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Mainsheet Size


Dave R1

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I use 3/8 inch soft braided poly.

As far as interesting mainsheet ideas, I've developed a habit (possibly a bad one) of using my mainsheet as a makeshift hiking stick.

The mainsheet comes off the boom in the normal place, and then takes a couple wraps around the tiller handle, and then I sit up on the rail and hang onto the end of it. Periodically I have to adjust the wraps on the handle to adjust for minor course changes, or variations in the wind. But if the wind is reasonably steady, this seems to work well. I'm sure it is less efficient than handling them independently. But I really like sitting up on the rail.

If a strong puff comes up, letting out the sheet both spills wind out of the sail and turns the boat into the wind.

Noel

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Dave,

I use 3/8 too and like it. I am no where near bold enough to sit on the rail and chill....that must come later....it scares the bajesus out of me when the boat takes off and there is wind and stuff....I must be the world's most timid learner/sailer --- I'm sure I'll gain confidence this spring.

a.

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Thanks for the replies. So far I've had good luck with my 1/2" sheet but I might go down to a 3/8" one to reduce the mainsheet block size. Those hanging on the boom have a fair amount of mass.

There's a mark that some student pilots wear on their foreheads called the "Cessna Star". It comes from walking into the trailing edge of the wing which, due to the stiffening creases in the aluminum, leaves a diamond-shaped mark. I was warned about that and never got one. I do think I might have a "Harken Crescent" on the back of my noggin, though. :)

So, I've been overengineering again and this is what I have come up with.

The idea stems from a thought of having a bimini over the cockpit to keep from cooking the crew quite so badly. Ian, my little midshipman, is so fair that he gets sunburned looking at a picture of the sun in a book. Well, maybe that is a bit of a stretch but not by much.

I want to gain as much clearance under the boom as I can get and I thought this might help. Of course this idea might not go anywhere, too.

A new boom built using the birdsmouth method. The two side staves are wider to give an oval section. A pair of through deck blocks let into the underside of the boom lead the mainsheet foward inside the boom instead of allowing it to hang below. A piece of PVC pipe in the boom between the blocks provides a smooth guide for the line. There's still an important detail to work out or if not resolved might send this idea to the recycle bin. The lead of the line is fine as long as the boom is on or near the centerline of the boat. It gets a little iffy when the boom is swung out. A boom that can roll at least a few degrees might be the solution of maybe setting the blocks up to roll a bit from side to side is the ticket.

Here's the drawing so far.

boom1.jpg

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Dave,

Most sailboats don't have internal (inside the boom) mainsheets. This is because of the wide range of angles that occur between then boom and the mainsheet at the different points of sail. If you're thinking binimi, I'd consider not leading the mainsheet forward, and replace one of the blocks at the end with a ratch block - or a becket with a cam cleat if you feel comfortable with that. If you get a chance, check on the mainsheet on Precision 18 and 21's, they are rigged in this manner. The weekender sail area isn't that big; so moving the mainsheet attachment points shouldn't be a big deal.

On bigger boats, with dodgers and binimi's the mainsheet is often attached forward of the companion way and the sheet led back through the dodger.

If you're not going to rig your boat until the ice is out, you could always go up to Lake City and check out the different options used on the big boats. When rigging a boat, size doesn't matter as much as convenience.

Good luck

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Jeff, Thanks for the comments. I'll take a look at the Precisions. I knew the angle between boom and sheet would need to be dealt with but this drawing was a start.

I've thought about having the mainsheet come down forward of the cabin hatch hatch but I'd have to build some sort of bridge to clear the hatch when it slides foward. My feet get to be about 4 sizes larger when I get on board my boat and that bridge would take up valuable foot space when I'm raising or lowering the mast.

I'm kind of avoiding going up to Lake City right now. There's an Irwin 34 waiting for my attention up there but I don't want to even look at her right now. :D

I'd love to have the space to rig my boat now so I could do some tuning and stuff. Unfortunately, the boat is stored elsewhere while all the spars and rigging are at my place.

I need to find a heat garage with about 24' of ceiling height. Not likely here in the Mayoville.

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I am no where near bold enough to sit on the rail and chill....that must come later....it scares the bajesus out of me when the boat takes off and there is wind and stuff....

Ahh!! :-D I know that feeling exactly. That is precisely why I am sitting up on the rail! I know you are supposed to heel them over a bit and let the leeward chine dig into the water good and deep, but I still can't shake the feeling that the boat is supposed to be a bit more... upright. So there I am up on the rail hiking out waaaay before I probably should be. (Which is why I added that it may be a bad habit).

Noel

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Dave,

I saw a neat setup that may work for you if you have a tiller. The mainsheet runs from the starboard corner of the transom to the end of the boom, to the port corner of the transom, back to the boom-end, and then down to a block on the rudder box, and forward parallel to the tiller handle. You can hold the sheet and the tiller in the same hand that way. And all the lines stay out at the end of the boom, out of the way of your bimimi.

If you have a wheel, maybe you could run the sheet back to the starboard corner of the transom, and forward into the cockpit, rather than to the rudder box.

Noel

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Dave,

If you build the internal mainsheet as your pictures show, here's one concern to consider with the design: the PVC is a good idea to prevent line chafe, but if the PVC is allowed to move at all inside there, couldn't it possibly bind against the block sheaves and prevent them from rolling? You could affix it in place to prevent it from doing this, but then my other concern would be how hard it might be to run the mainsheet through in the first place... you might have to use a piece of wire, I guess, as a guide to thread the mainsheet through when you install it.

I would also have the concerns about angle that another poster mentioned... With the blocks as designed, the tendency will be for the boom to twist which, depending on how it is configured, could place a lot of unusual rotational stress on the gooseneck fitting between boom and mast.... could be a problem.

Just food for thought. It's a neat design, though. Is that CAD you're using to illustrate it?

Wes

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Dave, most modern gooseneck fittings permit the boom to rotate quite a bit. Some use a "captive ball" kind of deal, most are spring loaded. The most simple arrangement I've seen for a gooseneck that permitted rotation was two links of sizable chain. One was attached to the mast with an eye, the other attached to the boom with a strap of stainless. Simple, but very effective and about bullet proof, though I would think the chain would make some noise or possibly kink with certain movements.

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Noel, I've been thinking about the idea of leading the sheet down at the aft end of the cockpit but with a wheel, I think this would be awkward. Or maybe it is me who is awkward. :?

Wes, you're right about the PVC and I did have in mind to fix it in place. I share your concern about the gooseneck and have been thinking about that. It looks like PAR might have an easy solution. I was wondering about possibly mounting the blocks so that they could pivot on the centerline line of the horizontal portion of the mainsheet (or slightly above it). I have some ideas about how to do that but I suspect that it would be more complex than needed.

The drawings are done in an application called SketchUp. Not really a CAD app., it is the brainchild of an architect who wanted a digital version on sketching on a napkin. It works quite nicely for woodworking and other things too. That picture and words adage comes to mind.

It can output CAD files if desired.

SketchUp is not as expensive as most 3D CAD software and it is considerably easier to learn and use.

PAR, that chain idea is interesting. Thanks for that.

Like I said before, I've been overengineering here. This is mostly an excercise but I appreciate the input. It might be that this would be a workable way to rig the mainsheet. Maybe not. I might give it a try if I can find some good wood for a hollow boom. I can always go back to the old one or at least a conventionally-rigged one if it doesn't work.

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