step is dynamic tune. You do this during a sail in your “typical” wind conditions by tightening the shrouds to eliminate the slack on the leeward ones. Then use the Loos to confirm the tension so you can replicate the tension later. Headstay is a little tougher insomuch that you want to reduce (eliminate) the “sag” to leeward (note that this is also adjusted out by using your backstay adjuster). Too much rigging tension will make your boat a pig in light air and too little will make your upper portion of the sail inefficient. Out here in SF, I have a heavy air, “summer”, tension and a lighter tension for the winter. When you are doing your tuning, you want to keep your mast in column and with the proper rake. Too little rake will again, make you boat a pig and not point. Too much and you will have excessive weather helm.

Shroud tension affects VMG. Rake affects tacking angle.

A little war story. Back in ’09 we took the Cal 40 to the Rolex Big Boat Series. We noticed that a Cal, whose owner, with a really big checkbook, had Stan Honey optimize the boat for performance. The thing that struck us was the total lack of lower forward shrouds. The morning of the second day we went aloft and removed ours. Another boat did the same, and another until by the end of the regatta, no Cal 40 had lower forwards. We have been racing that way ever since.

PS. I've been thinking about Gamayun's comments, and you actually might be seeing the effects of leeway in your track. That would show up as an "opening" of the course angle as your boat sags off to leeward. Don't worry, all boats have it.

GeorgeB, I can't thank you enough. With every post, you are teaching me something. Like you, I just want to sail well.

With regard to the forestay: I have always had a deuce of a time getting the jib's upper telltales to act right. Trim it, ease it, move the cars fore and aft ... nothing. From what you just said, perhaps I've always been leaving my forestay too loose!

My boat is not yet equipped with an adjustable backstay, sadly. It will be, rest assured, as soon as funds become available. But this week alone, I ponied up for new rims and tires for the trailer, and two Mustang Survival PFD's with harnesses. (These last were ordered by the Admiral, after we watched the port side jib winch momentarily disappear beneath the water on our last sail. Little old pop-up thunderstorm, on a little old bathtub lake, darn near knocked us down! Several new safety regulations have since been enacted.)