Manny (Havre De Grace, MD)

[Don Guillette]

Manny has an interesting situation with his boat. He does not have a traveler, vang or Cunningham and the outhaul does not work.Let’s say Manny and I are dock neighbors and one day we are shooting the breeze about the above situation. Better yet, he invites me out for a sail so he can show me what is happening.The first thing I would tell him to do is to fix the outhaul. Next we would add a simple Cunningham so he did not have to mess with the main halyard. Then I would ask him to show me how he eliminates twist in the mainsail and he would release the halyard.Before we go any further, please review the QUICK REFERENCE chart I provided in a previous post. The reason we are "draining the swamp" in this situation is to induce twist. Please note that on the quick reference the halyard is not used to adjust twist. The twist controls are the boom vang (which he does not have) and the mainsheet.At this point I’d probably ask Manny for a “tinney” (Aussie for beer)and we would then start talking about what actually happened when he released the halyard.When Manny released the halyard, what he actually changed was the DRAFT POSITION.The first thing I would do is show him what draft position actually is. It is so much easier to see it than to describe it. Under normal conditions you want your draft position to be at about 50%. A draft position forward of 50%, say 45%, produces LESS power and is more forgiving. A draft position aft of 50% produces MORE power and is less forgiving.Why do we care about draft position anyway? One reason is that as the wind pipes up it wants to push the draft position in the main and jib AFT and you have to have a way to pull it forward to around 50%. That is why you have sail trim controls. Now that I’ve shown Manny, on his boat, what draft position looks like and demonstrated how to move it forward and aft he sees what is happening.What is actually happening when he released the halyard? What he did was move the draft position AFT and is powering up the boat.What Manny and I do next is have another “tinney” and figure out how the top of the sail opens up. First, we ease the mainsheet to see what twist actually looks like and then we compare it to the shape he gets by easing the halyard. Does everyone know what draft position is and can they describe it to their dock neighbor?Thanks Manny. I hope you enjoyed the virtual sail we just took!!!

 

[Brian M H23]

Twist is awesome

This weekend, I was on a LONG upwind tack (15 miles) across lake ontario. The winds started out around 8 knots, increasing to about 18 before getting light again. The traveler was all the way to windward the entire time. I started out with the genoa and the main sheeted all the way in, genoa cars forward. When the heel started to get a little exessive, I dropped about 3" of mainsheet. Then i pulled the genny car back a notch (on my 23, i just grab the genoa sheet in front of the lead with one hand, pull it to unload the block, and move the pin with the other). Rinse and repeat. I managed to keep the same sails trimmed tight to windward and getting an awesome point, and simply depower with TWIST

 

[Don Guillette]

Blown Main & Cunningham

Manny: The cunningham is easy. Buy the cheapest and smallest soft boom vang from West marine or BoatUS or better still and even cheaper - make your own. You'll find it is a lot easier to deal with than messing with the halyard.I thought my main was wasted also and was all set to buy a new one when I decided to take a chance and brought it to a sail maker in Torrance, Ca. I expected him to sell me a new one but he said with a little "nip and tuck" here and there I could easily get a few more years out of it. He charged me $125.00, which is a long way from a new mainsail.

 

[Don Guillette]

Twist

Brian: That is nice to hear. Isn't it great when the sail trim lights go on and you know exactly how each control works so you can get 100% performance out of your boat.

 

[Clark]

Manny, I too wondered about Draft Position re: airfoils.

My guess is that it is very difficult (impossible?) to get that shape from a very flexible (fabric) material. Obviously, I did not sleep at an HI Express last night.

 

[Joseph Shirley]

Manny, Your picture shows a tight luff on your jib but a soft luff

on your main. These are not compatible. You can use a soft luff in light air and a tight luff in heavy air, but both sails should have similar luff tensions.I suspect in this case that it is the main which is to soft and the halyard should be tightened. the leech is tight (no twist as you said), so it looks like your main sheet is very tight. You have some diagonal "wrinkles" almost parallel to the leach which shouldn't be there. They could be caused by a soft out-haul, an uneven mast bend (bending from the spreaders up) or a high tack pin. Since we can't see your boom we can't tell, but something is off. Your main should be relatively smooth regardless of twist or draft placement.You also appear to have a halyard in front of your jib luff, and that may be a convenient place to keep it, but a serious racer would never do it. It disturbs the air flow before it gets to the jib, and usually helps your luff telltales lie to you. You will get better performance if you relocate it.I'm trying to be informative here and not just critical, so please don't take offense at my comments.Have funJoe S

 

[Manny]

Thanks for observations Joseph

I will look at the luff situation, and pay closer attention to the tightness of it. I'm not sure if it is the extrusion you are seeing, but there isn't a halyard in front of the jib. It seems like that would be kind of awkward, couldn't that cause some headaches when trying to gybe?Speaking of luff tension, is it common practice to adjust it on a roller furler genoa? Mine would be a nightmare to adjust while under sail...I guess some more Cuba Libre's are in order ;DThanks guys!Manny

