No matter how complicated folks try to make sail trim, there are only 4 things you are adjusting and we have discussed 3 of them. DRAFT DEPTH is the amount of belly you put into the main or jib. DRAFT POSITION is where an imaginary vertical line that is draw through the deepest part of the sail intersect a point on the chord line. TWIST is the amount of sag in the top of the sail. The last element is ANGLE OF ATTACK. Sailing authors make this item very difficult when it actually is the simpliest to understand. All of them start out with the definition and I hate to do this but to prove a point ---- "angle of attack is defined as putting the sail at an angle to the wind so that the sail turns the wind so the high speed flow and low pressure are on the leeward side and the low speed flow and high pressure are on the windward side, thus causing the boat to move forward". Name me one beginner to intermediate that would understand that mouthful? Here's what it means in plain English. The more you trim in your main or jib or move the fairleads inboard, the more power or lift the sails develop. The reason is your forcing the wind to turn around the sail. The more you ease your sails out or move the fairleads outboard, the less power or lift the sails generate because the wind just slids off the sail. The controls for angle of attack on the mainsail are the mainsheet and traveler and on the jib it is the inboard and outboard placement of the fairleads and to some extent the jib sheet. That's all there is to the concept of sail trim. All of the sail trim controls for the mainsail and jib on your boat are designed to adjust those "4 Elements".The next thing that you have to figure out is what is the proper adjust for each point of sail and wind condition. When you get to that point you'll know more about sail trim than 75% of the sailors worldwide. To help you understand where your at from a sail trim standpoint I'm going to post quiz. Have some fun with it. After you finish with it, give it to your smartest sailing buddy and see how he does with it!!!
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Respectfully disagree, Don
You say "The more you trim in your main or jib or move the fairleads inboard, the more power or lift the sails develop." This is only true up to the point that you begin to stall the sail and get a separation 'bubble' started on the leeward side of its luff. Any further trimming from that point results in less lift. You say "the more you ease your sails out or move the fairleads outboard, the less power or lift the sails generate . . ." Most beginners overtrim their sails and are told, "when in doubt, let it out." I know you didn't mean to, but you seem to be implying sheet everything all the way in, all the time. Or did I miss something along the way?
You say "The more you trim in your main or jib or move the fairleads inboard, the more power or lift the sails develop." This is only true up to the point that you begin to stall the sail and get a separation 'bubble' started on the leeward side of its luff. Any further trimming from that point results in less lift. You say "the more you ease your sails out or move the fairleads outboard, the less power or lift the sails generate . . ." Most beginners overtrim their sails and are told, "when in doubt, let it out." I know you didn't mean to, but you seem to be implying sheet everything all the way in, all the time. Or did I miss something along the way?
Bob:I hope I didn't mislead too many people. Sometimes I assume sailors know more than they do and I address my stuff to the middle beginners, who have some idea of what they are doing. To add to Bob's point, which is obviously correct, there is a point of diminishing return with everything. I guess I should add that caveat to every discussion but hopefully mates would understand that you can only trim in or ease out so much and the sails stop working. They would find out quickly enough when they tried to put the principles into practice. That was the point of my sentence that said "you have to figure out the proper adjustment for each point of sail and wind condition". The point we are at in the discussion is that I hope everyone understands what draft depth, draft position, twist and angle of attack is. I'll explain later, how they all work together. As I explain in my book "you should not move onto the next chapter until you have a complete understanding of the 4 elements because if you don't, nothing that follows will make any sense".
The trickiest parts
for me, are the transitional areas where two controls affect the same variable, twist, for example. I know that all the controls are inter-related, and your point of UNDERSTANDING what and why a given configuration acts the way it does is right on the money. So many "learn to sail" volumes just say things on the order of: "if the sail luffs, sheet it in some," with little explanation of why. A concept I don't feel totally knowledgeable about is POWER - there is a lot of discussion of powering up and depowering. Perhaps it is the seeming implied contradiction that when depowering the sail, in some situations, the boat still sails faster.
for me, are the transitional areas where two controls affect the same variable, twist, for example. I know that all the controls are inter-related, and your point of UNDERSTANDING what and why a given configuration acts the way it does is right on the money. So many "learn to sail" volumes just say things on the order of: "if the sail luffs, sheet it in some," with little explanation of why. A concept I don't feel totally knowledgeable about is POWER - there is a lot of discussion of powering up and depowering. Perhaps it is the seeming implied contradiction that when depowering the sail, in some situations, the boat still sails faster.
