I Think I'm going to put sail slugs on our boat for the convenience and being able to get the sails down fast in bad weather, but is there any significant change in performance? Seems like you could lose some pressure on the sails by it leaking between the mast and the sail at the slugs thus minimally decreasing performance. On the other hand if any pressure leakage is negligible then your sail is effecitively larger ---about 1" x ~28'(whatever the height of the sail is). I am anticipating fun answers such as if I'm that worried I should probably lower the weight of the boat by not bring an extra pair of shoes or by not wearing underwear. Or that I should go back to my 18' Hobiecat.
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Jeff K
Is the sail tight against the mast?
So I guess a corolary to my question is how tight do the slugs pull the sails against the mast?
So I guess a corolary to my question is how tight do the slugs pull the sails against the mast?
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John S
Sails in Flight
Well, this question goes along with something I was looking at this weekend. I am currently flying the foot of my mainsail free from the boom. It is attached at the corners only and seems to work better than having the boltrope in the slot. So why not do the same thing vertically? Why not fly the mainsail with only three points of attachment? I am sure you have seen pictures of large sailing boats where sails semm to hang in space in every possible way..(see Herreschoff Americas Cup designs)... Sorry to add a layer of confusion to your post, but I think that many parts of the boat are a compromise and the sail slugs are one of them. John S
Well, this question goes along with something I was looking at this weekend. I am currently flying the foot of my mainsail free from the boom. It is attached at the corners only and seems to work better than having the boltrope in the slot. So why not do the same thing vertically? Why not fly the mainsail with only three points of attachment? I am sure you have seen pictures of large sailing boats where sails semm to hang in space in every possible way..(see Herreschoff Americas Cup designs)... Sorry to add a layer of confusion to your post, but I think that many parts of the boat are a compromise and the sail slugs are one of them. John S
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bruce cornell
speed
if you are a racer with a phrf below 150, you may want to keep the luff rope, may drop 1/4 to 1/2 knot at most, nothing to a cruiser, but important to a racer. and, reefing is much easier with slugs since the sail remains on the mast.
if you are a racer with a phrf below 150, you may want to keep the luff rope, may drop 1/4 to 1/2 knot at most, nothing to a cruiser, but important to a racer. and, reefing is much easier with slugs since the sail remains on the mast.
Slugs
My 26S mainsail came with slugs on the luff and foot. The sail is baggier than I'd like it, but it's old and blown out anyway. My opinion is that slugs do make the sail less efficient, but the difference is immaterial to me and the benefits of slugs more than outweigh any loss in speed. There's just no comparison in ease of raising, reefing and dropping the sail. If/when I replace the main, I would definitely go with slugs on the luff. The foot doesn't really need them, since I keep the boat in a slip with the sail covered on the boom. John S raises an interesting point about loose-footed mainsails. They're common on in-mast roller-furled boats and on some daysailers that have no boom. I wonder about the no-boom option every time I jibe in strong winds.
My 26S mainsail came with slugs on the luff and foot. The sail is baggier than I'd like it, but it's old and blown out anyway. My opinion is that slugs do make the sail less efficient, but the difference is immaterial to me and the benefits of slugs more than outweigh any loss in speed. There's just no comparison in ease of raising, reefing and dropping the sail. If/when I replace the main, I would definitely go with slugs on the luff. The foot doesn't really need them, since I keep the boat in a slip with the sail covered on the boom. John S raises an interesting point about loose-footed mainsails. They're common on in-mast roller-furled boats and on some daysailers that have no boom. I wonder about the no-boom option every time I jibe in strong winds.
Could not notice
I recently added slugs to ease in reefing. Never noticed the slightest difference in performance or speed. Not a racer or an enginneer but it seems due to the shape of the sail at the mast it would be insignificant. i.e. if the "space" were in the belly of the sail it may be more significant. Realisticly how often is the space between the sail and mast in line with the wind? Only at an exact beam reach?
I recently added slugs to ease in reefing. Never noticed the slightest difference in performance or speed. Not a racer or an enginneer but it seems due to the shape of the sail at the mast it would be insignificant. i.e. if the "space" were in the belly of the sail it may be more significant. Realisticly how often is the space between the sail and mast in line with the wind? Only at an exact beam reach?
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Keith
Same Here
Adding slugs to my Mac 23 was the best thing ever. Now the sail goes up and down like a window shade – quick. I’ve noticed absolutely no difference in performance. Now, I’m not an aerodynamics specialist, but I’ve taken a few physics classes. As we all know, sails provide lift by having lower pressure on their backsides than on their front sides – the same as an airplane wing. It seems to me, on as sail, the main area of lower pressure is in the mid and aft portion of the sail – the leading edge just directs the air one way or the other. I think that the mast will have way more effect on leading edge air – slugs or no slugs.
Adding slugs to my Mac 23 was the best thing ever. Now the sail goes up and down like a window shade – quick. I’ve noticed absolutely no difference in performance. Now, I’m not an aerodynamics specialist, but I’ve taken a few physics classes. As we all know, sails provide lift by having lower pressure on their backsides than on their front sides – the same as an airplane wing. It seems to me, on as sail, the main area of lower pressure is in the mid and aft portion of the sail – the leading edge just directs the air one way or the other. I think that the mast will have way more effect on leading edge air – slugs or no slugs.
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Jeff K
Are slugs easy to take off?
If I decide I dont like the slugs are they easy to take off? Is the sail damaged by them? And regarding the gap between the raised sail and the mast when using slugs is it usually something like 1/4", 1/2", or and inch?
If I decide I dont like the slugs are they easy to take off? Is the sail damaged by them? And regarding the gap between the raised sail and the mast when using slugs is it usually something like 1/4", 1/2", or and inch?
slug tested
I've now had two weeks of test saililng my 26X in light air 0-10mph with slugs installed. I can't see any difference in sail shape or performance than with just the bolt rope. I know the theory about turbulence caused by the mast and the 1/4" gap,but I think in any kind of wind our Macs could take without reefing,it would be almost immeasurable. I think the factory just orders bolt ropes only because it's significantly cheaper that way.
I've now had two weeks of test saililng my 26X in light air 0-10mph with slugs installed. I can't see any difference in sail shape or performance than with just the bolt rope. I know the theory about turbulence caused by the mast and the 1/4" gap,but I think in any kind of wind our Macs could take without reefing,it would be almost immeasurable. I think the factory just orders bolt ropes only because it's significantly cheaper that way.
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Jeff K
thanks everyone for the input.
Mike.The 26M might have the mast and sail in line more in the area adjacent to the mast since the mast rotates. significance is still up in the air.
Mike.The 26M might have the mast and sail in line more in the area adjacent to the mast since the mast rotates. significance is still up in the air.
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