I have just installed a new roller furl system and with it a new sail. The new sail is about 4' shorter than the HML, but its a 130% instead of the 100% the old sail was. Which gives better performance, having the sail ride high on the headstay so it clears the deck by 4' or have it ride low on the headstay?
headsail Ride high or ride low?
- Thread starter Donald6441
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Giving up 4' of luff means that you are giving up a large amount of sail area. In fact if you were to compare the relative sail areas of the two sails, you will find that you don't really have as big a 130 as you could have. Racing boats will buy "deck sweepers" for a very good reason, their faster. Why would you intentionally give away sail area if you were buying a larger sail? It's like buying 9 gallons of fuel and paying for 10!
We might not all race anymore
Ahoy Don; Have the sail ride high off the deck. Two reasons for this. The higher off the water the greater the wind speed, and you will be able to see under the sail. Oh I am guessing but you don't race your boat alot. If you did you wouldn't use roller furling Fair Winds Cap'n Dave EX racer
Ahoy Don; Have the sail ride high off the deck. Two reasons for this. The higher off the water the greater the wind speed, and you will be able to see under the sail. Oh I am guessing but you don't race your boat alot. If you did you wouldn't use roller furling Fair Winds Cap'n Dave EX racer
Somewhat Reluctant
I am somewhat reluctant to give sailing advice, because I have only been sailing for about seven years and none of it racing. However, keeping the sail down close to the deck prevents the airflow from rolling around the bottom part of the sail. It is similar to the winglets they are now putting on aircraft. They improve performance. Raising the sail a foot or so will not significantly increase the wind speed. I do agree with the better visibility and I prefer to keep my sails high.
I am somewhat reluctant to give sailing advice, because I have only been sailing for about seven years and none of it racing. However, keeping the sail down close to the deck prevents the airflow from rolling around the bottom part of the sail. It is similar to the winglets they are now putting on aircraft. They improve performance. Raising the sail a foot or so will not significantly increase the wind speed. I do agree with the better visibility and I prefer to keep my sails high.
Mount it as low as possible ......
Sail efficiency of a 'deck sweeper' is increased by the 'end plate effect' ... so that the flow from the windward side doesnt 'short circuit' across the foot to the leeward side. A sail that is high off the deck will have a lot of 'recirculation' leakage from high pressure side to low pressure side. A high jib/genoa will generate more heel and less forward drive; a deck sweeper adds more 'drive' but little increased heeling moment. If you want better visibility, you can install a vinyl window(s). Windows arent necessiarily near the foot of the sail but are usually 'higher up' so that when the boat is at normal heel the sight/visibility angle is correct. Many folks who have their jibs/genoas far off the deck cannot see well because the sail material above the foot is still blocking their sight when the boat is heeled over. A correctly placed window is usually the 'best' for good vision. ;-)
Sail efficiency of a 'deck sweeper' is increased by the 'end plate effect' ... so that the flow from the windward side doesnt 'short circuit' across the foot to the leeward side. A sail that is high off the deck will have a lot of 'recirculation' leakage from high pressure side to low pressure side. A high jib/genoa will generate more heel and less forward drive; a deck sweeper adds more 'drive' but little increased heeling moment. If you want better visibility, you can install a vinyl window(s). Windows arent necessiarily near the foot of the sail but are usually 'higher up' so that when the boat is at normal heel the sight/visibility angle is correct. Many folks who have their jibs/genoas far off the deck cannot see well because the sail material above the foot is still blocking their sight when the boat is heeled over. A correctly placed window is usually the 'best' for good vision. ;-)
Raise it off the deck 4 feet?
We have exactly the same situation. Our 150% has a luff length that matches the headfoil length of our furler. Out 130% is about 3 1/2 ft shorter. I realize it is not the maximum area possible for our true 130% measurement but that is not terrible important to us. We chose to add a wire rope extension to the top of the sail (to allow the halyard to reach the top of the headfoil to prevent wrapping when the sail is furled) so that we could keep the centre of effort lower and reduce the heeling effect especially given the fact that we only bend this sail on when the wind is higher thus causing greater heeling. I could just as easily swap the extension to the tack but it makes no sense to me.
We have exactly the same situation. Our 150% has a luff length that matches the headfoil length of our furler. Out 130% is about 3 1/2 ft shorter. I realize it is not the maximum area possible for our true 130% measurement but that is not terrible important to us. We chose to add a wire rope extension to the top of the sail (to allow the halyard to reach the top of the headfoil to prevent wrapping when the sail is furled) so that we could keep the centre of effort lower and reduce the heeling effect especially given the fact that we only bend this sail on when the wind is higher thus causing greater heeling. I could just as easily swap the extension to the tack but it makes no sense to me.
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