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Catamaran skills: Mooring and anchoring a multihull

Catamarans are becoming ever more popular, whether in the UK or on charter holidays, but handling one requires a new set of catamaran skills, as Rachael Sprot discovers

How do you make an average passage speed of 7 knots, fit in three double cabins and a huge saloon in under 36ft of boat length? Add another hull of course and head off but fist there are some catamaran skills you will need to familiarise yourself with.

The advantages of catamaran sailing are obvious, especially if you’re chartering and want to take a larger group of friends and family sailing. But many people are daunted by the prospect of taking on new catamaran skills, such as manoeuvring so much boat in confined spaces.

I’m ashamed to admit that although I’ve worked on twin-hulled jet boats servicing offshore windfarms, until last month I’d never set foot on a sailing catamaran. So I decided to go back to school for a masterclass in boat handling.

Grenville Hauser, Training Director and Yachtmaster Instructor with Flexisail, valiantly took up the mantle of teaching an old (sea)dog new tricks and we spent a day aboard Issamella II, a Mahé 36 at their Hamble base learning some key catamaran skills – here, we are going to cover mostly how to handle a cat under power.

With high topsides and shallow draught, windage is much more of an issue than on a monohull. Photo: Richard Langdon/Ocean Images

As with any boat handling, before turning the key in the ignition you need to know what lies beneath. The underwater profile of a catamaran is very different to that of a monohull. For a start, there’s a lot less of it. Utilising their natural form stability, they don’t need to situate tonnes of ballast down low so there’s no deep fin keel.

With a displacement of just 5 tonnes, Issamella II is considerably lighter than many cruising monohulls of the same length. This means she accelerates and decelerates more quickly, holding her way less.

With twin hulls come twin screws and twin rudders. There’s much more power at your disposal than on a monohull of the same displacement, with two 30hp engines instead of one. It’s common for the engines to be situated well aft in the sugar scoop to maximise space inside the hulls, and Issamella II had the stern drives aft of the rudders and steering gear.

For slow-speed manoeuvring, using the engines in opposition will turn the boat, while the rudders do very little. Photo: Richard Langdon/Ocean Images

Catamaran skills: under power

Steerage

This configuration upends our conventional understanding of steerage. When you put the engine in gear, rather than throwing prop wash over the rudder, the propellers just throw the water straight astern. ‘You need to be making over 2 knots before the rudders start to work efficiently,’ Grenville explained.

For slow-speed manoeuvring, the rudders can be all but ignored, save for keeping them straight. Steerage instead comes from ‘splitting the sticks’; putting one engine in forwards and the other in reverse. This pivots the boat around the centre point allowing a change of direction without any forwards motion at all.

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Windage

The flip side of having so little boat in the water is that there’s a lot of it above. With high topsides, a raised saloon and fixed bimini, we’re manoeuvring an inverted iceberg. ‘There’s nothing you can do to avoid the effect of windage,’ Grenville counselled. ‘You just need to take it into account.’ Death, taxes and windage, as that well-known multihull sailor, Benjamin Franklin, put it.

Springs

To my even greater consternation, the whole concept of springs needs re-evaluation too. Springing a monohull with a slim stern off the pontoon is easy: reverse on a stern spring to draw the quarter in, the bow comes out and off you go. Catamarans are almost square in dimension, so you can’t spring off easily and need to be hyper aware of what happens to the rest of the boat if you do.

My first task was to come out of our finger berth, but since Issamella II was well aft in the pen any springing action would have swung the offside transom into the pontoon behind. Grenville explained that setting an aft-running stern line as a slip was the key: drive forwards on it with the inboard engine to keep the boat alongside whilst you remove the other lines.

When you’re ready to depart, ease a metre or so out to gain clearance astern, before engaging the outboard engine in reverse. This twists the boat away from the pontoon. Once the desired angle is achieved, slip the line and put both engines in slow ahead to make your way out.

Use the two throttles separately to ‘split the sticks’ and generate turning moment. Photo: Richard Langdon/Ocean Images

Tight turns

Immediately after departing the finger berth, there was a tight fairway to negotiate. It’s hard to ignore the instinct to turn the boat through an arc, but on a catamaran there’s no turning circle, they turn on the spot by putting the outside engine ahead, and the inside engine astern.

Having driven straight out of the pen, Issamella II pivoted beautifully mid channel. Then it was simply a case of matching the throttles in slow ahead to go out into open water.

With the turn under way, windage moved the boat slightly towards the pontoon, seen by the slick to windward. A touch more throttle ahead on port kept the port quarter clear. Photo: Richard Langdon/Ocean Images

Slow speed manoeuvring

With directional control achieved from the twin screws rather than the rudder, slow speed manoeuvring is best done with the wheel central. To turn to port, simply increase the forward revs on the starboard engine or reduce (or reverse) them on the port engine, and vice versa to turn to starboard. It’s as though you’re turning the inside hull into a pivot point, around which the outside hull will swing.

In reverse the principles are the same – increase the reverse revs on the outside engine, reduce the revs, or engage slow ahead on the inside engine. To turn faster, increase the revs on both engines, which accentuates the effect.

