How often do we hear this question! It can be really annoying if you think you have trimmed the headsail properly but the leech (the outer edge between top and clew) is still fluttering at best or flapping at worst… And it definitely spoils the photo’s…

Ric Hawkins – Windcrafts sailing guru- reckons that leech lines have to be the most forgotten about sail trim on a yacht. To be fair to us who are guilty – most leech lines are so well hidden that we tend to forget them. .! After all – eyes are usually on the tell tales and the luff aren’t they!

But many sailors /boat owners don’t realise that there is a handy little trim tool that enables you to stop this flapping with an appropriately tensioned leech

Before we listen to Ric note that we are assuming that you have a perfect headsail/main sheet trim – which you will of course if you have read an earlier post in this blog by Alby Pratt of North Sails. If the sail is still fluttering it is because the tension of the leech lines is incorrect for the wind strength and or angle

Most modern sails come with an adjustable leech line which runs the full length of the leech from the top to the bottom. It is here just above the clew that you can adjust it – usually protected by a Velcro pocket. This one is on a furling mainsail.

It has a couple of different purposes – it does take the flutter out of your leech and the stronger the wind the more tension you need in the leech line- consider it part of the trim of your sails.

Most people don’t touch this line throughout the life of the ownership of the boat! I’m very passionate about pulling this little line on according to the wind conditions at the time – and releasing it again.

See this little cleat here – you just pull the line to whatever tension you want and jam it off in the cleat. To release the line, pull it back and let the line run itself back through.

If you’ve tensioned the leechline up in a strong wind it is important to release it when the wind eases so that you don’t end up with an over tensioned leech which curls the sail and will slow you down! It’s even more important to release it when you finish sailing to “relax” the sail. A good tip is to do this before you furl the sail – so that you are using the wind pressure to stretch the leech line back out. Preferably a good 20 minutes before you finish for the day so that the sail has a chance to reset to its resting position. This really looks after your sail and will prevent the sail taking up a “memory shape” e.g if the leech line tension is tight it might create a permanent “curl” on the leech of the sail.

Extra tip – even many of the finer asymetrical sails come with a leech line – they are not easy to spot but have a close look and you may find the trim that takes out that last small but annoying flutter on the leech of an otherwise perfectly set gennaker!

So that’s it on leech lines – remember, they should be treated as your halyard tensions are – adjust according to the wind at the time of sailing – or not sailing. And no more flapping leeches.