Dragonfly - Loss of reported depth and ability to produce a bottom plot

[Chuck - Raymarine - Moderator]

Dragonfly - Loss of reported depth and ability to produce a bottom plot

Raymarine has introduced significant improvements to Dragonfly sonar performance via changes to the product's software. Correspondingly, it is recommended that customers update their Dragonfly with the latest available Raymarine product software updates.

Engine electrical interference or aeration effects are visible within the sonar image prior to loss of bottom contact. Testing for electrical interference may be accomplished by placing the engine into neutral and then increasing engine RPM. Should no similar noise be observed when engine RPM is increased, then the problem would appear to be linked to aeration of the transducer.

Loss of reported depth and loss of ability to produce a bottom plot will occur if a depth sounding transducer is exposed to a aerated flow of water across its face, or if the connection between the fishfinder's transducer socket and transducer cable is intermittent. Start by ensuring that the transducer plug and socket are free of corrosion, that the transducer plug is firmly seated in the transducer socket, and the locking ring is present and has been rotated into the lock position. This problem can also be caused by incorrect transducer selection (ex. installing a transom mounted transducer on a vessel having steps, trim tabs, inboard powered vessel, through hulls forward of the transducer, etc.) and/or incorrect transducer installation (ex. mounting a transom mounted transducer too high, too low, or at the incorrect angle, mounting the transducer on the port side of the transom, etc. ... some experimentation may need to be performed to determine the best location, height relative to the hull bottom, and angle), and/or marine growth on the hull or transducer. Please refer to the transducer installation instructions to ensure that the transducer is properly installed. Many customers will install a transducer mounting block on the transom to permit multiple transducer mounting locations to be tested, while limiting the number of holes in the transom to those required to secure the transducer mounting block to the transom. All hulls are not universally suited to transom mounted transducers and such determinations can only be made through trial and error. Should then hull not be suited to a transom mounted transducer, then a thru-hull transducer may need to be considered.

Marine growth on the transducer and hull may cause loss of bottom and as such (particularly planing speeds and speeds approaching plane), the hull should be inspected to ensure that the transducer and hull are free of such growth. Hull protrusions (ex. steps, lifting strakes, thru-hulls, etc.) and other hull features forward of the transducers can also cause transducer aeration at planing speeds and speeds approaching plane causing the fishfinder to loose contact with the bottom. In the case of the latter, relocating the transducer or using a different type of transducer may be the only way to correct the problem.



Transducer aeration can be fault isolated by testing the equipment while the vessel is stationary or at trolling speeds. Should the problem not be reproducible while the vessel is stationary or operating at trolling speeds, then then problem may be diagnosed as an aeration issue and consideration should be given to lowering the aft end to the transducer a notch or two, relocating the transducer, or installing a thru-hull transducer.

Should one feel that the correct transducer for the application has been installed and that it has been installed properly, then it would be recommended that several photos of the transducer (from side and rear), transom, and hull bottom be attached to any threads/posts seeking support for bottom loss.

RAYFAQ#