The sails look great and you’ve just spent money on having the keel faired and the bottom sprayed, but today the boat is off the pace, so what’s the issue?

Rather than fiddle with the backstay tension perhaps you should be thinking ‘weed’. It only takes a small clump to get caught around the keel or rudder to slow the boat and with races often won and lost by less than ten seconds, a 0.1 per cent hit on your boat speed is all it takes.

Unless it’s a lobster pot and you’re stationary, detecting that something is caught on the foils is not always easy and some basic rules are needed to prevent loss of concentration and even more time wasted. Weed and plastic bags caught low down can sometimes be spotted by looking over the side, but judging how serious it is further up is a tougher call.

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Prevention is better than cure so making sure the boat is clean before the start is important, and during the race the helmsman and forward crew can work together to spot and avoid weed and debris, including lobster pots, lurking to windward.

For each of the techniques outlined here safety must always be considered. For example ‘backing down’ – ie reversing the boat while head to wind – will be done under sail alone in sportsboats without inboard engines, while on larger boats it’s more likely to be with engine power. Finding space to do this safely in a busy starting area is important as other boats may not always spot that your boat is moving backwards. Hang on tight to the helm to prevent the rudder slamming over, and leave time to run the boat forward to close the propeller.

To stop or not?

It’s a judgement call. The shorter the race, the less likely you are to stop, the longer the race, the more important it is to get debris off quickly.

If you are under spinnaker, put up a headsail, drop the kite and very aggressively slow the boat down. The better you get at the back down technique, the more comfortable you will be in getting rid of the debris.

Knowing your target boat speeds is important to be able to judge whether you have weed or not. We don’t carry gear for removing weed on the TP52 or the IRC72; both boats are very fast so a weed stick will do more damage to the rudder even if you were to get rid of the weed, but always ‘back down’ before the start.

We have a routine on Rán of doing it eight minutes before the starting gun. We combine this with the final jib call and hoist to get us out of the back down. It helps to concentrate the minds of all the crew.

Fluorescent paint on leading edges of the rudder and keel can help. It can make it easier to spot weed or debris.

2. Flossing the keel

Using a length of line that you throw off the boat and sail over to floss the leading edge of the keel is a popular way of removing debris.

A flossing line does not have the same effectiveness with modern T style bulb shapes as on the older L shape keels where the line can slip over the bottom of the keel with the weed.

There is no hard and fast rule over the line length, but it needs to get to the bottom of the keel and have enough slack on deck to hold on. Putting knots every 1-2m will help. Make sure you tie on one end of the flossing line to the guardrail near the shrouds, take the remaining line and, choosing your moment, throw it in front of the boat.

As the boat sails over the line it will wrap itself around the keel. Then saw the line up and down as it works its way down the keel fin to dislodge the weed. People have tried adding a small amount of lead shot to the line, but this could cause damage.

3. Making a rudder weed stick

A weed stick is a useful device for removing weed from the rudder and is quite simple to make. A weed stick needs to be stiff – when we made them for 40-footers the best ones were built around the hull.

We used to wrap the back of the boat in plastic and then bend the batten around the hull down to the centreline so it was formed to the shape of the boat. We then glassed it so it held its shape and built it up so it was nice and stiff.

You have to put a lot of padding around the bottom and give yourself a handle as there is a reasonable amount of load, and then add a rope tail to the bottom. To use it, dangle over the back and try to get the weed stick to hit as high up the rudder as possible. Then saw your way down the rudder and the rope tail will flick off any weed.

4. Offshore routine

Offshore we will have a routine of checking the foils with the endoscope every watch and particularly at last light and first light. These come from the medical world and are about 5mm diameter with an eye-piece at the top.

A through-hull fitting is required for each foil and you insert the endoscope through the fitting to see what is happening below. You can’t use them at high speed, but they are very good in normal conditions.

I would say that any boat offshore racing should also carry goggles and fins. You just have no idea what debris you might pick up in the water so you have to be ready for any eventuality. If we have to send someone over, the boat is slowed down to around two knots, the swimmer will jump in from the bow and as the boat slowly goes over him he can clear the debris.*

We have a line on the swimmer, but we will also trail a line over the stern for him to grab if necessary. It is always worthwhile discussing before the race who the swimmer(s) will be.

5. Lobster pots

If we are going into an area of potential lobster pots, such as around headlands, we will try to get some extra eyes forward, but generally the helmsman has the best view.

Hopefully there won’t be many fishermen reading this, but the easiest and most reliable way of getting rid of lobster pots is to cut them off. If this is not an option, then you have to back down and most likely send someone over the side. As soon as you back down you run the risk of getting extra wraps around the foils, so having someone in the water is probably wise.

* Editor’s Note: Putting crew over the side is a procedure with obvious safety risks that needs careful consideration, including an assessment of wind, wave and tidal conditions, as well as crew experience and fitness.

Tim Powell is a veteran of four Whitbread and Volvo Ocean Races, helmsman of the Mumm 36 Barlo Plastics, top boat in the 1999 Admiral’s Cup, Tour de France winner and now team manager/mainsheet trimmer on Niklas Zennström’s Rán, a TP52 world champion.