Depth Transducer

[Porthandbuoy]

I removed an old, redundant and u/s thru-hull depth transducer and its external fairing block when I lifted Ladybird out of the water last Autumn.

She has an internal transducer which works fine in relatively shallow waters, say <15m, but not when it gets deeper (there is oil in the tube). I have a dual range spinning LED type display and the deeper range cannot be used.

Ladybird's hull is pretty thick, @ 22mm, so should I go back to an externally mounted transducer? Would that likely increase the depth range of my sounder?

It was the thread on GPS failure and alternative navigation methods that got me thinking, ie. 'contour navigation'.

 

[earlybird]

A through hull transducer will almost certainly increase the range. Even so, 15m seems rather poor. I seem to remember at least 30 to 40m on an Incastec sounder of mine with internal transducer, but it depends on the nature of the sea-bed.
It's possible that the present position of the transducer is over say, a small void in the hull layup. Can you temporarily reposition it using, perhaps, a blob of grease to couple it, to see if an improvement is possible?

 

[fergie_mac66]

i thnk a lot of inhull units are located with a big blob of silicone now , if carefull and no bubbles very easy to fit this way , but worth testing in several places first with grease to make sure no bubbles, voids, in layup of hull .

edit easy to move aswell

 

[Porthandbuoy]

"Big blob of silicone". I'd not heard of that. Got to be worth a try. Thanks.

 

[fergie_mac66]

"Big blob of silicone". I'd not heard of that. Got to be worth a try. Thanks.

use translucent no colours , important no bubbles and so press down slowly get down to minimum underneath.

 

[smeaks]

I had an old seafarer unit and left the tranducer in place whilst changing the instument for a cheap nasa head unit... digital read put and much easier to use. compatability was not a problem.

 

[the far canal]

The old spinning led type and the Nasa sounders use a 150 hz transducer which is accurate at medium depth but not so in shallow or deep where as most of the others use a dual band 50/200 hz tranducer which is more accurate shallow (200 hz) and deep (50 hz) but not medium depth. you could there for have a dual band transducer connected to a single type sounder which would only work on the nearest freq (200 hz shallow). see if there is a name on the transducer, airmars are dual band.

 

[Porthandbuoy]

The old spinning led type and the Nasa sounders use a 150 hz transducer which is accurate at medium depth but not so in shallow or deep where as most of the others use a dual band 50/200 hz tranducer which is more accurate shallow (200 hz) and deep (50 hz) but not medium depth. you could there for have a dual band transducer connected to a single type sounder which would only work on the nearest freq (200 hz shallow). see if there is a name on the transducer, airmars are dual band.

Huh?

Isn't the frequency selection then a function of the display unit deciding which to send to the transducer?

 

[the far canal]

Yes, if you have to use a dual band head unit to use both freq of a dual band transducer.