gstojk

My older model garmin worked fine when I mounted the ducer that way but my new one wont read the bottom very well. All I get is a faint line and the depth number. I've heard of a way to do it by cupping it in a mineral oil bath. Sounds complicated. Some of the "thru the hull" transducers I've seen say they will only give you a depth number and no bottom info. I hate to mount it on the transom but do I have any choice? Its a Garmin 440 combo and I dont have alot of money to spend. Any advice is appreciated...Thanks

Ironworker

My advice is not to use expoxy. I used a blob of silicone Caulking and its worked just fine for a depthsounder.

I like the transom mount or Thru Hull better for a fishfinder

abbor

You will have to use slow curing epoxy to get this to work. Silicone will dampen the signal.

icyb

first find out if your boat hull is solid glass or if its cored hull. cored hull wont work as good. i would anchor the boat in 40 fow, and set the bottom range at 80 feet. hang the ducer over the side of the boat and turn up the sensitivety till you get a double echo. you will need another person to help you. know dont change anything on the garmin, but put the ducer in the bilge. have somebody hold the ducer in place as you watch the finder. did the second echo go away or did you just lose some reading. move the ducer around till you get the best reading, then mark that spot. J-B Weld 24 hour cure works good.

abbor

I was using my phone when answering previously, so here are some more details.

Go out with the boat to a location with some interesting targets to study with a fishfinder. Fill a small plastic bag with water. Get somebody to push the transducer down into the surface of the bag while you are checking the fishfinder. In this way different locations can be tested to find the optimum placement before it's glued in place.

zigzag

I had a company tell me one time to put my xducer in a zip lock bag of water and do pretty much what " icyb" said, find the place on the hull where the picture is best and epoxy it in place, I was checking mine with the boat moving though, worked out like a champ.

semperfifishing

Are talking about a "Shoot through the hull"..?

If so, they will give good bottom detail if mounted correctly and as long as you are working at their depth limits.

An Airmar P79 should work just fine for you if you are looking at a shoot thru the hull unit.
Around a $100. for a Garmin. And if will outperform most transom mounts just epoxied to the inner hull.

rwidman

That's what I have on my Camano and what I had on my previous two boats. They work just fine.

colecaz

I bought a Garmin 546s and epoxy'd the transducer in the bilge of my 20' Grady after testing locations with the ducer in a bag of water. Once it was down it had problems holding the bottom at speed and reacquiring once the bottom was lost. I attributed it to water flow over the hull due to ablative bottom paint coming off leaving steps in the paint making the water get turbulent. I made a 4 wall box and siliconed it down by the transom, again inside in a shoot-thru configuration, mounted another ducer in it and filled it with water. It worked about the same as the epoxy'd down one. Not satisfactorily. Finally I gave up and put it on the transom like it is intended to be and it now works fine. I think it takes a real smooth bottom to avoid water turbulence and make shoot-thru-hull work. Mounting it on the transom lets you lower the ducer until it's about 1/4" in the water and out of the hull turbulence. Anyway, that's my conclusion.

If you do epoxy it down, I agree on the slow cure epoxy. Mine was fast cure and I have some bubbles. I built a well out of packing foam to contain the epoxy in a puddle so the ducer had good wetting.

First picture is the Garmin ducer epoxy'd down. Second pix is the box with water mounted right at the transom and capped with a piece of foam to hold a round test ducer. Final setup on the box was to mount the Garmin transom mount ducer to the side of the box, shooting straight down thru the box of water and the hull.

semperfifishing

I have a P79 for a Garmin that is still new in the box..it was just used as a counter display and I can sell it for $65. shipped.
And still cover it with warranty of course.

rwidman

There you go. Problem solved.

It may just be me, but I figure if you want a shoot through the hull transducer, it's best to buy a shoot through the hull transducer. If you want a transom mount transducer, it's best to buy a transom mount transducer.

Gluing a transom mount transducer inside the hull may work, but it's not the best plan.

Oh, and unless the hull is parallel with the surface of the water, it's going to be shooting at an angle and won't give an accurate reading if it gives one at all. The P79 that's designed to shoot through the hull is adjustable for different angles so it can be pointed directly at the bottom.

gstojk

Thanks for all the input. Like rwidman and semperfi say...use the right tool for the job !

philgorp

ditto