Centralising the rudder

With no wheel lock on Issamella II I had to physically hold the wheel central whilst ignoring the overwhelming urge to turn it in the direction I wanted to go. It takes
a concerted effort to retrain the brain and think in terms of throttle control for steerage. Centralising the rudders is particularly important when going astern because the reverse thrust flows straight over them.

There was also very little feel on Issamella II’s rudder due to the complex linkage system, which has implications when sailing too. It’s another reason for decreasing your rudder dependency.

Stepping off the high topsides isn’t an easy option, so position the crew by the transom steps. Photo: Richard Langdon/Ocean Images

Catamaran skills: coming alongside

Approaching a pontoon

With the high topsides making it almost impossible for crew to step off, the best approach to a pontoon is in astern, allowing someone to take a line ashore or lasso a cleat from the transom.

Most twin engine vessels will have counter-rotating props so that any prop kick effect is evened out when both engines are set equally. The result is that they go astern much better than a shaft-driven monohull which must overcome prop walk first.

The fact that steerage comes from splitting the throttles, rather than waterflow over the rudder means it’s much easier to control the boat at slow speeds.

Approach angle

However, the approach angle needs re-imagining. Since a catamaran twists rather than turns, and the hulls are quite slab-slided, you can’t glide in at a steep angle and turn the helm away at the last minute as you might with a pointy-nosed monohull.

If you arrive at a steep angle on a catamaran and then try to twist the boat to straighten up, you’re more likely to bring the boat away from the pontoon because it’s based on a pivoting motion rather than part of a turning circle.

Forget about the perfect parallel park, the focus needs to be on getting the stern close enough to get a stern line ashore, and then driving forwards with the outboard engine to bring the rest of the boat alongside. I tried this a couple of times and once I’d got my head around the change of strategy it was straightforward.

You don’t need an elegant coming alongside. Focus instead on getting the stern close enough for the crew to step off. Photo: Richard Langdon/Ocean Images

Offshore wind

Issamella II is lighter than the same-sized monohull but she’s got the windage of a much larger one. In conditions where you are being blown off the pontoon it’s particularly important to use the technique above rather than rely on crew strength to pull the boat alongside.

It’s not without hazard though: there will be a lot of load on the line. Before engaging forwards gear ensure the line is safely made off and the crew are safe with all fingers accounted for.

Use the minimum power necessary – if a line snaps the recoil can be dangerous.

Depending on helm position, there is usually
a blind spot somewhere on a catamaran. Photo: Richard Langdon/Ocean Images

Helm position

The offset helm position feels unnerving initially. It’s harder to judge the distance between the offside hull and the pontoon, and on Issamella II there was an awkward blind spot created by the hard bimini.

Until you’re familiar with the dimensions of the boat, asking a knowledgeable crew member to call distance off is essential. The blind spot is also an important consideration when under way, particularly in congested waters. I was surprised by how easily small vessels like RIBs are obscured. Before changing course you also need to have a good look.

Tidal set

Fortunately, the principles of tidal boat handling remain the same so there’s no need to learn a new set of rules. Wherever possible an approach should be made up tide to maximise control and keep speed over ground to a minimum. Ferry gliding sideways is just as effective as it would be in a monohull and will help you slip into an alongside berth.

What is different, however, is the wind vs tide equation. As a result of the increased windage the tide seems to have less impact. It isn’t, but you need to reassess the hierarchy of these elements as wind plays a greater role. The extra beam means you have less margin for tidal drift.

Get a good look at your berth before beginning the manoeuvre, and double check there is space for your beam. Photo: Richard Langdon/Ocean Images

Catamaran skills: mooring on finger pontoons

My final task of the day was to put Issamella II back into her finger berth. It was a case of reversing the procedure that we used earlier to get out: drive up the fairway,
turn the boat on the spot and back into the berth.

You may not be able to see the opposite quarter, so get crew to call out distances off the stern. If in doubt, go ahead to stop. Photo: Photo: Richard Langdon/Ocean Images

The conditions were benign, which helped, but even so it was remarkably stress-free. On a monohull you would need to keep some way on to maintain steerage in reverse, and then choose the right moment to stop the boat. On a catamaran steerage isn’t linked to speed, so you can inch back into a berth, making small adjustments as you go. It feels odd to deliberately lose steerage, but it’s much easier to correct mistakes, and any that do happen will be less costly as there’s no speed involved.

Position the crew on the quarter with a coil of line in each hand. Photo: Richard Langdon/Ocean Images

Catamaran skills for the crew

It’s always the skipper’s job to put the boat in the right place and at the right speed to allow the crew to get a line on, but it’s down to the crew to attach the right line at the right time. Line handling can make or break a manoeuvre.

From a high-sided catamaran this means lassoing the cleat. There’s a real art to this and it’s important to give them an opportunity to try this before it becomes critical; even the best cowboys need to practise.

