A Good Question

[Don Guillette]

I get most of the material posted on this forum from questions I receive from beginners to intermediate sailors. I figure if the caller has a question others probably do also. I know I had these questions when I was learning to sail.

A forum lister told me he wanted to know how to work the boom vang on the mainsail and the fairleads for the jib. Sounds like a reasonable request except he’s a bit ahead of himself. My first question with regard to the boom vang was to inquire if he understood draft position and twist. The answer was a little. With regard to the fairleads I asked if he understood draft depth and angle of attack in addition to draft position and twist. The answer was a little. I could have asked him to explain these 4 elements to me but I already knew the answers I would get and why embarrass a mate who is trying to learn something.

Instead, I spent time explaining the “4 elements of sail trim” because if you don’t understand these 4 element sail trim will never make any sense. Once you have an understanding of draft depth, draft position, twist and angle of attack you are ½ way home. The next step is to understand which controls for the main and jib are used to adjust the 4 element. At this point your almost there. All you need now is an understanding of the proper setting for each jib and mainsail control for each point of sail and wind condition. Sounds like a lot to know but it really isn’t. Well, it is a lot but nothing worthwhile in life is easy and if you own a sail boat you may as well know how to sail it. If you can get to the proper settings point you know more about sail trim than 75% of the sailors worldwide and you are no longer guessing about any aspect of sail trim on your boat.

Does anyone out there have any questions on any of this stuff?

 

[Ken Prichard]

For those of us that don't have a traveler how about a discussion of " vang sheeting ".

 

[Don Guillette]

Kiprichard: Go for it!! You've got the floor. Start by defining it and then go from there.

 

[Rick]

Looking forward to the response abour vang sheeting! My question Don, is controlling draft depth and position on my particular rig. I have a slotted main foot meaning bolt rope on a track on the boom. I find that although there is some effect, the outhaul does little in increasing or decreasing draft depth. I compensate by using my other controls. I set twist with the vang which does "seem" to give me some draft position control. The mainsheet compensates a bit depending on the point of sail. Finally, I use the traveler to set the angle of attack with respect to the slot. Of course I tinker with all three once I set my point of sail. Any thoughts? I feel that my setup limits that aspect but.... there has got to be a way. Hunter 336, high roach main, pedestal mounted traveler and mainsheet, cunningham. 110 jib.

 

[Don Guillette]

Rick: I have my own thoughts on vang sheeting but I want to see what others have to say before I give my 2 cents.

Regarding you situation with the outhaul. The outhaul is a very important sail tim control as it is the primary control for setting draft depth. It fact, it is the only one. Actaully there is another one and it is mast bend but I don't want to bring that subject up ever again!!

Most bolt rope setups are a bit tough to operate because of friction between the rope and the track but you don't need a lot of travel to get the results you want. The max amount would be about 20%. A loose footed main is obviously a frictionless system but most folks with that system induce too much draft depth, which ends up being counter productive.

So what do I mean by 20%? That is how draft depth (and draft postion) is measured. Here's how it is calculated. Say you had a 10' boom. If you induced a 2' belly that would be 20%. A 1' belly would be 10%. It is measured by an imaginary line dropped from top to bottom through the deepest part of the sail.

In your case, how much travel do you get with your outhaul? Measure from fully tight to fully loose.

The problem I had with my outhaul was very common on older Catalina30's and that was that the internal system stunk and it was frozen in place. The frozen setting was like the broken clock that was right twice a day. The frozen setting was right for some point of sail and wind condition and wrong for all others. Additionally, the slug would dig into the boom due to the downward pulling motion of the outhaul and it was difficult to move. How I solved the problem was to install an external system using two small Harken triple blocks and dumped the alum slug and internal system. It worked great for me.

A friend of mine Max Munger, who I raced with at the C30 Nationals, had an even better outhaul setup - I'm hoping to race with him again this year at the C30 Nationals in San Diego. He mounted a track on the end of the boom and had Garhauer build him a small car to ride on the track. His system does requires the clew of the sail to have inset cut out. My system is the poor mans way out of the problem.

Another way around the problem is to pull the foot of the sail out of the track thus making it loose footed and it is what I considered before I came up with the other fix.

Anyway, let us know the amount of outhaul travel.

 

[shemandr]

Back to vang sheeting: I've always had trouble with this. Someone has to respond so I guess it can be me.
Vang sheeting - the use of the vang to apply downward force on the boom when it is undesirable to do so with the main sheet or main sheet and traveler.
This might be useful for a boat that has no traveler or on a close reach when the boom should be further outboard than the traveler will allow and when the main should be powered up.
It's a start.

 

[Moody Buccaneer]

For those of us that don't have a traveler how about a discussion of " vang sheeting ".

If you don't have a traveler, you can try to control twist with the vang. I think you will find that either the vang does not have enough power or the boom will flex enough to prevent you from trimming the sail properly using the vang.

Randy

 

[Warren Milberg]

It addition to the outhaul, I thought that halyard tension and the Cunningham also help control (and move) the draft of the main.

 

[Don Guillette]

Warren: There are 2 drafts - draft position and draft depth, which are two different things. The halyard or Cunningham (I prefer the Cunningham) only adjusts draft position.

 

[Don Guillette]

Here’s my view on vang sheeting. This situation assume you have no traveler. Some smaller boats do not have a traveler and boats such as a Catalina25 have a traveler but it is so small that it is almost wasted space.

For vang sheeting to be effective you need two things. One obviously is a boom vang and the other is a bendy mast. Without a bendy mast you’ve lost half the effect you’re trying for with vang sheeting. When you crank on the vang you are pulling down the boom and thus tightening the leach of the sail which has a flattening effect. If you had a bendy mast you would flatten the sail a bit more when cranking on the boom vang.

Let’s say your sailing closehauled (which is where vang sheeting mostly comes into play) and your hit by a solid and prolonged gust. If you had a traveler you could drop it down thus changing the angle of attack and keeping the boat on its feet and doing nothing to the shape of the sail. After the gust passes you merely pull the traveler back to its original position and sail merrily on your way.

Since you don’t have a traveler your only recourse in this situation is to ease the mainsheet. What you have now done is allows the top 1/3 of the mainsail to twist off to max twist thus spilling power. Maybe you don’t want to spill off all the power. This is where the vang comes in. With it you can dial in the amount of twist and shape you want into your mainsail.

In all of this lets not forget the jib, especially if you have a masthead rig. Obviously, you have to deal with the mainsail but not to the detriment of the jib, which happens to be your engine.

As with anything, understanding of what you are adjusting with each of the sail trim controls for your main and jib is everything. If you don’t believe just ask Alan, Stu, Joe from San Diego, RichH and a few others and they will tell you the same thing. I’ve seen it a million times where the skipper orders an outhaul, boom vang, fairlead or any sail trim adjustment and I ask him WHY. Generally he can’t tell me. It gets further complicated when I ask what he intends to do with the other sail trim controls to compensate for what he has just done.

 

[Rick]

Thanks Don,
Headed over to San Diego for a week or so in Feb to dry out the boat. Hopefully winds will be back to normal and I will experiment with the outhaul under as fixed a point of sail and apparent wind as I can. Will take some notes and some pics for you to take a look at.

Thanks

 

[Warren Milberg]

Don: it may useful to explain the 'when and how' of draft depth vs draft position.