A68 (replaced A67) and older thru hull transducer

[Cp111]

Until last month, my sailboat had a Raymarine A67 with an older transducer. I believe it is an Airmar B744V (possibly even a B44). The A67 died, and I found a grear deal on an A68 with no transducer. Sounded good. I guess I assumed, incorrectly, that an A68 would be a newer version of an A67.

I can't really pull the boat out of the water to put in a new transducer. The one in the boat now works fine. I only need depth from it; I don't need temperature or speed. I don't even need fishfinder display, I just need depth.

So, since A68 and B744 seem to be incompatible, I am trying to figure out some options. I'm hoping someone can tell me whether any of these will work:

1) If I am willing to give up the fishfinder, and just want depth, is there a way to wire the A68 to the B744 directly, and run the A68 in non-chirp mode?

2) Install an i40 Depth, connected to the B44/B744. This seems like a great option for me because I can mount the i40 near my line of sight and see the depth easily. It looks like the i40 depth just has three pins to connect to the transducer, and I've seen B744 as being supported. Will that work? Wiring diagram somewhere?

3) Add a converter (itc5?) to convert the signal to Seatalk ng. This sounds like it would work.. I don't have a Seatalk network, though, and sound like more complication and expense than I'd like.

4) If #2 works, then can I assume that I could run a seatalk cable from the i40 to the A68 to display depth on A68? Not as critical but might be a nice to have in the future.

Thanks,
Chris

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Chris,

General comments: The ax8 and ax7 MFDs feature different internal fishfinder sounder circuitry, requiring fundamentally different transducers. Please click here to view a FAQ addressing this subject. I would recommend that a CP370 be installed and interfaced to the a68 MFD. Then, the currently installed B744V transducer may be then be adapted to be mated to the CP370's Transducer socket using an 33-562-01 Transducer Adapter Cable. Alternatively, an i40 Bidata Instrument display (display-only) or i50 Tridata instrument display (display-only) may be installed onboard. Please click here to view a FAQ addressing how to adapt a 50/200kHz fishfinder transducer for use with one of these instrument displays.

Q1) 1) If I am willing to give up the fishfinder, and just want depth, is there a way to wire the A68 to the B744 directly, and run the A68 in non-chirp mode?
A1) No

Q2) Install an i40 Depth, connected to the B44/B744. This seems like a great option for me because I can mount the i40 near my line of sight and see the depth easily. It looks like the i40 depth just has three pins to connect to the transducer, and I've seen B744 as being supported. Will that work? Wiring diagram somewhere?
A2) See the general comments above addressing this subject.

Q3) Add a converter (itc5?) to convert the signal to Seatalk ng. This sounds like it would work.. I don't have a Seatalk network, though, and sound like more complication and expense than I'd like.
A3) As MFDs cannot calibrate instrument transducers and cannot assign alarms and offsets for instruments transducer, this is not an option unless an i70 MFID is also added to the system.

Q4) If #2 works, then can I assume that I could run a seatalk cable from the i40 to the A68 to display depth on A68? Not as critical but might be a nice to have in the future.
A4) As the a/c/e/eS/gS-Series MFDs do not have a communications interface supporting SeaTalk communications protocol, it would be necessary to install a SeaTalk to SeaTalkng Converter Kit to which the i40 instrument and MFD would each be interfaced. Should the option of an i50 Tridata Instrument display be exercised, then the i50 Tridata Instrument display and MFD would each be interfaced as spurs to a powered and properly terminated SeaTalkng backbone.

[Cp111]

(10-20-16 01:32 PM)Chuck - Raymarine - Moderator Wrote:  Welcome to the Raymarine Forum Chris,

Thank you. And thank you for the timely and informative reply.

(10-20-16 01:32 PM)Chuck - Raymarine - Moderator Wrote:  Please click here to view a FAQ addressing this subject.

Wish I would have seen this before.

(10-20-16 01:32 PM)Chuck - Raymarine - Moderator Wrote:  I would recommend that a CP370 be installed

Looks like a good solution but expensive. At some point when I next haul the boat (hopefully at least a year), I may consider installing a chirp transducer, but I am thinking the i40 will suit my needs in the meantime.

(10-20-16 01:32 PM)Chuck - Raymarine - Moderator Wrote:  Alternatively, an i40 Bidata Instrument display (display-only) or i50 Tridata instrument display (display-only) may be installed onboard.

I've ordered an i40 depth. I assume this works too (you mention the bi and tri data not the solo depth). And thank you for the faq link for wiring that. That looks relatively easy.

Thanks again for your help. I will let you know if I have any success. (or more questions ;))

Regards,
Chris

[Chuck - Raymarine - Moderator]

Chris,

You're welcome. While the solution provided within my initial response will also work for the i40 Depth and i50 Depth Instrument Displays, the Bidata and Tridata displays are only marginally more expensive and will permit temperature and speed data to be displayed.

[Cp111]

Hi Chuck,

I took your advice about getting the bidata instead of just the depth, and am quite pleased with it. I really like the large display of the depth - easy to see from anywhere in the cockpit. Thank you!

I have one question though... sometimes (pretty rarely) the i40 will get confused about the depth when we pass over a "noisy" area, such as when I back down during anchoring. (and of course in the wake of a large ship, though I wouldn't expect it to work in that case) The depth shows as about 2.7 feet which is clearly wrong asI have a 6 foot draft (note that I have the offset at +1.1ft, so the depth from the transducer is reporting is actually about 1.6ft.) . I know it is possible that my old transducer is not performing well, and I can live with it, but just thought I would see if there is anything I can do.

In reading the manual, it looks like "Depth Response" might be the only real adjustment available. Is "Depth Response" useful for reducing this effect? i.e. reduce the sensitivity to shallow noise? Or can anything else be done?

Thanks,
Chris

[Chuck - Raymarine - Moderator]

Chris,

Depth sounding products are dependent upon a non-aerated flow of water across the face of the depth transducer. Conditions such as backing down the engine or transiting a heavily aerated wake will cause the symptom reported. While less likely, it is possible that the performance of the transducer may play a role in the symptom reported. Power output to the transducer is also a factor in the performance of sounding products operating under such conditions. Depth instruments transmit relatively low power via the interfaced transducer than do fishfinding products which are less correspondingly less susceptible to the conditions described ... particularly that of crossing another vessel's wake.