Want to understand better how to manoeuvre a yacht under power? Yachtmaster Instructor, Rachael Sprot walks through her most important rules for handling under power
When handling under power is done well, it’s like a black art. It wasn’t until I became an instructor that I realised it could be broken down into a few key concepts. I called them ‘The 10 Golden Rules of Boat Handling’. However, when I wrote them it was largely from the perspective of a heavy displacement yacht with fine ends, using a shaft drive. Most of the large yachts I’ve sailed in the past 10 years, such as the Clipper and Challenge yachts, matched this profile.
Recently, I’ve realised that the rules need updating. Yacht design has moved on considerably, and sail drives, long waterlines, bow thrusters and high topsides are now the norm, and twin rudders are increasingly commonplace.
Flexisail, which operates a fleet of modern cruisers, kindly lent me the keys to Varvassi, a Hanse 418, for a day last winter to refine these Golden Rules, and in this two-part series I’ll explain how to make manoeuvring under engine so much easier.
There are two elements to good boat handling: understanding the boat’s handling characteristics; and understanding the external factors which impact a manoeuvre. In the first of this series we’re going to look at how a boat behaves, and next month we’ll consider the real-world scenarios we find ourselves in.
Rule 1: Slow is pro
The number one rule of boat handling, especially on large yachts, is that if it’s all going wrong, go wrong slowly. You’re unlikely to do much damage at 1 knot. At 3 knots things become expensive. There are times when a burst of power is necessary and, carefully applied, this is an important tool. However, panic revs can cause more problems than they solve. If in doubt, step away from the throttle and pick up a fender – just use the throttle to maintain slow control.
Minimum speed is essential on a heavy boat which carries its way. Once moving, many manoeuvres can be done in neutral. However, the Hanse 418 didn’t hold her way as much as I expected so I had to be more assertive on the throttle, both to keep her moving and to stop her.
Rule 2: Maintain steerage
The counterpoint to Rule 1 is that you always need steerage. Steerage is created when water flows over the rudder. There are two ways of achieving it which I call Type 1 and Type 2 steerage.
Type 1 is what you experience when you’re actively propelled through the water, either by the engine or the wind. It’s easy to forget that the wind can still be used for propulsion, even without sails up. If you’re doing a downwind park (perhaps into the tide), or have some way on, you might not even need the engine in gear to achieve Type 1 steerage.
Type 2 steerage is what is generated when a burst of prop wash flows over the rudder while the boat is stationary. This is an effective technique for tight turns when you need to control the direction of the boat without covering any distance.
In a lighter boat like the Hanse, Type 1 steerage is more effective than Type 2. Under way, Varvassi’s high-aspect spade rudder was extremely efficient. She was responsive in both ahead and astern. However, there was less response from a power burst. This is probably due to the saildrive, which positions the propeller further from the rudder and creates a delay between action and reaction.
I suspect also that the high aspect rudder profile, though powerful when making way, can’t ‘catch’ as much of the jet created by the propeller. I’m no hydrodynamicist, but a big barn door of a rudder seems to make better use of this thrust. It felt like Type 1 steerage was much more effective than Type 2 steerage in this modern design of boat.
If the boat has twin rudders, Type 2 steerage is nearly impossible to achieve. The propeller sends water straight between the two, missing the rudders entirely. You’ll need to keep the boat moving faster in order to maintain steerage and predict what the boat will do until the rudders have gained steerage.
Rule 3: Gear then steer
I once overheard a watersports instructor coaching teenagers in a RIB. ‘Steer, then gear, Henry!’ he exclaimed, too late, as they drifted into a raft of dinghies.
Henry looked crestfallen, but he’d demonstrated that RIBs and other outboard-powered vessels work the other way round to most sailing yachts. In displacement boats with rudders, the rule is: gear, then steer.
In a tight spot every centimetre counts and there are gains to be made from following this simple rule of timing. In a heavy displacement yacht change gear from ahead to astern (or vice versa) first but don’t change the way you’re steering until the boat has actually started moving and water is flowing over the rudder in the desired direction.
This is particularly important when switching from ahead to astern since it takes longer for the boat to stop and water flow to reverse over the rudder. From astern to ahead the steerage switch is more immediate because the prop wash hits the rudder before the boat has started moving, negating the reverse flow sooner.
Varvassi was quicker to regain steerage after a gear change than a more traditional, heavy displacement yacht. The power bursts were less effective but, once moving, steerage was quickly established. It gave me more confidence to change gear in a confined space which, in turn, changed the kinds of manoeuvres I might attempt.
Rule 4: Use your prop walk
I’ve learned to love prop walk over the years. The sideways push from a burst astern is like having a stern thruster, albeit in one direction. With a propeller shaft, the steeper the angle, the greater the kick will be.
Boats with skeg-hung rudders often have offset prop shafts too, which induces even more kick one way or the other. On a shaft drive boat I tend to think of it as being right- or left-handed. A boat that kicks to port in astern is right-handed and favours a turn to starboard, and vice versa.
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Many shaft-driven boats will turn in a boat length if you utilise a few short bursts of astern propulsion, just enough to boost the stern around but not enough to get going in, and establish, reverse steerage. This shapes your manoeuvres. In confined spaces a right-handed boat is best positioned on the port side and is easiest to park portside-to, since the prop walk draws it in that way, and creates an escape route by making room for a starboard-hand turn. There are times when this is thoroughly inconvenient, but if you plan your manoeuvres with prop walk in mind it’s largely a blessing rather than a curse.
Varvassi had very little prop walk thanks to the saildrive whose propeller sits vertically rather than tilted downwards as on a shaft drive, so the thrust comes off more cleanly. Furthermore, a saildrive is located further forward, so has less leverage around the boat’s pivot point. I found that a traditional tight turn method isn’t effective on a yacht with a saildrive, and would be even more difficult on a twin rudder boat.
In such cases, a bow thruster would be a really useful tool. Without one you’ll need to keep the momentum and stay in forward gear, but the turn will be wider. Or make a three-point turn by turning hard one way, then reversing back into the space you’ve come from, reversing the steerage too and bringing the bow around in reverse.
Rule 5: Use the pivot point
Understanding the location of a boat’s pivot point is important for any close quarters handling. However, the pivot point is hydrodynamic and changes with the direction of travel. Going ahead it’s just behind the mast; going astern it shifts aft to somewhere around the cockpit, and during acceleration it shifts further to each extreme.
In forward gear we need to be aware of how much boat is behind the pivot point. In reverse it’s the bow we need to watch. It’s important to remember this when dodging an obstruction you’re being set onto. Once the pivot point is past the obstruction you need to turn towards, and not away from it, to keep the rest of the boat clear.
Varvassi’s full-width stern is a bit like manoeuvring with a pantomime bustle: the danger is not just where you’re looking, it can be behind you. The bigger the boat, the bigger the bustle. To exit a berth I sprang the bow out and drove away with a straight rudder. It took much longer to get clear enough to turn the helm away than it would on a fine-ended yacht.
Bringing it all together
In reality, there’s a complex relationship between the boat and its environment. However, when you’re skippering a new boat it can be helpful to isolate handling behaviours by practising in benign conditions. Is that twitch on the bow when you go astern the result of prop walk? Or was it a gust of wind? Understanding steerage, gear changes, prop walk and pivot points allows us to respond with more precision.
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