Getting wiring through under deck trunking

BogMonster · 29 August 2011, 09:43

I am shortly going to install a bilge pump in Seawolf so I'll need to run some cable for it through the under-deck trunking from the console to the transom boxes.

Trouble is the under deck trunking is already pretty full with battery leads, fuel hose, engine, VHF, nav light wiring etc. I'm pretty sure it won't just push through, that would be too easy...

I've so far come up with two possible ideas - either disconnect something else, pull through some nylon twine and then pull both wires back through together, or try and find some fairly stiff wire to push through as a "leader" to attach the other stuff to, and pull it through like that.

Any other ideas / how do those of you that do it quite a lot (or rigged your own boats) do this particular job?

Mollers · 29 August 2011, 10:18

My sparky pal has a roll of stiff nylon stuff about 4mm thick specifically designed for pushing through cables. I left a pull-through cord in my cable duct, I used it when pulling new VHF coax through and tied another cord to the coax as a replacement.

Pete7 · 29 August 2011, 10:30

Quote:

Originally Posted by BogMonster

I've so far come up with two possible ideas - either disconnect something else, pull through some nylon twine and then pull both wires back through together, or try and find some fairly stiff wire to push through as a "leader" to attach the other stuff to, and pull it through like that.

That's the normal way, but run a messenger line as well ready for next time.

Quote:

Originally Posted by BogMonster

Any other ideas / how do those of you that do it quite a lot (or rigged your own boats) do this particular job?

You might be able to use an old throttle cable, but if not back to option 1.

Pete

BogMonster · 29 August 2011, 10:37

Thanks, hadn't thought of a throttle cable but offhand I don't think I could find anything long enough anyway (only for bikes etc). A bit of high tensile agricultural fencing wire is probably the best option I can lay my hands on but hopefully that will work. I also know an electrician so will pursue that option as well, ta

Must admit I have not checked to see if there is a pull through left in there so I will have a look first!

willk · 29 August 2011, 11:22

Fine plastic piping works a treat. Think lorry air lines, beer gas, etc. Pour a bit of dilited detergent in there too, or spray the lines well with WD40 or whatever. I used some silicone oil I had, but I gather it's a no-no around hypalon...

It helps A LOT if you have a buddy to feed the line in!

Chris · 29 August 2011, 14:14

I would be surprised if Roy had not left a pull through. One piece of advice is lubricate the wire with some washing up liquid if it really is a tight fit...

jyasaki · 30 August 2011, 08:01

Go to a hardware store and ask for a a fish tape. It's a strip of steel tape or fiberglas wire, in various lengths, retractably spooled, and made for pulling wires through ducts, conduit, walls, or whatever.

jky

Erin · 30 August 2011, 08:36

The other option is one of those fibreglass tent rods. They make a thinner version specifically for mousing wires through ducts for electricians.

Courageous · 30 August 2011, 08:49

Wot Mollers said and here it is:

Electricians fish tape / Draw tape - Nylon 10 metre | eBay

two stroke mick · 30 August 2011, 10:38

use KY jelly for lube in conjested spots

BogMonster · 30 August 2011, 10:43

Quote:

Originally Posted by Courageous

Wot Mollers said and here it is:

Electricians fish tape / Draw tape - Nylon 10 metre | eBay

Excellent, ta, have just ordered one

Courageous · 30 August 2011, 22:58

Ya welcomez.

spartacus · 01 September 2011, 23:25

I've used flexible coiled drain rod (minus the business-end). Works a treat.

sirib · 02 September 2011, 00:03

I have just had to pull a load of cables through my duct. There was no way a fish tape / or rod would be pushed through as the final bend is tight and packed with cables. I disconnected the main battery cable to the engine, used the crimped eye to attach a draw wire/rope and pulled it through from the other end. Pulling is far more effective than pushing.

jyasaki · 02 September 2011, 01:27

Umm; you usually run fish tape all the way through, then use it to pull the cables back through. They're made fairly stiff so you can push it through some resistance, but are somewhat pliable to get around corners. Probably won't go around a tight 90, though, at least not without a lot of fiddling.

If you have a fairly clear duct, another method is to tie a small pice of cloth to the end of a string or rope (to generate more air friction), and use a shop vacuum to suck it through the duct, then use the string as a pull line.

jky

Nasher · 02 September 2011, 08:23

A few of you on here may remember Mark Halliday who was a regular on here before he ripped the rotten deck out of his 6.5M Porters to replace it, then never got around to putting a new one back in.

Anyway, I was round at his place one day and we were looking at the extension he was half way through building on the side of his house. I noticed that he’d installed a 1&1/2inch conduit under the floor from the old kitchen to the new room, a run of about 12 feet, and I tentatively asked how he was going to pull the cables through it without a ‘mouse line’ to help.

What he did next made me laugh, but will stick with me as a ‘top tip’.

He grabbed a ball of string and the handkerchief out of his pocket, tied the end of the string to the corner of his hanky and stuffed it in the end of the conduit. We then went to the other end of the conduit where he used a vacuum cleaner to suck the hanky through in what seamed like @1/2 a second. He then of course had his mouse line through the conduit.

It probably wouldn’t work where there were lots of cables already through the conduit, but it was very impressive.

Nasher.

BogMonster · 20 September 2011, 21:47

On a related issue ... I now have the pump (it was a bit late turning up!) and the fish tape so at some stage when weather and free time coincide, I'll be putting it in.

I figured that rather than drilling holes in the deck and potentially creating a water ingress point in the future, I might just stick the pump base onto the deck with something like Sikaflex (you can't buy that here but there is an adhesive sealant called Stixall which seems pretty good).

I've never really tested the tensile strength of Sikaflex type adhesive sealants on a small plastic fitting onto GRP - what do people think - will it be strong enough for this? I think it would probably be better than an Araldite type epoxy adhesive as they are usually quite brittle but any thoughts welcome...

Courageous · 20 September 2011, 21:57

I'm sure you want to keep the pump as close to the deck as possible but your chances of success are obviously much greater if you increase the contact area. Can you find some 3mm plate and bolt the pump through with small countersink bolts and nuts? Then stick that down with ya sticky gear.

Nasher · 20 September 2011, 22:01

Sikaflex type adhesives need a bit of surface area to work really well. I don't know what design base is on the pump, but I'm sure it's worth trying.

The technical term for the way Sikaflex 'Grabs' what's being stuck is:- L.S.T.A.B.

Or:-

Like
S**t
To
A
Blanket.

Nasher.

Nasher · 20 September 2011, 22:02

Quote:

Originally Posted by Courageous

I'm sure you want to keep the pump as close to the deck as possible but your chances of success are obviously much greater if you increase the contact area. Can you find some 3mm plate and bolt the pump through with small countersink bolts and nuts? Then stick that down with ya sticky gear.

Cracking idea