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US27inKS 06-03-2012 08:26 PM

Keel shape and pointing
A few years ago I helped a friend template his keel.

The shape started out as a complete disaster, and we had very little to go on for specs. So we guessed. Now I'm second guessing the decision on what shape to use.

I've known all along that we have been out-pointed by every other boat in our PHRF fleet, but this weekend I tracked it using a great little app I found for my phone. In playing back the track from the race I can see that our actual tacking angle was 105 to 110 degrees in 10kt winds at 5kt boat speed. This contradicts what we see on the masthead wind indicator that has been carefully set at 90 degrees. We can pinch a little higher than 45 degrees to the wind, but we lose enough boat speed to make it unpalatable for very long. So I have to believe that we're just making that much leeway.

My question for you super smart guys here is this: given the foil shape that we used (and it looks really fast), should we have opted for something a little more forgiving like an 0010 foil shape that would produce more lift at lower speed vs the 63-009 (with an actual foil thickness of 9.786%) foil with lower drag? Would the 0010 foil given us less leeway?

The other possibilities are that I suck at trimming, or Bill sucks at driving, or both.

Night_Sailor 06-03-2012 11:40 PM

Keel shape and pointing
Try lengthening your forestay or head stay an inch or two.

SchockT 06-03-2012 11:47 PM

Re: Keel shape and pointing
The shape that you chose initially looks reasonable. I won't comment on the merits of all the different sections you considered as that stuff is not my forte, but if you faired your keel to to that foil shape I would be very surprised if that was the cause of your pointing woes.

There are so many other factors that could be contributing to your problem; and you've already identified 2 of them!:) 45 degrees is downright painful! What about your sailplan? Have you done every thing you can to improve those foils, before you start re-shaping your keel?

jackdale 06-04-2012 12:17 AM

Re: Keel shape and pointing
One thought - when you installed the keel, did you change the centre of lateral resistance?

US27inKS 06-04-2012 12:37 AM

Re: Keel shape and pointing

Originally Posted by jackdale (Post 880048)
One thought - when you installed the keel, did you change the centre of lateral resistance?

Installed the keel? The keel remained attached to the boat when fairing. The draft of the keel remained approximately the same at 30% of chord. I don't think there's anything I could have done to change the center of lateral resistance.

Schock - I'm betting on the problem being crew related, and more likely me than him. We have new foredeck crew in training, but for now I trim both sails, set the pole, hoist the spin, fly the spin, douse the spin, call tactics etc. Basically everything but a little bit of traveler trimming and steering. The end result is that I do nothing very well.

Night Sailor - Good thought on the mast rake. I'll take a look at that.

SchockT 06-04-2012 03:02 AM

Re: Keel shape and pointing
Sounds like you have your hands full! I wouldn't be surprised if there was a bit of attention deficit on the part of the helmsman too! With all that going on, and green crew it would be tough for the skipper to concentrate on finding and staying in the "groove". It is entirely possible that your keel profile has made that groove narrower, but I'll leave that to the engineers to debate!

One piece of advice that was given to me years ago when I was struggling with pointing problems on my Hotfoot 20 was to stop TRYING to point. Just sail the boat fast and the point will come. It worked! When I stopped worrying about trying to stay as high as the boats around me, (some of which I would never be able to point with,) and focused on my own boat, the problem went away.

You say you are only getting 45 degrees out of her right now...if that is the case you must be getting absolutely buried right at the start! You can't hang with anyone right now?

US27inKS 06-04-2012 07:44 AM

Re: Keel shape and pointing

Originally Posted by SchockT (Post 880091)
You say you are only getting 45 degrees out of her right now...if that is the case you must be getting absolutely buried right at the start! You can't hang with anyone right now?

No, we can't hang with a soul. Even if we get a great start, inevitably someone will quickly pass us to windward. I expect to get passed, as Bill's ranger 22 is the slowest boat in the fleet, but every single boat out points us.

