Knotmeter and Temperature Transducer

[Merit]

Has anyone replaced a knotmeter and temperature transducer?  Can the cable be spliced?  If I splice it will I still receive an accurate reading?  Or, should I pull a whole new cable?  Is the cable a coaxial style?  Where does the wire usually run?  Where is it most likely to get stuck? :rolleyes:

[captaingary]

I just replaced mine last week because the temperature was not reading. I spliced the cable which has 4 wires and a shield around the cable. Everything works good and I made the splice just at the base of the mast and kept it as high as possible to avoid getting wet in the bilge.

[sselinger]

I also spliced the wires without any problems. If you want to do a neat job, the manufacturer of the transducer (I forget their name, but any marine store can probly provide it) make a neat,waterproof, splice block with screw connections.

Steve Selinger
Aquila #1047

[jentine]

I would replace the entire cable.  I wrongly assumed that the problems I was experiencing were the result of a faulty transducer.  Much to my chagrin, the cable was faulty.  I discovered the error when I spliced the bad cable onto the new transducer.  You have a new cable.  Use it.

[Mike Smith]

Steve, et al -

I need to resplice my knotmeter cable. Do you (or anyone else) recall who makes the waterproof splice block for shielded cable? Is this a commonly available item?

Mike

[reedbr]

I just replaced mine.  I spliced it under the V-berth up high.  I looked long and hard at replacing the whole cable.  I finally decided I would break more stuff running through the wire looms along the port side of the boat rather than if I did a simple splice.  From my network cabling experience, I found the more I touch the more potential I have for causing problems (maybe it's just me!).

I read a notice from Raymartine indicating the standard problem with these transducers is that they get waterlogged.  Symptoms are that they work at least eratically in your hand after drying out.  However, the speed reading dies after you install them in the water.  The temperature reading will be erratic, but you will still get a reading, usually abnormally high.  If you don't get a temperature reading, you might have another problem you should identify before splicing in another transducer.  Certainly you can connect the new transducer direct to the back of the instrument as one diagnostic test.  At first I only installed a paddle-wheel kit and it worked...for one trip.  I didn't realize until later that it worked primarily because it dried out.

I got my parts from Gem Electronics, 843-394-3565.

Good luck.

[Mike and Theresa Vaccaro]

Another source of waterproof plugs is Eurocomp in California.  They make a series of solder-less plugs that will work.  The phone number is (800) 846-6777.  For a typical transducer cable, you'll need two parts per plug (the body and the terminal connector).  Be sure to order parts to build one male and one female plug!  You'll need:

1 HPX0800 Sealed mounting body (one is male, one female)
1 HPX0801 Sealed mounting body
1 HSA3243 Mini seal screw terminal, six way (one is male...)
1 HSA3244 Mini seal screw terminal, six way
The dust cover p/n is HPX0810 if you need it

Total cost for parts is about 15 bucks per plug.

Another option is to simply splice.  For a speedo, you may need to splice the shielding from one of the twisted pair into the ground circuit (this is the "bare" wire you'll find inside one of the bundles.  A coax stripper works well to open up the outer cover and inside, you'll find power and ground wires as well as insulated twisted pair.  You'll have to carefully strip the aluminum foil that insulates the twisted pair.

All of these techniques will also work for an autopilot cable as well, allowing you to make a quick disconnect for a wheel pilot, for example.

Cheers,

Vac

[Steve S.]

I have a more basic question.  Where did y'all get the transducer without having to buy a whole new unit?

[Stu Jackson]

... a transducer sure must depend on what model "Thingy" you have.

I have a 1896 Datamarine.  They don't make 'em anymore.

I sure don't expect a swap-out.

Nor do I look forward to having to deal with some of the cr*p being offered today.

I sure hope they keep working.

If not, I'll simply have to depend on my wind over the shoulder sense, speed thru water by dropping a forward crewman overboard and counting the seconds, and finding, finally, a lead line to hit soundings.

:)

[Ken Krawford]

Stu,
I recently replaced my depth sounder display with a different brand and it worked perfectly.  The transducer was the original Standard Horizon and the display was a used Signet.  Now if I could only get the speed/log to do the same !
Ken