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-   -   For Pete's sake! I just want a speed transducer! (https://www.sailnet.com/forums/electronics/315114-petes-sake-i-just-want-speed-transducer.html)

BillMoran 03-26-2018 06:16 AM

For Pete's sake! I just want a speed transducer!
 
What I'm looking for is a thru-hull speed transducer that will send data onto an NMEA 2000 network so all my instruments can use it. Preferably it would 1.25" diameter to fit in the hole from the old (no longer functioning) device.

On the surface, if anyone can point me to a model that fits that need, I'd be eternally grateful.

On a deeper level, I'm wondering if it's just me, or is it insanely difficult to find information about this stuff? Looking at the advertisements, they say nothing about mounting dimensions or even the data technology in use. Especially with the data technology, it's frequently some proprietary protocol that may or may not be NMEA 2000 compatible.

Maybe I'm just impatient or really bad at research ... but it feels like I spend an inordinate amount of time trying to find out important bits of information about the equipment I'm considering buying. Is it just me?

colemj 03-26-2018 07:04 AM

Re: For Pete's sake! I just want a speed transducer!
 
Airmar makes them for pretty much all manufacturer brands. You will want the ST800 or ST850: http://www.airmar.com/uploads/Brochures/st800.pdf

Mark

svHyLyte 03-26-2018 09:31 AM

Re: For Pete's sake! I just want a speed transducer!
 
Or... see Airmar

FloridaBoy 03-26-2018 10:13 AM

Re: For Pete's sake! I just want a speed transducer!
 
It's not you Bill. I just purchased a Raymarine BiData I40, speed wheel and temp for the port side and depth finder for the starboard. Both to replace aged Datamarine stuff. I had a heck of a time finding info on the Raymarine site. I had to find the manuals on line and read those for pertinent information. Like, size of the hole, 2 inches in my case, which was perfect. And no where did it say the speed wheel came with a plug, or how long the cords were, in any ad. I finally went to a local Raymarine Dude, here in Cocoa and he let me know what was going on. After that, it was simple Got the Bidata set up for 420 bucks, out the door. sweet. Can't say for sure if it will hook up to the NEMA stuff, but I do remember asking him if it would and he said sure, it would. kevin

FloridaBoy 03-26-2018 10:15 AM

Re: For Pete's sake! I just want a speed transducer!
 
And HyLyte is correct. Raymarine transducers are made by Airmar. Gotta look for their manuals, as well, to get any info. Kevin

BillMoran 03-26-2018 10:41 AM

Re: For Pete's sake! I just want a speed transducer!
 
Still really frustrating. The only place I've found online that sells the Airmar st800 is here:
http://www.imarineusa.com/AirmarST80...iABEgJOp_D_BwE

However, even though colemj's link claims it's an NMEA2000 device. That vendor claims it has spade connectors for Raymarine gauges. I suppose it's possible that I could just replace the end of the wire with an NMEA2000 connector and it would work?

FloridaBoy 03-26-2018 10:45 AM

Re: For Pete's sake! I just want a speed transducer!
 
Here, Call this guy. Marine electronics for 40 yrs. Does all the tugs, ships, whatever, down here. Been to my boat a couple of times. He is component certified, which means he can replace transistors and such on a board. Great guy. Give him a call and he will help you out, I am sure. Zach Duys, as in boyz. 321-302-6158 kevin

colemj 03-26-2018 11:15 AM

Re: For Pete's sake! I just want a speed transducer!
 
Quote:

Originally Posted by BillMoran (Post 2051437106)
Still really frustrating. The only place I've found online that sells the Airmar st800 is here:
http://www.imarineusa.com/AirmarST80...iABEgJOp_D_BwE

However, even though colemj's link claims it's an NMEA2000 device. That vendor claims it has spade connectors for Raymarine gauges. I suppose it's possible that I could just replace the end of the wire with an NMEA2000 connector and it would work?

Airmar doesn't sell direct. Contact Gemeco https://www.gemeco.com and tell them what you need. They will tell you where to buy it.

We bought one this way, and it is definitely NMEA2000 with a canbus connector.

Mark

Jeff_H 03-26-2018 11:29 AM

Re: For Pete's sake! I just want a speed transducer!
 
Knotmeter transducers do not send NMEA information. They either send an electrical pulse or voltage reading. The Display head or 'black box' takes that pulse frequency or voltage, crunches the numbers and converts that to useful data such as a read out on an instrument or a NMEA sentence. Some of the newer systems use a 'smart transducer' but those do not work with older equipment.

Since different manufacturers, or even different models of equipment from the same manufacturer use different transducers which produce different pulse rates or voltages, its extremely difficult to find alternate transducers for any given display head, even if you do know the transducer manufacturer.

One of the things which has happened with great frequency is that the design of transducers has changed over time. Manufacturers claim that these changes have resulted in more reliability or better functionality. So with every new upgrade to the display heads, the transducers seem to change as well. But with each change, the transducer in your hull and possibly thru-hull in your boat, will no longer be correct for the replacement black box or display head.

My best suggestion would be to start with the company that made your display head. Find out what the input characteristics need to be to work properly with by your instruments. Failing that, find out the specific model number for the transducer that was used by your display. Once you have that information, Airmar (or who ever made your transducer) should be able to tell you whether they have other transducers with the output characteristics of the specific transducer that you are replacing.

Jeff

Noelex 03-26-2018 12:17 PM

Re: For Pete's sake! I just want a speed transducer!
 
As Mark has said the Airmar DST800 is the most popular choice. A number of companies sell this transducer such as Simrad:

https://www.simrad-yachting.com/simr...5khz-f57ab51d/

Garmin also produce an adaptor that converts some standard transucers into one that will transmit NMEA2000 messages. I think they sell the black box with or without the transducer

https://buy.garmin.com/en-US/US/p/26510


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