  • Attach one end of the line to the cleat on board
  • Loosely coil the line into two loops, one for each hand
  • One hand needs to keep hold of the bitter end, or stand on it with a foot
  • Lead with the hand which is holding the middle of the line with a wide underarm throw
  • Follow through with the coils in the other hand, but keeping hold of the end
  • Throw the line so that it covers as large an area as possible – don’t worry too much about precision, as long as the line lands beyond or around the cleat it will work
  • Pull in the slack and secure it around the cleat on deck

Throw one coil and follow through with the other to create a large loop, keeping hold of the bitter end. Photo: Richard Langdon/Ocean Images

Well-briefed crew will help an inexperienced skipper out of a tight spot. Giving them a heads up on the possible pitfalls and how things might go wrong means that they’ll be able to adapt more quickly to changes of plan. There’s nothing quite like the gratitude of a skipper whose crew quickly move a fender to the other side when it’s needed.

Catamaran engine failure

One of the major advantages of a catamaran is the redundancy: two rudders, two engines, two props. If one engine’s disabled the other will get you home. However, it’s not quite as simple as it sounds because the uneven drive veers the boat towards the disabled side.

This is especially true at slow speeds where the rudder isn’t effective enough to counterbalance the offset thrust. It becomes hard to drive the boat straight, and almost impossible to turn the opposite way.

If one engine fails, a backed headsail to the failed side can help push the bow back on track. Photo: Richard Langdon/Ocean Images

Grenville had a solution for this scenario in the form of a backed headsail to neutralise the turning effect of the single engine. There was very little wind available to test out the theory, but we put one engine in neutral and sheeted the jib to the side of the ‘disabled’ engine. The apparent wind created from our forward motion was just enough to put pressure on the bow and keep the boat tracking true.

With a little more speed than normal the rudder gave some directional control and we were able to bring the boat alongside. It’s a neat trick to have in the toolbox, and with roller furling you could precisely match the headsail area to the wind strength to find the right balance.

Catamaran skills: anchoring

Dropping Anchor

If your first introduction to multihulls is chartering somewhere warm and exotic, the chances are you’ll be doing much more anchoring than alongside berthing.

Anchoring techniques are much the same as for monohulls: stop the boat by bringing it head to wind or current, and drop the anchor swiftly, paying out the right amount of chain for the depth.

There should be an anchor bridle already rigged. Lead this through the bow roller to secure to the chain, then pay out. Photo: Richard Langdon/Ocean Images

The big difference is that catamarans have a tendency to sail around the anchor, so a bridle is essential to stabilise the bow. Most of them have a bridle pre-rigged to strong points which can be slipped over the chain and allowed to take up once the anchor is set.

We dropped the hook off Netley in Southampton Water. Once I’d reached beneath the netting to attach the bridle it was simply a case of letting out enough chain for it to take up, which was a surprising amount. Issamella II then sat happily whilst we had lunch.

With a 5m bridle, you may need to pay out another 10m of chain. The hook will be underwater. Photo: Richard Langdon/Ocean Images

Another consideration is that multihulls behave differently to monohulls at anchor due to their windage. Dissimilar vessels should give one another a wide berth at anchor, especially in gusty wind. Shallow draught means catamarans can creep closer inshore, so there’s a natural filter easing the tension between the subspecies.

Approach in astern, positioning the buoy on the same side as the helm, slightly outboard, taking care of lines in the water. Photo: Richard Langdon/Ocean Images

Catamaran skills: mooring buoys

I’ve always thought that picking up a mooring buoy is one of the hardest jobs on board. Not for the skipper, for them it’s simplicity itself, but for the poor old foredeck crew.

No sooner have you hooked the pickup buoy then the bow blows off leaving them grappling with a monster from the deep. A battle for the boathook ensues, and if you’re not careful Neptune retains custody. Whilst the air becomes thick with seaweed like the fur off warring cats, the skipper looks on with embarrassment.

How would this work on a multihull with twice the windage I wondered? You’d need a harpoon to stand a fighting chance of getting secured. Grenville had a solution though: approach astern instead of ahead.

With a long line led aft from the bridle on the bow, make an upwind or uptide approach just as you would normally, but approaching with the stern and not the bow. Keep the mooring buoy just off to one side to make it easier for a crew member to pass a line through the ring and reduce the chances of running it over.

Use the engines to spin the boat. It’s not the crew’s job to manually drag the bows up to the mooring buoy. Photo: Richard Langdon/Ocean Images

The props and rudders are close to the surface under the sugar scoop, making them vulnerable to fouling from any lines in the water, so care is required. Once the line is through the eye of the mooring buoy, the helm needs to turn the boat 180° to bring the bow up whilst the crew pull in the slack.

With the catamaran’s effortless pivoting this is far easier than trying to hold the bow up to the wind. The skipper brings the boat to the monster, rather than relying on the crew to muscle it aboard.

Catamaran mooring conclusions

Once you’ve relinquished your grip on the wheel, splitting the sticks soon becomes intuitive and you can achieve an impressive amount of control through the infinite throttle combinations.

The difficulty in handling a catamaran is not in learning new catamaran skills but forgetting the old ones. And handing the keys back afterwards because, for this salty old seadog, learning to swing a cat was surprisingly good fun.


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