Confident catamaran handling: how to master multihulls

It’s official: this year, for the first time ever, yacht charter holiday businesses ordered more catamarans for their fleets than monohulls, writes Gavin Le Sueur.

Capable of creeping into the shallowest of anchorages, sailing flat and fast, while being incomparably spacious, catamarans win the numbers game hands down and are the choice of many sailors looking for a perfect charter abroad.

Still, for even the most experienced monohull sailor, taking command of two hulls and two engines can seem a tall order.

No need for trepidation though. The wind and sea remain the same. The theory of sailing is unaltered.

What does change when sailing a multihull are the handling characteristics and some basic seamanship rules.

These changes are the result of using beam rather than ballast for stability.

Inherent in this is a lighter, more stable platform that accelerates quickly and has higher windage and different motion.

Seamanship is an evolving knowledge base.

Just when we think everything is as good as it can get and there’s no need for innovation, along comes a new idea that we eventually feel is essential.

From a design viewpoint, for instance, there are now production cruising cats being foil assisted to reduce wetted surface area and drag.

Materials tech also keeps changing the goalposts for multihulls.

As they get lighter and stronger, follow-on changes occur in beam and rig styles.

Multihulls come in all shapes and sizes.

Good seamanship requires knowledge of the theory behind sailing a multihull and understanding the characteristics of the specific design you are sailing.

Like all yachts, each multihull model has its own quirks.

This article provides an outline of some of the features you should be aware of when chartering a catamaran for the first time.

This knowledge base will also be of use to those sailing and anchoring in company with a multihull.

Manoeuvring a catamaran in a harbour

Twin-engined catamarans have wonderful manoeuvrability.

They can turn in their own length, which is good as they usually have twice the beam (or more) of an equivalent monohull and will slip sideways in crosswind due to reduced lateral resistance and higher hull and cabin tops.

Most of the boat is out of the water.

When docking, know the crosswind and current effects and allow for them, and how quickly you will come to a stop with engines in neutral or hard astern.

Because multihulls are lighter and have a higher wetted surface area than a monohull, they have reduced momentum and will generally pull up quicker.

Twin-engine knowledge is needed to exit and enter berths.

There is little advantage in using the helm under 2 knots boat speed when you have two engines well spaced apart.

Learn to control your catamaran with engines alone at low speeds.

If both propellers rotate in the same direction, there will be an advantage docking in a specific way.

Counter-rotating engines lessen this effect.

You will be handling a much larger platform and, under you develop a feel for the size of the vessel, having crew on the bows help guide distance control.

If the multihull has daggerboards, lowering these while manoeuvring will reduce any sideways slip due to windage and increase it if your sideways movement is due to current.

Many multihulls have mini-keels and the effect on these of crosswinds and currents needs to be rehearsed before attempting a tight marina berth entry.

The stability of a multihull comes with a price: the platform is level, but the motion tends to be quicker.

There is reduced momentum and, as a result, they accelerate and stop much more quickly.

When manoeuvring, ensure the crew keeps ‘one hand for the boat’.

When sails are raised, be aware that the sheet lines are loaded immediately and wind gusts can cause rapid acceleration.

There is no heeling to spill the power.

Avoid sitting on or near loaded sheets.

Coming alongside leeward in a catamaran

1. Position the boat parallel

Position the boat parallel, with the bow angled slightly off the pontoon, aiming to bring the aft quarter alongside a cleat.

2. Let the wind bring you alongside

Control the boat’s angle while the wind pushes you on, then step ashore from the aft quarter with the sternline.

3. Use the outboard engine to hold steady

With the stemline secure, a few forward revs on the outboard engine will hold the boat in place while you secure the bow,

Coming alongside windward in a catamaran

1. Line up the aft quarter with a cleat

Instead of fighting the wind, simply aim to bring the aft quarter of the boat in line with a cleat.

Don’t worry about being parallel.

2. Secure a line and turn the boat with engine

With a short line to the pontoon, motor ahead with the outboard engine to bring the bows up into the wind.

3. Balance the power for a neat alongside

A few revs astern on the inboard engine will balance the boat to keep the aft line at 90° and the quarter clear of the pontoon.

Casting off a catamaran

1. Cast off forward

Remove the forward mooring line using the engines to hold position on the pontoon.

2. Make life easy with engines

If necessary, disengage the outboard engine to ease pressure on the remaining aft mooring line, then remove it.

3. Swing the stern out

Use the outboard engine to swing them stern out.

Stop the boat moving forward with the inboard, while the bow rests on a fender.

Taking control: Under sail

Under sail, multihulls respond to the wind quickly.

They accelerate with gusts and slow with lulls.

As a result, the apparent wind (the wind you feel) changes quickly also.

On many multihulls, it is easy to become complacent as to the true wind direction and strength.

You may appear to be pointing high and flying along when in reality, you have moved the apparent wind forward as you have accelerated and are actually laying off and losing ground to windward.

There is a sweet spot for each multihull where the sea state and wind strength combine to give you the optimum velocity made good (VMG) to windward.

This is not usually pinching hard to windward and it is also unlikely to be screaming away on a reach thinking you are tight on the breeze.

Downwind, a catamaran will outperform most similar-sized monohulls. Beware of the apparent wind in this situation.

It might be blowing 25 knots, your multihull running at 12 knots and you feel a gentle breeze.

