Why don’t cats sail very well to windward? Nigel Irens explains and has some tips on how to get the best out of a cruising catamaran upwind
If you were a visitor to Earth and found yourself sailing a run-of-the-mill cruising catamaran for the first time it would be easy to conclude that sailing upwind is not something these boats do well. But then you wouldn’t have had the extraordinary experience of witnessing that 2013 America’s Cup face-off between the 72ft catamarans Oracle Team USA and Team New Zealand in which upwind boat speeds of up to 30 knots were achieved with an apparent wind angle of as little as 16°!
The trouble is that here on Earth the laws of physics are absolute and wondering why your average cruising catamaran doesn’t thrill you with its upwind pace is like wondering why your family’s modest car doesn’t give you a Lewis Hamilton buzz as it cruises down the M5 at a barely legal speed against a stiff south-westerly.
The answer, of course, is that although there are performance cruising catamarans that do sail very well – even upwind – many cruising cats are under-powered floating homes, impeded by plenty of windage.
So how do you get the most out of a typical cruising cat? Your satisfaction will come from the seamanship involved in getting your crew safely upwind from A to B without frightening them or making them ill.
Assessing your VMG
The most important single objective must be to develop an understanding of your velocity made good (VMG) in different conditions and sea states.
If the boat you are sailing is equipped with high-quality wind instruments the task is obviously easy because the VMG is constantly being monitored. If you don’t have that luxury then you can get the information by studying the boat’s progress on the chart plotter.
Your experience and instincts will allow you to set sails and course to yield what you feel is the best VMG, so try to keep your course and true wind angle (TWA) constant for long enough to allow the plotter to produce a meaningful track on the chart.
If you’re in open water you might choose to put in a tack just to see how it feels on the other tack.
The wave direction may be different from the wind direction – perhaps because of a recent windshift or the influence of nearby land topography. You may find that the different rate of encounter of waves from one tack to the other makes quite a difference in terms of both performance and ride comfort.
Sometimes it’s quite hard to know why things are going better on one tack than the other, but if you’re aware of the difference you’ll probably devise a strategy that makes the most of it.
As you cover the ground you’ll begin to see what the course made good (CMG) is looking like by watching the track and trying to check the tacking angle on the plotter.
Course made good
If your plotter doesn’t allow you to obtain that information then holding a school protractor up to the screen works pretty well and will give you an idea of how things are panning out.
The chances are you’ll notice that cracking off a bit and footing a bit faster will improve the VMG, and that trying to point higher doesn’t usually pay. That may be because you get more lift from the centreboard as you sail a bit faster, but also because the apparent wind speed (AWS) will be higher. The boat may also be handling energy-sapping waves better (so the crew will be happier too).
If you’re on a charter boat you’ve only got a week or two to make sense of it all, but if you regularly sail the same boat all the information will have entered your subconscious memory after a while so you know pretty much what works best both in choosing your course and trimming your sails for windward work.
Correct trimming is, again, very much a matter of trial and error, but as a general rule keeping the mainsheet somewhere near the centre of the track is a good starting point. Most cruising catamarans are not equipped with very powerful winches so sheeting in upwind will require a good deal of grunt on the winch handle.
In lighter airs you’ll probably do best to allow a bit more twist in the main than in stronger wind, but unfortunately taking the right amount of twist out of the mainsail in stronger winds may prove impossible because the deck gear (and/or the crew) probably won’t be up to it.
That said, trimming a catamaran’s mainsail is no different from trimming that of a monohull’s in that a common mistake in lighter winds is to over-sheet to the point where upwind progress (VMG) is compromised. Trial and error – during which the boat will often sail at sub-optimal VMG values for a while – is nonetheless a great way to develop a ‘feel’ for what works best.
Some cruising catamarans save the cost of a mainsheet traveller and control the main with a pair of tackles – each attached to a deck eye somewhere near the rear beam/hull intersection. The two tackles share the mainsheet load when sailing reasonably close to the wind and the mainsail clew position can be trimmed by proportion of load on each one. This arrangement can work well – especially if the boom is very high, which it certainly will be by the time a flybridge has been added.
The same is true of headsail sheeting, where you have options to open or close the leech by moving the car forward or aft in the track. You almost certainly won’t have deck gear capable of trimming for optimal twist while the sail is loaded, so you’ll probably need to adjust the car position on the windward side track and tack onto it next time a tack is called for.
Motor sailing upwind
In Part 2 we briefly touched on the idea of motor sailing upwind. Unless you are sailing a reasonably high-performance catamaran you’ll soon find that getting the engine cranked up is a very practical way to get you to your upwind destination comfortably.
Doing this is not some kind of admission of defeat. Your job as skipper is to sense when your crew’s enthusiasm for a long beat in a boat that doesn’t go to windward well is about to decline. They’ll be reassured rather than put out when they hear that you’re playing the ‘get me out of here’ card, although it might be good to make sure there’s something near a consensus before hitting the starter button.
We tested this strategy during our sailing trials and rediscovered how well it works. With just the leeward engine running at about 60 per cent power output, we took the boat speed from four knots to six and, more importantly, we gained at least a 20° course improvement.
Even the motion seemed to improve.
Do’s and don’ts
- DO experiment with the trim of the sails and the course sailed to seek out the optimal VMG in a range of conditions.
- DO motor sail upwind when it becomes obvious that the crew will have had enough long before you get where you’re going.
- DO try changing headsail car position between tacks to find what works best.
- DON’T pinch! Optimum VMG will never be optimal if your boat speed is low.
- DON’T hesitate to race two boats against each other if you are lucky enough to be sailing in company with another. Learning time for both skippers will be much reduced, and crewmembers will be much more likely to have a good time.
- DON’T be too ambitious when planning a trip with inexperienced crew on board – especially upwind. Their threshold of pain will probably be much lower than yours.
Our eight-part Catamaran Sailing Skills series by Nigel Irens, in association with Pantaenius, is essential reading for anyone considering a catamaran after being more familiar with handling a monohull.
Series author: Nigel Irens
One name stands out when you think of multihull design: the British designer Nigel Irens.
His career began when he studied Boatyard Management at what is now Solent University before opening a sailing school in Bristol and later moving to a multihull yard. He and a friend, Mark Pridie, won their class in the 1978 Round Britain race in a salvaged Dick Newick-designed 31-footer. Later, in 1985, he won the Round Britain Race with Tony Bullimore with whom he was jointly awarded Yachtsman of the Year.
His first major design success came in 1984 when his 80ft LOA catamaran Formule Tag set a new 24-hour run, clocking 518 miles. During the 1990s it was his designs that were dominant on the racecourse: Mike Birch’s Fujicolour, Philippe Poupon’s Fleury Michon VIII, Tony Bullimore’s Apricot. Most famous of all was Ellen MacArthur’s 75ft trimaran B&Q, which beat the solo round the world record in 2005.
His designs have included cruising and racing boats, powerboats and monohulls, but it is multis he is best known for.
A special thanks to The Moorings, which supplied a 4800 cat out of their base in Tortola, BVI. www.moorings.com