Humminbird Side Imaging Forums
Other Interest => DIY - Side Scan Sonar and towfish => Topic started by: Rüdiger on August 10, 2011, 04:13:25 AM
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Hey towfisher
How do you sealed the cable connection for your towfish
mvh
Rüdiger
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Hi Rüdiger.
I used a shrink-tube containing some kind of melting glue.
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Hi,
I make the connections permanent by splicing and soldering the wires and sealing them with hot melt glue and shrink tubing, like Kron does - so I really don't have an answer for your question. During some tests I have used provisional sealings (bury the connector in a lump with hot melt glue) that didn't hold up so I got water inside. But the system worked well even with wet connectors (freshwater)! I once got a leak in the ethernet cable and it was filled with water with no sign of malfunction. Of course this doesn't mean sealing is unnecessary, it simply shows the system is rather resilient.
But I have similar plans as yours because I want to move the transducers between different setups without soldering everytime or having to move around with a sometimes needlessly long cable. Therefore I will test filling the connectors with water resistant grease before joining them, and then use some type of tape for extra, but not necessarily waterproof, protection. The pressure at depth will squeeze the grease, but since it has nowhere(?) to go I think the joint will stay 'dry'. The spot where the cable enters the connector should be sealed permanently, though.
Remember, use the full potential in the extension cables and replace the original transducer connector for a connector from an extension. This will provide separation of ground circuits for the SI channels and preserve the effect of twisted pairs. But, the units have only one ground pin so one must make a short cable with an extension connector at the transducer end and a standard transducer connector in the unit end. Inside that cable the ground wires are joined to the same wire that leads to the unit ground pin. (An extension connector can be used at the unit end also, but the ground wires must still be joined to a common ground wire). If a transducer with separate ground circuits is plugged into the unit only temp and the downward channel will work. There is also a risk for damaging the unit, so such a transducer should be marked in a very clear way!!
I'm curious to hear what people think about the grease sealing method?
Rickard
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Probably the cheaper way to go, but there are commercial grades of water tight connectors for use underwater.
It just costs more....
Also something else to consider is circuits using DC current will for the most part not conduct in water.
Take a battery for example and put it in water. Come back later and it will not have discharged.
Take a light bulb and put the two ends of it (cable) in water and it will not light...
This does not in any way say we should not strive to make our connections water tight.
There are circuits that are sine wave in duration..
Chuck
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Check out Alibab.com ($$$$$) they work well.
Roddy
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I sealed my cable after splicing with shrink tube. Works well so far up to 42 m water depth.
Regards / Harry
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Hey Harry
Only shrink tube, no adhesives or sealants ?
mvh
Rüdiger
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They make a marine shrink tube that has a sealant in it. I coat my connections in liquid tape first with a few coats to make sure they are sealed really good, then put the marine grade shrink tubing over the sealed connections.
No leaks so far!
Robert