Sonar problem

[stul]

Garmin 55 cv Echomap chirp chart plotter
I having problems with the sonar not detecting at speed ( not getting a depth reading)it is fitted on the transom of a stepped hull
Fitted to Rib used for scuba
Many thanks for any help
Stuart

[Striker]

I’d be interested to find out if this can be avoided also, as every planing boat I’ve had does this at speed.
I’ve always believed it to be because of the bubbles running under the hull and beneath the transducer.

Hopefully someone on here can give some tips on reducing it.

[Pikey Dave]

If it's a transom mount, you will do well to get a reading over 20kn due to turbulence. You may get better results with a through hull transducer or by glueing your transom mount inside the hull. I have had through hull transducers on the last 2 boats & they work well at upto 30kn

[simonl]

Try the transducer in the bilge, leaving it covered in water. If it works you can come up with a more permanent solution as suggested by PD. Worked well for me

[boristhebold]

I had a transom external mounted transducer for a number of years, depending upon water conditions and speed it would often not give a reading over so many knots, changed it to a through hull transducer and a huge huge huge difference was able to maintain depth reading at all speeds, so as many would say a through hull transducer is the way to go.

Only niggle is after about 5 years I think ive got a seal gone (through hull type is mounted onto a mounting filled with some light oil) as when hull is dry of any water it no longer reads so need a small amount of water in lower part of bilge for it to work which isnt a problem as small amount of rain water usually sits in the bilge.

[paintman]

Mine's transom mount & at speed on the plane & I lose depth. Not really surprised as there isn't a lot of the boat in the water & the transducer is in high turbulence.

Whether an adjustable pole type extension as in link below would give me a better result - or be strong enough - I've no idea but sod's law (or a senior moment) says I'd forget to lift it & the mooring dries out twice daily....
https://www.thelurebox.co.uk/product...ducer-brackets

[Xk59D]

When I had transom transducer it was fine up to about 30mph then lost depth or it came and went.

This boat has an in hull and even flat out it never loses depth (garmin plotters), the downside with in hull is no fancy side scanning etc available.

You can try repositioning or change to an in hull worst case.

[Last Tango]

Depends on the depth as well. My Humminbird with a transom transducer works ok at 30kn if the the water's 50mtr deep. If it's 100mtr+ then I'd have to slow down but that has to be expected.......you're gone by the time the echo comes back.
You have to follow the fitting instructions to the letter with a transom mount and that will probably give some scope for minor adjustment. Another trick is to fill the gap between the transom and hull with silicon....sometimes helps.
Not sure about the stepped hull. I think the concept there is to introduce air into the flow. That could be causing a problem.

[Pikey Dave]

Originally Posted by Xk59D

When I had transom transducer it was fine up to about 30mph then lost depth or it came and went.

This boat has an in hull and even flat out it never loses depth (garmin plotters), the downside with in hull is no fancy side scanning etc available.

You can try repositioning or change to an in hull worst case.

I have an M260 through hull & a Structure Scan transducer on the transom. Best of both worlds.

[jeffstevens763@g]

Check ping speed settings I always set mine to auto but as said lots of variables to affect readings