Bob and all the mates that are following this discussion. When you are first trying to figure out the proper setting for each sail trim control for the mainsail and jib for each wind condition and point of sail, it ain't easy. I've been there but I have a solution on the transitional area where there is confusion on what settings are required for the main and jib in every situation you will encounter. I've developed a SAIL TRIM CHART that identifies all the sail trim controls for the main and jib and gives you a setting for each point of sail and wind condition. In other words, I've taken the guess work out of jib and mainsail adjustment. Say your sailing in 8 knots of wind - all you do is follow the chart and set each control where I tell you to. You may have to tweek it a bit because all boats are different but you'll be in the ball park. You can see the CHART by visiting the ships store on this site. There is just one problem with the CHART and that is that it tells you WHAT to do but not WHY you are making a particular sail trim adjustment. The WHY is everything. If you know WHY your making a change, your miles ahead of the average sailor who pushes and pulls things with no real purpose in mind. How do I know that? I get request to sail with crews all the time and the first thing I have them do is do what they normally do. After they go through a few sequences, I ask them why they did this or that and they really don't know. I've also solved the WHY problem. I wrote a book called THE SAIL TRIM USERS GUIDE, which is also available on this site. It describes every sail trim control for the main and jib and tells you what happens when you ease or trim them. It gives a bunch of other stuff also. It is written in plain English - so I can understand it!! After you finish reading the book (you may have to read it a couple of times)you'll be way ahead of the average sailor. The BOOK and CHART are all you'll need to become a better sailor. Ask some of the guys on the list, who have bought my stuff if they have become better sailors and see what they say?
Trimmng your sails
I have bought Don's book and to understand what he is saying I read it and experimented under sail to see just what he was talking about. Don, what you put in your book works very well for me. My sail and trim performance has dramatically improved. The book made it much easier to understand what to do not just the theories and formulas behind why a sail works. I have attached a link I found on sail trim also that talks about tell tales. Hope it helps Fair Winds Gerry
I have bought Don's book and to understand what he is saying I read it and experimented under sail to see just what he was talking about. Don, what you put in your book works very well for me. My sail and trim performance has dramatically improved. The book made it much easier to understand what to do not just the theories and formulas behind why a sail works. I have attached a link I found on sail trim also that talks about tell tales. Hope it helps Fair Winds Gerry
Gerry: That is a good link. I used it when I was researching my book. Aditionally, if you click on the section that says "wb-news articles index", which takes you to a series of articles and then click on "sail trim sim", you'll find a nice little simulator you can play with. The simulator gives you immediate feed back to every adjustment you make.
Jib Draft Position
Got your book, Don. I feel like an expert already *bzz but I did not see anything about shifting draft position on the jib. Did I miss the page?
Got your book, Don. I feel like an expert already *bzz but I did not see anything about shifting draft position on the jib. Did I miss the page?
Mike: Thank you for your nice comments about my book, Actually, you probably know more about sail trim than you think. To test it, just ask some of your sailing friend to explain the difference between draft depth and draft position and then ask them what controls are used to adjust both on the main and jib plus waht happens when the ease or trim each control. You'll be amazed at the ansewrs you get. To anyone reading this, if you can't answer that question I have the solution for you - visit the ships store and review my book!! The information on adjusting draft position for the jib is on page 47 and it is also contained on a "quick reference sheet" I include with the Sail Trim Chart. There are two adjustment for the jib. The primary one is the halyard and the secondary is the fairlead. Increasing pressure on the halyard moves the draft position forward and decreasing pressure moves it aft. Moving the fairlead forward moves the draft position aft and moving the fairlead aft moves it forward. Unfortunately, when you mess with these controls your also adjusting the draft depth plus twist and angle of attack so its a bit of a "dance" to get DP where you want it, which is about 35% to 40%. As the wind pipe up, it pushes the DP aft but too far aft is ineffective and you have to use the controls to move it forward. Actually, I don't use the halyard for DP adjustment. The reason I don't is because every time I loosen the jib or mainsail halyard I lose a foot or more of sail because of the weight of the sailing. I have a better system. I use a cunningham for both sails. On the jib, I purchased the smallest soft boom vang Garhauer makes and I attached it to the tack of the jib so I don't have to mess with the jib halyard. I get a more precise adjustment as I can actually see the DP move as I crank on the cunnigham.
Cunningham on roller furler?
Don - I assume that the cunningham trick wouldn't work with roller furling? What can you say about jib halyard adjustment with roller furling? Should the sail be loose enough in the track such that this adjustment can still be made? Do you see people actually doing this?
