windward steering.

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trebor
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windward steering.

Post by trebor » Mon Jun 16, 2014 8:12 pm

apologies for topic title.
I have a problem when sailing really fast, the boat keeps trying to turn into the wind ( I know their is a name for this, but I cant remember what it is ), this takes a lot of tiller to keep going straight, enough that I snapped tiller extension in half, possible reasons and solutions if possible please.
Robert
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Michael Brigg
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Re: windward steering.

Post by Michael Brigg » Mon Jun 16, 2014 8:37 pm

Its a common problem with boats designed as Low end non performance beach boats. Toppers and the original windsurfers were especially prone.

You have an unsupported monosailed rig with a spar that is inexpensive and so it is also bendy.

In higher wind strength the mast has nothing (like Shrouds and spreaders or a forestay) to stop it bending. Going upwind in a blow you pull the main in ever tighter and the mast bends to the back of the boat bringing the centre of effort behind the plate. A relatively small rudder has little to compensate for this. The fullness of the sail also is moved back unless you have a very stong downhaul, a stiff mast or a very stiff cloth, and so the sail ceases to produce a forward drive and merely pushes the boat sideways. The centre of effort of the sail being behind the centre of effort of the hull will cause you to round up into the wind. In a less dramatic situation this simply causes "weather helm" where you must pull the rudder toward you to keep the boat on line.

In the extreme situation all you can do is let the main out so that you don't round up, and get enough speed on the boat to give you steerage. You must then continue to sail free, on a balance between making forward progress and maintaining upwind progress. Sacrifice course made good in order to maintain speed. The closer to the wind you try to get (in strong wind) the worse the effect of mast bend will be.

If you have a centreplate that is on a pin then half lifting it on the beat will move the centre of effort of the hull backwards and so allow you to steer more easily. If you have a daggerboard then pulling it up a bit going upwind in a blow again may lessen the weather helm, but you will make more leeway.

The only other alternative is to reef the sail enough (if you can) so that it doesn't bend the mast so much.
Last edited by Michael Brigg on Mon Jun 16, 2014 8:51 pm, edited 1 time in total.
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Rupert
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Re: windward steering.

Post by Rupert » Mon Jun 16, 2014 8:40 pm

Firstly, check that the rudder is going all the way down. 2nd, check that you are sailing the boat flat. Really flat. Get someone else to tell you, as it is hard to tell from inside the boat.

If both the above are happening, then you have a balance problem. By the sound of it, this is when you are reaching. You need to ensure you have raised the centreboard half way, to bring the centre of lateral resistance further aft, to bring things into balance again.

Also, ensure your sail is far enough out - just on the edge of flapping. It may also be that sail settings (amount of kicker, letting the cunningham off) need looking at, but impossible to tell without seeing.

The Minisail does this. My tiller extension is strong enough, so if I get it wrong, it is my shoulder that gives out!
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trebor
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Re: windward steering.

Post by trebor » Mon Jun 16, 2014 9:00 pm

Hi Michael, the problem does not occur when beating, it is on a fast reach, the boat is flying along not stopped., thanks for putting correct term, weather helm.
Hi Rupert, The rudder is definitely down, yes, it may not be flat, this would be an easy fix, with an observer, I will try this thursday, presumably it is turning because boat is heeled ?
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Re: windward steering.

Post by davidh » Mon Jun 16, 2014 10:47 pm

It can also be an issue when the hull form is flat - worse again when there is a hard chine. This can grip and dig in and help turn the boat into the wind. As the other replies say, keeping the boat flat and not oversheeting are the other ingredients of making it successfully down the reaches

D
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Re: windward steering.

Post by jpa_wfsc » Thu Jun 19, 2014 2:55 pm

In mirror dinghy race training, - which also often had similar problems on the orriginal gunter rig - we were often told to actualy heal the boat to windward slightly. It feels bad to do this but it is definitely quicker!

Did you say what boat it is you have this problem with? It makes a hugge difference..

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trebor
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Re: windward steering.

Post by trebor » Thu Jun 19, 2014 5:31 pm

The trouble occurs with the Aquabat.
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Re: windward steering.

Post by Nessa » Thu Jun 19, 2014 8:49 pm

As well as keeping the boat flat, sit further back than you might usually do.

It's worth looking at the Boat Whisperer Downwind video, it's pretty helpful for this sort of sailing.
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Re: windward steering.

Post by trebor » Thu Jun 26, 2014 10:10 pm

Hi all, I tried all things suggested, they all worked to a degree, but keeping boat flat virtually eliminated it, then moving slightly aft totally eliminated it, thanks for help, just thought I would give a bit of feedback.
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Re: windward steering.

Post by Rupert » Fri Jun 27, 2014 5:54 pm

Excellent. Hopefully we will have enough wind next weekend for you to demonstrate!
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