Zanshin I Bow Thruster

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Vetus Bowthruster pictureUnlike cars which are steered directly, boats are steered indirectly by means water moving across the rudder or steering mechanism. With little or no speed through the water a boat is at the mercy of the wind and current. Under power there is also an effect called prop-walk, which is force to the side from a moving propeller; akin to precession in a gyroscope.
Sailboats can be steered well when moving fast and respond crisply to directional changes. While such speeds are great when proceeding from point A to B, they are not to be recommended for docking. At the slow speeds used while approaching a dock, a sailboat is sluggish and without much control - entering a narrow slip is like trying to thread a needle in the dark after having had one or two drinks too many. Unfortunately, a sailboat weighing in at over 15 tons has significant momentum and making a mistake while docking can be a rather expensive proposition, to say nothing of the embarrassment felt when bemused spectators watch your antics as you do your utmost to cleave the dock in two.
Luckily, I have a bow thruster aboard Zanshin I and that removes many of the fears, worries and problems involved in docking a boat - particularly as I single hand and don't always have someone at the dock or on board to help set and tie the docking lines.
A bow thruster is a propeller mounted below the waterline as far forward as possible and mounted sideways so that it pushes the boat to the left or right. I have a Vetus bow thruster installed in Zanshin I which is permanently mounted and powered by 2 80Ah batteries. The batteries are necessary as the power drain of the bow thruster during operation is extremely high and putting an appropriately sized power cable from the main batteries to the bow would be too expensive and heavy, so the batteries are there to provide short-term “oomph” and are then recharged slowly.
The bow thruster is driven by two buttons in the cockpit, where one can push the bow left or right. It is recommended to only run the bow thruster for a couple of seconds at a time to avoid overheating the motor as well as to not drain the batteries, but that is usually all one needs.
Unfortunately, despite my glowing praise of what bow thrusters can do to help docking, mine was INOP much of the first year aboard, I had a bad battery connection and a bad battery which prevented me from using it. Fortunately I only had to dock a couple of times, mainly to tie up alongside a fuel dock and replenish diesel; and fuel docks tend to have easy access so there was no problem.
I finally ended up replacing the 2 batteries forward with new ones in April 2010 and what a difference that made, the bow thruster now rumbles and roars and pushes the bow around when switched on instead of a just a weak gurgle and a bit of water moving to the side.

Downloadable Manuals page - Vetus Bowthruster Manual
Windlass and Bowthruster controls Windlass and Bowthruster controls
Windlass and Bowthruster controls
Bowthruster batteries Bowthruster batteries
Bowthruster batteries
Bowthruster batteries Bowthruster batteries
Bowthruster batteries
New Bowthruster batteries New Bowthruster batteries
New Bowthruster batteries
464 views since 2017-02-04, page last modified on 2017-04-12.