Don - I assume that the cunningham trick wouldn't work with roller furling? What can you say about jib halyard adjustment with roller furling? Should the sail be loose enough in the track such that this adjustment can still be made? Do you see people actually doing this?
Re: - clarification
Rick, The cunningham will be able increase the tension in the lower part of the luff as wind increases. The halyard has a harder time because the load on the luff in the foil is pretty high. During a tack that load spreads out along the luff because the load is off the sail, but tensioning the lower luff without releasing the load is difficult. To give you an idea of the loading, when the wind is up try to pull the headsail down after releasing the halyard and sheet. Then try the same with the sheet still on. The difference is the friction of the luff tape in the foil.
Rick, The cunningham will be able increase the tension in the lower part of the luff as wind increases. The halyard has a harder time because the load on the luff in the foil is pretty high. During a tack that load spreads out along the luff because the load is off the sail, but tensioning the lower luff without releasing the load is difficult. To give you an idea of the loading, when the wind is up try to pull the headsail down after releasing the halyard and sheet. Then try the same with the sheet still on. The difference is the friction of the luff tape in the foil.
Rick Macdonald: Yup, it easily works with roller furling, which is eactly the setup I have. It is tough (for me anyway) to fool around with the jib halyard and a roller furling and that is why I like the jib cunningham. Contact me off forum at yankee3223@juno.com with your Email address and I'll send you a picture of the setup, which would take you about 5 minutes to install.
Jib cunningham with roller furling
Thanks, Don. I sent you a direct email too. I suspect others will ask to see the picture as well. My boom vang seems fairly light-weight to me. Tha manual says 1/4" line but it might be a bit thicker than that, but still seems light weight. I was thinking of replacing it with something more robust. I guess what I'm hinting at is why shouldn't it be similar to the mainsheet itself? If I replace the boom vang I could use the old one as a jib cunningham, or perhaps even a main cunningham? The existing vang has a "V" jam cleat which I don't like. I imagine if I use it as a jib or main cunningham I won't like the V-cleat there either. Are there any rules-of-thumb here? Compared to the jib and main halyards, should or could the cunninghams be the same size line or is that overkill or might it potentially lead one to rip the sails by hauling too hard on it? I realize the purchase/mechanical advantage is more of a factor than line size. Any advice on these issues would be helpful.
Thanks, Don. I sent you a direct email too. I suspect others will ask to see the picture as well. My boom vang seems fairly light-weight to me. Tha manual says 1/4" line but it might be a bit thicker than that, but still seems light weight. I was thinking of replacing it with something more robust. I guess what I'm hinting at is why shouldn't it be similar to the mainsheet itself? If I replace the boom vang I could use the old one as a jib cunningham, or perhaps even a main cunningham? The existing vang has a "V" jam cleat which I don't like. I imagine if I use it as a jib or main cunningham I won't like the V-cleat there either. Are there any rules-of-thumb here? Compared to the jib and main halyards, should or could the cunninghams be the same size line or is that overkill or might it potentially lead one to rip the sails by hauling too hard on it? I realize the purchase/mechanical advantage is more of a factor than line size. Any advice on these issues would be helpful.
Don's picture
Here's Don's picture (Sorry Don, I had to cut you out of the picture to make it small enough to post!) Hmmm, I looked at the picture and expected to the the cunningham between the jib tack and the top of the furler cage, such that it is permanently attached. By the looks of it, you have to attach it after letting the sail out full and detach it before furling it again. Is that right? I've only had my furler for part of a season, so I don't have much experience with it yet. One of the reasons I wanted it was so I could just wind it up if I became overpowered. I sail a lot with wives and kids or single-handed, so I wanted to eliminate going forward as much as possible. Putting the cunningham on like you have negates that aspect of the furler, or have I misunderstood? Going forward to fine tune a cunningham would be OK, but I don't want to go forward every time I furl/unfurl.
Here's Don's picture (Sorry Don, I had to cut you out of the picture to make it small enough to post!) Hmmm, I looked at the picture and expected to the the cunningham between the jib tack and the top of the furler cage, such that it is permanently attached. By the looks of it, you have to attach it after letting the sail out full and detach it before furling it again. Is that right? I've only had my furler for part of a season, so I don't have much experience with it yet. One of the reasons I wanted it was so I could just wind it up if I became overpowered. I sail a lot with wives and kids or single-handed, so I wanted to eliminate going forward as much as possible. Putting the cunningham on like you have negates that aspect of the furler, or have I misunderstood? Going forward to fine tune a cunningham would be OK, but I don't want to go forward every time I furl/unfurl.
