Raymarine depth readings going wonky

[Tarantelle]

I bought a new to me Ocean Alexander 55 Pilothouse with Raymarine electronics. The fish finder is doing some really strange things and I’m not sure if it’s a transducer problem or some other issue. The problem mostly happens when I’m in a light chop (about a foot or so). I’m going to try and post a photo of me chart plotter to show what I’m seeing. Fortunately, this was happening in an area I know well and wasn’t worried about running out of water. Any ideas of what might be the problem would be appreciated.

 

[DDW]

One possibility is there is air entraining from the bow, strakes, or other, passing over the transducer location. The fact that it is rhythmic, and in a light chop, suggests this to me. In the same location if you stop does it settle down and show the correct depth? How far aft is the transducer located? If this is the case, you may have to relocate it.

 

[Tarantelle]

I did not come to a stop to test. I did slow down to about 5 knots and still had the problem. I talked to the prior owner who said he didn’t have the problem. I forgot to look up the transducer model number so I haven’t called Raymarine support yet.

 

[Dan3281]

I have the same issue on my Beneteau 34ST with what looks to be the same Raymarine system. As said above, it generally seems related to air from chop,or boat wake, and yes is aggravating. The transducer was installed at the factory so I assume they picked the best place. I have found that if i change from auto-range and set manually, I can usually determine the depth even if the digital display can’t. Please let us know if you find a good solution.

 

[Tarantelle]

Dan,
Thanks for the reply. I still haven’t found a good solution. I haven’t had the boat out lately to test anything. One possibility is that there’s a sensitivity setting that can be changed from 200 hertz to 50 hertz. It seems I saw a somewhat related post somewhere that made me think that’s a possibility. Also, as soon as I find the model number of my transducer, I intend to call Raymarine tech support and see if they’ve seen this issue before and know a solution.

 

[Carriage Guy]

We just launched our trailerable Rosborough with a (circa 2004) Raymarine depth sounder in Skagway Alaska a few days ago and had similar issues. I think our issue is the radical range in depth, from 20' to 2,000+' that sometimes trips up the automatic gain control circuit that slowly increases or decrease the depth range while looking for a return from the bottom. As we leave an anchorage or dock and head out into deeper water if our system "stair steps" the gain by changing gain, looks for return, changes gain, looks for return, changes gain..... for a while without success in getting a bottom return it seems to get confused. Reverting to manual mode and selecting a matching depth range for the water we are in fixes the problem although our transducer seems to be limited to 1,600' or so. If we are in compatible water, say <1,500', we can usually then change back to automatic mode and the system will then work again. The lower the frequency, the deeper the penetration can go so if you are in deep water select 50 hz and try manual mode set to whatever approximate range of water you are in.