Traveller versus mainsheet?

Mike B1026 · Jul 21, 2013

I have had the same question. The obvious difference is that the attachment point to the boat can be moved with the traveler. Therefor the boom can move pass the midway point where the mainsheet usually is attached. I can see that this would make quite a difference but would enjoy reading more.

BigEasy · Jul 21, 2013

I attended a North Sails seminar last year. The moderator explained as follows, think of the traveler adjustments as "opening or closing the barn door"; basically controlling the angle of attack of the mainsail. If the traveler is set to leeward, you are dumping quite a bit of air; conversely, if the traveler is set to windward, you are capturing quite a bit of air. So, in higher winds you can use the traveler to dump excess wind thereby reducing excess healing & rounding up and in light to moderate winds you can set the traveler to windward to capture more air.

On the other hand, the mainsheet controls twist in the upper 1/2 of the mainsail. Easing the mainsheet induces more twist in the top of the sail allowing air to be spilled from the top of the main and tightening the mainsheet captures more air in the upper part of the main.

Supposedly there is approximately 60% more wind in the top part of the mainsail as compared to the lower part of the mainsail because of reduced friction aloft. Therefore, you are really using the mainsheet to control twist aloft to enable a more symmetrical flow of air across the entire sail, top to bottom for better performance. Of course, in higher winds, you can induce more twist ,by easing the mainsheet, to spill more air from the top of the sail. More twist in higher winds equates to less heel, less weather helm, and reduced tendency to "round up" in gusts/lifts.

I am no sail trim expert; however, these are a few basic things that differentiate the traveler controls vs mainsheet controls. I am sure there are many more nuances that are beyond my grasp.

Allan12210 · Jul 21, 2013

The mainsheet sets the sail shape (flat, full, whatever is needed). The traveler sets the trim (relative to the wind direction). With only one control, both shape and trim are changing as the sail is eased when falling off from close hauled. With two controls, shape and trim can be managed independently.

Don Guillette · Jul 21, 2013

BigEasy is on to it. The traveler analogy of the barn door is a good one but I prefer the screen door. Assume your screen door had a pin in the corner that rides in a groove on the floor. When you open and close the screen door does the shape of the screen change. Obviously, it doesn't. Same with the traveler -- when you move the car from side to side the shape of the sail remains the same. All you're changing is the ANGLE OF ATTACK.

The mainsheet can also be used to change the angle of attack and if you don't have a traveler that's what you're stuck with but when you adjust the mainsheet you're also messing with twist and draft position.

Here's why I use the traveler to get the boat back on it's feet when hit by a gust. I just drop the traveler, changing the angle of attack, and the boat comes back on its feet. When the gust passes I merely move the traveler to it's former position and sail on my merry way. Some mates prefer to use the mainsheet and if that's all you have you have to use it and it's basically the same thing. Once the gust passes you put the mainsheet in it's former position. The traveler is easier to use, if you have one.

That's just a common seaman's explantion. RichH, Joe from San Diego can explain it better than I can.

HukilauMike · Jul 21, 2013

Jonny: if you don't have a traveller (and I don't either), then you should at least have a boom vang. Using the vang and mainsheet in combination, you can approximate the effect of a traveller. However, it is only an approximation. Those of us without a traveller are really only making due. I agree with Don in the use of the traveller as the quickest, easiest and most efficient way to trim the main in response to changes in the wind velocity. On my boat (Oday 23), there is no easy way to install a traveller short of putting a track across an already-crowded cockpit. Not happening for me.

Don Guillette · Jul 21, 2013

Jonnyquest: Nope, on one point, the traveler can't induce TWIST. The BOOM VANG is your primary twist control and the mainsheet is secondary. As sail trim technology developed sailors took one mainsail control (mainsheet) and added to it (traveler) to obtain better sail trim -- sorry RichH, I just made that up!!!

As I explain in the first chapter of my book, a mate has to understand draft depth, draft position, twist and angle of attack or sail trim will never make any sense. Next they have to understand how ALL the sail trim controls on the main and jib relate to those 4 elements. You're almost there brother and I was there like you many years ago until the sail trim lights went on.

