In Hull Transducer

[Natch]

Chuck,
I have a dealer installed, P-74 transducer in the hull of my bass boat, that is my A127, 2D transducer. I'm not really impressed with its performance at any speed and wondered if the P-79 would do a better job.
I also have a new P-319, but no one is willing to install a thru-hull in a bass boat. Looking for some professional advice.
Thanks

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Steve,

I have a concern about your comment regarding performance at any speed, as it may indicate a problem within the MFD's fishfinder circuitry. Please click here to view a FAQ addressing this subject. At trolling speed (i.e. speeds up to approximately 8 mph, is the fishfinder tracking the bottom and marking fish? If not, then it is recommended that the MFD be sent to Raymarine’s Product Repair Center to be bench checked / serviced. However, should the the fishfinder track bottom and mark fish under these conditions, then an aerated flow of water may be preventing the system from tracking bottom at higher speeds. If so and as you have suggested, the P319 would typically be recommended for those seeking a thru-hull transducer for a planing hull. However, should a thru-hull not be desired and a transom mounted transducer not be suitable for the hull, then it would be recommended that the A80170 P79 transducer would typically be recommended.

[Natch]

Chuck,
I just checked to see which transducer selections were available on this A127. Transducer set up was done by the previous owner, with the current internal 2D sonar transducer selected being P58/P65/P66, which is probably the default.
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. 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. Additionally, from the surface down to about 3 feet, the screen is useless, filled with clutter and nothing adjustable, makes a difference. 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.
I've read numerous theories on ping rate and speed for all electronics Mfgs and they're suggestions range from 14 to 26, which is the default for this unit. Any tweaking tips, would be appreciated.
My bow unit, an A128 is in Nashua now for warranty repair, as you suggested.
Appreciate all your help and quick responses.
Thanks,
Steve

[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.

[Natch]

Again,
Thank You Sir

[Chuck - Raymarine - Moderator]

You're welcome.

[Natch]

Chuck,
Ran the boat today and switching the transducer selection to P79, really improved the A127's ability to mark fish and cover, without [censored] up the sensitivity. It didn't seem to improve the bottom return at higher speeds, but one thing at a time.
Thanks
Steve

[Chuck - Raymarine - Moderator]

You're welcome.