Water from the port side cockpit locker might be condensation from the refrigeration unit.  If so, this can be solved by having a drip tray below the unit and emptying the tray every few weeks.

Depth transducers are installed two ways:

Thru hull
These are removed by unscrewing the nut from the inside of the hull and then pushing on it from the inside of the hull so that it exits from the outside of the hull.  Naturally, you do this while on the hard.  There might be quite a bit of sealant holding it in, so try unscrewing the entire body clockwise; if this does not work, then a bit of pounding with a hammer may be necessary.  Since you're throwing it away, it does not matter how hard you hit it.  If you don't have enough swing room for the hammer, then from the outside of the hull chisel off the lip of the thru hull (if plastic), and try unscrewing from the inside of hull - either direction at this point it fine.  Again, if this does not work, then (because the lip is gone) push the thru hull from the outside of the boat into the inside of the boat.  Hammering will be necessary.

Shoot through
Same model of transducer, but are generally epoxied to the inside of the hull and don't require you do be on the hard.  A hammer and a chisel or a grinder will do the trick, but you might just opt to leave it alone and install the replacement nearby.

Regardless of the installation method, best to go ahead and cable up the new transducer to the back of the instrument and press the transducer to a downward facing area of the inside of the hull away from the keel or the rudder to see if you detect bottom you commit to a more permanent installation.  Naturally, you'll want to do this while you're in the water.

Hey Kenny.  Please consider adding some information to your signature line, such as boat year, engine, options, sailing area.

Almost any depth transducer that fits via thru hull can be used as shoot thru.  I think your first task is to make sure it's the transducer/cable vs. the instrument:

• Purchase a transducer that is compatible with ST60 instruments. 
• You'll have to "adapt" the end of the cable for the new transducer to fit into the back or your ST50 instrument.
• Once you've done this, place the new transducer against a portion of the hull that is clear of the rudder, propeller, and keel and see if you can detect bottom.
• One you've detected bottom, then make the decision to remove the old transducer and replace it with your new transducer (or) simply epoxy the new transducer to a suitable place in the hull and call it a day.

We had water leaking into the mattress in rear cabin too.  It was a blocked vented loop on the wall in the port locker.  Replaced the valve and water leak was solved. 

We had water leaking into the mattress in rear cabin too.  It was a blocked vented loop on the wall in the port locker.  Replaced the valve and water leak was solved.