VMG questions in a asymmetric sportsboat

Kevin Sproul answers...

Famed for his Scottish accent and catchprase, 'I knew that', Kevin has a broad racing background from 420s to Wally yachts. He was RYA Youth Champion in the 420 and 4th at the Youth Worlds in 1981, he then went on to mount a 470 Olympic campaign. His first major role in the marine industry was with Topper, where he was involved with the development of the Iso, Buzz and Boss. During this time he also started to make a name for himself as a one design sailor, picking up the European titles in the Melges 24 and Mumm 30. A move to Hyde Sails as Sales and Marketing director meant more yachting for Kevin and many championship wins in a variety of classes from IRC to Farr 40s. Now Sales Director for Sobstad Sails UK, he regularly races as tactician for Glynn Williams on Wolf . Sobstad UK build sails for dinghys through to 50 foot racing yachts and are the exclusive manufacturer of patented Genesis sails for UK and Ireland. They can be contacted on +44 2380 456205

Rob Van Landingham
I have been following with great interest the Daily Sail series on asymmetrics. I own a Viper 640 - a very light 21' sportboat that I race in PHRF here in the States. One of my biggest challenges is competing against larger, symmetrical rigged displacements boats. When the wind is 15kts or higher the Viper planes easily and downwind angles are simple. However, when the wind drops below this range it becomes difficult to select the most effective angle to obtain the best VMG. I'm all for technology so my request to the team is feedback on the possibilities of using a handheld GPS to assist in VMG measurement. Would any of the handheld units provide this capability (using the time to waypoint function)? Are updates frequent enough to be useful? Any recommendations as to which specific handhelds would meet this need? Do I forget modern conveniences and just bite the bullet to soak down as much as possible but watch the bigger boats pull away (which rate even with me)?

Rob,

Most if not all handheld GPS should have a VMG readout which if you have a spare crewman who can monitor it constantly would be really useful for getting the best performance downwind in lighter conditions - its also quite exciting to see just how fast you can sail in stronger winds! The late, great Giorgio Zuccoli won many Melges 24 regattas using a speedo to get the best out of the his boat downwind. A GPS with its VMG readout will be even more useful especially when sailing in mixed fleets.

I have found that racing with an asymmetric is not usually a disadvantage even when sailing in fleets of boats with symmetric spinnakers. The asymmetric equipped boats usually have an advantage in less than 10 kts of wind when all boats have to sail the VMG angles with the pole forward and then in more than 15 kts, as you have indicated, things are OK. The secret is cracking the 10 - 15 kt range.

I think technique is important here and it can take quite a lot of practice to get the best out of asymmetric boats in the 10 - 15 kt range. It is very easy to get tricked into sailing too low and never really getting the boat moving properly. In the Melges 24 we used to sail higher than most boats to build speed and our VMG was invariably better than the rest of the fleet. So, here we go....

1. The mainsail trim is straightforward for downwind sailing. Ease the vang, the cunningham should go off completely and the outhaul be eased until there is about a hand's width gap between the foot of the sail and the boom.

2. Once you are sailing downwind with the asymmetric hoisted, trim the vang so that the back of the top batten is parallel to the boom. Always fully hoist the spinnaker halyard. In the 10 - 15 kt range try easing the tack line 500mm. This works really well on some boats (Cork 1720, J92) as it helps the sail to rotate further around to windward.

3. Sheet in and get the boat moving fast. This is more important than direction sometimes, as once you have speed you can then work out your options and then set up your course from speed, rather than going slow. Sailing downwind the skill is in treading the fine line between power (speed) and how deep you can go. When running low be careful not to go so deep that you lose sheet tension. In light airs trim the boat down at the bow to lift the stern and heel the boat to windward which helps project the asymmetric luff to windward as well.

4. Practising your spinnaker trim and steering is only half of the job downwind. The downwind angles give you a lot more tactical options than do conventional boats and symmetrical spinnakers. If you see a gust - gybe over to it, run deep, or come high to stay in it. Keep trying to work the boat deep, until the breeze and waves increase sufficiently to allow for steady planing. Wait till you have the speed built before you bear away in a gust or a wave. Watch the wake if you are not sure if you are planing - as soon as it starts to flatten out, you're off. Once it is breezy enough that planing is a foregone conclusion, you must start to try and work low again. Keep bearing away but not so much that you drop off the plane. Try to trim the boat between a slight windward heel to dead flat. Keep watching the gusts and remember - pressure is everything, if you're in it, you'll win.

Good Luck
Kevin

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