For some boaters, the key benefit of a twin-engine boat is the redundancy, and that’s a true advantage should one engine give out offshore. But in tight quarters — especially around a dock — a boat designed to maneuver with twins quickly becomes a liability if one engine fails.
Whether running dual outboards, stern-drives or poddrives, maneuvering can become quite a challenge with one engine out. But the effect is most dramatic in rudder-steered twin inboards, because rudder impact on the dead engine is nil and the running engine tends to steer by way of its unbalanced force.
With practice and preparation you can learn to use the adverse forces to your favor, minimizing stress and aggravation. Get the hang of how your boat responds by practicing with one engine in neutral. Chances are you’ll quickly learn that your best friend in this type of situation is a reversing propeller.
1. In this docking scenario, a twin-inboard vessel is hobbling into the marina with its starboard engine down. The port engine’s prop turns left-handed in forward, meaning the boat’s stern will naturally walk to port, pulling the bow to starboard. Reverse gears and this so-called prop walk will kick the stern to starboard and the bow to port. The boat needs to back into its slip, which is coming up on the starboard side. So slow the boat, gently bumping it in and out of gear. Take careful consideration of prevailing wind and current, and keep at least half a boat length away from the finger pier.
2. Once the pier is about amidships off the starboard side, begin executing your turn. Shift the engine into reverse with the wheel/rudder centered. Doing so not only will get the boat moving backward, but it will kick the stern to starboard while pulling the bow to port, slowly aligning the transom with the slip. Remember: Reverse is your friend in this type of situation, because a boat steers from the stern, and because aligning the stern is key to a successful docking.
3. The chances of lining up dead straight and stern-to on one maneuver are slim. To tweak your setup, leave the wheel/ rudder centered and toss the engine into forward, applying just enough thrust to create momentum so the boat travels in a straight line. Then toss it back into reverse to continue the turn. This back-and-forth process between forward and reverse may be repeated several times. Much as when maneuvering a shopping cart in a crowded grocery-store aisle, you will use alternate short bursts of forward and reverse to “back and fill” your way into the slip.
4. Once you’ve established the correct angle of attack, back in to the starboard side of the finger pier, ideally at an angle that leaves the stern slightly canted away from the dock to give some wiggle room, since the prop walk will tend to pull the stern in that direction. You’ve made it. Docking a dual-inboard boat on a single engine is not as difficult as it may seem. But it does require patience and practice to learn the fundamentals of how a boat responds to the force of propeller torque. Once you’ve learned that skill, you can build on it and begin using the rudder to fine-tune your approach.