Advanced Dinghy Lessons Start with a Bang!

Philippe on the subject of sail trimming and especially use of the gnav (according to him, an under-used tool).

Philippe is an an incredible sailor and an amazing instructor.  We spent about half of the time on land with an RS Venture looking how the various sail controls affected sail shape and talking about what sail shape you want for what conditions (it was blowing over 15 kt. this evening, by the way, with pretty big seas - we  had a lot of weight on the boat on land to make sure it didn't capsize into the cars parked near the clubhouse). On land, it was much easier to see the effects of various controls on the sail shape.

This is my lesson summary (feel free to comment):

Scope: Dinghies which generally don't have travelers.

  1. Sail shape is very important. The usual things about depth and power, and location of sail draft. With lighter winds, you want a fuller sail and a draft a bit aft. With heavier winds, you want a tighter sail and a draft forward.
  2. In heavier seas, you want more power, even with stronger winds.
  3. Tensioning the Cunningham brings the draft forward.
  4. The outhall affects the lower third of the sail.
  5. Several controls bend the mast aft, which tighten the sail and move the draft forward. Tightening the mainsheet and the gnav do this.
  6. In high winds, you don't want the boom near the center of the boat, as the lift from the sail is mostly sideways to the boat. But just easing the mainsheet induces twist in the sail. Tightening the gnav overcomes this, allowing the mainsail to go to a better angle, but preserving the sail tightness.
  7. Bearing off from close-hauled, you want to do several things.  One is ease the mainsheet. Another is to keep weight on the windward side to help turn the boat downwind. A third is to ease the gnav (and then tighten it when on course).
  8. Gybe-ing:
    1. Blow the gnav before the gybe (this will depower the sail and cause the top of the sail to back-wind before the bottom of the sail, producing a gentler gybe).
    2. Weight the boat to windward to turn it down-wind through the wind. If you reach across to pull the boom across, you'll mess this up.
    3. If done correctly, the wind will gently pull the mainsail across. Grab the sheets as this happens to buffer it.
    4. Power up after the gybe by tightening the gnav

Then we went out and did it, both upwind and downwind. And it worked. I was prepared for hikiing really far out with the winds we had, but we didn't have to. And it was amazing how gentle the gybes were with this technique. Note that in bearing off and gbye-ing, you're doing what you would do rudder-less - moving weight to turn the boat. After the class, I discussed that with Philippe, and  his opinion (as a racer of some renown) is that the more you can use your weight to  maneuver the boat, the better (i.e. faster) you'll sail.

For me, this was an excellent complement to the Senior Study Group session by Saul on Advanced Sailing Theory (which was also excellent), and to the book Saul recommended - Tom Whidden's The Art and Science of Sails.

The Advanced Dignhy season could not  have started better. Grazie, Philippe.

 

There be dragons here!
Downwind sailing and the evils of rounding up

Related Posts

 

Comments 5

John Bongiovanni on Wednesday, 22 April 2015 19:52

I want to add a couple of things to this.

One is that I talked with Philippe today and asked hiim if I got it all right. He said mostly, except for item 1. In light winds, you don't have to worry about the draft. It will pretty much be in the right place. In heavier winds, that will also be true of a new sail. As the sail stretches, you'll have to recognize and deal with the draft moving aft and move it forward.

The other is that when I single-handed a Bahia today in pretty high winds, I wanted easy control on the gnav. Single-handing, you can't reach the gnav to blow it and re-tension it when you're gybe-ing (you're way back in the boat on a broad reach/run). So I lengthened the gnav line with a 4' rope and tied it to the U-fitting so it was always within reach. Use your favorite bend to tie the extension to the gnav line. Seemed to work.

I want to add a couple of things to this. One is that I talked with Philippe today and asked hiim if I got it all right. He said mostly, except for item 1. In light winds, you don't have to worry about the draft. It will pretty much be in the right place. In heavier winds, that will also be true of a new sail. As the sail stretches, you'll have to recognize and deal with the draft moving aft and move it forward. The other is that when I single-handed a Bahia today in pretty high winds, I wanted easy control on the gnav. Single-handing, you can't reach the gnav to blow it and re-tension it when you're gybe-ing (you're way back in the boat on a broad reach/run). So I lengthened the gnav line with a 4' rope and tied it to the U-fitting so it was always within reach. Use your favorite bend to tie the extension to the gnav line. Seemed to work.
Francisco Kattan on Thursday, 23 April 2015 18:07

Thanks to John and Philippe for the great writeup and lesson. I've got some new things to try, especially releasing the gnab during a gybe. However, I would like to comment on this recommendation for gybes:

"2. Weight the boat to windward to turn it down-wind through the wind."

