Migrating spiders help with sail trim!

[Cowpokee]

I frequently read that for proper sail trim, the top batten should be parallel with the boom. When the batten curves as in the following picture, which part of the batten is being referred to?

The red lines are highlighting captured migrating spiders. The top web is off the windex and is aligned with the pointer. The lower web is close to the batten in question. Notice none of my telltales are flying but the web shows no sign of turbulent air coming off the sail.

Obviously I am close hulled, the travel is full to windward with the boom on the centerline. I don’t think I had the backstay on at the point this picture was taken.

So what’s up, what should I be doing differently (if anything) to properly line up the top batten and get my tell tales flying?

 

[dlochner]

I frequently read that for proper sail trim, the top batten should be parallel with the boom. When the batten curves as in the following picture, which part of the batten is being referred to?

When the top batten is not a full batten, it should be parallel. That means the leach of the sail is properly tensioned. With a full batten, it is a bit more difficult because the batten follows the curve of the sail. Better to rely on the tell tales.

Ease the mainsheet and raise the traveller. That should take some pressure off of the leach of the sail and allow the top batten to fall off a bit and align better.

When close hauled, the boom should be at centerline or a little above. Use the traveller to center it. Then trim mainsheet until the telltales stream aft. It may be necessary to go back and forth trimming the main sheet and adjusting the traveller to get it right. If things get really screwy, just ease everything and start over.

 

[mm2347]

The spiders hate us! They believe we are invading their territory and try to disable or disrupt all that they can. My windex (at the top of the mast and hard to get to) has been so totally and tightly lashed in spider webs that it would not turn. When I'm not looking, the spiders, some huge, crawl up my tiller onto my bare arm!! I'm sure they believe sooner or later Ill jump high enough that I'll fall from the boat. I am sorry Cowpokee, compared to spiders, sail trim is a minor issue.

 

[Roland5048]

It also looks like your reef line is a bit tight, cupping the leach. Loosening that should improve the shape of the sail some.

 

[Cowpokee]

The spiders hate us! They believe we are invading their territory and try to disable or disrupt all that they can.

I agree, you can't get away from them anywhere. Even flying a hang glider at 3 - 4000 feet I find those migrating spider webs all over my support wires!

 

[Cowpokee]

It also looks like your reef line is a bit tight, cupping the leach. Loosening that should improve the shape of the sail some.

I didn't notice that while on the boat, but now, looking at it, I'll definitely loosen it some for the next sail.

 

[Jackdaw]

As a guideline, the last 1/3 of the top batten should be parallel with the boom. As a guideline. Just like your windex is. The real gauge of trim are your telltails.

But be careful. Many of the reasons that you cannot get your batten parallel with the boom are not trim related. Causes:

Batten to long
Batten to short
Batten to stiff
Batten to soft
Batten in backwards
Sail blown out.

Dlochner called the trim fix.

 

[Roland5048]

Batten in backwards

My new main, as well as the old one, is fully battened. When putting in the battens I didn't notice any difference on the ends of them. How does one know front from back?

 

[Jackdaw]

My new main, as well as the old one, is fully battened. When putting in the battens I didn't notice any difference on the ends of them. How does one know front from back?

Better battens are not the same flex over their entire length. Often they will be called 'tapered battens'. In this case, the tapered or softer end goes towards the mast.

If they are, usually they will be marked so you know when end to insert.

 

[Roland5048]

Thanks, Jackdaw. Next time I take the battens out, I will give it a good look.

 

[Cowpokee]

What about batten tension? What guideline should I use when inserting the battens after a sail change?

 

[Jackdaw]

What about batten tension? What guideline should I use when inserting the battens after a sail change?

Just enough to remove wrinkles. For most conditions you don't want any camber created by the batten. Exception: Light air top battens, where some camber is desirable, but not so much that the wind pressure (or you snapping the sail) will not pop it into correct shape on the new side after a tack. NOTHING worse than an inverted batten than won't pop.