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With the SM, at least 95% of the time, seawater in the area of the depth transducer and watertight bulkhead is seawater that has leaked past the bow thruster seals, as little as one drop at a time. These drops of seawater run along the inside of the hull and downhill until they accumulate in this area. All other areas will be dry. Sometimes in rough conditions seawater collected in this area can be thrown to small pockets under the shower pan, where they will stay until the right rough conditions will allow the water to escape. When it does, it accumulates in the same spot between the Depth transducer and the watertight bulkhead.
In rough seas with the bow moving up and down, there is a tremendous amount of pressure on the bow thruster shaft seals. In rough conditions, this pressure can cause minimal seepage of seawater past the foam and lip seals. The best thing to do to minimize this is to change the seals every two years and to be sure to use the safety pin which should compress the 2 bow thruster outside seals causing a very good seal. Some of the last SMs and all amels made after the SM have a seawater capture system that captures this seawater and drains it into the gray water tank.
I recommend monitoring the area between the Depth Transducer and the watertight bulkhead using a simple battery-powered water alarm.