Airmar DST810

Jul 3, 2021
53
Tartan 33R Lake Michigan
My Tartan 33R has a B&G version of an Airmar DST800 speed/depth/temperature transducer and the temperature reading hasn't worked since I got the boat. I'd like to replace it with a DST810 transducer. Apparently the DST810 has a bunch of wiz-bang features that I probably don't need, accessed through an app via BlueTooth. Last year when I pulled the transducer out of the housing for bottom painting, I was surprised that it didn't seem to key into the housing. On installation, it was difficult to get it oriented correctly as it would rotate when tightening the cap nut. Many years ago I had a boat with Signet instruments and I seem to recall that the speed transducer would only fit into the housing in one orientation.

I suspect that the housing on my Tartan is not specifically for this transducer as the boat has had numerous instrument upgrades over the years. There is also an unused and plugged housing adjacent to this one, so at one time the boat most likely had separate depth and speed transducers. Anybody familiar with these DST810 transducers? I'm wondering if the housing that comes with a new DST810 will be keyed to the transducer so it can't rotate? This question has proven to be difficult to get an answer to from Airmar, I emailed them a week ago and haven't gotten a response. Busy I guess.
 
May 17, 2004
6,110
Beneteau Oceanis 37 Havre de Grace
I also have a DST 800 that we’re considering upgrading. The housing on ours isn’t keyed either, and I know it’s the original. I don’t really have the problem with it rotating while being tightened, but it does take some care to make sure its pointed the right way in the first place.

Last year we noticed that the depth sounder part of our 800 would get flakey in some conditions, and the temperature part hasn’t worked well in warmer temperatures for several years. I emailed Airmar to ask if the 810 would fit in the 800’s housing, so we could replace it while in the water, and they said it could. I presume that means the 810 isn’t keyed either.
 
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colemj

.
Jul 13, 2004
1,036
Dolphin Catamaran Dolphin 460 Mystic, CT
The housing is not keyed. There is a large arrow on the top of it, and the wire comes out at that point also. You hold the top in the correct orientation while you tighten the nut and it doesn't rotate.

The ST850 speed only transducer does come with a keyed housing.

Mark
 
Jul 3, 2021
53
Tartan 33R Lake Michigan
The housing is not keyed. There is a large arrow on the top of it, and the wire comes out at that point also. You hold the top in the correct orientation while you tighten the nut and it doesn't rotate.

The ST850 speed only transducer does come with a keyed housing.

Mark
My transducer is located under the head and accessed through a deck plate. There is no way to get two hands in there, it's almost impossible to even get a grip on the cap nut. I had to make a tool out of PVC pipe to loosen/tighten the cap nut.

IMG_2224.JPG
 

colemj

.
Jul 13, 2004
1,036
Dolphin Catamaran Dolphin 460 Mystic, CT
Yeah, that's tough. Is there any way to either enlarge the deck plate, or install another on the adjacent wall to allow both hands? Picture doesn't have enough perspective for me to see if this is possible.

Mark
 

colemj

.
Jul 13, 2004
1,036
Dolphin Catamaran Dolphin 460 Mystic, CT
The ST850 speed only transducer does come with a keyed housing.
To clarify this, the ST850 uses an insert to the common thruhull that the DST800/810 uses. It is this insert that is keyed.

I think the DST810 thruhull is a universal one, so a key would prevent it from being used with other transducers, where the key position would need to be different (for example a tilted element depth sounder).

Mark