# tacking angles

3612 Views 15 Replies 6 Participants Last post by  snotter
I always thought that, since I can sail approximately 45 degrees off the wind, that I should be able to tack 90 degrees. But in practice, I'm not getting anywhere near that. My angles look closer to 45 degrees to me.

(I also don't know how much leeway is normal for my boat).

Here are a couple of tracks from recent sails in approximately 10kt winds. You can easily see where I'm running and where I'm beating. What do you think of the angles? Am I making decent windward progress, or should I expect more?

My boat is a swing keel, if that makes any difference, and the keel is in excellent condition.

Thanks for looking!

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Assuming little or no current on such a lake, those do look like rather wide angles! Unfortunately the GPS track includes effects of leeway and current, so it's difficult to analyze without being on the boat.
Yes, I don't think there is any current to speak of in either of the lakes pictured. And leeway is something I understand, of course, but I have no way of knowing how much progress it is costing me. The ninety degrees I "should" be able to tack, minus the 45 degrees I'm actually getting, makes it seem that I'm losing 45 degrees. This is more than I would have expected, but of course I'm a newbie and have nothing to base that on.

By the way, I understand how excessive heeling leads to excessive leeway, so I do try to keep my boat on her feet for the most part. I use the traveler and the mainsheet to limit heeling to generally 15 degrees or less, and weather helm to a minimum.
A more revealing index would be the change in compass heading between tacks. THAT's what should be somewhere between 90/100 degree difference, though I suspect many non performance boats will be closer to 110 degrees as a rule.

If there's negligible current, and your compass numbers are "OK" then the wide angles on your GPS track will most likely be due to the leeway you're experiencing.
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.
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Looks to me like something is off on your port tack. Maybe check the slack on the shrouds.
Gamayun, are you looking at the Lake Harris plot? I attributed that tail-off on port as 1) getting headed along that shore (persistent wind shift) and, 2) perhaps a little heating up before they tack. I like the symmetry from the Lake Eustress one. The tacks are pretty much running parallel to each other and they are in the center of the lake where I assume the wind is pretty consistent. If one tack was performing much better than the other, I’d look to see if the mast was in column first. For me, uneven shroud tension shows up in VMG but not necessarily in tacking angles.
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.
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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.
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What size jib do you have? Are you sure your jibsheet leads are set correctly?
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.)
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Dixie, Glad you’re having fun. I have a tender spot in my heart for the C22 as it was my first keel (and “real”) boat. I sailed her all over Monterrey and San Francisco Bays, doing things that now as a responsible grown up I’d never do. The fairlead tracks on the C22 are really short, but try moving the car forward to straighten up the upper part of the sail. But also make sure you don’t have excessive headstay sag. When you “sight” up the “LP” line (Clew to a right angle on the luff), where does it intersect on your fairlead track? That is where you position the car first then fine tune from there.
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What size jib do you have? Are you sure your jibsheet leads are set correctly?
Hey Sandy - In one of the tracks shown, I was flying a class jib, in the other a 150. No, I've never been sure if I had the cars set right. I gather you move them forward for light air, aft for heavy, but that's about all. And despite a lot of jockeying the cars fore and aft, I never really perceived a dramatic change in the sail shape.

I'll be implementing GeorgeB's suggestion about using the LP line to find the starting point from now on. It makes perfect sense, geometrically. Perhaps between that and a little more forestay tension, I'll find some power and/or pointing ability I never knew I had!
Dixie, next time you're out take some photos of your rig and sails so i can better visualize things. I had a 150 too, but it had a low clew which I couldn't position my fairlead properly. It was a royal pain to tack and it was happiest in a reach.

Couple of quick notes: Once you find your dynamic tune, check with the Loos and make sure you have equal tension, port and starboard. And don't be afraid to mark with tape where your initial settings for the fairleads. It will be different for your two sails and final fairlead adjustment is dependent upon prevailing windspeed. Windy days they will be a little "aft".
Will do, George, thank you!
Your tracks look identical to mine. Since I, too, can point in the low 40's, I figure my tracks are indicating the affects of leeway. My boat has a full shoal draft keel and draws only 4' 3". My beam is just shy of 14'. I have no main-sheet traveler and cannot sheet the genny so that it is inside the stays. Like you, I sail on inland lakes and have to work hard to go up-stream and up-wind. An electric winch handle is my best friend when tacking.
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