Garmin Transducer location

[1132MM]

I have a 2004 280 Sundancer with twin 4.3L and Alpha one Gen 2 outdrives. The previous owner installed a Garmin 74CV and the installation team installed the transducer between the starboard outdrive and the trim tab. The depth reading works fine at slow speeds up to 7-8 knots, anything over those speeds and the depth reading doesn’t change or goes blank. Anyone have a similar situation? My buddy has a Grady 300 Marlin and his transducer reads up to 34 knots.

 

[Lazy Daze]

Just being "between" the engine and the tab is not the problem. It's how close to one of those it is and/or if there's an edge of a lifting strake close enough to cause water flow disturbance or even a thru-hull directly in front of it. Grady vs Sea Ray is not the problem - it's the exact location of the ducer and other things that cause flow issues. It is, however, a little tougher since it's a narrow boat to have twin engines and the stern drives complicate things a little more than OB's that are set back from the transom.

Take a better look at the things I mentioned with the idea of water flow on your mind. If you suspect a problem - which is most likely the issue - you could verify by putting a waterproof phone or camera on a stick and recording the water flow off the transom on plane. This would also tell you a GOOD location if it's not something you feel comfortable "just figuring out" by looking at things.

Another option is to install a thru-hull ducer like your current (standard equip) depthfinder uses. "Sometimes" you can get away with a shoot-thru ducer - but you should experiment with the ducer in a bag of water, first, at various locations. With either of these methods, you still have to pay attention to other thru-hulls and strakes - but overall, they are easier to find "clean water" than off the transom.

 

[ColoSR]

I have a thru Hull in the factory location and it reads up to 35 mph. It’s about 3 feet in front of the transom, just off the keel

 

[Lazy Daze]

I have a thru Hull in the factory location and it reads up to 35 mph. It’s about 3 feet in front of the transom, just off the keel

The OP has that one, too, Colo. What he's referring to, though, is a fishfinder transducer - it's in addition to the original/standard depthfinder ducer.

 

[ColoSR]

Shoot, sorry

 

[1132MM]

Thanks for the responses! I'm going to try to relocate the transducer and see what happens.