GL: Bow, stern thruster

[LRZeitlin@aol.com]

A boat usually pivots about a point 1/3 of the way back from the bow. If your 
rudders are in the prop wash, you can move the stern in the direction you 
want fairly easily by putting the rudder hard over. The prop wash, deflected by 
the rudder, produces a sideways force that swings the stern. Not so with the 
bow. To move the bow right, for example, you must swing the stern twice as far 
to the left. Sometimes the geometry of the docking situation makes this 
impossible.

Single screw boats need a great deal of helm skill to dock in crowded places. 
A bow thruster enables you to move the bow enough to make a diagonal approach 
to the dock or to swing the bow out when leaving the dock. With both bow and 
stern thrusters, you can actually move the boat sideways.

That being said, it is wise not to have to depend on either bow or stern 
thrusters. Most single screw trawlers can be pivoted 360 degrees in their own 
length by appropriate manipulation of throttle, reverse gear, and rudder. It takes 
practice, practice, practice. Of course it helps to have the agility of a six 
ball juggler.

The Vetus marine catalog has a lot of information on bow thrusters, including 
thruster power required for boats of different sizes. They also sell some 
quality thrusters. Bear in mind that the price of a suitable thruster plus 
installation for a 36' boat will be in the region of $5000.

Larry Z