In the second part of our series we look at how best to utilise a cat’s engines when they are needed and point out some of the pitfalls
As you may be one day, we were new to the catamaran we were offered for this mission so we spent a good half hour in fairly open water practising handling under power.
We chose a suitable buoy well outside the channel as our reference point. This is important as you need to get immediate feedback on the effect your work at the controls is having. It is a really useful exercise and one I’d recommend to get you started.
The most important tool in the box to effect these manoeuvres is learning how to use the twin engine configuration to best advantage. There’s no great surprise about the fact that if you power ahead with one engine and astern with the other the boat is simply going to rotate.
It does take practice to develop the degree of spacial awareness needed to recognise if the boat is moving in a certain direction – which may or may not be intentional. In our case, in a reasonably steady 15-17 knots of wind we learned the following about the boat – which would prove to be invaluable in planning and executing subsequent manoeuvres for real.
Beam on to wind
The boat seemed to settle well with the wind on the beam in stable equilibrium. Lateral drift was not measurable in terms of speed, but was enough to cause a pattern of disturbed water to windward. We maintained this position by applying a bit of power – usually ahead on one engine and astern on the other.
Learning about this is something that could be used to advantage next time you need to slot into a berth with at least a component of onshore breeze. The twin engines will allow you to stay parallel to the dock and also keep abreast of the berth, so even a light breeze should do the rest by making you slide with some precision sideways into the berth (maybe even to a round of applause).
If the wind is offshore (ie pushing you away from the pontoon) then you’ll need to think up a new strategy. One useful tactic is to approach the berth stern first – at, say, 45°. Doing this will probably allow the helmsman a much better view of what’s happening than he or she would have if approaching the berth bow first.
If there’s any wind you’ll probably approach the berth from the downwind side because the bow is so prone to being carried away by the wind that pulling her into a berth stern first will offer more directional control than pushing her in bow first.
Head to wind
Unlike the beam-on situation it was surprisingly difficult to keep the boat head to wind with no way on. There was no point in spinning the wheel from lock to lock as even the backwash from the props was a long way from inducing any meaningful power from the rudders.
As soon as the bow fell off even a couple of degrees we found that she’d be 10° off or more before you’d had time to call up a swift burst of power from one engine to force her back head to wind.
Getting the feel for this phenomenon in open water will be very useful next time you’re faced with the same situation in a crowded marina or, more importantly, when you need to drop anchor or pick up a mooring.
This is simply a way of feeling what the rudders are capable of at different speeds – again this is useful knowledge when you’re manoeuvring for real.
Once again in any situation where a tight turning circle is needed you’ll be using the twin engine configuration to advantage. That way you can avoid that situation where you’re tempted to try the old ‘helm hard-over and full-ahead’ tactic, which can either work rather impressively well – or not. The cost (literally) of failure is so dire that it probably best to give it a miss.
Will she or won’t she respond to the helm when going astern? Give it a try to find out if this works. If not then best hold the helm amidships and use the twin engines to steer you in. In the case of our boat the position of the rudders didn’t seem to make much difference, especially at slow speed, so the default position was inevitably rudders amidships.
Although the manoeuvring aspect of operating under power is important, you’ll also need to know something about passagemaking under power, especially if the catamaran you’re responsible for is not that able a sailing boat.
Here most owners and skippers tend to settle for a comfortable cruising speed that seems to offer the best compromise between speed, noise and vibration and fuel consumption.
Normal practice is to fit a propeller with a diameter and pitch such that the engine (or engines in this case) can just reach maximum speed (rpm) under normal conditions. It is important for the health and longevity of the engine that this condition can be achieved; engine manufacturers are not happy if an engine is being overloaded, even to the point of refusing warranty claims.
The importance of this is that there is a case to be made for cruising with only one engine at a time as this can result in reduced fuel consumption for a given cruising speed. The danger is, however, that because the boat is travelling more slowly under one engine than with two then the one that is running may not be able to reach the maximum revs achievable with both engines running, so the engine may suffer as a result.
The safe way to operate a catamaran under a single engine is to move the engine control forward slowly incrementally until the engine stops responding to the movement by increasing engine speed. From that point the lever should be pulled back again until the engine speed drops back by a measurable amount.
Like most people I am usually surprised by how well motor sailing works when the fun is over and you just need to get back upwind at the end of a long day – in a boat that doesn’t really like going upwind (and even less so if there’s a sea running). This works as well in a catamaran as it does in a single-hulled boat.
Do’s and don’ts
- DO get some manoeuvring practice somewhere where you can’t do any harm to your boat or anyone else’s.
- DO find out what the proper strategy is for efficient motoring (one engine or two) before taking over the boat.
- DO concentrate on looking around you all the time when manoeuvring; be aware of the boat’s real movement.
- DON’T forget to use the wide-spread engines to manoeuvre in close quarter situations; leave the rudders amidships.
- DON’T be tempted to effect make or break manoeuvres using lots of power.
- DON’T be so timid with your controls that you leave too much time for the wind and/or tide to have their way.
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