Setting Genoa

[spiller]

If I rig the headsail such that the tack is "on the deck", the sail fouls on the guardrails.

However, I have a 15" extension to raise the tack and thus avoid the fouling and wear on the foot of the sail.

Am I correct in thinking that with the extension in place the rig is not as efficient as it might be?

I have noticed that when racing, most boats have the foot of the headsail on the deck so to speak.

Thanks to all who contributed on the Cunningham subject.

 

[BAtoo]

You probably wont notice the difference & it will save the sail as it is intended to.

Some headsails also have cunninghams about which you know quite alot now!!!

 

[Leighb]

I am not an aerodynamics expert, but if I recall correctly having the headsail close to the deck increases efficiency as it reduces high pressure leakage under the foot of the sail, however there are other factors at play, the lower the tack the further the leech is from the mainsail, thus affecting the slot for better or worse?

The racers seem to go for a low deck sweeping sail, but visibility is adversely affected, and in close quarters may be downright dangerous unless you have a bowman in the pulpit.

If they do it one has to suppose that it is faster?

 

[geoffatstanpit]

Raising the tack on a strop will slightly reduce the efficiency by taking away the "end-plate" effect of the deck and it will also increase the heeling moment by raising the centre of effort of the sail. Wear on the foot of the sail shouldn't be a problem if the sail can be sheeted well inside the guardwires on a beat and you have a crewman appointed to "lift the skirt" if the sheet man isn't quick enough on a tack. Plastic-coated guardwires also help (whatever you think about the chemistry!) or those little wheels you can get to help the sail hop over.

 

[spiller]

Thanks all,

You confirmed my thoughts.

 

[flaming]

[ QUOTE ]
Wear on the foot of the sail shouldn't be a problem if the sail can be sheeted well inside the guardwires on a beat and you have a crewman appointed to "lift the skirt" if the sheet man isn't quick enough on a tack. Plastic-coated guardwires also help (whatever you think about the chemistry!) or those little wheels you can get to help the sail hop over.

[/ QUOTE ]

Or, if cruising a short sharp luff will bring the Genoa back within the guardrails without anyone having to put their cup of tea down and scamper off to the foredeck!

 

[William_H]

If yu put the jib on a strop don't forget to move the sheeting point further aft. (on the genoa pulley track)
Racers more than likely don't use this idea of extension because they always have as much sail as possible up. Limited by rules or by the heeling moment on the boat. Because heeling moment is worse when genoa is higher you have it as low as possible.
Yes you do in theory lose some efficiencyas pressure moves from one side of the jib to the other under the sail.

good luck olewill

 

[KINGFISHER 9]

Have you got a spare 15 inches at the top of the forestay?