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I've got a 30 foot Islander Bahama and it's time for a new main. It's been recommended to me that I should consider a "full batten, shelf footed main". Anyone heard of this and (here we go) anyone have any opinions?
 

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Well...I like full-batten mains and there seems to be a lot of favorable comment about loose footed mains and the shelf-foot seems to be a more expensive variant on the loose foot:
From Halsey Sails...
<table width="570" border="0" cellpadding="0" cellspacing="0"><tbody><tr><td valign="top" width="389">Shelf Foot and Loose Foot
The Shelf-Foot and Loose-Foot constructions are options that allow us to add a substantial degree of extra fullness in the lower portion of the mainsail in order to improve racing performance on reaches and runs. In very light air, the improved performance is achieved even to windward. The extra fullness is removed by tightening the outhaul. When the outhaul is eased, the sail maintains an airfoil shape down to the boom. With the Shelf-Foot option, a light piece of material connects the sail to the boom. With the outhaul eased, the connecting material unfolds and forms a shelf between the bottom of the main and the boom. When the outhaul is pulled tight, the shelf closes up and lays against the side of the boom.
</td> </tr> <tr> <td valign="top" width="181"> </td> <td valign="top" width="389"> Loose-Foot construction does away with the shelf material. The sail is only attached to the boom at the tack and clew. This attachment method is equally as strong as that of the foot attached to the boom. Many boats are switching to Loose-Footed mains because they make it easier to bend on your mainsail and to remove the sail from the boom — and it's less expensive.</td></tr></tbody></table>
 

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That is a fairly standard cruising mainsail arrangement.

The "shelf-foot" refers to a sail foot that is connected to the boom along it's full length. This is as opposed to a "loose-foot", which is attached only at the tack and clew corners, with the foot hanging freely and independent of the boom.

The "full-battens" refers to battens that run from the leech edge all the way to the luff edge, where the inboard ends nest in pockets. This is as opposed to "partial" or "partial-length" battens, which only extend part way into the sail from the leech.

The advantage of full-length battens is that the sail tends to flog and wear less than a sail with partial battens. The down-side is that it is less "tuneable", i.e. it is less responsive to tweeking and shape adjustments.

Many sailors go for a compromise between the two approaches, choosing a combination full/partial batten arrangement, where the top two or three battens are full length and the lower one or two are partial length. this allows the lower, larger portion of the sail to be more responsive to tuning, while better controlling the upper portions that are subject to the greatest amounts of wind.

As for loose- or shelf-foot, there are again pros and cons. Many cruisers feel more secure with the foot of the sail captive in the boom, while performance-oriented sailors like the shape and extra sail area of the loose-foot.

Our old mainsail was full-batten, shelf-foot. It was a nice sail, but had exceeded it's service life. We went with a 3 full-, 1 partial-batten, loose foot replacement. It is a much more tune-able sail and I would definitely not go back to a shelf-foot.

Edit: Sorry to be redundant -- Camaraderie hadn't posted when I began typing.
 

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What's the alleged advantage of a shelf-footed main over a loose-footed main?

Jim
Some folks worry that if the clew grommet were to let go, or if the outhaul were to part, they would have a wildly flogging mainsail, like a genoa without sheets, right over their head. And the boom could drop down if there is no topping lift.

In reality, the clew is pulled aft by the outhaul, but there is usually an extra slug below the clew that runs in the boom track anyway. It is attached to the clew corner of the sail independent of the clew grommet. If the clew were to let go or outhaul part, the slug in the boom track would contain the clew well enough to get the sail under control.
 

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I like the shelf foot ;)


On the C&C 35 the delivery main is shelf foot and the race main is lose foot i cant really see a big differance other than the race main is new


I gotta say i can drag the footed main out of the cabin myself and install and flake it MUCH harder to do the lose one solo
 

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That is a fairly standard cruising mainsail arrangement.

The "shelf-foot" refers to a sail foot that is connected to the boom along it's full length.
Well, yes, but with extra material that unfolds if the outhaul is eased, thus creating the "shelf." There is also a footed main, which our boat's original main is, which simply has slugs, a bolt-rope or some other attachment mechanism for holding the length of the foot to the boom.

Jim
 

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One major advantage of the loose-footed main is that you don't need to have slits cut to pass the reefing lines through. Another is that the loose-footed main may be easier to shape since it'll have less friction, since the sail only has two or three slugs rather than a full bolt rope connecting the foot of the sail to the boom—making using the outhaul easier.
 