Attachments
Jib fairlead adjustment
Don, I have a question. I have your book and chart and read it often. I am setting up my jib sheets so that they will run aft through my fairleads in the cockpint as well as through the ones that are forward. I am setting up for single handing, so I'd like those sheets to run all the way back. My question is that when you are adjusting the forward fairleads for proper adjustment either moveing them foreward or aft, do you also have to adjust the ones by the cockpit as well, or do you now have the adjust the cockpit ones instead? I hope this is not to confusing. I'm just not sure if I have to adjust both, or just one of them. Thanks
Don, I have a question. I have your book and chart and read it often. I am setting up my jib sheets so that they will run aft through my fairleads in the cockpint as well as through the ones that are forward. I am setting up for single handing, so I'd like those sheets to run all the way back. My question is that when you are adjusting the forward fairleads for proper adjustment either moveing them foreward or aft, do you also have to adjust the ones by the cockpit as well, or do you now have the adjust the cockpit ones instead? I hope this is not to confusing. I'm just not sure if I have to adjust both, or just one of them. Thanks
Don, what should you have done?
When you turned the boat round and the wind hit you, should you have rounded up and reefed on the spot before proceeding or flattened the sails and got some twist into them as well to control heeling? I am still working on which line to pull and I have not got your book to hand, but I am thinking this means fairlead as far back as it would go but have the jib sheeted in tight; traveller way up wind and out-haul tight; vang is slackened to let the boom rise; rather than let the main out keep it sheeted almost to stalling, or am I an optomist?
When you turned the boat round and the wind hit you, should you have rounded up and reefed on the spot before proceeding or flattened the sails and got some twist into them as well to control heeling? I am still working on which line to pull and I have not got your book to hand, but I am thinking this means fairlead as far back as it would go but have the jib sheeted in tight; traveller way up wind and out-haul tight; vang is slackened to let the boom rise; rather than let the main out keep it sheeted almost to stalling, or am I an optomist?
loose footed main
i have just bought a hunter 40 with an inmast furling main that is loose footed (battenless also). i have been reading your book concerning trim adjustments and this configuration has given rise to a couple of questions. I can see no cunningham to adjust with the furling main . Are the halyard and boom vang adjustments also a none issue due to the loosefooting sail? if so are there any other ways to adjust twist and draft?
i have just bought a hunter 40 with an inmast furling main that is loose footed (battenless also). i have been reading your book concerning trim adjustments and this configuration has given rise to a couple of questions. I can see no cunningham to adjust with the furling main . Are the halyard and boom vang adjustments also a none issue due to the loosefooting sail? if so are there any other ways to adjust twist and draft?
Tom: Nope, that fact that your main sail is loose footed doesn't have anything to do with the controls. Either the sail is attached with a bolt rope or its not. The sail trim controls don't really much care how the sail is attached to the boom. The bottom line is that "you've just gots to use what you've gots" and adjust what sail trim controls you do have as perfectly as possable (if you want to get 100% efficiency out of your boat) because some of the more crucial sail trim controls have to be among the missing when you go to in mast furling. You already know the controls but for those that don't, here are a list of the controls for draft depth, draft position, twist and angle of attack. Draft position; boom vang, cunnigham (or halyard) mainsheet, mast bend and outhaul. Draft Depth: mast bend and outhaul Twist; Boom vang and mainsheet Angle of attack: mainsheet and traveler I think the only ones you might be missing is mast bend and the cunningham. The cunnigham is no big deal as you can use the main halyard and get the same result. I think you have a boom vang. If you don't have one I think one could be added and you'd like the results. I think my friends over at Garhauer Marine make one for a Hunter. You could check with them to be sure. You'd really like that control. It is hard to remove twist without it.
Mike; My problem at the time was I didn't have a clue as to what to do. I was a "raise the main and roll out the jib" kind of sailor. I really wanted to know how to sail well but I could never get a straight answer out of anyone I asked so I just messed around and called it sailing. Also, even if I knew what to do in that situation, my wife would not take the tiller until I got the boat on its feet so I was in a real "catch 22". I asked her, how am I supposed to adjust the control if you won't steer the boat. Her answer was just do it!! Had I seen the situation developing I could have taken steps to keep the boat under control. First, I could have induced twist in both the main and jib and when that didn't work I could have flattened the sails to depower them and then the last resort would have been to furl the jib and put in a reef. It was a great lesson for me and after that is when I decide to really learn how to sail.The sea can be mighty unforgiving and it can be dangerous not knowing what you are doing.
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