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Old 17-12-2015, 10:07   #31
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Re: Going hard to wind, main sail trim.

Every situation is different, but If heeled a lot I would adjust the headsail for speed and pointing, not bring the traveler up too much, then slack the mainsheet until the boat is moving how you want. Even a touch of luffing on the mainsail is ok often. If overpowered and not pointing well put a reef in as mentioned.
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Old 17-12-2015, 10:10   #32
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Re: Going hard to wind, main sail trim.

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Originally Posted by KeepInTune View Post
As I don't have experience with adjustable backstays, can you give us a quick explanation of how adjusting backstays (therefore bending mast) affects sail design and performance? Obviously, this is only an option on fractional masts(?).
thanks.
Assuming you have no pre bend in the mast, keeping the backstay loose keeps the mast straight. If you tighten the backstay, the top of the mast bends backwards creating a bow in the middle of the mast which tightens the luff of the sail at that point. The net effect is the sail flattens somewhat and the draft of the sail moves further aft than it was with the backstay loose and the angle of entry to the wind narrows and makes pointing easier. Easing a backstay that was tight has the opposite effect - draft moves forward with a more rounded entry.

Add halyard and/or cunningham tension and you can move the draft forward while keeping the sail relatively flat.

Use all three controls simultaneously (cunningham, halyard, backstay) to get the draft position and depth where you want it for various wind and sea conditions.

Clear? Probably not...
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Old 17-12-2015, 10:15   #33
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Re: Going hard to wind, main sail trim.

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Originally Posted by canyonbat View Post
Not going to offer an opinion on the trim, not an expert! I do, however, have a suggestion, or maybe a question. We use the "VMG to Wind" function on our chartplotter to find the best pointing angle. Our best VMG seems to be at about 31 degrees on our Seaward 25. Is this a good idea or are we fooling ourselves?
nothing is more important than vmg when going to weather and pointing 31 degrees is great but the real question is, 'how do you point that high?' that is the crux of the entire problem here, is it not? how do i sail the boat the most efficiently hard on the wind in a 20 kt blow? or to put it your way, how do i make the best vmg when going to weather?
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Old 17-12-2015, 10:18   #34
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Re: Going hard to wind, main sail trim.

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Originally Posted by OldFrog75 View Post
Add halyard and/or cunningham tension and you can move the draft forward while keeping the sail relatively flat.
I'm a little confused: Wouldn't tensioning the halyard and/or Cunningham effectively tighten the luff, thus flatten the forward part of sail...therefore transferring more draft further back?
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Old 17-12-2015, 10:22   #35
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Re: Going hard to wind, main sail trim.

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Originally Posted by canyonbat View Post
Not going to offer an opinion on the trim, not an expert! I do, however, have a suggestion, or maybe a question. We use the "VMG to Wind" function on our chartplotter to find the best pointing angle. Our best VMG seems to be at about 31 degrees on our Seaward 25. Is this a good idea or are we fooling ourselves?
I've never been on a sailboat that could point that high. Sounds pretty special.

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Old 17-12-2015, 10:28   #36
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Re: Going hard to wind, main sail trim.

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Originally Posted by KeepInTune View Post
I'm a little confused: Wouldn't tensioning the halyard and/or Cunningham effectively tighten the luff, thus flatten the forward part of sail...therefore transferring more draft further back?
It is very confusing but the short answer to your question is "no". Advanced math isn't my strong suit so I generally just memorize the rules and apply them to the best of my ability. Usually more interested in what works than I am in how it works. I'll leave it to the rocket scientists on CF to explain the physics of it...

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Old 17-12-2015, 10:31   #37
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Re: Going hard to wind, main sail trim.

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Originally Posted by Cheechako View Post
Every situation is different, but If heeled a lot I would adjust the headsail for speed and pointing, not bring the traveler up too much, then slack the mainsheet until the boat is moving how you want. Even a touch of luffing on the mainsail is ok often. If overpowered and not pointing well put a reef in as mentioned.
many here seem to have trouble understanding the full benefit of the traveler. yes it can be eased when hard on the wind and yes this will reduce heel and weather helm but it also means pointing lower to get maximum drive out of the mainsail. pulling the traveler to weather and easing the main sheet has the same effect of reefing the main only much easier to do. by keeping the boom centered and the lower portion of the main driving strong while spilling air out of the top of the main to leeward with the 'twist' that you've induced is what's needed. as the wind increases, keep the traveler up and ease the mainsheet. when it gets to the point that easing the sheet further causes the main to flog it's time to shorten headsail.
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Old 17-12-2015, 10:34   #38
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Re: Going hard to wind, main sail trim.

