Trojan Boat Forum

I would like to install a new depth finder - as the boat did not have one when I purchased her.

I noticed what looked like 2 thru-hull transponders, but I can not tell if they are any good or not.

I was wondering if any one has done the inside mounting technique, glassing the transponder to the hull.

If so - how did it work? Also, was there a particular brand that one would recommend for this type of installation. I hate to drill another hole in the hull.

My other thought would be the transome mounted approach - but I would still need to drill a hole above the waterline to snake the wire through.

Thank you - John.

Why not check the make of your existing transponders... they may still function.
Also measure the diameter of the probe... you may find that the diameter is suited for replacement with a new probe at next haul.
If you have two holes not being used it makes sense to use at least one of them rather than going another direction.

John ,the tru hull always seen to work the best IMO, why not remove on that is there and install a new thru hull in the same hole . I have never had any luck with the shoot tru the hull type myself , others have . Transom mount may work too make sure it is clear of the prop wash.

Many good sounders can be ordered with the transducer you need . if you just go to the store they may just have the transom mounts , buying the transducer separate can be costly , so order the unit with they one you want .

Using the old ones is a gamble at best

Thanks for the advice - I will go crawl under the tarp and check things out today - supposed to be in the high 40's here in Maine which for the middle of February is a nice surprise.

Transom mounts are not typically recommended for inboard applications. Do as others have suggested, and reuse the location of existing thru-hull units. Probably time that these were rebeded anyway.

Inboard is best through a hole in the hull. My f28 had two old transducers mounted through the hull with rotten wooden fairings. The ducers did not go to any current equipment, cut the wire and removed them. Airmar makes most transducers and I am using a through the hull B744V from Airmar which will work with my equipment and using their High Speed Fairing. Airmar website shows diagrams of the best mounting location for various installations.

The hull at mount location, about 16 inche forward of my rear bulkhead is about 3/4 to 7/8 inches thick. IMO mounting in a hole through the hull will work better than shooting through the hull.

I also had two old transducers in the hull of my boat. I was scared to mess with them. For now I attached a shoot thru on the inside bilge area of my 87 Trojan Int Express per airmar's instructions. It seems to work alright, but don't have anything to compare it to.