Discussion about Traveller's, Heel, and something I am confused about

[Signaleer]

So,

I fancy myself both a good looking bloke, and one who knows a bit about sailing. But alas, I may be confused about one, so I turn to my merry group of dolts on the Mac site.

So, a traveller, is used to induce, or reduce, twist in the mainsail.

Adding a traveller to an X, first, if the mainsail is flattened, moderate or heavy winds, by the vang - would lowering the traveller to leeward reduce heel? The point at which the main sheet attaches to the boat? Does this matter?

Aka, if the traveller is far aft, and low in the boat - would induced heel be less vs. a traveller at the cabin top and more forward?

I just can't work this out in my mind. The torque induced by the center of effort would not change in either scenario, but the points where it attaches to the boat would. I don't know if that actually matters.

I am trying to think about where to put a traveller on an X - over the cabin top, or across the sette's aft. Would either location matter wrt sailing performance?

Ed

[Tomfoolery]

Aka, if the traveller is far aft, and low in the boat - would induced heel be less vs. a traveller at the cabin top and more forward?

I just can't work this out in my mind. The torque induced by the center of effort would not change in either scenario, but the points where it attaches to the boat would. I don't know if that actually matters.

It does not matter. It can be hard to wrap your head around without a background in statics and machine design, but for a given sail trim, including boom location (vertical and horizontal orientation), how it gets there is irrelevant to the performance of the boat.

Where it IS relevant is in the loading and reactions of all those components. Putting the main sheet at the end of the boom vs in the middle of the boom will change a pile of things, like line tension and bail and deck/coaming reaction forces, boom bending moment, hinge reaction forces and moments, etc.

A simple two dimensional example would be a cable or rope under tension load. Cut it and insert a straight link in the middle. Nothing changes. Replace the link with a link that's shaped like a banana. Still nothing changes, but there is bending moment in the link now, along with tension (and possible compression) stresses, whereas the straight link had only tension stresses in it. So the shape of the link matters to the link, and how it does its job, and even how it's designed since the bending moment will add stress that the straight one doesn't experience.

But to the two ends of the rope, it makes no difference.

The differing locations of the sheet (via the traveler), the presence or absence of a vang, the mounting location to the boom, etc. all make a difference to those components and other load path items including the mast and the deck, but to the performance, it makes zero difference how that boom is held at that location - just that it's held at that location.

[Tomfoolery]

Maybe a better example would be lifting your boat so it stays level in both planes. You can put a lifting eye right over the center of mass (or CG if you prefer), hook to it, and lift the boat. If it's in the right place, it will remain nice and level.

You can also hook two or three cables to different locations on the deck, such that the lifting point is still over the CG, and it will lift nice and level.

You can also 'attach' (somehow) a big hook or banana shaped structure somewhere on the deck, far from the CG, but with the lifting ring still directly over the CG, and it will lift nice and level.

All three methods will put very different loads and moments into the boat structure, including a really big bending moment where the banana structure attaches, but as a boat-shaped lump of a mass the orientation will be unchanged no matter what method you use - it will still lift nice and level. But internally, the reaction loads and stresses and moments are completely different.

Same thing with holding the boom at precisely the same orientation using different rigging methods.

[Highlander]

Check with Gazmn , he put a traveler on his above the companion way entrance , he may b able to give u some insight to his mod

j

[Signaleer]

...Everything you said...

I completely get what you are discussing with moments and the stresses introduced to the components, so wasn't my question but the answer definitely is sound thank you very much for the detailed discussion.

Your point though is that there are really only a few forces that act on the overall boat - CE, CG, CLR, L, D, etc. (There may be a few more... Buoyancy (B)). Those forces are what act on the boat, the attachment points do not change the overall math of torque & leverage. They do introduce moments on the components in which they are individually exerting force.

I once heard there were only like 3 points on a sailboat that actually induced acceleration - mast & mast step, keel, and forstay? The question is does the mainsheet attachment impact leverage? (You said no, but I'm continuing to think this through, I'm not disagreeing with you)

I agree though, if I am thinking of this properly (which is where my mind was going) the CE and CLR would not change even if the boom was welded in place is and had no rigging.

I guess what I was thinking is that there is a force locally at where the mainsheet attaches to the hull, on which it is exerting force (Is it? torque...) If the traveler is to leeward, you are in fact moving the CE to leeward as well, but the CG does not change, thus reducing leverage. I suppose this is the question. It may be minimal, but if I attach windward, I am moving CE to windward, thus utilizing leverage to induce more heel.

