Forestay deflection

[Ausluke]

Hi,
Could all please see the photo attached, and comment if this is to much flex of forestay. If not, what would be considered too much?

Cheers
Luke

[Nicholson58]

It’s all about the resultant sail shape. Too much sag and the sail starts to look like a spinnaker. Ideally it should have a uniform foil shape top to bottom. If in doubt, consult a sail maker or rigger or both.

If the sag is too much, your roller furler foil can be damaged

[MartinR]

Hard to say from a photo. There is always some sag. Easiest to check your forestay tension,
which of course is dependant on backstay tension.

[Bill O]

Agree hard to tell from the pic how much sag you currently have, but the sag should match the luff sag built into the sail.

In our genoa, we have a 5" luff sag built into the sail mostly for reaching conditions. Racing type head sails may only have 3" or so. Not sure where the article is located, but "Rich H" did a very good write up on this topic, Here is a link to another discussion from Rich H on the same. Ill try to find it again and post a link.


Bill O.

[Suijin]

Too much for what, exactly?

Off the wind you loosen your backstay, introduce some “sag” in the forestry, and move the sail draft forward. Beating you tension the backstay to move the draft aft so you can point.

If you don’t have an adjustable backstay then you probably want it tuned for going to windward. And that will be a function of how much you can tension the backstay within the specs of your rig. If you crank it down to it’s max and you don’t have a relatively straight luff then you have another rigging issue to address.

Hard to tell from the picture exactly how you’re doing. What is the length of your forestay and how much wind was there? It looks pretty good to me as a moderately tight luff for cruising if that was taken in 12-15 knots.

[Bill O]

Found it, here is the article on Matching Luff Hollow which includes a way to measure your luff hollow if you don't know how much was built into the sail.


Bill O.