This is the opposite of what I teach at the club (and how I was taught), so I would like to pursue it a little further. It would be great to hear pros/cons of both approaches from others reading this.

Just before a gybe I tell students to slide a bit toward what will be the new high side after the gybe (which is to leeward, not windward). This is because:


    you want to be on the high side right after the gybe to help avoid roundups
    this makes it easier to reach the falls, so you can bring the main across easily and gently


I can see that moving your weight to windward will help turn the boat down through the gybe, but this is never a concern if you have a rudder. It's quite simple to turn the boat with the rudder alone. The bigger concern (in my view) is not turning the boat, it is avoiding a roundup after the gybe. Obviously, in a rudderless situation you need to use your weight to turn the boat. Is there another situation where the weight is required to turn the boat? (at the expense of possibly being late to the new high side to avoid a roundup?)

Comments?

Thanks to John and Philippe for the great writeup and lesson. I've got some new things to try, especially releasing the gnab during a gybe. However, I would like to comment on this recommendation for gybes: [i]"2. Weight the boat to windward to turn it down-wind through the wind."[/i] This is the opposite of what I teach at the club (and how I was taught), so I would like to pursue it a little further. It would be great to hear pros/cons of both approaches from others reading this. Just before a gybe I tell students to slide a bit toward what will be the new high side after the gybe (which is to leeward, not windward). This is because: [list=1] you want to be on the high side right after the gybe to help avoid roundups this makes it easier to reach the falls, so you can bring the main across easily and gently [/list] I can see that moving your weight to windward will help turn the boat down through the gybe, but this is never a concern if you have a rudder. It's quite simple to turn the boat with the rudder alone. The bigger concern (in my view) is not turning the boat, it is avoiding a roundup after the gybe. Obviously, in a rudderless situation you need to use your weight to turn the boat. Is there another situation where the weight is required to turn the boat? (at the expense of possibly being late to the new high side to avoid a roundup?) Comments?
Christian on Thursday, 23 April 2015 18:56

Great stuff. Thank for the post!

Great stuff. Thank for the post!
John Bongiovanni on Friday, 24 April 2015 21:51

Good discussion.

First, let me say that I'm basically reporting what Philippe taught, so I'm not an authority here.

Also, this is advanced dinghy, so the target audience is someone who already has a good gybe and wants a better one. Philippe's focus is on speed, getting the most in every situation. And they say that when he races here he wins always, and by a huge margin.

To Francisco's point, I would never teach this tecnhique at a basic level. What we teach beginners is not always what we do ourselves. When I teach gybe-ing, the thing I get them to focus on is stopping the turn with the rudder. It ain't hard, and if you do it, you'll (almost never) round up. Getting students to think about having to throw weight on the new windward side (in case they screw up) is not a bad idea, but personally I'd work on not having to do that.

Good discussion. First, let me say that I'm basically reporting what Philippe taught, so I'm not an authority here. Also, this is [i]advanced[/i] dinghy, so the target audience is someone who already has a good gybe and wants a better one. Philippe's focus is on speed, getting the most in every situation. And they say that when he races here he wins always, and by a huge margin. To Francisco's point, I would never teach this tecnhique at a basic level. What we teach beginners is not always what we do ourselves. When I teach gybe-ing, the thing I get them to focus on is stopping the turn with the rudder. It ain't hard, and if you do it, you'll (almost never) round up. Getting students to think about having to throw weight on the new windward side (in case they screw up) is not a bad idea, but personally I'd work on not having to do that.
Francisco Kattan on Monday, 04 May 2015 12:21

Thanks John. Good point about speed. I think that in very high winds the risk of rounding up is high for many skippers, not just novices. Having weight on the correct side to keep the boat as flat as possible is helpful in those cases.

Thanks John. Good point about speed. I think that in very high winds the risk of rounding up is high for many skippers, not just novices. Having weight on the correct side to keep the boat as flat as possible is helpful in those cases.