in hull transducer

[cazzascotta]

Hello, I have got a Hummingbirdi 565 fishfinder and more than one friend said to me to use the default transducer (transom transducer) as in hull transducer and then, if it doesn't work, buy a in-hull transducer. I have found this phrase in a post in this forum on 3rd sept 2008:
"do you need to bother with tubes and fluid? Just a smear of silicone and stick it on. You can use epoxy, but its a bit permanent if the location isnt perfect! "
My questions:
1-I will put this aside of the existing through hull depth transducer withour removing it. But the GRP surface is not smooth as you know, not painted. Will the thing work? Will the silicone bed be enough to make it work?
2-I was thinking of putting a wood base on the GRP and then mount the transucer on this base with the silicon (or sikaflex) to get a horizontal surface, as the hull there starts to get a little inclination, though with a little gradient (Beneteau Oceanis 311). Will the transucer transmit also through the wood?
Has anyone any suggestion or comment?
Thanks
Cazzascotta

 

[nimbusgb]

Getting tired of the bottom of my boat resembling a sieve I wanted to mount ( actually use an existing ) internally mounted transducer.

Wood is not the ideal transmission medium.

Most important is to ensure no air between the transducer and the water so no bubbles in the silicon or epoxy etc. ( that's why an oil bath is used frequently )

Going through the hull will reduce the sensitivity of the system by as much as 60% or even more!

When a barnacle or piece of weed grows right outside where the transducer is and completely wrecks the operation you can't withdraw the transducer to clean it.

I stuck with a traditional through hull, retractable transducer.

 

[Pete7]

If your not sure stick the transducer in a plastic bag filled with water and stick it in the hull. You will be suprised at the quality of the picture. We glued one into the club dive rib 10 years ago during a lunchtime stop before diving in the afternoon. It's still their and working well. As divers we do like to know how deep it is and what is down there before jumping in. Once you have found a good location just glue it in with sealant. A wooden block will stop the signal but sealant and GRP won't.

Pete

 

[Anthony]

depends entyirely on the hull layup, tranducer etc. To test it fill a sandwich bag (or even better a water ballon) with water and tie it closed, place on inside of hull and put transducer on top, so the bag / balloon forms a nice temporary water column, and test the depth sounder. This genarally gives a worse result than when its properley bedded in so if it works then its a good start. If its a very bumpy surface then it may not work, but worth a try as no harm done.

If you epoxy it in use slow cure, the extra hours drying time allows the bubbles to rise out before it sets.

Anthony

 

[Norman_E]

Stick it on with Blue Tack first to try the location. Stick it directly to the GRP. Putting wood between it and the hull will reduce the signal, probably to the point where it won't work.

Once you find a spot where it works OK then you can epoxy it down. As Blue Tack is soft it will degrade the signal a bit and epoxy, once hard, will improve the signal.

My fishfinder back up depth sounder is still attached with Blue Tack as I have never bothered to replace it with epoxy, and it works down to at least 22 metres.

 

[Eeyore]

[ QUOTE ]
1-I will put this aside of the existing through hull depth transducer withour removing it.

[/ QUOTE ]


I read somewhere recently that the two transducers have to be operating on different frequencies to work. eg one on 150, t'other on say 200.

 

[nimbusgb]

[ QUOTE ]

[ QUOTE ]
1-I will put this aside of the existing through hull depth transducer withour removing it.

[/ QUOTE ]


I read somewhere recently that the two transducers have to be operating on different frequencies to work. eg one on 150, t'other on say 200.

[/ QUOTE ]

True but only if you want to run both simultaneously. For testing its a good tactic

 

[oldsaltoz]

The water test is the best to find a good location, however if you wet the area the bag or balloon of water is being tested you will get a truer result even if the surface is a bit rough.

Avagoodweekend......

 

[cazzascotta]

Thanks to all of you, the last questions:
1-is it a good idea to sandpaper the surface or is it useless?
2-putting the two depthsounder one aside the other will influence the result if they run contemporarily?
Thank you again.
Antonello

 

[Mrnotming]

I use children's modelling clay or "plasticine" to hold my NMEA transducer in place . as it has'nt moved, and works,cI'll leave it alone.Good sailing.