Seacraft Hull Construction & mounting transducer

[hedgehog1957]

I just recently bought a 1978 Scepter, and picked up a Garmmin 178C Fishfinder/GPS. I need to mount the transducer and would prefer not to use transom mount. Garmin says that if hull does not contain core (wood or foam), and thickness of hull is less than 1" thick, I can use "shoot-thru-hull" and mount in hull rather than drilling holes in transom. Can someone help me out with the hull contruction, and make any recomendations? Thanks.

[RS]

Hey neighbor,
I mounted my transom mount p66 that came with my Garmin 320C as a shoot through. I put it in the bilge, using pvc pipe parts and mineral oil. I never lose bottom unless the boat comes out of the water. [img]/images/graemlins/shocked.gif[/img]
You can stop by to see it if you like. I'll e-mail or PM my info to you.

[Bigshrimpin]

roger - could you post some pics of the PVC work? How did you manage to keep the ducer level within the PVC mount?

[RS]

I didn't take pics of the assembly. To answer your Q's: The transducer is too big to fit into a 4" pvc pipe, so I made it with a 4" connector glued edge to edge to a 4" cleanout with 5200.

The connector has a lip on the inside. That lip along with a few scraps of glued in pvc holds the transducer upright and horizontal to the water. The pvc connector is angled to fit the hull dead rise.

I drilled a hole the size of a wine bottle opening in the top of the cleanout plug. I passed the transducer plug out though that hole. I also drilled through a wine cork to accommodate the size of the transducer cable. I cut a slit in the wine cork so that I could insert the cable.

The pvc assemble was glued to the hull with 5200. The transducer was dropped in and the pvc filled with mineral oil (baby oil). The top of the cleanout is screwed on and the cork/cable is inserted into the hole on top to prevent oil from splashing out and water from getting in.

[rockdoc]

Hedgehog1957-

I'm going through the same set of decisions right now. Do a search here for "transducer", you'll get plenty of ideas and pros and cons. The "shoot through the hull" option looks intriguing. The problem is no temperature readings. So I might finally end up with a through hull transducer, to get temps as well as soundings.

Another option is to glue (5200, 4200, epoxy, marine-tex, etc) a starboard or acrylic plate to the appropriate region on the transom, and screw the transducer to that. No holes in the transom that way, and the transducer position can be tweaked and moved a little if need be. My problem with the transom mount is running the wire up and over the closed I/O transom. I don't think running it through a scupper hole is a good idea. Decisions, decisions.

Any advice from the group on through hull transducer choices?

Steve

[RS]

Another option is to glue (5200, 4200, epoxy, marine-tex, etc) a starboard or acrylic plate to the appropriate region on the transom, and screw the transducer to that. No holes in the transom that way

Don't do that with starboard or seaboard. It does not bond well with 5200 et al. The result might be that the assembly comes loose at 40 mph and swings up into the cockpit killing someone. Also, the cable should be mechanically fastened to the transom for all transducers so that if the bracket breaks, there is not enough reach to swing into the cockpit.

[rockdoc]

Thanks for that advice, Roger- wouldn't want an angry transducer coming unglued from the transom and killing anyone on my boat!!! And I imagine at 40 knots or so they could get moving......

And from all the reading I've been doing the past two days on transducers and mounting options, it seems the brackets DO break occcasionally.

Steve

[RS]

I had one break and all it did was swing up and crack in the motor well. Still surprised the crap out of me. That's one reason mine is in hull now. Another is that I could not find any really clean water off the back of my transom. My old transom setup used to be good up to about 32mph.