Transducers..Hull or Transom?

SolarisRIB · 23 November 2012, 12:17

I'm about to fit a new fishfinder on a Zodiac Medline. Whilst a transom mounted transducer would probably be easier to fit, will it be as efficient as a hull fitted one or will it suffer from being in aereated water? Any feedback would be useful.

Pikey Dave · 23 November 2012, 13:19

As you say, transom mount is easier. I currently have a 1kw in hull txr & get a good echo at all speeds upto 40kn, you allegedly lose some power by shooting through the hull, but this is offset by the (imho) superior readout. I've had transom mounted txrs on previous boats but the echo starts to break up at around 15kn & goes completely at +20kn. If you're prepared to put a bit of extra effort in, the in hull is a better bet.

SolarisRIB · 24 November 2012, 07:08

Quote:

Originally Posted by Pikey Dave

As you say, transom mount is easier. I currently have a 1kw in hull txr & get a good echo at all speeds upto 40kn, you allegedly lose some power by shooting through the hull, but this is offset by the (imho) superior readout. I've had transom mounted txrs on previous boats but the echo starts to break up at around 15kn & goes completely at +20kn. If you're prepared to put a bit of extra effort in, the in hull is a better bet.

Thanks for that. My guess is that it's best put in the hull about three quarters back from the bow !!

Pikey Dave · 24 November 2012, 09:15

Quote:

Originally Posted by SolarisRIB

Thanks for that. My guess is that it's best put in the hull about three quarters back from the bow !!

Mines about 0.5m forward of the transom, slightly off to the port side. You need to make sure that you have an area of solid GRP with no voids, wood or foam. I assume that you're talking about a "shoot thru hull" txr bonded to the inside of the boat (I am), rather than a "Thru hull" which is fitted in a hole drilled through the hull. People on here have had good results bonding a normal transom mount type transducer to the inside of the hull using silicone. Mines an Airmar M260 specifically designed for in hull mounting. It was a bit of a faff fitting it but the results are worth it.

SolarisRIB · 24 November 2012, 10:23

Quote:

Originally Posted by Pikey Dave

Mines about 0.5m forward of the transom, slightly off to the port side. You need to make sure that you have an area of solid GRP with no voids, wood or foam. I assume that you're talking about a "shoot thru hull" txr bonded to the inside of the boat (I am), rather than a "Thru hull" which is fitted in a hole drilled through the hull. People on here have had good results bonding a normal transom mount type transducer to the inside of the hull using silicone. Mines an Airmar M260 specifically designed for in hull mounting. It was a bit of a faff fitting it but the results are worth it.

I haven't bought it yet but it will be a through the hull unit bonded in with silicone or similar. I've just about convinced myself that a Standard Horizon combo GPS/fishfinder is best value for money. The fishfinder is for locating dive/wreck sites, not fish and I think that one is up to the job. Did you check for voids by tapping around the area?

Turbodiesel · 24 November 2012, 19:08

I have just fitted a Airmar 260 in a Scorpion rib, just back from the transom, fitted it to a Garmin GSD24, was pretty easy to fit, and works really really well!

BogMonster · 25 November 2012, 08:10

Quote:

Originally Posted by Pikey Dave

Mines about 0.5m forward of the transom, slightly off to the port side. You need to make sure that you have an area of solid GRP with no voids, wood or foam. I assume that you're talking about a "shoot thru hull" txr bonded to the inside of the boat (I am), rather than a "Thru hull" which is fitted in a hole drilled through the hull. People on here have had good results bonding a normal transom mount type transducer to the inside of the hull using silicone. Mines an Airmar M260 specifically designed for in hull mounting. It was a bit of a faff fitting it but the results are worth it.

That's where mine is. It is also an Airmar 260, or rather half an Airmar 260 since the original fit had it pointing in the wrong direction so it didn't work well unless you were in a tight RH turn! I tried to chisel off the base but couldn't move it, so rather than damage the hull I glooped the inside bit (the transducer itself) onto the hull with silicone about 30cm inside the transom and as close to the keel line as it would fit, and it's worked brilliantly ever since and much, much better than the transom one on my old boat, which like Dave's was useless above about 20kt.

Probably a minor point, but for a single engined boat it's probably worth putting it on the side it sits down on (ie port side on RH rotation engine).

SolarisRIB · 26 November 2012, 08:29

Thanks all for your input. Bits ordered today for in hull fitting.