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I've never been on a sailboat that could point that high. Sounds pretty special.

ha. ditto.
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Old 17-12-2015, 10:42   #39
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Smile Re: Going hard to wind, main sail trim.

Reef? He should trim properly to go as fast as he can! He's a sailor not a cruiser! With the rail down you are slow. You have to depower by trimming. Your best bet is to ease main sheet until you feel less weather helm. Then the traveller to leeward from where it is now in smaller increments with the vang eased or off to create enough twist at the top to dump wind and depower that way. It may end up to leeward of center but not to the point of flogging. And bring the jib car back to create twist in the upper part of the jib. Flat sails and a flat hull is the goal but in 20 you will need twist! Gradual changes will get you there for your hull and sails. You can't sail by a checklist. Keep experimenting. Speed =smiles
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Old 17-12-2015, 10:43   #40
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Re: Going hard to wind, main sail trim.

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Originally Posted by KeepInTune View Post
I'm a little confused: Wouldn't tensioning the halyard and/or Cunningham effectively tighten the luff, thus flatten the forward part of sail...therefore transferring more draft further back?
no, in fact tensioning the luff does move max draft forward. i get numerous questions when i teach sail trim and some i simply can't answer. one such question is exactly the one you ask and my reply is that i don't know why but it's the way it is. there are a number of things in sailing that can only be explained with TLAR, or, that looks about right. hard to teach, even harder to learn. you either get it or you don't.
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Old 17-12-2015, 10:47   #41
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Re: Going hard to wind, main sail trim.

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Originally Posted by pitlaw View Post
Reef? He should trim properly to go as fast as he can! He's a sailor not a cruiser! With the rail down you are slow. You have to depower by trimming. Your best bet is to ease main sheet until you feel less weather helm. Then the traveller to leeward from where it is now in smaller increments with the vang eased or off to create enough twist at the top to dump wind and depower that way. It may end up to leeward of center but not to the point of flogging. And bring the jib car back to create twist in the upper part of the jib. Flat sails and a flat hull is the goal but in 20 you will need twist! Gradual changes will get you there for your hull and sails. You can't sail by a checklist. Keep experimenting. Speed =smiles
yes, twist in the main is the answer but you cannot achieve that by easing the traveler to leeward. pulling the traveler to weather while easing the main sheet is the way to get er' done.
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Old 17-12-2015, 11:35   #42
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Re: Going hard to wind, main sail trim.

As my friend Dave from Kansas used to say, "a flat sail is a fast sail". He sailed Lightnings, but I think this is true with cruising boats as well.

I'd advise you to play your traveler. Drop it down 6" to 12" and allow the main to luff more. That should reduce the tendency to round up in puffs.

Backstay tension, if adjustable, does two things that are helpful: it flattens the headsail by removing sag, and it flattens the main by pulling the middle of the mast forward. Unfortunately, many (most) cruising boats have a set it and forget it backstay, which limits the amount of sail control on the main in particular.

Christmas cheer,

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Old 17-12-2015, 11:41   #43
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Re: Going hard to wind, main sail trim.

Sounded to me like his traveller was "hard to windward" which I take to mean too far and thus hooking or closing his main. Agree you generally dont ease all the way past center to leeward but assuming he is too far, easing a bit could help. Depends on the look of the sail, the feel of the wheel and the heel.
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Old 17-12-2015, 12:08   #44
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Re: Going hard to wind, main sail trim.

You say you only backwind in top third of luff? It sounds like your jib sheet lead is too far forward, causing top part of jib to be over trimmed compared to foot. All sails should be trimmed so foot is slightly closer to relative wind than the head. If done right and with decent set of sails, you should see backwinding more in center to lower luff not at all at top.

Never set boom to weather of centerline and yeah, get a racing skipper out on your boat if possible.

Doug
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Old 17-12-2015, 12:10   #45
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Re: Going hard to wind, main sail trim.

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Originally Posted by OldFrog75 View Post
I've never been on a sailboat that could point that high. Sounds pretty special.

That is apparent wind angle and bearing. With our shoal draft and taking into account leeway, we are probably lucky to be getting 60!
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