Precise Docking

You can’t leave docking to luck or always hoping it will be a nice day. You have to become an expert. You have no choice in the matter otherwise you will be taught a lesson. The lesson will be after some expense – it will be that you must become an expert. If you again choose not to become an expert, you will be taught another lesson again.

Precise maneuvering options

Until now we have introduced 4 basic types of engines

• Inboard shaft drive systems: This has a propeller on a fixed shaft. The propeller pushes water over the rudder in forward gear. While in reverse the rudder must rely on backward boat moving speed to gain any steering. It also suffers from Propwalk. It is the most difficult setup for maneuvering and not ideal for precise maneuvering. A bow thruster is a great assist device in this setup. Still, mastery can be achieved with a lot of practice – big hint for virtual reality training. Stay away from shallow water with inboard drive systems.
   
• Stern and outboard drives: This setup allows the propeller to pivot giving the operator the ability to maneuver the stern of the boat quite effectively in both forward and reverse. There is no need for a rudder as water directional flow is controlled by the pivot. An advantage is the ability to operate in shallow water due to the tilting ability of the drive units.
   
• Jet propulsion drives: These act in a similar way as a stern drive except it has a sluggish response. Shallow water? Not even a problem.

Now we introduce a fifth type of drive system

• Azimuth: This is called an azimuth or pod drive system. Volvo calls it their IPS system. This is a 360-degree pivoting vertical shaft driving a horizontal propeller. It allows for an even higher degree of flexibility in close-quarter maneuvering. When combined with a bow thruster, this can allow your boat to move sideways in either direction and spin in either direction. Some have counter-rotating propellers which removes the effect of prop walk. Some systems are even software driven which connects the bow thruster to the azimuth drive system both of which are controlled with a separate rotating joystick. It is almost a dream maneuvering tool. Salty dawgs and technology laggards will surely call it cheating.

Twin Drives

The game changes more in your favor when twin drives are introduced

• Inboard shaft drive systems: These still rely on a rudder aft of each of the propellers so pure reversing is still cumbersome. However, the advantage is that while the rudders are not independent of each other, the throttles and gears of each engine are independent of each other. For the rudders, if you turn the helm both rudders move simultaneously in the same direction. For the engines you have the option of putting one in reverse and the other in forward and applying different engine power to each. This allows great flexibility in maneuvering where the operator can spin the boat clockwise or counter-clockwise as well as move the stern sideways. When a bow thruster is introduced, the boat can move sideways and even an experienced operator can move the boat sideways using a combination of rudders and independent throttles. The setup has counter-rotating propellers so that the boat does not suffer prop walk.
   
• Stern and outboard Twin Drives: Simpler setups of twin drives have a singular engine and gear control for both drives. This provides no real maneuvering advantage over a single stern or outboard drive. However more modern or upgraded older systems have independent controls for the gear and throttles. This gives a heightened advantage to maneuvering – spinning and stern control in both reverse and forward. Add in a bow thruster and you can control the bow independently as well. It is almost a dream.
   
• Twin Azimuth Drives: This is the ultimate. It allows for every combination of maneuvering and when connected with software and a bow thruster via a rotating joystick, about the only thing you can’t do is go up. Twin units even each operate directionally independently. When connected to a GPS, the system can even hold its exact position and in exact constant heading. The downside? Cost! In addition, below the water line, the entire unit is exposed and unprotected. You are well advised to stay away from shallow water.

Here are two videos explaining the azimuth systems. The first is a bit of an advertisement for Volvo but it has a good visual explanation of the azimuth system. The second shows the azimuth in operation.

Azimuth in operation.

The following pages discuss various combinations of getting in and out of docks with various wind conditions and the various drive systems. In the explanations, we leave out azimuth because in each case you have the complete flexibility of spinning and moving laterally. Do note however that wind and current remain a complexity to the docking equation and so you must still make an intelligent docking plan in each case.