 

[Joseph Shirley]

Manny, you may be right about the extrusion. My eyes sometimes

play tricks on me. About the jib however, it still is a jib, and all points of sail control apply whether it is roller furling or not. A tight halyard will move your draft forward and flatten the sail, so you can profit from a softer luff in light air. It will roll better if tight though, so you might want to tighten it back up before you furl it.If your comfortable with it the way it is for casual sailing, leave it. My comments are only intended to tell you how to get a little more out of what you have. I am no longer the competitive racer that I used to be, because, even though I know what I should do to go faster, or make more ground to weather, I'm mostly too lazy, and I often just sit back and sail it the way it is.Have funJoe S

 

[Don Guillette]

Streaming Telltales

Jim: They look great. Not only are they streamin but the middle one, which is the most important one, has a little lift to it. That is exactly what is needed to get a little extra out of the boat. The reason for it is that at that point you are at the top of the lift/drag curve and the sails are producing 100% and the boat is responding accordingly.

 

[Manny]

Hey Don

I didn't get much of a chance to play with the main this weekend. I went out on Thursday and the wind kept shifting around on me like crazy. I actually had a couple of accidental tacks due to the wind shifting so suddenly. I couldn't keep the boat trimmed at all, I finally gave up and headed back in. Friday the winds were pretty strong. It had me pushed up against the dock and I couldn't get out until someone came along and pushed me off. I tried reefing the main and genoa but I was still over-canvassed. Finally I just doused the main completely and let the genoa out some more and life was good - reached hull speed quite often with very little heeling. It was a bit choppy and one of my dogs seasick shortly after I got back to the dock. Saturday I had guests aboard and couldn't really play with the sails. Winds were very light, I did notice that my draft position looked a bit forward of your recommendations...Here's one thing I was thinking about and wanted to run by you. Can the topping lift be used to create twist on my set up?Manny

 

[Don Guillette]

Topping Lift

Manny: The topping ligt can't be used to induce twist. Try it for yourself and see what happens to twist.The topping lifts main function is to hold up the boom when the mainsail is flaked. It does have one small use in very light air. In those conditions you would crank on the topping lift and lift the boom to about 10 degrees above horizontal. It powers up the sail. I mean you don't take off and set the land/sea speed record but the boat will gain a little speed for the very light condition.On my boat, I eliminated the topping lift when I installed a rigid boom vang. The rigid vang was installed so that when the boom was at rest the boom was about 10 degrees above horizontal so I was set for light air conditions and merely cranked down on it for other conditions.My main reason for eliminating the topping lift was I got sick of watching it flop around and bang the edge of the mainsail. It upset my sail trim carma!!!

 

[Alan]

Don

In very light air, how does the topping lift raising of the boom increase power in the main?As I understand it in very light air the breeze has a very hard time staying attached on the last third of leeward side of the main. This detachment creates turbulence and decreases the power in the main. On a flat main the attachment is far better and the sail can generate a greater percent of the breeze into forward motion.From my own experience we flatten the main as much as possible in very light conditions to generate the best combination of power and lift with the least amount of drag.

 

[Don Guillette]

Light Air

Alan: I really don't know scientifically how it works but it does. In wind under 3 or 4 knots that slight little lift does something and the boat creeps slowly ahead a slight bit faster than when the sail was as flat as possible.I lerned that trick years ago during a seminar in San Diego conducted by none other than Dennis Connor. Next time your in those conditions give it a try and see what happens. If it works for you see if you can figure out why. No one really had the gumption to ask Dennis Connor why it would work.

 

[Alan]

Always willing to learn...

Next time I'm in these conditions I will give it a try. I don't have a topping lift but I can raise the boom with the spring loaded solid vang effectively doing the same thing(maybe an inch or two). I will take note of boat speed before and after this adjustment and see which works best. If this technique proves successful I will use it in the future.I do know that in near zero breeze the tight leach technique works because this is something that I have tried. Three or four knots is a whole order of magnitude higher than near zero.In "Sail Power" by Wallace Ross, "Drifter: 0-2 Knots, ...you should have a medium amount of draft and keep a slight twist in the leech.""Light Winds: 2-5 Knots, ...with this little wind, it is important to develop all the power you can; so the boom should be trimmed to the farthest inboard point(centerline)and the leach should be relatively tight"In the quote of the first point, 0-2 knots, 'slight twist' I suspect is because there is a greater percent gradient change in lighter air due to the friction of the water.In the second point, of 2-5 knots, a relatively flat leach with maximum draft should be used. A maximum draft as much as 18% and location of 50% in the main.In either scenario the amount of induced twist will be very slight and I suspect that many will greatly over play this as an important 'control' line....anyway, just my 2 cents worth. Cheers