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I have no slugs

on my loose footed sail from Hood. It attaches to the boom via the clew/which is attached to the outhaul. the second boom attachment is at the tack. Obviously, there are slugs that go up the mast for the luff.

DrB
 

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Discussion Starter #10
The Cal 29 of the guy that suggested this has a bolt rope at the bottom so it is attached through the whole length of the foot. I notice that the main advantage for him was that even with little to no wind he seemed to be able to keep his boat moving a lot faster than anyone else. (We awarded him the nick name "5 knot" because of he could go 5 knots without the wind blowing) The "shelf" of his main must be the reason for the outstanding performance of his boat. Mel passed away after a bout with cancer a few months ago so I'm left with answering this question by inquiring here. I really appreciate the responses. Mel told me that other than the extra speed he was able to obtain the other thing he really liked about the shelf foot with full battens is that the sail is a lot quieter both when tacking and while reaching. His thoughts were that this translated into less turbulent air flow around the sail and thus better performance. Based on how well his boat handled under the conditions I had the pleasure of observing him in I would have to agree BUT I never got to see him reef the main OR handle the boat in heavier air (more than 25 knots). I suspect part of the reason for the outstanding performance of his boat was the fact that "5 knot" was just an outstanding sailor. I did note though that in winds around 20 knots I could stay up with him so it seemed to me that the majority of the improvement was in lighter air. Does this correspond with anyone's experience with this type of sail?
 

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One obscure advantage of a footed or shelf-footed main for cruisers/passage-makers is that you can catch rainwater with it.:D some cruisers even have zippers stitched into the foot so they could let the extra pootch out or zip it away.

A bolt rope spreads the forces most evenly, but when you reef all the downward/outward strain is on the clew anyhow. I should guess there's less spillage at the base of a footed main, but you can get a cleaner airfoil shape down low with a loose foot. Six of one, half dozen of the other.
 

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Proponents of shelf/footed mains will tout the "end plate" effect of the shelf reducing pressure loss around the "loose foot"... Personally I doubt that that effect is significant in the end.

The more uniform shape, easier outhaul loads and ease of bending and unbending the sail that comes with the loose foot (along with simplified reef line rigging, as per SD) come out in its favour for me.
 

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You're a very wise man... :)
Proponents of shelf/footed mains will tout the "end plate" effect of the shelf reducing pressure loss around the "loose foot"... Personally I doubt that that effect is significant in the end.

The more uniform shape, easier outhaul loads and ease of bending and unbending the sail that comes with the loose foot (along with simplified reef line rigging, as per SD) come out in its favour for me.
 

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Discussion Starter #14
So, does that mean that with a loose foot there's less heeling as the wind picks up and thus you don't need to reef as fast?
 

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So, does that mean that with a loose foot there's less heeling as the wind picks up and thus you don't need to reef as fast?
I wouldn't say that that is necessarily true... but you will find that with a new, flatter sail you'll end up reefing later because you'll get more drive/less heeling forces due to it's more efficient shape and adjustablility.

But you'd likely have the same issues with a "bagged out" loose footed sail as with an attached-foot main.
 

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I think you guys are confusing terms. The choice you have to make is not between a loose footed main and a shelf footed main. The choice is between a mainsail with an attached foot and and one with a loose foot. A shelf foot is an option that you can get with either of those types of sail.

A sail with a standard, attached foot has a shape that's good for most purposes, but a shelf foot allows you to shape the mainsail with a very deep pocket along the foot, which generates more power in light air. As the boat's speed increases, you adjust the outhaul to gradually decrease the depth of the pocket.

Because the shelf foot is used in light air, most sailors won't feel or perceive a difference in the boat's speed or the sail's power, unless you're near another boat, where you can compare your speed.

I raced and cruised with a shelf footed mainsail for many years and loved it, but, it works best with a little more active trimming than a mainsail without a shelf foot. I can't think of any reason why either a racer or cruiser wouldn't want a shelf foot, but most people don't have them. I suspect it's just because most people don't know about them. If you get a shelf foot, I'd recommend you also get a flattening reef, for those occasions when you have a lot of wind and need to flatten the sail to the max. The flattening reef is especially useful with an attached footed mainsail. It might not be as useful with a loose footed sail. If you're going to buy a loose footed sail, I'd suggest you ask your sailmaker's opinion on that question.
 
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