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Author Topic:   Transom Mount Transducer as Shoot-Through
zotcha posted 01-07-2008 07:31 AM ET (US)   Profile for zotcha   Send Email to zotcha  
I know this is an off the wall question, probably best suited for a Garmin, but I'm looking for real world experience. Has anyone tried mounting a [transom mount] transducer in the sump of a Whaler?

I know specifically Garmin does not recommend using this as a shoot-through due to the foam in the hull, but a friend is using this method on a 16 foot [fiberglass] boat with a Garmin 3210. I know, absurd, but you have to know this guy! And catch fish! Anyway, he states he can identify oysters on a shallow bottom.

Getting the transducer as far forward as possible is critical when "deep holing" for shrimp. Haven't tried it yet, and wondering if anyone else has. Thanks. zotcha.

zotcha posted 01-07-2008 07:32 AM ET (US)     Profile for zotcha  Send Email to zotcha     
Should have mentioned 1988 15 Sport and Garmin 545s.
ConB posted 01-07-2008 08:43 PM ET (US)     Profile for ConB  Send Email to ConB     
Maybe if your foam is water logged it might work.


zotcha posted 01-07-2008 11:00 PM ET (US)     Profile for zotcha  Send Email to zotcha     
I'm not sure, but don't believe the transom , nor foam, to be wet yet. Just curious if any other members had any success with this method. Thanks in advance. zot.
jimh posted 01-08-2008 12:22 AM ET (US)     Profile for jimh  Send Email to jimh     
I don't think results obtained in fiberglass boats with the usual laminate construction are going to be well correlated with results you will get from a Unibond hull in a Boston Whaler in terms of the performance of in-hull or shoot-through SONAR transducers.
Jefecinco posted 01-08-2008 07:01 PM ET (US)     Profile for Jefecinco  Send Email to Jefecinco     
Why not just give it a try? Put the xducer where you would install it and weight it down with a sock full of sand. Fill your bilge/sump until the xducer is flooded. Then try it out. If it works well you're in business. If not, you're not. It's a simple, no cost, little effort test wich will fairly closely mimic a transom mount xducer used in a shoot through the hull application.

The foam in your hull between the sump and the outer skin may be either thin or nonexistant.

If it works put a huge glob of silicone sealant in the sump and stuff the xducer into it. Support it until it has set up and go fishing.


zotcha posted 01-08-2008 08:49 PM ET (US)     Profile for zotcha  Send Email to zotcha     
Exactly what I was thinking. Just curious if anyone else had had any luck in the past. Thanks. zotcha.
dino54904 posted 01-15-2008 01:35 PM ET (US)     Profile for dino54904  Send Email to dino54904     
Here is something I did to my last Whaler and will likely do to my current Whaler. In the aft portion of the cockpit I used a 4" hole saw to saw through the upper layer of fiberglass and through the foam. I left the outside skin of fiberglass in tact. I then filled the hole I made with layers of fiberglass mat and West System epoxy to make a hard spot within the hull. In doing this I also made sure to seal the sides of the 4" hole to protect the foam from water intrusion. I simple spread some caulk on the surface of the transducer and stuck it onto this hard spot. It worked great and I didn't have anything hanging off the transom of the boat.
zotcha posted 01-15-2008 08:47 PM ET (US)     Profile for zotcha  Send Email to zotcha     
Very cool. I like the idea. Thanks. zotcha.
where2 posted 01-20-2008 08:22 PM ET (US)     Profile for where2  Send Email to where2     
I fear caulk is too soft and squishy for this project of bonding the transducer to the hull. Humminbird used to sell an epoxy kit to epoxy the transducer inside the hull of a non-cored boat. We had one in a boat once. My father has installed a PVC stilling well in the aft portion of his 20' Edgewater. PVC pipe was epoxied to the hull. The pipe holds a couple of cups of water, and the transducer just sits in the water. He cut a PVC cap to fit on top of the pipe to keep the water from sloshing out, yet allow the transducer wire to exit. It works very well.

On our 25' BW Frontier at work, we had a large well installed to mount the transducer in, digging out the foam to make it. (transducer is the size of a football!). The well holds roughly five gallons of water and the tansducer just hangs in the water inside. Some day I'd like to see if it will shoot over 1000' deep. (this isn't your average depth sounder, it's a survey grade that will do 20,000' if it's mounted in direct contact with the water).

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