Shape of Main

[Don Guillette]

Steve: I've tried to post an answer to you twice but I don't know where they go when I hit submit so I thought I'd try it as a separate topic. In my opinion there is NO difference between a loose footed main and bolt rope. I have match raced (two equal boats) with both systems and there was no advantage to either. Additionally, I've watched Congressional Cups boats race in Long Beach with both systems and saw no advantage. Actually, only about 2 or 3 Congressional boats were loose footed and if there was an advantage to that system they all would have it.Some sailors will say that a loose footed main is easier to shape but if you have a good working bolt rope outhaul system you can shape the sail exactly as the loose footed system. Remember we are only talking about a relatively small amount of outhaul travel for draft depth (belly) and in some cases with the loose footed system you can go beyond what is efficient.I prefer the bolt rope sytem only because I'm too old to change!! Sail makers should charge less for the loose footed because it is less work to build but they don't.

 

[Bob]

One advantage

A sailmaker in Florida told me he likes boltrope mains because the pocket in the sail keeps water off him when it rains. With a loose foot, all the water drains straight down off the main. I have to admit, though, that I like my loose footed sail and probably won't go back. (I don't sail much when it's raining.)

 

[Joe]

loose foot /shelf foot

The loose foot main seems to be the standard with many sailmakers. They charge extra for the shelf foot feature now. It does require extra labor and material. I assume when you refer to the bolt rope main that it has the "shelf" feature.

 

[Bob]

Reading the sail

When I ordered my mainsail 3 years ago I specified that it was to be loose-footed, more out of a desire to try something different than for any clear technical reason. But once it was up, I noticed that it was much easier for me to "read" than the old boltrope sail. Part of that was due to its freshness and better shape, but part was because I could look at the foot when adjusting the outhaul. You don't get the true draft shape at the foot, because there is some extra material there - sort of a foot "roach" - but you can really see the shape well just a little ways up. And seeing the shape better leads to being more willing to play around with different settings. Don makes the point that your adjusting controls should be easy to use, and seeing the sail better contributes to that process, too.However, I have always wondered why the sail does not lose drive from not having an 'end-plate' - boltrope sails have the boom to help stop pressure leakage around the foot, but loose footed sails don't, and yet it doesn't seem to hurt their performance. Perhaps that roach along the foot serves the same purpose as the shelf foot.

 

[Don Guillette]

End Plate Effect

Bob: I'm about as far from a areodynamist as one can get but I don't think the end plate effect is really a factor on production boats because the sail area is not big enouh as compared to say an America Cup boat. It is one of the reasons I did not mention it as an advantage to the bolt rope system. I don't think one saves enough of leakage with the bolt rope to make any difference. In my opinion, both sails are equal from an efficiency standpoint.In the match racing situations I was talking about I really tried as hard as I could to get everything possable out of the bolt rope to beat my friend in the loose footed but the other boat was no slouch from a sail trim standpoint and we ended up equal. When we reversed the boats I did the same with the loose footed sytem and the result was the same - no advantage to either.The choice of loose footed or bolt rope just boils down to a personal preference and what a sailor is happy with.On the end plate effect - I'm sure you have noticed the size of the boom on the America Cup boats - it is very long from top to bottom. They are trying to capture every bit of air they can. End plate effect is one of the reasons you will never see a loose footed main on an America Cup boat.