Docking a Twin with only One Engine

only one motor

Many of us have driven a car with one flat tire, but how many have driven with two flat tires on the same side? That’s what it is like to maneuver and dock a twin engine boat with only one engine.
Last Sunday after summerizing my Windy, I stopped to help a friend. I volunteered to drive his 40’ Sedan Flybridge from the launch slip to his dock, because his port motor refused to start and he had never driven his twin with one dead motor.
This was a teaching opportunity, so that he would be prepared when this happens again.
Since a twin with one dead engine doesn’t handle like a single, I encourage all captains to learn how to handle your twin with one motor, just in case you lose one, as he did. It is also a good idea to print out, practice this lesson and keep on board—-just in case.

You know the main advantages to buying a boat with twins:

  • Better maneuverability
  • Better performance for a larger boat
  • Assurance you still have power if one engine quits

BUT, what if one quits?    How to Dock? Whether Twin Outboard, Twin Sterndrive or Twin Inboard?

Do you know how to handle and dock your twin with just one live motor? Most boaters don’t. It’s totally different than docking with both motors running, and it is quite different than docking a single engine boat. How so?

motor off center

On a single engine boat, the motor is on the centerline of the transom and the thrust is therefore balanced; whereas, on a twin, the motors are off center.

Therefore, when operating a twin with only one motor, the thrust is off center and unbalanced, creating differences from handling a single, as well as several challenges to be prepared for.

The major difference is that your turning radius in forward will be greater or much, much greater, depending on which direction you are turning and which engine is dead. Look below in “Lessons Out on the Lake” to find out which is which, and how to outsmart them.

Power Steering

When the motor with the power steering pump dies, you will quickly discover how much work your power steering pump actually does for you. It will be like trying to push a shopping cart with one back wheel seized. It doesn’t steer or maneuver easily at all.

If you believe in Murphy’s law, it is will be the motor with the power steering pump on it that quits. Like they say “Been there, done that”. So, turning the wheel will be difficult, which changes from you palming the wheel around, to having to use two hands to pull it around. Knowing this, you want to make each turn count to the maximum to reduce the number of times, you have to turn the wheel from hard over to hard over.

Advance Discovery

On that weekend when there is nowhere to go and nothing pressing to do, I recommend you spend an hour with only one engine running—leave the other off. Practice handling and docking your boat. Then repeat with only the other engine. This practice will prepare you, when you are caught with one engine that just won’t co-operate.

Lessons for Out on the Lake

Exercise #1

port dead
port dead

Start in open water. Your first exercise is to execute a hard-over turn with your running motor on the outside of the turn. Let’s assume it’s your starboard engine that’s running and your port engine is dead and; therefore, you are turning to port.

The bow will come around to port in a gradual curve. To tighten this curve, give a very short shot of throttle, slow it, then pull into neutral. Watch it turn tighter, as the whole boat tends to rotate or fish tail, as well as continue on the turn to port.

You would expect that to tighten this rotation to port even more, you would pull the running (starboard) motor into reverse.

  • On a Twin Sterndrive or a Twin Outboard, turning the wheel hard over the other way, then, and only then, reverse will help pull the stern around further.
  • On a Twin Inboard, when you pull your starboard (outside engine) into reverse, the back end stops swinging and actually reverses against the swing—back on the track just traveled. So, use no reverse or very short reverse, so as to not kill the swing or rotation you had going from forward gear.

Exercise #2

one motor down 3
port dead

The second exercise is to turn against your running motor. Using the same motor as in the previous exercise, our starboard engine is running and we are going to turn hard over to starboard.

You may wonder why when it’s in forward, that the boat requires a lot larger radius to turn, than in exercise #1. That’s because the thrust is now on the inside of the turn.

When it comes time to approach your dock and turn within a narrow harbor, keep this much larger radius in mind; so that you allow enough space to negotiate the turn, you must make in the harbor.

Thus, it is better to turn with the running motor on the outside of your turn.

Exercise #3 and Exercise #4

Repeat #1 and #2 with the other (port) motor running and starboard off.

Lessons for In the Harbor

Once you are comfortable with all four exercises in the open water, repeat all four exercises within the tight confines of the harbor.

Then, when you can do that without problems, it’s time to approach the large gas dock or service dock. Do it here, because there is more space and fewer boats than in and around your slip, and you may even have a dock helper. In this case, dock helpers may come in handy.

It’s preferable to approach a gas dock with your “live” motor away from the dock and your dead motor closest to the dock. Have your lines and fenders ready with your First Mate on the aft corner with the dead motor, ready with the FLIPP Line, as described in each of our Introductory Docking Lessons.

Approach the gas dock with the shutdown engine closest to the dock. Regardless of drive system, forward gear will swing the bow in—not away; then reverse gear will draw the transom in—not away. (Depending on drive system, the wheel position is different as explained above in Exercise #1)

Being Prepared

Docking without one motor is a rare situation; but, as sure as it is going to rain on your holidays, at some point, you’ll lose a motor. You may lose it while cruising, which will give you time to prepare and/or worry. You may lose it while docking. Now what? No time to prepare or panic, just react!

Regardless which twin engine drive system you have, it will someday happen to you. Plus, there’s a 50% chance the motor that stops will be the one that drives the power steering pump, resulting in Double Trouble.

Being prepared, by practicing this free lesson ahead of time, you will get out of trouble and save the day–minimizing stress and aggravation.

More Tricks and Tips for Docking

In each of Dawson’s Advanced Docking e-Lessons for Twin Inboards, Twin Sterndrives and Twin Outboards, there are even more detailed instructions on docking with the live motor to the dock and docking with the dead motor to the dock. There are many other neat maneuvers like the gas dock shuffle, pivoting on a piling included in the Advanced e-Lessons as well.

When your one motor dies, fear not!

Perform the steps you learned and practiced here with

Doug Dawson

6 thoughts on “Docking a Twin with only One Engine”

  1. Doug, for safety may I suggest that you don’t shut the other engine down, just leave it in neutral. That way if something happens, you will have full control of your vessel immediately and not have to wait to restart the one engine.

    1. Doug, I forgot to say on I/O’s you would want to turn the other engine off so they experience the loss of the power steering as you mentioned. If you are docking using the engine with the power steering pump, I would leave the other engine running.

    1. James,
      It depends on your drive system. For twin outboard, it is best to trim the dead motor up all the way so that it is above the water surface and not dragging in the water. Whereas with twin sterndrives, when it is trimmed all the way up, it is still not clear of the water and it acts as a monstrous rudder just below the surface of the water. So, for twin sterndrives, it is best to leave it down all the way because it is a smaller rudder working against you than if it were trimmed up. For a twin inboard, there is nothing to trim. In all three cases, follow the instructions in the lesson. The most important part of docking with one dead motor, is to practice ahead of time so you realize what works and what doesn’t work without having to learn on the job as opposed to learning at your leisure.

  2. Bradford pellet Biggers

    I need to move a twin inboard boat to another location on a single engine . Should I use trim tab on dead engine side to help steer underway?

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