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Stepping up to a Twin Engine Boat.

So you just got this shiny new big- to-you twin engine boat you've always dreamed of and wonder if you haven't taken a bigger than you can chew bite...

Relax... the bigger the boat, the easier it is to handle. Really. A larger boat will usually be heavier and less succeptible to be blown away by the wind and two engines give at least twice the control.

The main difference between a single and a twin engine boat is that you can use asymmetrical thrust to turn it, even pivot it in its own length. This is true regardless of whether it's an inboard, diesel, gas, outboard or sterndrive although each type will react slightly differently.

Asymmetrical Thrust / Splitting the Gears

Whichever way you call it, it's a very simple process : put one engine in forward, the other one in reverse and the boat will pivot or turn toward the engine that's in reverse. Ever pushed a shopping cart ? Well, it's the same thing... pull with one hand, push with the other one and the cart turns, right ? Same thing with a twin engine boat ! Pull on one side, push on the other one and the boat will pivot. Better, your movement on the shopping cart handle match your hands on the gear levers on your boat... Push the port gear forward, pull the starboard lever back and the boat will pivot to starboard, as easily as a shopping cart.

Using the Throttles

Once you are familiar with this basic maneuver you can then experiment with throttles. Most boats will pivot nicely at idle especially inboards which have larger props; diesels with even bigger props will turn even better. Sterndrives and outboards on the other hand will often require bumping the throttles up to raise RPM especially if the engines are close together near the centerline.

You can also use the throttles to adjust the motion of the boat. In a perfect world the boat would pivot on itself without creeping forward or backward but as we all know it's not a perfect world out there... first, a prop in forward gear will be more efficient than a prop turning in reverse so you will likely need to increase RPM on the engine in reverse to stop the boat from creeping forward. But you also have to adjust for wind or current by adjusting power on either engine : if your boat is creeping forward, you will need to increase RPM on the engine that's in reverse. If the wind is pushing you backward, you will need a little more forward power.

Whatever you do, use only the minimum power you need....

Using the Rudders

Most people will tell you to center you rudders/drives as you get in the marina or near the dock and not to touch the wheel. While this is somewhat true, especially when you are new to twins, there many good reasons to use your wheel but let first mention the reason why you should NOT.

If you forget which way your rudders are turned, you may end up getting in trouble when you start moving and your boat suddenly turns when you don't expect it. Obviously less likely to happen with outboard are you can see where they're pointing but could be a problem with inboards and sterndrives. Keep that in mind.

Here are a couple of examples where it pays to use the rudders on a twin inboard boat.

  • Accelerate the rate of turn : when you are turning around in a fairway or in close quarters, you can usually just use the gears and let the boat turn around. Now if you need to turn quickly because of other boats or to minimize the amount of time you will spend at the mercy of wind and current, using both some extra power and the rudders will help. If you are pivoting to right, turning the wheel to the right and increase RPM a little will result in propwash from the engine in forward gear pushing the stern sideways accelerating the motion. Again, don't forget to return your rudders to center as you complete your turn.
  • Kick the stern sideways : if you are close to the dock but still have your stern a little too far, turning the rudders away from the dock and briefly putting one or both engine into gear will kick the stern sideways toward the dock. While you're not going to close a 10' gap with this method, if your stern is just a few feet away it will do the trick.

Basic exercises

You may have been told to go out on water, and throw a float tied to an anchor or something and use that as reference point to practice maneuvering. This method has a few drawbacks : you can't see the float when you're close (unless you're in a very small boat) and if you mess up you may end up with the line wrapped around your prop. I much prefer using a piling to practice because you will always be able to see it (higher above the water) giving you a much better and more precise reference. It will also help you learn how to judge the distance and the length of your boat. How can you do that when you can't see the float 3' from your bow ? While some may argue that you could hit the piling, it will also add an touch of real world to the exercise and when you get back to your dock or slip you will not be intimidated by a fixed object...

First, find a pilling which you can approach bow to the wind with clear water around the end of a T dock works great. Obviously, use common sense and don't get in the way of boats coming in and out.. Sometimes it's better do practice during the week or early in the morning on week ends where traffic is minimal. Obviously, make sure you are not going to run into shallow waters wile practicing... Have someone on board with you to keep an eye on other boats so that you can focus on the maneuvering.

Practice coming as close to the piling as you can bow first, lined up into the wind. Controlling the boat only with your gears. Start from one to two boatlength away and slowly bring your boat forward, keeping it as lined up as possible. If you can, use a reference point further up beyond the piling to visualize a centerline. With a little practice you will be able to come as close as just a few inches.

Next, practice the same maneuver but at an angle to the wind, which will be a little harder. The trick to this exercise it anticipate the impact of wind and aimed higher up wind so that when you are as close as you want to be, you are in the right position. Don't try to hold the position for too long if the wind pushes you away, there is not need for that. Instead back up a little and come back. Again, you will need to visualize the impact of the wind, bring your bow higher then turn back in line so that you end up lined up.

Each time, control your boat with the gears, using as little power as possible. As you gain confidence, start using the rudders to see how you can benefit. The key is to really focus on your bow and the piling, to see how each control



input or each gust of wind will affect your boat. Being close to the piling and able to see it will make it much easier to get a good feeling for your boat and how it reacts.

After practicing this a few times, turn the boat around and repeat the exercise but approaching with your stern. Select either the center or one of your corners; If using a sterndrive or outboard boat were the drive / props extends beyond the swimplatform you should obviously practice this maneuver using your starboard or port aft corner as reference.

Approach the piling in reverse, slowly. if the piling isn't where you want it to be, use forward on one engine to move the stern. Ex : if you are approaching with the piling on your starboard corner but find your stern to be too far to port and your boat slightly angled, put the starboard engine in forward. That will quickly move your stern over towards the starboard side. Leave the port engine in reverse unless you have to stop the boat. Practice this until you become familiar with how your stern react. Again, using a piling as a reference helps you visualise the effect.

How do you use this when docking ?

Again it depends on the boat and the situation you are facing. Sometimes, with a twin IO or twin OB boat, docking alongside can be done just as you did with the single : come in at an angle, put it in neutral with half a boat length, turn the wheel hard over towards the dock and briefly put the boat in reverse. That will stop the momentum and bring the boat alongside the dock. Well, it works very well with a twin IO or OB...

With an inboard boat, using the gears gives you an edge... as you approach the dock at an angle, you can swing your rudders hard over AWAY from the dock and put the offside (away from the dock) engine in reverse. That will slow and stop the boat while your rudders push the stern towards the dock. By leaving the dockside engine in forward (idle) a little longer, its propwash will help push the stern sideways. Depending on your momentum and how long you leave the dockside engine in forward, you may need to use a short and reasonable burst of power on the offside / reversed engine.

When backing into a slip, you will see right away how important the backing to the piling exercize was and how much control you have over your stern. If you are a little too close to the piling near your port stern, briefly putting the starboard engine in forward will quickly move the stern away from that piling on port.