I have an Airmar DST800 (Depth, Speed, Temperature) which I bought around 2005. It was for Raymarine ST60 instruments and did the job fairly well. When removing the transducer, I get an ingress of water because it does not have a self closing valve which would close as the transducer is removed. I believe (I have been told, correctly or incorrectly) this is still the case for the Raymarine DST800; and yet most of the other transducers of this model (post 2005) have the self closing valve. See their brochure here for the DST800. I was told the transducers were changed after 2005 so that they have the self closing valve, BUT not the Raymarine version. A little research was required.
My instuments (ST60 Tridata) work by taking an analog signal input from the transducer. My ST60 will only display seatalk input if changed to a repeater display. It will not display nmea 0183 or 2000 data, UNLESS one can convert that data back to seatalk (1)
My choices after some contemplation were
1. Stay as I am
2. Change to a new DST800 with nmea 0183 output, and get a nmea 0183 to Raymarine
converter so I can have the self closing valve.
3. Purchase a new DST900-EM which has no paddle wheel and picks up speed by electromagnetic induction, also with a self closing valve
Considering those choices, here are the problems.
- There are plenty of multiplexers out there that will convert Seatalk to nmea 0183; but I've yet to find one that converts nmea 0183 to Seatalk. This conversion would not be needed if the new DST800 has BOTH a self closing valve and analog output. The brochure here says it only comes in nmea 0183 & 2000 outputs.
- After contacting an Airmar dealer through email, the DST900 isn't on the market as yet. Here's what he said.(Oct. 2012) "The DST900 is still not available yet from Airmar. No date or cost on the release." AND (as the brochure reads only nmea 2000) I would then have to change nmea 2000 to nmea 0183 and then to Seatalk or analog signal. Can't be done, I think. More about that later. I made some more enquiries.
Sounds like it will just support nmea 2000,
But recent enquires put a different light on the question of legacy formats. A recent email had this to say... "The DST900 most likely will have the self closing valve. The DST900 will be capable of outputting Analog, NMEA 0183 and NMEA 2000 so it should cover all your needs including working with the ST60.
Here's another solution. Don't have a transducer at all!!
SOG1 NMEA 0183 to paddlewheel signal converterThe SOG1 creates an analog paddlewheel output signal from a GPS NMEA 0183 $GPRMC sentence so you can display Speed Over the Ground (SOG) on a standard analog or digital speed log.
Sooooo; my choices now are, I can wait for the NO paddle wheel DST900 and change out (choosing the analog version). Change to the upgraded DST800 (with self closing valve) but have to pull it out occasionally to clean the paddle wheel ( but not suffer the ingress of water due to a self closing valve), or go no transducer and loose the depth and water temperature in the process. Hmmmm, I think I will just sit and wait another year!
What would you do?