Height and lowth

Explain in simple terms what it means please?

I might not be the most knowedgable person going but been the "average" Y+Y reader, you will need to explain with diagrams and examples.

Thanks

Developing more height upwind is the easy bit; nice hard leeches, cars forward/down for the jib and plenty of vang/mainsheet on the main and board right down. Then sail with the inside tell-tale lifting as much as you can get away with.

My question would be regarding how to set the boat up if you wanted to foot, for example if you wanted to get over to a particular side of the course fast in order to lock into the next anticipated shift or if you were being lifted and wanted to take it as extra speed to drive over some boats clear ahead and to leeward instead of taking the height. Would doing the opposite of the height settings (i.e. loose, twisted leeches) be the best set-up and how would you sail the boat? Both tell-tales streaming? Would you chock the rig straighter, more bend or leave it? Would you ever lift the board slightly?

My issue with twisting the sails is that this would have the effect of flattening them and reducing power and I'd have thought you would need a nice punchy rig to develop the power to foot off. Same issue with raising the board; that's a depowering tool. Am I missing something?

I'm thinking single trapeze boat, but I guess the answer would be the same for a twin-wire boat too. In my experience, it very rarely pays to foot in most hiking boats.

I'm not sure I'd agree that lots of kicker makes a boat more pointy, but that aside I'd say its mostly to do with those tell-tales.  If you sail with the windward ones streaming upwards then you are going to get height instead of speed, if you drive the boat a bit they'll be streaming more horizontally.  I'm sure you need an open leech up near the top - so maybe a little downhaul if there's a tendency to be overpowered.

Now some boats benifit from being driven and my Laser4000 does once we're fully powered up - in fact we actually have to ease the jib a bit and then it really works because we increase our speed by 50% and only increase the distance by 10%.  I used to campaign a Laser and most of the time it paid to point but in light winds you could drive it and it would pay, however there were times when tactically it was worth it and then you really had to sit out hard or you didn't go any faster.  In fact I'd say as a rule that when driving the boat it is even more important to keep it flat, whereas pointing can be enhanced by a little heel to wieght up the rudder.

Now to another consideration - the wind is not constant.  So the time to point is in the lulls and the time to drive is in the gusts.  This is the opposite to the natural inclination of most boats and certainly the opposite to the natural tendency of the less expert helm.  This brings me back to the kicker, my boat needs more when the wind is stronger - so the opposite to when I want to point!

"Now to another consideration - the wind is not constant.  So the time to point is in the lulls and the time to drive is in the gusts.  This is the opposite to the natural inclination of most boats and certainly the opposite to the natural tendency of the less expert helm."

There is a theory about sailing fast planing boats upwind at shifty inland venues which says that it's sometimes faster to sail a straight line and ease the sails through a (short) lift , taking a bit of extra speed, instead of chasing the wind direction up and down. This is because it's quicker to ease the sails than to change the direction of the boat.

Presumably this would depend on the duration of the shifts though. I'd suggest that if the shifts were lasting more than 5 seconds it would be worth heading up.

Bruce, when I get a chance I'll try that technique. 

Now changing gear, in boats with a big roach the ability of the leach tension to control the angle of attack of the upper mainsail is significant.  The "threadline" from masthead to the end of the boom goes through the middle of the top battens and so by increasing the leach tension the roach can be brought up to windward.  This increases pointing ability but at the expense of the ability to accelerate.  This can be most easily achieved if the strop is adjusted so that the last few inches of mainsheet bring the boom into the centre line and then hardens the leach.

During a gust the mainsheet is eased and the leach goes softer as the boom goes out.  Giving a more twisted and open leach.  This is ideal for acceleration.  Once up to speed the main comes in a bit but not so much as to tighten the leach - this is good for fast windward sailing. And finally as you sail into lower pressure the mainsheet comes in that bit more tightening the leach and pointing the boat.  However that last setting is only suitable for dying pressure and if the wind stays light the mainsheet has to be eased to open the leach a bit and the crew comes in off the wire.

I wonder if Dennis Watson (or any other high performance boat helm) would agree?