Docking a boat in a slip on a calm day is pretty straightforward for most operators once you’ve done it a few times. But add a crosswind (or cross current) and it can quickly turn into a scary (and expensive) nightmare. It need not be that way – it will take practice and careful attention to all the forces at play.
Let’s start by remembering the concept of “walking” a twin-engine boat. I covered this topic in a prior post here. In a crosswind it is imperative to know how well your boat can walk and its limits.
Also let’s talk about thrusters. They are increasingly popular on boats these days and on smaller boats too. Some old salts may argue that their use is a sign of an unskilled helmsperson. It is true that many people learn to rely on them at the expense of learning basic skills, and they discover this on a windy day when the thruster decides to not work. On the other hand, there are certain conditions in which docking would be impossible without them. In this discussion I’m only considering bow thrusters. There is really no need for a stern thruster on a twin engine boat – the mains can do that job handily.
Crosswind Docking Without a Bow Thruster
First things first – ALWAYS know from where the wind is blowing. Exactly, not a rough guess. In a marina, just look up at the top of all of the sailboat masts. Every one of them has a Windex that points into the wind. And keep looking at them for any changes.
To set the stage, consider the following image. We intend to dock in a slip with a healthy crosswind (or cross current). The obvious risk is that the boat makes hard contact with the downwind corner or the piling. This is what we DON’T want to have happen…
There are two possible approaches – from the upwind side or the downwind side. Some folks prefer approaching from downwind and “use the momentum” of the boat to carry it against the wind and into the slip. This does work, and is really the best option for single engine sailboats with keels that better resist the leeway generated by the wind. With this method, you need to be a bit assertive with the controls, come in a bit faster, and enter with the bow as close to the upwind finger and piling as possible, then turn into the slip.
The above method definitely relies on momentum – if done too slowly the boat will end up plastered onto the downwind piling. A downside to this method is that it does not offer an escape route – it needs to be committed to early.
A better solution for twins is to rely on walking. Recall that a twin can be configured with left full rudder (in this example), ahead on port and astern on starboard with the result of moving forward and sideways.
So we will leverage this capability in our crosswind docking. Begin by setting up at an angle to the slip with no way on and with the bow as close to the piling as possible without touching…just inches away as shown below. The benefits of being close are that you are closer to your final destination and that an adjacent boat will help block the wind on the bow.
The boat should be angled quite a bit from the slip – this will allow you to better judge the wind effect as you let the stern swing down. All this time you are using only the shifters with rudder amidships or maybe just a few degrees of left rudder.
Continue to let the stern get blown down by the wind while keeping the bow near the piling. You can also start dialing in left full rudder in preparation for walking into the slip. This is the time when you begin to judge how rapidly the stern is swinging and whether or not you have the power (and skill) to continue with the maneuver or back away and try again.
As the stern continues to swing and the boat aligns with the slip, then the controls are set up for walking and the boat is brought in as close to the upwind finger as possible. As you enter the slip you can begin to neutralize some of the rudder and keep the boat parallel. If you begin to “lose the stern” downwind, it is still not too late to back away and reset on the upwind side.
Crosswind Docking With a Bow Thruster
Bow thrusters are spectacular devices that make boat operators look good. But they do have limitations. The most significant is their duty cycle. Most smaller vessels have electric thrusters. Some have proportional control – at 30% power then can run almost 100% duty cycle, but most are either on or off and may be limited to as little as two total minutes maximum per hour. When run too long, they overheat and trip offline (at the worst possible time) so it is important to not run them too much. On a larger yacht with a hydraulic thruster or a dedicated engine for the thruster the duty cycle is unlimited.
When using the thruster to hold position against the wind, the engine controls are REVERSED from the earlier walking method. We are using starboard ahead, and port astern. Basically just swinging the stern to starboard, with the thruster to take care of the bow position. Left full rudder is often not needed – perhaps only 10 degrees left or even rudder amidships.
The maneuver begins similar to the discussion above, with setup at the upwind corner with no way on. Note that this can be done from the downwind side as well but realize this – from the upwind side we only need enough power to stop the swing of the stern but from the downwind side we need even more power to force the stern and bow up against the wind.
As the stern swings downwind, engage the thruster and use the engine controls to hold the stern against the wind.
On boats with electric or undersized thrusters it is not uncommon to “run out of thruster” and not be able to use enough main power to stop the stern without overpowering the thruster’s effect. In these cases, it is possible to switch to “walking” mode to help the thruster a bit. By switching back and forth between modes you can ease the boat into the slip. Yes…this takes practice. Just remember to pause in neutral when shifting to let the gearboxes spin down.
One other thing – on most electric thrusters the joystick is momentary-on and your hands will be busy on the engine controls. On an especially difficult docking it may be handy to have an extra crewmember standing beside you to manage the thruster.
Docking a single engine boat in a crosswind is similar, with left rudder to hold the stern up against the wind while the thruster takes care of the bow. The main difference is that the maneuver happens with more headway to maintain stern control. It’s not possible to hold the boat in place against the wind. This is the case where a stern thruster may have some merit. If the wind happens to be on the side that your stern will propwalk to when turning astern, you can use that to good effect.
A word about cross currents – just a little bit of current will have the same effect as a lot of wind. But the techniques are the same. Sometimes the most challenging situation is when the wind and current oppose each other. As you approach the slip, it might not be obvious which one will “win”. As that becomes apparent it might be necessary to switch sides for the approach.
Also – sometimes having NO wind or current is actually a bit more challenging and you end up fishtailing back and forth to make it happen. It is sometimes easier to have just a bit of side force to have something to push against.
As they say – practice, practice, practice!