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?
Rest assured it is not just you - I went through the same process a month ago. I had a failed speed transducer (an old Stowe) and wanted to replace it with an N2K unit. Ultimately I went an Airmar ST800 unit, but even the options here are confusing. You have the ST800 and the ST850. The difference between the two being that the ST800 has a flapper valve built into the thru-hull, while the 850 I believe has an additional sleeve with the valve. I honestly couldn't tell the benefits of either one, so I just tossed a coin and went for the ST800.
However, each version has a choice of thru-hull materials - plastic or bronze for the ST800, plastic, bronze, or SS for the ST800. Just to add further confusion, Airmar produces branded versions with different connectors. The model number of the one I have is ST800PV-N2
- this is the plain (unbranded) Airmar plastic housing N2K version with a standard N2K connector - plugs straight into my N2K network and was picked up automatically by my chart-plotter, no fiddling needed.
Note that all versions require a 2" hole, so you will need to enlarge the old thru-hull. I just drilled out the old one - nice and simple even for a newbie like me. At least I think so - I'll let you know if she sinks when she's dunked in a week!