on a stepped hull what is the best way to mount a tranducer?
external type or internal ? I dont want to have a bunch of holes
to fill either. I want it right the first time. but I do want to have a reading when underway
reasonable speeds. which sounders work best?

On a stepped hull I have read that the external is the only one that will work with the boat on plane. If you don't care if it works on plane then the tru hull should be fine.

We had a pretty good discussion about this in the Fountain owners fourm awhile ago. Its about 4 pages back entitled 'depth finders' It pretty well covers it, step and non step.

I have a twin step 26 foot Donzi. The transducer is mounted externally approx. 6-10 inches away from bilge drain, starboard. At higher speeds the gauge still does not read accurately. It is a Gaffrig gauge - not sure who made the rest of the unit. I also heard that readings are much worse with transducer mounted internally on a ventilated hull.
Tim

If your hull is balsa cored it will work poorly, stepped even worse. I'm changing mine to external on the bottom of the extension box. It won't be in the water at speed but lower it will be and be accurate.