Transducer Cables

[PeterGR]

I was always told never to cut a transducer cable and splice it shorter as (other than often having to deal with many tiny cables and shielding) it messes with the frequencies etc and can lead to bad readings.
Is there merit in that? (assuming it has been wired back correctly).

I have the mast down at the moment as was getting no readings from the Nasa Clipper wind vane.
The masthead transducer has a short cable (less than 1ft) which then fits into a socket on the side of the mast, then runs down inside the mast and into the cabin etc etc.
This socket at the top of the mast has a broken collar to fasten the transducer cable so trying to figure out how to fix it.
I could cut both ends and splice together.
If I order a new wind transducer it'll come with a 30ft whatever cable so I'll still have to cut it short, rather than fishing the whole line through the mast, which is a really really awkward mast to do.

I also have a Nasa depth sounder which has a damaged end socket (because I sail with a crew of rhinos).
Is it possible to cut off, say the last inch, and splice in a new end with another old broken transducer I have laying around?

 

[Daverw]

I also don’t quite understand why you cannot cut a muticore cable, understand this may effect some if it’s a coax but multicore? Especially as you see statements like don’t cut or extend but buy our expensive extension cable and this is ok.

 

[VicS]

I was always told never to cut a transducer cable and splice it shorter as (other than often having to deal with many tiny cables and shielding) it messes with the frequencies etc and can lead to bad readings.
Is there merit in that? (assuming it has been wired back correctly).

I have the mast down at the moment as was getting no readings from the Nasa Clipper wind vane.
The masthead transducer has a short cable (less than 1ft) which then fits into a socket on the side of the mast, then runs down inside the mast and into the cabin etc etc.
This socket at the top of the mast has a broken collar to fasten the transducer cable so trying to figure out how to fix it.
I could cut both ends and splice together.
If I order a new wind transducer it'll come with a 30ft whatever cable so I'll still have to cut it short, rather than fishing the whole line through the mast, which is a really really awkward mast to do.

I also have a Nasa depth sounder which has a damaged end socket (because I sail with a crew of rhinos).
Is it possible to cut off, say the last inch, and splice in a new end with another old broken transducer I have laying around?

I'd cut the damaged inch or so of the depth sounder cable and fit a new plug , ( I have done this with a Seafarer depth sounder with no problems)

ITYWF that the wind vane cable is available as a spare if necessary (Several different type to choose from)

 

[Boathook]

Cutting and altering the length of the depth sounder cable can alter the depth reading. I suspect cutting a few inches of the end for a new plug won't be noticeable but then I have never tried it.
I have cut and altered the length of other cables as they normally only carry a 'signal'. Some of the concern by manufactures is that cutting a cable could add a bad joint and effect the working of the instrument.

 

[Yellow Ballad]

All of my cables (Nasa wind, log and seafarer depth) were cut and joined with choc blocks when I bought my boat with no issues that I know of. Since I've upgrade my instruments to STNG and haven't cut anything.

 

[Alex_Blackwood]

Cutting and altering the length of the depth sounder cable can alter the depth reading. I suspect cutting a few inches of the end for a new plug won't be noticeable but then I have never tried it.
I have cut and altered the length of other cables as they normally only carry a 'signal'. Some of the concern by manufactures is that cutting a cable could add a bad joint and effect the working of the instrument.

Agree, Depth sounder cables are part of the calibration system and cutting lumps out will effect the reading, possibly an inch may not make much difference for your requirements. Things like wind instruments won't make any difference. Unless the joint, if there is one, could conceivably pick up stray interference from other equipment if not shielded.

 

[jwilson]

I think the common instruction not to cut depth sounder cables is more to do with efficiently "tuning" the cable length to the high frequency audio signal going to and from the transducer. As others have said, a few inches alteration on a 40+ foot cable should not be critical. I cannot see thateven cutting the cable really short or extending it a lot would affect the depth shown in the slightest, but it might make the system less sensitive particularly to deeper depths where return signals are lower power. I can see no reason whatsoever not to cut or join wind or speed transducer cables as long as the joints and connections are good.

 

[bedouin]

For all they say don't do it I am sure the vast majority of people do and I have never heard anyone complain that it didn't work afterwards. I have cut and/or replaced the cables for most of my transducers with no adverse effect.

Take a lot of care with the joints to make sure they have a good contact and are protected from the elements - water or a bad contact in the depth transducer cable could cause issues.

 

[Jamie Dundee]

My through hull transducer cable has been cut and rejoined, I assume to make threading the cable easier. No issues, the depth reading matches my other transducer and sonar picture is as good as I would expect with an older tech transducer. As I remember 2 power cables and 4 data cables.

 

[andygc]

I was always told never to cut a transducer cable and splice it shorter

Why not just give NASA a call on 01438 354033 and ask which cables you can cut and which you can't? They have always been helpful when I have asked a question (including "can I cut the log cable to save having to rethread it through various lockers?" "Yes"). They will give you a definitive answer based on their knowledge of their equipment.

 

[MikeCC]

You will be fine doing both the things you suggest with no ill effects as long as the joints/terminations are good quality.

For the masthead connection, you can get small multiway connectors so you can undo it again. The ones I have are solder but compact and waterproof rubber construction. Not too bad if mast is down! Used to supply quite a few before NASA added a plug on the masthead unit.

 

[PeterGR]

Update.

I cut out the dodgy socket at top of the mast and carefully spliced, soldered and sealed the cables.
Still no luck on readings though.

Buying a new transducer is the easy next step, but would like to continue the fault finding.
The cables are probably too small to test with a multimeter.
Is there anything to be said for replacing the cups (which are a fraction of the cost) or a way to test this component?

 

[snowbird30ds]

With sounders it is measuring the very short time between ping and return so length will matter, with most other sensors it's a digital pulse so won't matter, a wind vane should just be a pulse so don't worry.

 

[TernVI]

I think the common instruction not to cut depth sounder cables is more to do with efficiently "tuning" the cable length to the high frequency audio signal going to and from the transducer. As others have said, a few inches alteration on a 40+ foot cable should not be critical. I cannot see thateven cutting the cable really short or extending it a lot would affect the depth shown in the slightest, but it might make the system less sensitive particularly to deeper depths where return signals are lower power. I can see no reason whatsoever not to cut or join wind or speed transducer cables as long as the joints and connections are good.

Mr Wilson is correct.
If it's a traditioal echo sounder, the transducer element is tuned to the electronics and changing the capacitance of the cable could stop it working at all, or more likely affect the output power and sensitivity.
I expect chopping an inch off would be within manufacturing tolerances, chopping out the excess 3m of co-ax is likely to change things!