Sail Triming with in-mast furling

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Curt Weaver

Mr. Guillette I am a customer and a fan of your sail trimming guide. It helped immensely on my H33.5. Now that I own a 410, with in-mast furling, I'm having to learn a new way to sail and trim. For instance, with the free-footed main, it seems that I now have to control draft depth with the outhaul. That's easy enough, but then every adjustment to draft depth moves draft position significantly. The end result is that I am finding it challenging to get the most out of this boat. Do you have a Sail Trim Guide for in-mast furling? Hope Floats
 
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warren feldstein

I'd be interested too!

I have long wondered if such a guide exists. Now I have the answer. With all of the in mast furlers out there, must be some market for it.
 
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Don Guillette

Curt: I'm glad you found my Sail Trim Chart helpful. Please refer to the Quick Reference Sheet that was enclosed with your Chart and which identified the sail trim controls for the main and jib that are used to adjust draft depth, draft position, twist and angle of attack. Mast bend and outhaul are primarily used to adjust draft depth (belly). As you decrease tension on the outhaul you are increasing the draft depth. When you bend the mast you are flattening the sail and reducing the belly. As you've noticed, when you adjust the outhaul, the draft position moves also. The reason for that is that mast bend and outhaul are also 2 of the 5 adjustments for draft position. The other 3 draft position controls are the boom vang, Cunningham and mainsheet. By INCREASING tension on the 5 draft position controls, you move the draft position forward and by DECREASING tension you move the draft position aft. So it is a balancing act and that is the reason you have all the sail trim controls at your disposal. It is like adjusting a 4 barrel carb on your car. You have to fiddle with all the jets to get it right. For example, assume you ease the outhaul. That increases the draft depth (belly) and also starts to move the draft position aft. Suppose you don't want the draft position aft. To compensate, increase tension on the boom vang, Cunningham and mainsheet and move the draft position forward to where you want it for the wind conditions you are sailing in. Your in-mast furling system works the same way you other system worked. There is no difference. Also, the free-footed aspect is really no different than the bolt rope system. If I've confused anyone with the terms draft depth or draft position, they should go way, way back in the archives to where I furnished a detailed description of these items. In order to get 100% efficiency from your sails, it is necessary that you completely understand draft depth, draft position, twist and angle of attack. Those 4 items are what sail trim is all about and if you don't understand them, sail trim will always be confusing.
 
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Don Guillette

I'd Be Interested Too

Warren: A Sail trim Chart does exist ( I wrote it) and it is available through the ships store at sailboatowners.com. It identifies all your sail trim controls for the main and jib and identifies the setting you need to make for each point of sail and wind condition. It tells you WHAT adjustment to make. The Sail Trim Users Guide is a book that tells you WHY you are making a particular sail trim adjustment. It also is availabel through Sailboatowners.com. Both these products will make your sailing experience much more enjoyable.
 
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Curt Weaver - Hope Floats

Further confusion

Thank you very much for the reply. I have a few follow-on questions, because I am still confused. First of all, since it is an in-mast furler, I don't have a Cunningham. So that control is gone. Second, since it is a B
 
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Don Guillette

Sail trimming with in mast furling

Curt: I keep forgetting how the Hunters are set up. Sorry. Mast bend and the cunningham are important controls to be missing but moving on, lets first discuss draft position and what happens when you increase tension on the controls. Draft position forward or under 50% equals less power. The more the draft postion moves forward the flatter the sail gets. As the wind pipes up, we always move the draft postion forward to depower the sail. One way we do it is to tighten the outhaul, which flattens the sail. If you ease the outhaul, you are putting in more draft depth (belly) - more belly equals more power and less belly (flat sail) equals less power. Draft position aft (over 50%) equals more power. The more you ease the outhaul, the more belly you put into the sail and the draft position moves aft. As the wind increases it is always pushing the draft position aft. Scientifically, I don't know how this draft position thing happens but I know it does. Sometimes the effect is different then we surmise. I can only take the word of an expert like Dennis Connors. Refer to his book "Sail Like A Champion", page 122 under Cunningham. I know you don't have a Cunningham and can't bend the mast but this is what he says about draft position movement -"The Cunningham works with mast bend. When bending the mast the draft moves aft and more Cunningham moves the draft position forward". So, when you tighten the controls, the draft goes forward and when you ease the controls it goes aft. On my boat (C30), which has all the normal sail trim controls, I can move the draft position forward and back say from about 40% to 55% without any problem. On a 12' boom the movement is less than 2' or not very much. It is hard to see the vertical imaginary line in the deepest part of the main move along the boom as the line is not perfectly vertical. Curt, I'm sort of at a loss to completely answer your question as I've never sailed on your type of boat and therefore have no real experience. I'd really like to try a BandR rig to see how it functions. I had a couple of Hunter owners in a recent sail trim seminar I conducted and we were going to put together a sail but it has not happened yet.
 
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Curt Weaver - Hope Floats

Invite

Don If you are ever in Jacksonville, Florida, let me know and we'll go shake down a Hunter 410 together. Curt
 
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