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.