Under spinnaker and full main, problems can quickly arise.

Although multihulls track well and tend not to broach, loss of concentration or autopilot failure can put you beam on and well overpowered.

Reef early. If you think you might need to reef, then reef.

Better to be underpowered than overpowered, especially in unsettled
 or variable conditions.

A well-reefed multihull with sails well set will sail flatter and faster than one overpowered.

In downwind gusty conditions, the correct action when hit by a gust is to 
bear away and ease the sheets.

Never luff up as this increases the apparent wind.

By bearing away, you ease the pressure on the sails.

As soon as the gust passes, it’s time to reef.

When overpowered sailing to windward, immediately ease the traveller or mainsheet.

Be aware that the increased relative power in the headsail will want to drive the boat off the breeze.

Round up slowly and keep control. Rapidly rounding up can stall the rudders and may worsen the capsize risk in big seas.

Spinnaker, headsail and main sheets should always be secured in a quick-release cleat.

A self-tailing winch or a cleat requiring tension to be taken to release 
is not quick release.

Never leave a winch handle in the winch as a released sheetline can easily foul on this.

Many multihull capsizes are a result of a series of issues – a squall, overpowered rig, inability to quick release, turning the wrong way to depower.

On a cruising catamaran these are reduced, but good seamanship dictates an awareness of what to do when the unexpected occurs.

Avoid getting caught ‘in irons’

Although not unique to multihulls, getting caught ‘in irons’ is a common problem.

‘In irons’ is the state of stalling when your multihull has pointed too high into the wind or lost momentum through a tack and all forward motion is lost.

It is possible to sail or drift backwards on a multihull with considerable skill.

To get out of irons, release the headsail and push the rudder over to the opposite side you would if going forward.

The multihull will drift backwards and around on to the tack required.

As soon as the bow falls away and the mainsail has wind on the windward side, sheet in the headsail, correct the helm and only sheet in the main once you are progressing forward.

Most cruising catamarans will generally have a conservative rig and minikeels.

Due to their higher windage, reduced momentum and increased hull surface area, sailing to windward requires a different skill set than on a monohull.

First of all, don’t try to point as high as the monohull you are used to sailing.

Lay off and go for a bit of speed.

You have less weight so will generally go faster, albeit it further off the wind.

Doing this in practice, the velocity made good equation will work out in your favour.

Sailing to windward is about making the best speed toward your destination.

You might cover more ground but will generally arrive relaxed and at the same time (or earlier).

If the sea state is choppy and you are pounding into it, lay off a bit, power up the sails and punch forward.

The sea state can stall a cruising multihull quicker due to their reduced momentum.

Use the sails to maintain drive.

1. Get sailing

Putting the wind just off the bow and dropping the sail on to the coachroof makes for a trouble-free hoist clear of crew.

2. Aim for boat speed

Having raised the main and unfurled the job, bear away.

Aim for boat speed before getting closer to the wind.

3. Use beam to shape sails

The extra-wide traveller track can be used in place of a kicking strap to put more shape in the sail on a catamaran.

4. Use your instruments

Use the yacht’s instruments to track velocity made good, as well as true and apparent wind speeds.

Cats sailing flat sail faster. Avoid becoming overpowered and always reef early.

5. Avoid overpowering

Keep an eye on your leeward shroud if it’s very loose.

Consider whether you might be overpowered and if it’s putting too much strain on your rig.

Daggerboards and their effective use

Daggerboards increase the lateral resistance and assist in tracking and sailing to windward more effectively.

To adjust boards when sailing you may need to ‘unload’ them – jiggle the helm, partially round up and bear away quickly or adjust them when tacking.

On catamarans, when sailing to windward in light to moderate conditions have the centreboards fully down.

In very light winds have only one centreboard down to reduce the wetted surface area.

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To windward in heavy conditions, partially retract the boards, starting with the leeward board.

When sailing downwind the centreboards should be adjusted to balance the helm.

When broad reaching this usually means the windward board is half down and the leeward board nearly fully up.

A small amount of board down will improve downwind steering.

In storm conditions consider the tripping effect of increased lateral resistance and adjust the boards accordingly.

Remember to retract your boards when coming into shallow water!

Trimarans

Not all multihulls are the same.

A trimaran generally has a wider beam, single engine and rudder, and less internal space.

They heel a bit more and are usually better windward performers.

Their wide hull windage is often less, and many have a central daggerboard which aids manoeuvrability and reduces lateral slide.

A trimaran will often be quicker to respond to the helm, and as they are proportionally lighter, will accelerate faster.

This is, of course, a generalisation as there are full bridge deck cruising trimarans with the internal volume and weight of a cruising catamaran.

Trimarans, like a single-engined yachts, require knowledge to the effect of the water flow over the rudder from the propeller when undertaking tight manoeuvring.

Further reading

Multihull Seamanship by Gavin Le Sueur (Fernhurst, £14.99)

After 22 years and five reprints, Multihull Seamanship has undergone a full rewrite to update the many changes that have come with further experience and design advances.

This book is an A-Z of skills for catamarans and trimarans, cruising and racing.

Dr Gavin Le Sueur is a lifelong multihull sailor with experience racing and cruising the seven multihulls he has owned.

He has survived cyclones and capsize, raced two-handed around Australia and cruised throughout the Pacific and Asia with his wife Catherine and their three children.