In Hull Transducer

[Chuck - Raymarine - Moderator]

Steve,

Q1. There is no selection available for the currently installed P74 puck. I just changed the selection to the P79, to see if that will improve running performance.
A1. As the P74 is primarily intended for use with trolling motors, where the transducer will be in direct contact with the water, you may see some improvement in performance by configuring the system to function as if it were interfaced to an in-hull transducer such as the P79. All hulls are not equally well suited in-hull transducers and per the previously referenced FAQ, a zip-lock bag test would typically be used to determine performance. Additionally, the performance of in-hull transducers will typically be less sensitive, often requiring manual adjustments such as you have indicated necessary to mark fish. Should the configuration setting change specified above to the Transducer selection not result in improvements in marking fish, then it would be recommended that a thru-hull or transom mounted transducer be installed onboard.

Q2. To answer your questions, currently, while running at low speeds (8MPH & below) it rarely marks anything while in auto. I have to get the sensitivity in the 80s to mark anything.
A2. See the response to Q1 addressing this subject. One would typically install a P74 inside a hull for the primary purpose tracking the bottom rather than marking fish, as the aforementioned sensitivity would be reduced due energy loss through the hull.

Q3. Additionally, from the surface down to about 3 feet, the screen is useless, filled with clutter and nothing adjustable, makes a difference.
A3. The minimum depth which may be sounded is slightly less than 3'. This range represents the depth penetrated during a ping from the transducer. As the transducer and fishfinder circuity is not designed to transmit and listen simultaneously, not imaging can be produced within this band. Accordingly, it is generally stated that the minimum depth which may sounded by Raymarine fishfinding products is slightly less than 3 feet below the depth of the transducer.

Q4. While on plane, I can maintain a bottom return until about 45MPH, but only in calm water. With any chop, the bottom return and digital read out is intermittent at best.
A4. See the response to Q2. Tracking bottom at 45 MPH would typically be considered quite good for any type of transducer ... particularly in shallow drafting hulls. Better performance may be achieved by configuring the fishfinder for 50kHz and/or as indicated in the response to Q1, installation of a through hull transducer.