Go back to my explanation using the screen door. You could have a traveler track that extends from one side of your boat to your neighbors on both sides of you and you could move it all day and twist would not be effected because it's a fixed horizontal movement. Nothing happens vertically, otherwise you'd need a new screen door every couple of months. Maybe at some point in my example (extending the track 60') it would but I doubt it.

zeehag · Jul 21, 2013

johnnyquest--the traveller is redundant.

Paul Mermelstein · Jul 21, 2013

zeehag said:
johnnyquest--the traveller is redundant.

I disagree, for the reasons provided by Don and BigEasy. Is a traveler critical? Maybe not. But with one, and in combination with the sheet and vang, one can control angle of attack, twist, draft, and draft position. Takes some practice, and I admit I am still learning after 22 years of sailing, but it does make a difference.

25yearslater · Jul 21, 2013

Hi Jonny. I too eliminated the traveller from my 27 because of placement. I pounded my shins more than enough going below with the cockpit layout. The vang and mainsheet don't equal the effectiveness of a traveller but with Don's book firmly ensconsed in my noggin I am just as happy with my mainsail control without the traveller. I did keep it and am looking at mounting it along the stern in some fashion if I decide to want more. I am regularly cruising along at or above hull speed without excessive heeling. I don't point as well as the original inboard jib tracks and traveller offered but I get great speed that makes up for the lost degrees.

Sprega · Jul 21, 2013

On the wind, traveler controls angle of attack, main sheet controls twist... Off the wind, main sheet controls angle of attack, vang controls twist....

zeehag · Jul 21, 2013

i sailed for most of my formative years without a traveller. travellers are redundant.

steve_in_Lex · Jul 21, 2013

Sprega said:
On the wind, traveler controls angle of attack, main sheet controls twist... Off the wind, main sheet controls angle of attack, vang controls twist....

Exactly. It's a fine-tuning thing for sure, but if you think about it, a lot of twist means that half your sail (either top or bottom half) will be at the wrong angle to the wind all the time. Vang's aren't strong enough to control twist when the sail is in relatively tight (say, 30% or less from center), so that's where the traveler and sheet combination work best. Going upwind in a good breeze, keep the sheet tight and play the traveler.

finding41 · Jul 21, 2013

Jonny: When You get a traveler remember that someone commented about banging there shins! You will too if you get a high one. (1" or more)
I have a low one (3/8" high 1 1/8 wide) with a T shape track for the above reason. I would get one strong enough for your boat and low enough you don't hurt yourself.
If you beer can race ocassionaly...You will LOVE it!

fruivita · Jul 22, 2013

Traveller and mainsheet but no vang

I just bought a S2 11.0CC and it has a traveller mounted just aft of the cockpit with the mainsheet running directly behind the helmsman's position. At times it's in the way but that's because I've been primarily using the mainsheet to trim and only use the traveller when on a broad reach. I single-hand a lot so it's easier to just have 1 control to manage on the main. Now I'll know better. However, the previous owner removed the boom vang - reasons unknown or maybe it was constantly obstructing access to the companionway - so I'm wondering what effect this is having on my seeming inability to get close to the wind. I think I may know the answer after reading these posts but wonder if someone smarter than me could explain. The vang is stored below and can easily be re-installed.

Don Guillette · Jul 22, 2013

Re: Traveller and mainsheet but no vang

Jonnyquest: I don't know if you have my sail trim chart and more importantly the QUICK REFERENCE that is provided FREE with the chart. Working with each sail trim control for the main and jib is one way of practicing but I think a better way is to work individually with the "4 elements of sail trim" -- draft depth, draft position, twist and angle of attack.

Let's say you want to focus on TWIST and this answers fruivita question. Twist is controlled primarily by the boom vang and secondarily by the mainsheet. You can see twist happen at your dock by hoisting the mainsail and cranking on ithe boom vang -- you'll see the top open and close. When you're sailing along you can do the same thing. Loosen the boom vang and watch the top of the sail open up (you're spilling air and power) and the boat will slow down. Crank on the boom vang and watch the top close and the boat will speed up.