Marine transducer cables - best butt connections?

[MarkFitz]

Hello from Maine... Can the professionals out there show, describe, and note parts to best butt connect 24 gauge and smaller wires that are contained inside a marine transducer cable? These cables often get damaged in engine rooms or when pulling through the vessel when building. We have a $4,000 Furuno transducer that is misbehaving and I suspect it is a wire connection problem. In the past we have soldered and heat shrink. Or find best small crimp butt connectors. I understand there are some new products out there: Wagos, Posi-Locks...? What would they do on aircraft where reliability is a must? Thanks in advance.

[Stray Electron]

  I physically worked on aircraft and missiles for years and was also an engineer on several US Gov missile programs and we NEVER used butt connectors,, not even on the launchers or the Ground Support Equipment, and I've never seen or heard of any kind of connectors similar to that being used on any military aerospace vehicles.  You should look into true Mil-SPEC connectors by Ampenol or one other other major manufacturers. It sounds like you may need to use a better grade cable too. You need to do some real failure analysis of the failed cables and see what the failure mode was and figure out what caused it.  If you're In the Profession, you can also call Amphenol or one of the other big companies and talk to one of their application engineers and tell them your situation and they will make recommendations.

  On a personal level, I replaced my well pump myself years ago and the company that I bought the replacement pump from gave me some good quality glue filled heat shrink tubing to cover the joints in the down lead to pump wire joints and it seems to work well. The pump is 40 or so feet underwater and has been down there for 15? years.  I don't know who made the heat shrink but you might talk to a well driller.  But it sounds like your problem is more in the wiring that you're using than in the joints.

[Terry Bites]

I'm a fan of Buccaneer IP68 types from Bulgin. Very tough and excellent VFM. They have a nautique je ne sais quoi.
Cable joiners and in line conectors are great and easy to use. eg

https://www.ebay.co.uk/itm/265865683977?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D259354%26meid%3Df970416c5d064f80a381e6db7a0ad6e8%26pid%3D101195%26rk%3D5%26rkt%3D12%26sd%3D121744242767%26itm%3D265865683977%26pmt%3D1%26noa%3D0%26pg%3D4429486%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V2V4ItemNrtInQueryAndCassiniVisualRankerAndBertRecallWithVMEV3CPCAutoWithPurchRecall&_trksid=p4429486.c101195.m1851&amdata=cksum%3A265865683977f970416c5d064f80a381e6db7a0ad6e8%7Cenc%3AAQAIAAABYAWo%252FNI5OFX2WyIHq1fXy1iF4Ddx2spHNhNqnWM%252FzbogM5nIU8ZYuzjctdFg5tXE61X%252FHWBA5d1sr4BKUHjFChEffDNgzoB3wF%252BaNIdMfGXxAtCPiCMa9E3M%252F4wwHceI3Re%252FKBwV80OoIYSwAsl0yL5n%252FuOaUs4ihSwf8MhKmANNk7OMNJ66KkxdzB2bQW5Z67vL%252FEpiB3jkFGxvMdCZOcZK1y%252BOx7tRunTcTFDGWBmmhpAy%252FYoARTFb17bcYieyn9oP3QTo9a7uNoYbqVOOP%252Bc2J9jRO5s3RsBbHmXLhkbAoLkG7AXtyVf28%252F2%252BmHxHb5rT%252F7MxSjhTDzk6NTRuia2VLcR9cWnHZ9fJYj7s2tVa8qHt6G2qtk1fjX9bCi%252Fogbn4O%252BC987CE6pInR%252FGLju3AhPsSkojoVjlxLLaIALgM364GEBjxFTRBkIlCWu9IJJpqmaKEcRp87n43Bg%252BT9Cs%253D%7Campid%3APL_CLK%7Cclp%3A4429486

[SeanB]

You need to get some adhesive lined heatshrink, in a few diameters, Large one is placed over the cable before you start fixing it, and then you peel back insulation, and use smaller ones to seal the individual wires after you solder then together. small diameter, shrink on each, then a large adhesive lined one over the join, shrink down , and then a second one, longer than the first, to seal.  Hellerman Tyton has some good quality ones, you want them to have an unshrunk diameter a little larger than the cables to be used on, and then you need to extend beyond the damage by around 10cm with the outer sleeve.

[JustMeHere]

Don't solder wires.  It creates a shear point.  It wire will eventually break near the solder joint.

Review this, there's a detailed book on this floating around the Internet

https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/407%20Splices.html

[JustMeHere]

Found it: https://standards.nasa.gov/sites/default/files/standards/NASA/A/4/nasa-std-87394a_w_change_4_0.pdf

There's got to be answer in there.

[StyxF2]

Raychem D-436 enviro crimps are what you're after. Aviation standard...

https://www.aircraftspruce.com/catalog/elpages/d-436raychem.php

[Berni]

  On a personal level, I replaced my well pump myself years ago and the company that I bought the replacement pump from gave me some good quality glue filled heat shrink tubing to cover the joints in the down lead to pump wire joints and it seems to work well. The pump is 40 or so feet underwater and has been down there for 15? years.  I don't know who made the heat shrink but you might talk to a well driller.  But it sounds like your problem is more in the wiring that you're using than in the joints.

I had a similar issue with a submersible sewage lift pump. The float switch on it cracked and sprung a leak that tripped the breaker, but the big metal pump was still fine. So it was well worth the effort to replace just the cheap float switch, but it is connected inside the pump, didn't want to take the whole thing apart and deal with sealing it up again. So i instead opted for cutting the float switch cable and splicing it onto the new float switch.

To do the splice i used soldering and heatshrink. However at the end i cleaned the wires really well and put a huge thick glue filled heatshrink tube over it all and heated it up real hot to the point where the glue was pushing itself out the ends slightly. Threw the pump back in there and despite the joint being submerged under sewage for years it just kept on working. Not only is the splice under water, but it is also mechanically moved around as the float switch bobs around while floating on the surface, the pump jolts when starting up etc. So with good heatshrink you can do a lot.

I use a similar method for splicing damaged extension cords, those don't get wet as much apart from some dew or occasional splash, but it does get a lot of mechanical stress of being pulled along. The trick to reliable solder connections is to not use too much solder or soldering time, intertwine strands and immobilize the vicinity of the joint with thick enough heat shrink.