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Datamarine Instruments

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Joined: 26 Sep 2003
Posts: 16
Location: Lake Rathbun, Iowa

PostPosted: Tue Sep 20, 2005 10:33 am    Post subject: Datamarine Instruments Reply with quote

This is information that may be helpful as others decide what to do with their original depth/speed/wind instruments. I assume P31-2s came with Datamarine instrumentation, yours may be different. My depth meter has never worked (displays large numbers or MSD) and knot meter always reads 0. I determined that the depth transducer and speed sender are both non-functional, the displays are functional.

I decided I wanted to stay with the 4" round instrumentation. I don't want to mess with three large 4" holes in the bulkhead. This leaves several options:
* repair existing. DMI repairs Datamarine instruments and sells replacement parts. Their website is www.dmimarine.com. They are a great source of technical support. Unfortunately the depth transponder (DX-111) is a one piece unit that must be replaced in entirety with a new through hull. The replacement has a drop in core and fits the existing hole and costs about $150. The speed sensor is a drop in (ADX120) and is ready to go. About $120. You will have to dissassemble the starboard settee to find the connection -- it was just inside the locker behind the cushion just in front of the cooler. I think this is the approach I will take but I hate to spend $270 on old instrumentation. I might consider using an Airmar P79 in hull transducer (~$85) in place of the DMI transducer but I'm not 100% sure it's compatible. It's 200 MHz but I don't know if it has an RCA connector or if there are other issues, but it's tempting to not have to replace a throughhull.
* replace with new instrumentation that fits the 4" holes. Moor Electronics and SR Mariner are the only two manufacturers I could find. Standard Horizon used to make a line too, but it has been discontinued. I originally planned to take this approach. I assumed (wrongly) that the transducer was good, so I bought a Moor depth finder ($200) and planned to install it and use the existing transducer since it was 200 MHz and the Moor uses a 200 MHz. The SR Mariner uses a different frequency and was about $80 more. Before I installed the Moor I threw the transducer over the side and plugged it into the Datamarine depth and discovered that the instrument was working fine. I do not want to install a new throughhull (I don't think they're the same size, and the Moor throughhull is flush, so you have to countersink the hole). Plus, you'll discover that it is a true PITA to remove the Datamarine instrumentation from the confined space it's installed in. It's possible, but unless you have tiny fingers, very difficult). Anyone want a slightly used Moor depth finder? It does fit the existing hull, but its plastic case looks chintzy next to the machined aluminum case of the original Datamarine instruments.

Hopefully this information will be useful to others, I know I could have used it before I started this process.
Trevor Richards
s/v 'Cecilia', P31-2 #231
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