Catamaran technique - part 3

Mitch Booth's Tornado crewman Herbert Dercksen gives his insight on upwind technique on a racing catamaran

In the opening article two weeks ago, Tornado legend Mitch Booth explained the importance of having the crew trim the mainsheet on high-performance catamarans. Here, Mitch's 'other half', Herbert Dercksen of the Netherlands, talks through his approach to mainsheet trimming.

Trimming the mainsheet varies according to the conditions. Initially, I'll try to move it as much as possible. Then gradually I’ll reduce the range of movement. This is the best way of getting ‘in the groove’ - by starting wide and finishing narrow. When we’re just getting on the trapeze and looking for power, I’ll move the sheet just 6 inches or so, but in big waves it’s more like a metre. It can vary from tack to tack too, depending on the wave conditions.

What I’m aiming to achieve is to give Mitch the opportunity to steer up and down. It's experience and feel that tells you what's right, plus a bit of talent. We talk about mainsheet tension between us. Sometimes I can't feel the helm and Mitch will say the rudder is stalling, but 90 per cent of the time you do it by feel.

Wind, waves, sheet

There are three factors involved in mainsheet trimming: the waves you see, the wind you feel, and the tension of the sheet. If there's a big wave coming three waves ahead, you have to pull it in hard, to lift the hull in time. It takes a lot of training, and the more you train the more you get used to it.

Aim to do everything by feel and don’t rely on looking at stuff. You can check if the tell tails are flowing, and you can check the depth of the main, but if you can do things by autopilot the better off you'll be. Some sailors use a mark on the mainsail, but we don't have a calibration strip because we prefer to sail by feel. I’d be surprised if I look up at the main more than two or three times in a race. But in really light winds, the helm takes the mainsheet and sometimes cleats it off.


Cunningham

There is an important relationship between sheet and cunningham tension. If you want to go high, then use less cunningham and more sheet. For more speed, pull on the cunningham and ease sheet to get rid of the drag. Again, getting the right balance between cunningham and sheet tension is largely down to experience.

On our boat, I control cunningham and mainsheet. It gives me a lot of work to do and a lot of focus inside the boat, and so the skipper has his focus outside the boat, which gives him the opportunity to read the tactical situation. Of course, that many not be the case on every boat. With the Tornado World Champions [Australia’s Darren Bundock and John Forbes], I believe that Darren does all the speed and John looks around for the tactics. I would guess John makes the calls 70 per cent of the time.


Mainsheet systems

We have always tried to make the mainsheet system as simple as possible. We've got a ratchet underneath our block so you can hold it on an 8:1 purchase. Others have 9:1. I used to have a 7:1, which is good in light airs, but too hard to pull in for medium airs. If the loads are too high, you’ll be tempted not to play the main as much as is required. On the other hand, you don’t want too much. I started with a 16:1, and some of the Danish guys still have it on. The thing that's really bad about this system is when there is a big breeze and they run out of sheet. The F18s tend to use 8:1 because the loads are lighter. Whatever you use, make sure your gear is good and up to the job. Harken is one of the most reliable brands.

The other choice is whether to use an internal or external mainsheet system. The World Champions are using the internal sheeting system, which is good for reducing windage, but as far as breakage is concerned it's hard to maintain because you can’t see what’s going on with it. Also, you’re limited on the range of the mainsheet. We keep it external and keep it simple so we know what's going on with it at all times.

Point of Focus

Sailing upwind, I’m generally looking forwards, two to three waves ahead. The more breeze there is, the more waves you're going to look ahead. Occasionally I’ll be glancing across my shoulder to see what the breeze is doing. But the main focus for me is on the waves. You can often feel when the gust is coming. But Mitch calls the gusts, so I have a good idea of what's going on before it happens.

TheDailySail's weekly catamaran technique series continues next Wednesday