So, I guess the fundamental question is does the mainsheet impact the CE to windward or leeward in any way, if so, leverage would be a factor - no?

And by the way, has anyone seen peaches?

Ed

[dlandersson]

Here's the thing - you have to be 10% smarter than whatever device you are dealing with. You and I are out of luck.

[Jimmyt]

Just to clarify the question:

Ed, are you wondering if attaching the main sheet at cabin top will increase heel; and conversely, attaching it to the bottom of the keel would reduce heel (absurdity for purpose of illustration). Is your thought that the main sheet pulls on the attachment point creating a heeling moment in the boat?

[Signaleer]

Just to clarify the question:

Ed, are you wondering if attaching the main sheet at cabin top will increase heel; and conversely, attaching it to the bottom of the keel would reduce heel (absurdity for purpose of illustration). Is your thought that the main sheet pulls on the attachment point creating a heeling moment in the boat?

Yes.

If the main sheet attachment point is a factor in determining CE, leverage must be considered. If I move the attachment point lower, and it is a factor, the CE must be lower, reducing leverage. If the attachment point is windward, and lower, I'm moving the CE both down, and off the centerline, and thus reducing leverage.

I am essentially saying, that the CE vs. CLR is what creates heel. If I move CE, that will change the the moment of heel as CLR is fixed.

The amount may be negligible, or not.

But I wonder if there aren't 3 points that create CE - head, mast step, mainsheet attachment to hull.

It just seems intuitive to me if I move CE to windward or lower - it would affect the leverage, and therefore, heeling moment.

But then again, I drank a lot as a younger man... so...

[Jimmyt]

Well, Tomfoolery covered it in detail above, but basically nope.

The traveler and mainsheet change heel through sail trim/movement of CE; not through moment induced through the connection point.

Sorry

Wish you had saved me a beer!

[Jimmyt]

On the bright side, you seem to have a firm grasp on the rest of it. Internal vs external forces/moments seems to be snagging you.

[BOAT]

My dad liked to be in regattas. The club he was in had regattas all the time all over the place-
They had regattas in Mexico, on lakes, in rivers, in bays and in the Ocean. all kinds of places.

50% of the time I was on my dad's boat as a kid we were in a race. It's one of the reasons I am not interested in racing anymore. I got tired of it. My dad was good at shooting the start line and gauging the committee boats and his timing was pretty good. We did our fair share of cheating too without getting caught. But all that time I was a trimmer. After hundreds of hours on the water as a trimmer you start to figure things out.

The thing about a traveller and a vang and the sheets is TWIST. I was forced to sail on many different kinds of boats between the ages of 13 and 17 because as a youngster I was loaned out a lot to other boats in the club. I can tell you that TWIST in the main is a big deal on every boat - and the thing is to find the right twist for the boat your sailing.

You can use a traveler to catch all the wind near the surface down low in the bottom ten feet of the sail but if you let the sail twist so the top of the sail is open it will allow the wind at the top ten feet to spill out and that will reduce heel. It's the wind in that top ten feet of sail that heels the boat.

You can play with the twist of the sail by changing the angle of the boom from the mast - the tighter the boom is away from the mast of course the flatter the sail will be - and if you let the boom ride up the sail will billow with a big pocket in the middle. You can shape the sail using the boom, and that shape you choose effects greatly depending on it's attack into the wind.

All the tools you can use to shape the sail are good to have. A vang is not such a big deal on the M boat because the main bale is already pretty close to the mast. Boats with a main sheet attached to the END of the boom can be greatly helped with a vang.

But the bottom line is twist and shape - in light winds when racing I would actually stand up in the cockpit and grab the boom and pull it this way and that to get the right twist. It makes a difference.

[Jimmyt]

I am trying to think about where to put a traveller on an X - over the cabin top, or across the sette's aft. Would either location matter wrt sailing performance?

Ed

To this part of your question, I would say the cabin top location would be better. The traveler would be functional over a considerably larger angle of boom travel, compared to locating it across the cockpit aft (assume that's what you meant).

[Newell]

I built a traveler over the cockpit on my X and yes I think it is a great control and would not want to be without it. However, moving the mainsheet further away from the pedestal makes it more difficult to adjust or let off in a gust.