GET IN THE MODE

It’s the last race of the season at Mudhoppers Sailing Club. I glance at the other 200’s set up before the start: surely, they are never going to get upwind with a rig looking like that? Olympic coach Mark Rushall explains what happened next...

Their jib is sheeted tight along the foot, with the top inside tell-tale permanently vertical. The main is flat and twisted, with the top batten pointing toward the leeward quarter . I look smugly at our set up: windward jib tell-tales lifting simultaneously as I luff slightly, mainsail top batten in line with the boom, with the top leech tell-tale flicking forwards around 20 percent of the time: textbook for today’s max power conditions. A subtle line up before the start reinforces our smugness: though they are slightly faster through the water, this is more than compensated by our consistently higher pointing performance.

As usual at MSC we are beating against the tide, with shallower water toward the shore on the left-hand side. We opt to start mid-line above the bulge, avoiding the group of bigger boats and giving us a clear lane toward the favoured side. We lose our rivals in the melee near the pin. Next time we see them we are half-way up the beat, as they cross ahead of us on port tack, 10 boat lengths clear and still ahead of many of the faster boats. It’s going to be a long hard race!

So, what is going on? Our VMG (velocity made good: effective speed of progress towards the wind) is superior. If you like numbers, a polar diagram may help to visualise the situation.

Fig 1 represents my best guess of a polar plot for a typical hiking asymmetric dinghy. In fig 2 I’ve concentrated on the plot for 10kts true wind speed. Speed through the water at a given sailing angle to the wind is represented by the distance of the line from the centre of the plot. Equivalent VMG for that angle can be read off the vertical scale.

In theory our low pointing rival was around 0.2kts faster through the water, but their progress towards the wind some 0.1kts less, all else being equal. By starting near the pin end, they were able to sail fast and free into the shallow water, keep clear wind by staying forward of the mass of the fleet, and benefit from the least adverse tide on the left.

Half-way up the beat, that 0.1kt would give us an advantage of around three boat lengths or 10 seconds. If the oppo were sailing in half a knot less adverse tide, that’s more than enough to negate the VMG loss and give them that 10 boat length strategic advantage. If they found a nice left shift to tack on, even better!

While polar plots for many keelboats are accessible online, its notoriously difficult to find good data for dinghy classes.

But my experience is that most contemporary dinghy classes have a similarly flat curve around optimum VMG beating angles, giving plenty of strategic and tactical opportunities for sailing both dinghies and keelboats in a high or low mode.

When might you sail in high mode?

A high mode can get you out of trouble in many tactical situations. Off the start line, on the exit to a leeward mark, when fighting for a clear lane, and when on a marginal layline, setting the boat up for

high pointing without stalling foils can be a race winner. And a high mode to make the leebow really stick and force a windward boat to tack can make the difference between a nice layline to the windward mark or an overstand. If you are on port tack, ducking a line of starboard tackers in close proximity to another port tacker on your leeward bow, switching to high mode on the approach, sailing high and slow, while they reach around the stern of the right of way boat could give you a clear lane after the duck.

When I’m in close company on the same tack as another boat, approaching the layline, I might deliberately sail in high mode to let them make the first decision: it’s often much easier to judge the layline when there is another boat pointing toward the mark.

There are plenty of strategic opportunities too. Once our 200 friend had reached the slack water area, he could have switched to a high mode to avoid tacking and stay on the left as long as possible. If your boat has a big tack loss, when shift frequency is high, sailing in a high mode in the headers and a low mode in the lifts will get you to the windward mark quicker than sailing through the shifts at theoretical optimum VMG. And on a very offset beat, sailing high in the headers is a great alternative to tacking onto the short leg and limiting your options later.

When might you sail in low mode?

There is a boat to windward, creeping forward, not quite on our wind: they soon will be. Strategically, I may not want to tack. The chance is that if they are creeping forward, the wind is lifting. So, I sail fast and free, keeping my wind clear, sailing where I want to go. By increasing my leeward separation, I maximise the gain when the wind heads too.

If I’m to windward of a bunch of boats and the wind lifts, I’ve made a paper gain. If we all keep sailing on the same tack, that will disappear if the wind shifts back. By sailing in low mode, I’ll move forward over the fleet and ‘bank’ some of the gain. And again, in shifting conditions, if I don’t want to tack on every shift, sailing low in the headers will get me there quicker!

And as our reachy friend at Mudhoppers showed, if there is a strategic advantage on one side of the course, through tide, wind, or waves, why not get there as quickly as possible?

How to get in the mode

All boats are different, as are sailing styles. I know my default is to sail in high mode all the time, so I have to work hard to change the habit. A bit of encouragement from the crew helps…

We might be looking at subtle adjustments to rig or sailing style: any more than one or two degrees angle change will see us falling off the flat part of the polar curve giving too big a VMG penalty. A small change in centreboard rake, backstay tension, or simply the way we react to a gust or lull may be all that is needed.

High mode

We are looking to maximise the lift from foils and sails without stalling either. Pushing centreboard right down moves lateral resistance forward and increases weather helm. Sail set up might be slightly fuller (less backstay or use more mainsheet instead of vang). Use less twist in both sails, but watch the tell-tales and helm feel for signs of stall. Allow a little more feather (the boat to luff slightly in the gusts) and less sheet ease in the gusts. Watching for the lulls is key: trim on and move promptly to leeward: never bear off to power up. If you are having to push on the tiller in the lulls, change something!

Low mode

Every extra bit of power should accelerate the boat, not wind it to windward. Watching and calling the gusts is key: hike hard and ease sheets in the pressure rather than feathering, keeping the boat dead flat or, in a dinghy, over-upright. Raising the centreboard reduces weather helm, drag, and lift. Sails might be flatter and more twisted (more backstay?) than normal: if you are having to pull on the tiller in the gusts, change something!

Next time you have some free time on the water, have a play with your rig and sailing style and practise optimising for low and high mode in each condition. Get a feel for the extremes, and work back to an optimum gear change for your craft. Once these skills are in your strategic tactical toolbox, you’ll find it difficult to leave them alone!