Wiring

[Titanic]

Could anyone give me some advice . I am fitting (trying) a horn to my boat. Horn mounting no problem and I have fitted a momentary switch to the console. Now how do i wire it . I am not familiar with the wiring of the switch panel which to me looks like a mass of wires. I rang my dealer and he talked about a earth block but lost me . I understand the switch has to interrupt power from the battery to operate the horn Is there a drawing somewhere of a simple digram or can someone advise me how to wire it through the switch panel which I assume would be a more proffessional way.

[ozscott]

Mate - assuming that you have bus bars under the dash, you run a red coloured wire from the positive bar to one side of the momentary switch and the same colour wire from the other side of the switch to the positive side of the horn and a black negative wire from the negative side of the horn to the negative bus bar. I have not wired a horn, but thats a basic circuit and the switch traditionally is on the positive side.

Cheers

[oldboot]

Ok the principle of operation of any electrical device is as follows.

We'll assume DC

from the positive terminal of the supply ( battery) along a wire thru the switch, thru the device and back to the negative terminal of the battery.

Now

if we use an earth return system like in a car, the conductive metal chasis is conected to the negative terminal ( usulay) so you dont run all the way back to the battery for the negative connection.


back to the boat
People will argue the matter if it is a good idea to use the hull of an aluminium boat as an earth return.

I probaly wouldn't.

so you'll have a battery...somewhere...... you will probaly have a switch panel... somewhere else.

there will be " cabling" to bring positive supply, and hopefully negative supply to the panel.

the positive supply will be distributed to the switches ...... somehow... it might just be chained from switch to switch or there may be a distribution block ( a positive link block)

Hopefully there will be a some form of negative distribution block......or there may just be an earth connection to the hull and you get your negative by bonding to the hull ( i'm not keen on this)

you will need to find a source of positive supply.......cable that to one terminal of your switch (if your switch has more than 2 terminals it is a little more complicated)..
cable from the other terminal of the switch to one terminal of the horn.
cable from the other terminla of the horn to a source of negative supply.

job done.

now some other detail.
It would be a good idea to have a fuse in there somewhere......either derive a supply from an already fused source ( that has spare capacity) or fit an fuse as close as possible to where you get your positive supply from.

now an easy wiring method.
I assume the horn switch is not on the existing switch panel and the horn is somewhere else.

get some " suitable" fig 8 cable or better still double insulated twinn.

run the red or stripe wire thru the new fuse to positive supply, run the black or unstripe wire to negative supply.
head of in the direction of the switch.
carefully seperate the wires at the switch and cut only the red or stripe wire and connect those two ends to the switch.
continue on to the horn and connect bothe wires to the horn.
neat fast easy.

on boats you need to be very carefull and do good clean work use crimp lugs where possible and use a proper crimper.
Do not solder unless you can't avoid it. solder and vibration and corrosion, not good together.
Never solder a wire that will be put in a screw terminal or any form of clamping terminal.

if any wires penetrate any metal sheet use a gromet to prevent chafing.

any further problems give me a PM.

cheers

[finga]

on boats you need to be very carefull and do good clean work use crimp lugs where possible and use a proper crimper.
Do not solder unless you can't avoid it. solder and vibration and corrosion, not good together.




cheers

Why not solder??
I've found joining 2 wires with crimp terminals doesn't last very long.

What sort of boat is it??
A lot of the larger boats have a switch ready to rock and roll and all you need to do is run a wire from the panel to the horn
In some areas the horn is mandatory and that's why they're ready to rock and roll.
Don't forget to use tinned wire as well.

[oldboot]

problems with solder
in the spirit of worthwhile discussion
(finga most of the following is for the benifit of others)

first the big no no....
soldering a wire the putting it under a screw terminal or in a clamping terminal has this problem.
the solder is soft.... much softer than the wire and the terminal.
At first the joint will clamp down well.... as time passes the solder will yeild under preasure and the preasure in the joint will be lost, resulting in a poor contact.
If you tighten the screw again the whole process starts again.
This is why this method is specificaly forbidden in SAA wiring rules. ( but you know that)

I know that wasnt what was questioned.

just soldering together.
If you are a good at soldering and the joint is properly restrained and protected from moisture by glue lined heat shrink or something similar there is nothing wrong with soldering.
But most people working on their own baots are not that fussy and may not have the skill or materials to do it nice.
so here are the problems

soldering a flexible wire introduces a point of fatigue.....the portion of the wire that is loaded with solder will be rigid or close to.....this soldered section will stop abruptly and beyond will be flexible.
so at that point there may be a fatigue problem.
the clasic example of this sort of falure is a wire fatiguing off at the back of a switch.
the solution to this problem is to ensure the wire is properly restrained close to the termination and the issue does not arise.
As we are all aware vibration is an issue in small baots.

soldering and corrosion
because the solder we use for wiring has a resin based flux in it, a protion of this flux remains in and on the wire beyond the soldered portion.
this flux is hydroscopic and can lead to greatly accelerated corrosion.
To a certain extent insulation tape can protect a joint from moisture but should moisture get into the tape covering..... and it does.... it retains the moisture accelarating the corrosion.

