Why does marine cable need to be tinned.

[JimC]

This looks like the stuff

www.lidl.co.uk/cps/rde/xchg/lidl_uk/hs.xsl/index_9515.htm (taken from the YM forum)

 

[elton]

If you use untinned wires but spray the exposed copper generously with a silicone spray, the silicone will not only prevent the exposed copper strands corroding, it will penetrate a long distance up the wire under the insulation (many metres) and the result will be, to all intents and purposes, as good as if you had used tinned wire.

Where's the evidence for that?

 

[JimC]

Where's the evidence for that?

On boats which myself and others have owned, on which the method I described has been used with complete success over the past 18 years or more with no deterioration in electrical performance to date. The strands of the conductors, where visible, are bright copper with no black oxidisation. Moreover, the highly penetrative nature of the silicone oil means it gets into every interstice so that terminal screws and spade connectors etc stay clean & un-corroded and don't seize.

 

[cimo]

On boats which myself and others have owned, on which the method I described has been used with complete success over the past 18 years or more with no deterioration in electrical performance to date. The strands of the conductors, where visible, are bright copper with no black oxidisation. Moreover, the highly penetrative nature of the silicone oil means it gets into every interstice so that terminal screws and spade connectors etc stay clean & un-corroded and don't seize.

true enough - its what I do. apply a barrier for air & moisture. I ripped all cable from a boat this month. A mixture of both tinned & untinned copper installed. I was in two minds about tearing it all out as both were in pretty good shape (age unknown). The entire layout was a mess and really required a blank canvas, so out it came. not unheard of to re-wire
every 15-20years anyway (& much sooner for the damper installations). It doesn't take that long to run cables once the installation design is nailed down.

re: skin effect - where electrical current has tendency to conduct along the outer section of the copper conductor. applies to all electrical currents. can't recall the % breakdown - but it follows somewhere close to the 80/20rule I imagine.

lovely weather today & looking good for the weekend too.

 

[nimbusgb]

Consider the auto pilot failing just when you need it on a single handed night sail and you'd wish you'd done the installation correctly.

Also consider the time and cost of re-wiring any major job in a few years time just because you didn't use tinned cable.

Pick a boat, any production boat. 5'll get you 10 that you wont find a single metre of tinned cable aboard. Yes plain copper will corode. In a few years? Nope. I have extensively rewired a 25 year old Benneteau and I have only had to remake about 5% of the terminations. Cutting back some wires to remove excess slack revealed perfectly good clean copper no more than a few inches from the original end. Remember cable technology has moved on in the past 50 years. Better plastics and better cable construction techniques. When tin went through the roof manufacturers didn't just throw up their hands and give up.

If all it took to ensure autopilot reliability was a bit of wire there would be very few failures about!