I have 32 sedan bridge. I am going to install a depth,fishfinder and gps combo unit on the bridge. I have been told by various people including different West Marine staff as to the type of thru-hull transducer required. The issue is either plastic or a brass/wood block type. The boat is used on Lake Erie. All help is appreciated.

When running wires through a tube some light fishing line, a piece of sponge , an old nylon stocking, and a vacum cleaner with a hose works wonders.

Put the nylon over the end of the vacum, tie the sponge to the fishing line, have your helper vacum one end of the tube and stick the sponge in the other. Within a minute the sponge will work its way through to the nylon, if your fisherman keeps paying out line. Now you can pull through a heaver line and follow that with the wires.

Airmar makes almost all of the depth transducers so I strongly recommend you spend some time on the Airmar website. You start with the thruhull unit you want and cross-reference to the OEM that makes the readout unit you want. Then special order it if they don't keep it in stock. I like the retactable housing used on the DST800 and DT800. You slip in the type of pickup you need depth, speed, temp etc. A new model even has a camera. If you want to upgrade or change OEM's you just buy new inserts. If you start top-down with the OEM all you get is the cheapest transducer they can put in the box. The retractable units fit in a 2" hole in the hull. The cheap thruhulls are 1 7/8'. These units are low profile - almost flush - forget fairing blocks. Get the plastic housing. New units also have the NMEA 2000 electronics built right in. Here is an Airmar brochure for the DT800 Hummingbird.

http://airmartechnology....d=69&manf=Humminbird