Sail rattle / mast bend?

Red rosie · Post by **Red rosie** » Sun Feb 15, 2009 11:11 am

I have a relatively new 32ft sail boat which regularly develops a rattle in the luff of the mainsail half way up the mast - not always in the same place but roughly so.

I have tried tightening the halyard and playing with the vang and the outhaul but they do not resolve the problem which occurs mainly in a reach. tightening one or other of the halyard etc can move it around a bit and changes the pitch slightly.

is it possible that I need to change the bend in the mast to pull it forward ? - I am running out of options (and patience)

any thoughts welcome

Mike · Post by **Mike** » Mon Mar 23, 2009 8:37 pm

You could certainly put some prebend into the spar which would help flatten the sail. Depending on the rig there are different ways of doing this. If its a fractional rig with aft swept spreaders you could give the rig a bit more capshroud tension which will produce more pre-bend.
If its a masthead rig with for/aft lowers give the forward lowers a bit more tension which will induce some pre bend.#

mike

Red rosie · Post by **Red rosie** » Thu Mar 26, 2009 11:58 pm

Many thanks - I will try this.

I observed the sail closely last week - the luff is definitely flapping from half way up the mast to about 2/3rds up whereas it is tight elsewhere. I have tried using the single line reefing to get extra tension on the luff but even that seems unable to achieve tightness all the way up the mast.....weird

Steve

Mike · Post by **Mike** » Fri Mar 27, 2009 10:25 am

You didn't say if the boat was new or new to you? Its possible that the main has stretched & therefore fuller than it should be down the luff, however, putting some pre-bend into the mast should take the `round' out of the luff of the sail flattening it.

Red rosie · Post by **Red rosie** » Sat Mar 28, 2009 10:59 am

The boat was new to me (a beneteau 323 lift keel) 2 years ago. Funny you should mention the possible stretch of the main - I was out yesterday (rather breezy!!) and was wondering if in fact the main was literally unable to be pulled any tighter up the mast as the halyard shackle was right at the top.

however I used the single reefing to pull the luff down and it still rattled in the top 2/3.

I was however wondering whether it was worth getting a sail loft to reduce the sail length by 6 inches or so at the top - is that possible?

many thanks for the advice

steve

Mike · Post by **Mike** » Sat Mar 28, 2009 1:43 pm

Steve,

There should be no problem in shortening the luff, it will involve removing the headboard & possibly adding new doubling to the head of the sail & bringing in the leech tabling slightly before the headboard is re riveted back into place.

While they are doing this I would suggest that you get them to check the sail for fullness, if it has stretched which I suspect has happened then they should be able to take a bit of the `round' out of the luff curve to flatten the sail which should bring the draft of the sail forward which may also help improve your pointing ability & stop the sail from `lifting' down the luff near the mast.

mike

Red rosie · Post by **Red rosie** » Sat Mar 28, 2009 11:10 pm

Crumbs - this sounds complicated but a useful approach if all else fails.

I will start by trying your earlier thoughts - "If its a masthead rig with for/aft lowers give the forward lowers a bit more tension" when I have worked out what that means!

The base of the shrouds are set just behind the mast and I assume that if I tighten the ones that go direct to the mast at the point where the spreaders meet the mast (as opposed to the ones that go higher up via the spreaders) that will then tend to straighten the mast at the point where most of the bend is evident.

many thanks

Steve

Mike · Post by **Mike** » Sun Mar 29, 2009 9:41 am

Steve,

go to the following link: http://www.seldenmast.com/frameset.cfm? ... =946876835

Then go to the English hints & tips PDF, you will find all you need to know on setting up ALL types of rig, page 34 covers single spreader masthead rigs with fore/aft lower shrouds.

mike

Red rosie · Post by **Red rosie** » Sun Mar 29, 2009 5:50 pm

Excellent - very many thanks Mike

I have aready asked a local sail loft to quote for the work you suggested as well - so that I am prepared!

all the best