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Go Back   SailNet Community > Skills and Seamanship > Learning to Sail
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  #1  
Old 05-15-2014
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What creates the most power...

A couple weeks ago I was participating in the 61st Annual Mug Race (the longest river regatta in the world at 44 miles long) with my 1976 Chrysler 22, which had moderately strong winds and very rainy conditions. My 38 year old genoa was not feeling it and she ripped apart about 6' down from the head, and tore all the way from the leech to the luff. I had to drop the sail and hank on the storm jib for the rest of the day, which is where my question comes from.

Shouldn't I get more power by elevating the jib off of the deck, by connecting a line from the tack of the jib down to the deck, so i could raise the jib as high as possible? The luff of my jib is only like 20' but the forestay is around 27'. When the jib was flying high it seemed like I actually had less power, then when I had the tack attached to the deck.

My thoughts were the higher from the water the sail was, the faster the air is moving, therefore the sail should create more lift.

Thoughts?

P.S. If you have a good condition genoa that you could send my way I would be greatly appreciative. I do not have the funds right now for a new sail, so hopefully someone has a used one I could buy for not too much money.

As a side note in case anyone cared...
92 boats started the race.
Based on handicap ratings I was the fourth slowest boat so I was the fourth boat to start the race.
I raced my way into 1st place within 45 minutes or so and then my genoa tore apart at about 1 1/2 hrs into the race.
The race is from south to north along the St Johns river and the wind was out of NW at about 15-20mph and higher gusts.
Only 11 boats made it all the way to the finish line 44 miles (probably 80 miles due to all the tacks needed when sailing upwind)
You needed to get to the what they called the Mid-Course Marker by 7:30pm in order for your time to count and for individual class rankings to be decided.
Only 61 boats made it to the Mid-Course Marker and I was the second to last boat to finish in time

I consider this to be a pretty good achievement for my very first regatta and making it to the marker with the storm jib, while 31 other boats either dropped out or couldn't make it in time. Based on the GPS we actually travel 35 miles but only made it 24 miles into the course. We just barely made it to the marker in time, so once we passed it we dropped the motor and puttered as fast as we could back to the my dock. 14 1/2 hours on the boat was quite the day.
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  #2  
Old 05-15-2014
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Re: What creates the most power...

It is all about the slot grasshopper.

Follow this link in search of enlightenment.

WB-Sails - Aerodynamics

BTW Kudos for finishing inside the time limit. Now get saving for some crispy brown sails.
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Old 05-16-2014
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Re: What creates the most power...

The wind is likely stronger, and possibly from a slightly different direction up away from the surface of the water. This is why you see pictures of square-rigged ships sometimes with their sails at the top of the mast trimmed slightly differently from the sails at the bottom. On those ships you're looking at masts more than a hundred feet high.The difference in the two or three feet you'd get from adding a pennant to the tack of your storm jib would be absolutely minimal. There are also other things to consider. Setting your sail higher up will increase the heeling - which will likely slow you down. Ocean sailors do sometimes rig pennants to the tacks of their storm jibs, but this is for other reasons. It gets the sail away from the deck so that waves don't rip it apart (it is a STORM sail!). You also don't want a wave to hit the sail and flip the boat over. Some sailors may also think it puts the sail up in a steadier wind - where it will not be blanketed by oncoming waves - possibly reducing the shock loads on it so it holds up better. Having a sail cycle from 35 knots to 50 knots, perhaps filling and emptying with every wave, is not condusive to its longevity. It might be better for it to have a steadier breeze. Good luck in your next race!
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Old 05-16-2014
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Re: What creates the most power...

Higher is better, but a higher jib will block the higher part of the main which means the total force created will decrease.
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Old 05-16-2014
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Re: What creates the most power...

well done on the race, and kudos for "adapting to circumstance and keeping her going after something breaks", an essential skill for sailors ;-)

I echo the good advice above. Another thing to keep in mind is the angle of jib lead, you want the sheet to sort of bisect the angle of the clew corner. Or put another way, the sheet, projected "upward" in the same line as it has from block to clew, should bisect the luff, up to maybe 10% above that mid-point. Poor sheet angle will slow you more than you might gain or lose by having the tack itself higher or lower than "standard".
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Old 05-19-2014
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Re: What creates the most power...

Quote:
Originally Posted by nolatom View Post
Another thing to keep in mind is the angle of jib lead, you want the sheet to sort of bisect the angle of the clew corner. Or put another way, the sheet, projected "upward" in the same line as it has from block to clew, should bisect the luff, up to maybe 10% above that mid-point. Poor sheet angle will slow you more than you might gain or lose by having the tack itself higher or lower than "standard".

I love coming across little nuggets like this. I have noticed things like this while sailing casually, but about the time I begin to see the correllation the conditions change or I tack, or something changes before I come to really understand what I'm seeing.

Would you mind expanding on your comment, but on a Sesame Street level so that I can picture it in my head as you explain it? Where you lost me is "10% above that mid point." I'm sitting here at my computer trying to imagine from memory what "that mid point" refers to.

Thanks in advance!
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Old 05-19-2014
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Re: What creates the most power...

Quote:
Originally Posted by ShoalFinder View Post
I love coming across little nuggets like this. I have noticed things like this while sailing casually, but about the time I begin to see the correllation the conditions change or I tack, or something changes before I come to really understand what I'm seeing.

Would you mind expanding on your comment, but on a Sesame Street level so that I can picture it in my head as you explain it? Where you lost me is "10% above that mid point." I'm sitting here at my computer trying to imagine from memory what "that mid point" refers to.

Thanks in advance!

Let's say the jib luff is 20 feet tall. Midpoint is 10. I'm thinking the imaginary dotted line that projects "forward and upward" from the clew on the same angle as the sheet when close-hauled, should be between 10 and 12 feet above the tack fitting as it crosses the jib luff and heads off into infinity.

Last edited by nolatom; 05-19-2014 at 01:54 PM.
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Re: What creates the most power...

Thank you for the very quick response!
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Old 05-19-2014
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Re: What creates the most power...

Brown's Creek Sailing Assoc. hosts the annual Great River Race on Lake Guntersville, part of the Tennessee River. That race is over 70 miles, with 24 hours to complete.

Unless I am mistaken, there are even longer races on the Columbia River.

44 miles is a long race, sounds like you did a great job.

The higher jib moves the center of force higher,one of the main disadvantages of a roller furling jib when reefed. Higher center of force means force generated is applied farther along the lever, creating greater heeling/lateral force.

'
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