I have a Lowrance LMS-337C DF combination gps/charplotter/sonar unit.
Just recently bought it and haven't installed it yet. It came with a
transom mount transducer. Do I need to buy a thru-hull transducer (for an
additional $300) for this unit. Of note, I think, is the fact that my boat
is an inboard engine. I'm running a 26 ft. LOA, 10.5 ft beam, single screw
inboard in salt water with depths in my area usually from 30 to 150 ft. The
Lowrance thru-hull accessory for this is part 106-79 which is a 50/200 kHz
transducer and best price for this is around $279 before shipping and taxes.

I've gotten mixed advice on this. Most people tell me the transom mount is
fine but when talking to tech support at Lowrance they answer in a manner
that suggests they don't know for sure and when I point out it's an inboard
engine, they end up saying "It might be a good idea if you go with the
thru-hull." Well, for $300 additonal, plus mounting costs I'd like to be
absolutely CERTAIN it's a good idea!!

Any help would be appreciated. Thanks in advance.

Chet