Shoot thru hull fish finder questions

[7lazy77]

I purchased a new(er) 25' fiberglass boat & I would like to look at installing a shoot thru hull fish finder. I don't really want to put any holes in the boat, if I can help it & the only transducers that I am familiar with are the transom-mount like I have had on all my previous boats & am NOT familiar with the thru hull options. So I am looking for a little guidance on what to look for & how to go forward from here. Any help or suggestions on makes, models, etc is greatly appreciated!

 

[gozierdt]

Re: Shoot thru hull fish finder questions

I just did a quick search on "installing a through the hull transducer" and got lots of hits, both here
on the iBoats forum and on a web Google search. I'm sure you can get all the information you
need. I do know it's suggested you try mounting a small, circular dam on the bottom of the boat
where you are thinking of mounting the transducer, arrange to hold the transducer horizontal inside
the dam, fill the dam with water, and try out the readings. This will tell you if there are bubbles or
other discontinuities in the hull that will disturb the transducer beam.

 

[pullin]

Re: Shoot thru hull fish finder questions

I just did this with my boat. I don't know if my methods are the right one, but here's how I did it. I was trying to mount a Raymarine E22054 fish finder.

IMO, the problem was making absolutely sure that I picked a spot on the hull where I could get a good signal from the transducer.

I got one of SWMBO's tupperware containers that were big enough to hold the transducer and cut the bottom out of it. The top has a "lip" that can fairly easily seal to the bottom of your hull. I used plumber's putty to make a gasket along the top of the tupperware container, and then mounted it upside down in the bottom of the hull. I then just made it into a waterbox by filling it with water and placing the transducer in it. Then I went out on the lake and tested it idling, backing, at speed, in turns etc.

The first few tries didn't get a good signal (and one spot got no signal at all). The good thing about the plumber's putty is you can peel it up and reseat the waterbox in another spot (without harming the hull). I finally found the best spot and marked it with a felt-tip.

After that I got a stronger plastic container and carefully cut it so the transducer would fit tightly in it when upside down. I spent a couple of hours cleaning the marked area in the hull (it was under the engine), and mounted a hairdryer to blow on it for about 45 minutes on low. It really needs to be clean and dry for the permanent mounting. Then used marine sealant/adhesive to glue the container in place. After letting it cure, I filled it with clean water and inserted the transducer. Then dressed up the wiring and ran it with the rest of the cabling to the helm and mounted my fishfinder. I tested it yesterday for about 3 beers (I mean hours ) and it works great.

Here's a not very good pic of the waterbox, it's just visible forward and slightly to the right of the engine. It's the plastic box just below the belts on the floor of the hull (I hope this makes sense).

The waterbox makes sure there isn't any air between the transducer and the hull (and the lake). It's a lot less permanent than using epoxy to mount it. Occasionally I'll need to add water to it, but that's the only drawback. If something goes wrong with my fishfinder, it's a lot easier to r & r than a permanent epoxy mount.

Hope this helps. Let me know if you need more pics or info.

on edit: The transducer was a regular transom mount, if that matters.