pointing, pinching, VMG - SailNet Community
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post #1 of 23 Old 4 Weeks Ago Thread Starter
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pointing, pinching, VMG

Hello,

I am racing my boat in a double handed series. This is simple, casual, non-spinnaker racing (for me). I am sailing with my daughter and we're having lots of fun.

Last night we sailed in just about perfect conditions: Wind 7-10 true, flat seas. On the upwind leg I had the sails trimmed in hard. Halyard and outhaul set properly (IMHO). I had the upwind mark programmed into my plotter (B&G Vulcan), I was displaying SOG and VMG to the mark.

I noticed that VMG was highest when it felt like I was pinching. SOG would decrease but VMG would increase. The inner tell tails on the headsail were fluttering. The heasail was in all the way, the cars were set right too (even break of the tell tails from top to bottom.

I definitely felt like I was pinching and if I headed down a little the SOG would increase and the telltails looked better but the VMG decreased.

So, am I best off trying to maximize VMG or steering to the tell tails?

Thanks,
Barry
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post #2 of 23 Old 4 Weeks Ago
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Re: pointing, pinching, VMG

Quote:
Originally Posted by BarryL View Post
Hello,

I am racing my boat in a double handed series. This is simple, casual, non-spinnaker racing (for me). I am sailing with my daughter and we're having lots of fun.

Last night we sailed in just about perfect conditions: Wind 7-10 true, flat seas. On the upwind leg I had the sails trimmed in hard. Halyard and outhaul set properly (IMHO). I had the upwind mark programmed into my plotter (B&G Vulcan), I was displaying SOG and VMG to the mark.

I noticed that VMG was highest when it felt like I was pinching. SOG would decrease but VMG would increase. The inner tell tails on the headsail were fluttering. The heasail was in all the way, the cars were set right too (even break of the tell tails from top to bottom.

I definitely felt like I was pinching and if I headed down a little the SOG would increase and the telltails looked better but the VMG decreased.

So, am I best off trying to maximize VMG or steering to the tell tails?

Thanks,
Barry
If the VMG number is better, then that is what you should do, barring any other factors. You were probably able to get away with pinching because of the flat water. Had there been bigger seas you likely would have been forced to foot off a bit for power through the waves.

When you say you were "pinching" how close to the wind were you sailing?

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post #3 of 23 Old 4 Weeks Ago
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Re: pointing, pinching, VMG

You’re racing. The fastest time around the course wins. If your electronic way points give you the fastest way around the course then vmg is the only thing that counts. Of course this assumes your electronics account for current, set and there are no wind shifts.
A possible explanation lies in your sails. You’re right they should be the perfect foils to give the best vmg. In which case it’s possible if their are places where there aren’t telltales that are producing most of your drive. This could be from trim or the shape of the sails themself (stretch, creep (if laminated) or other issues.
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post #4 of 23 Old 4 Weeks Ago
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Re: pointing, pinching, VMG

Inner headsail telltails just starting to break or flutter is exactly where you want the sail trimmed/boat pointed. For the main, you want the top one or two breaking ~50% of the time.

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Re: pointing, pinching, VMG

Good experience
I hope she hets tired hauling away the silver...
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Re: pointing, pinching, VMG

in those conditions the VMG is what you want to go with.
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Re: pointing, pinching, VMG

You didn't say much about how your mainsail was trimmed, except that generally your sails were "trimmed in hard." That suggests that your mainsail was trimmed in to the boat's centerline.

What's the first thing sail instructors teach about trimming the mainsail? Trim it in close and then ease it out until it just begins to lift at the luff. But most racers trim it in to the centerline, so that the sail lays down smoothly from luff to leech.

Maximum speed and efficiency are achieved when the jib and mainsail are in balance. If the mainsail is over-trimmed, the mainsail drives the transom to leeward, and the helmsman must use rudder to counteract that tendency and keep the boat on it's heading. Using the rudder creates drag and slows the boat. If the boat has a tiller, you can feel the tiller pressure, and adjust the mainsheet or traveler to eliminate the tiller pressure. If the boat has a wheel, there isn't much "feel" to help you, and you just have to know that it's happening and trim the mainsail accordingly.

Why did you "feel like it was pinching?" Was it because the mainsail was lifting slightly at the luff? If so, then that means you were probably well-trimmed and steering in the groove.

If the jib telltails are streaming correctly and the mainsail telltails are streaming correctly and the mainsail is lifting very slightly at the luff, your sails are well balanced and rudder drag should be minimal.
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Re: pointing, pinching, VMG

When used to race, I would take some races just as practice sessions. Using other boats as trial horses, I would tweak and test, focusing on what worked, without fretting about out come. In fact, those races often accidentally went pretty well, because I focused on sailing well instead of stressing over position. With beach cats, it's usually more about speed than tactics anyway.

Sailing alongside other well sailed boats is a great way to tune. The best trim is boat and condition specific. That's the fun!

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Re: pointing, pinching, VMG

Sailing to your best VMG angle doesn't mean your sail trim is optimal. It merely means you're at the most favorable angle, despite the fact that your sail trim might be poor. If you want to maximize speed and pointing, you first have to fine tune your sail trim, and then find the optimum angle for the best VMG.

Optimizing performance to windward is primarily about optimizing sail trim, not about optimizing your VMG angle.
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Re: pointing, pinching, VMG

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Originally Posted by Sailormon6 View Post
Sailing to your best VMG angle doesn't mean your sail trim is optimal. It merely means you're at the most favorable angle, despite the fact that your sail trim might be poor. If you want to maximize speed and pointing, you first have to fine tune your sail trim, and then find the optimum angle for the best VMG.

Optimizing performance to windward is primarily about optimizing sail trim, not about optimizing your VMG angle.
VMG angle is a bit contradictory, My understanding of VMG is velocity made good toward a fixed point. The actual angle will vary as you approach that point.

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