The rest of the fleet is made up of a pair of J-29's, a pair of Ultimate 20's, a J-80, a Laser 28, and occasionally a J-24. We will have a Santana 20 starting in a few weeks that belongs to our women's group. Perhaps we can hang with a rotating crew of inexperienced women. Maybe.

anthemj24 06-04-2012 07:10 PM

Re: Keel shape and pointing
If the helmsman is spending a lot of time pinching and "trying" to point, he could just be disrupting the flow over the keel and ultimately hurting your ability hold a lane. The other thing to consider is how flat you are sailing the boat. It sounds like you are sailing shorthanded, which means you probably don't have a lot of weight on the rail, which means you are likely heeling more than other boats. The less flat you are sailing, the more you are going to go sideways, and go sideways quickly.

The other thing is, you really should not be trying to compare how you point to the bots you mentioned. Those are all well developed one design and or performance classes, with a lot of time spent by sail makers to get a shape ideally suited to making that particular boat point. Even that Santana 20 has a cult following and therefor time spent by sail makers optimizing shapes.

My advice would be to focus on sailing the boat fast and working on crew work and boat handling , and not so much on pointing. Sail fast, sail in pressure, and make fewer mistakes than the next guy. Your boats ability to point or not point as well as the one next to you is already factored into your handicap. The fact that you have one person doing 4 jobs is not.

GeorgeB 06-04-2012 07:25 PM

Re: Keel shape and pointing
Wow, you guys are certainly committed to your racing program. How much weight did you guys remove from the keel and did you try to put it someplace? I do not think that you can take your bottom sides any faster assuming you faired, sprayed and burnished the bottom. Have you done something similar to the rudder? I have heard that some miter a inch flat on their trailing edge – but this is a speed thing and not a pointing thing.

I think you need to start looking aloft. First things first, 110* tacking angle is probably pretty normal for this mast head boat. Also, the masthead fly is measuring apparent wind angles and not the true tacking angles you are getting on the chart plotter. To bring your tacking angle in, can you re-run your T-Track so you have an 8 * sheeting angle on the jib? Tighter sheeting angles are what gives the fractional rigs their tighter tacking angles. After that, it is all rig tune. What is your designed rake on the mast? I’m assuming that a plumb bob should be about 5” from the ram’s horn. After that, it is all about wire tension (dial in the boat with a Loos gauge in hand). After that, it is all about driving and trimming. Most likely you are not in sync with each other on your tacks and are turning the boat much more than you should. Trimming also gets into the area of boat speed, another topic. If you need a coach, I work for beer, sandwiches, plus expenses.

Jeff_H 06-04-2012 07:44 PM

Re: Keel shape and pointing
First of all, since this is a friend's boat it might be helpful to mention the type of boat that you are sailing.

But as I read your post, I am skeptical that its a keel sectional problem, or a mast rake problem. You do not describe a lee or weather helm, so mast rake seems like a red herring, and even if you completely screwed up the foil shape, I doubt it is the problem.

What you are describing is a classic case of bad sails, bad rig tension or bad sail trim. It is surprising how little it takes for a set of sails to be blown out enough to kill speed and pointing enough to be very noticable.

And frankly, it sounds like your boat is point extremely badly, not just slightly so. If the 'squares' on your windex are truly set at 90 degrees this boat should never get near a race course. Because the windex reads apparent wind on each tack, the typical angles between the center of the squares (i.e. wires) on a decent race boat is somewhere around 40-50 degrees.

I suggest that you walk us through the basics.
What kind of boat is this?
Does the Jib have top, middle and bottom forward telltales?
Has the lead been set so that each break at the same time?
When the jib is full in, does the leech curl sharply inward or flutter?
When the jib is full in, what is the angle between the centerline of the boat and a line between the Clew and the Tack?
Are there leech telltales on the mainsail?
When the mainsail is set properly, is the boom on the centerline, and sighting from below the boom, is the upper batten set parallel to the boom?
Here's the trick question, do any of the battens **** to windward and do all the telltales fly?
When the main is set properly?
Are the sails too full or too rounded? (within reason this is about outhaul tension, halyard tension, backstay tension and sheet tension- throw away the cunningham)

Okay, when everything is set properly, can the helmsman keep the jib telltales flying?

If your answers are that the sails are in good shape and properly set and you still only show and apparent wind of 45 degrees, I would suggest that you delegate this boat to be the boat that you cruise and find a decent boat to race. ;-)

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