Finga... i know from your background doing a joint nice would be second nature, & I would trust any of your joints.
But I've seen suficient underequiped, underskilled soldering to be...... hesitant.
We aren't all electricians or technicians.

personaly I would avoid any joins if possible.
yess there are circumstances where I would use a solder joint but I would probaly heat shrink it after.

I am very fond of crimp lugs and heat shrink tube.

I can see you may have issues with crimp lugs too.... but if the correct lug is used for the size of wire and they are crimped with a proper tool they are pretty damn good

You can get these great crimps now that have a glue lined heat shrink sleeve.....oh they are nice...... but they aint cheap.


cheers

[oldboot]

Tinned wire.... good point..... inhibits corrosion.
That can be a bit hard to lay your hands on these days.
I supose marine stores should have it.


cheers

[finga]

Goodo for the explanation matey

And I totally agree about the stress thing and that should be considered in any joint or any termination. Especially terminations where the wire is hanging from a switch or fuse.
Another thing to watch out for is too much heat when soldering. The insulation can be affected a long way up the wire and the wire can become brittle due to hardening of the wire.
An easy way I found to prolong the life of a crimped termination that isn't under dual wall heatshrink (ie spade lugs or ring terminators) is to just warm the termination up and dip it in lanolin grease thusly sealing the termination or put a dab of the goo on the top and warm it up with a heat gun etc so the grease goes into the joint.
I'll always bung one of those ring terminals on before just placing the wire under a terminal screw. The wire under the screw looks like a dogs breakfast

[oldboot]

I hadnt thaught of lanolin grease ans a contact treatment grease.

I am very fond of cantact "cleaner & lubricant" type products for improving electrical reliability in joints.
I believe there are a couple of marine specifc products commonly available.
treating all joints and connections with one of these products would be a good idea...they would certainly reduce in joint corrosion..... would probaly reduce erosion due to friction & vibration in some pluged joints too.

cheers

[Spaniard_King]

Guys,

It would be interesting to hear of how long boats wiring has lasted using the crimp method against the solder one. I for one have been soldering my stuff for years. The new crimps with heat shrink wraps have changed things a little IMO, certainly the tinned wire is worth the extra $$ and the time taken to find. Like everything on a boat wiring needs maintainence as well.

[oldboot]

The secret with crimps is in the quality of the joint.

good quality crip lug

correct size crimp for the wire

properly prepared joint

and a good crimper.

They've been using crimped joints on containerised refrigeration for ages. i worked with a bloke who worked as a comtainer fridgey for a while..... aparantly they are very touchy about the details..... use the wrong lugs or the wrong crimper......your feet don't touch the ground......

In a properly made crimp joint the strands of wire should be forced together such that the strands and the metal in the sleeve form a solid mass and all air is excluded.



I'll have a chew on the fatherinlaw's ear... he was on oil tankers for 30+ years and would have seen the introduction of crimp lugs.


cheers

[finga]

Personally I prefer to solder and use the dual wall heat shrink but problems can occur with this if you don't know how to solder correctly. Too hot or too cold can cause problems. So this is where properly crimped terminations are good.

Those crimp and heat joiners could be a godsend...don't know...never inspected one closely.

One of my boats has been wired for about 5 years now and never a problem with the solder/heatshrink method. Even the bilge, which has a join underwater sometimes, has never given a problem.

IMO any crimp type terminations need protection against corrosion as I've found most problems in boats (that has them) are caused by them or directly linked to them.
I've looked at boats 3-6 months old and problems happening in these suckers but if a preventative measure is taken they last a lot longer.

Handy hint 1....bung a loop or two near any termination just encase of needing a smidge more wire sometime in the future.
Handy hint 2...spray copious amounts of Lanotex or Lanolin spray around all the switch/fuse panels. It saves a lot.
handy hint 3....I put a dab of Lanolin grease on the ends of the fuses. These suckers are prone to corrosion and I've found this helps a lot with them

[ozscott]

sheep wool goo is your friend

[ozscott]

A good crimp is nice. I use both methods depending on what im doing. If I solder I make sure its heat shrinked up after. I love Lanotec - but you cant wrap tape around it after, you have to use heatshrink, because the tape wont stick to lanotec.

[mjbpjk]

Being an industrial sparky myself ive used allot of different connectors in a wide range of applications.

“Oldboot” speaks the truth indeed. Its all about using the right tools and the right gear and doing it properly.

Joining wires should be avoided but that’s not always practical.

If i must join then My fav way to join wires are the crimp lugs with there own heat shrink on them. These are worth a small fortune but we used them for a range of high vibration oily and wet applications and they are proving themselves very well.

I also like the comment on leaving extra cable when doing terminations. Im sure most would struggle with that concept as even the tradies cant seem to remember that one.

Cheers Pete

[ozscott]

Pete - i got some of those connectors from a Marine shop and 4 out of the 5 did well but the 5th using the same method of heating and same intensity etc did a poor solder inside and the wire was easily pulled out one side...do you have an reccommendations of brands?

Cheers mate