Extending wires

[Roc]

Can anyone think of a reason not to extend wires, if done properly with butt connectors and shrink tubing?  I'm talking about extending something a couple feet or so.  I know the length of the run (both ways) dictates the gauge and if the added length still falls within the recommended gauge, I would think it's ok.  Any thoughts?

Thanks!

[Mike and Joanne Stimmler]

Roc, I think you'll be OK as long as you keep within the distance limits for the gauge wiring you're using and you use good splice connectors as you mentioned, unless you're talking about coax in which case you would need to use the proper coax connectors.

I was wondering about a similar issue with my upcoming radar installation. Does anyone know if there are any special considerations with radar cable. The one that came with it have special connectors on both ends and is 15 meters long and I'm thinking that the length will be close, going from the middle of the mast to the helm area.

[tonywright]

For the radar: Any splice is a potential area of failure. Standard approach is to use a black box with terminal block connectors. If it is a Raytheon radar cable there are a total 13 connections to be made, including two sets of shielding. Tiny wires most of them: maybe size 22.

You need to consider how often you plan to remove the mast after it is installed, and where you want to cut the cable and make the splice. You want to position the splice out of reach of bilge water if possible.

Tony

[waterdog]

Roc,

The reason not to extend wires is that splices are going to introduce resistance / loss / voltage drop and cause a reliability problem.   Wires don't often fail - it's those nasty connections.   

So it depends on the application whether pulling a new wire is worth the effort.   If it is something sensitive, critical, or power hungry pull a new wire.  If it really doesn't matter, don't worry about it and splice away.   Autopilot with splice in a damp locker - don't do it.  Moving the cabin light a few feet in the aft cabin and don't fee like pulling 20 feet of wire - make a splice.

[Roc]

Steve,
Your point is one of the things I was thinking about...resistance.  Does the splice itself create resistance, or are you talking about the 'potential' corrosion that could happen in a splice that creates the resistance.  I believe if you have a good connection with shrink tubing (adhesive type), then the connection is protected from possible corrosion.

[Ken Juul]

Radar cable from middle of the mast, under the head floor ends about at the shaft packing nut.  Watched a friend do the terminal strip when he installed his radar.  Very tedious but can be done.  I considered it, but couldn't find any left over radar cable.  Now I have most of the extra 15 meters coiled under the aft cabin before it runs up the pedistal.  On the good side, next time I pull the stick, I can uncoil the extra and pull it forward to the mast, when I restep I won't have any problem rerouting the cable to the aft cabin.

[Craig Illman]

Roc - I had to extend everything behind the panel 8 inches when I replaced my panel. It's a pretty benign, protected location. It's worked ok for two years. Will it last twenty? I think I'll be re-wiring the whole boat before then anyway. The benefit of toggle breakers on every circuit out-weighed the risk of an individual circuit failing from a splice.

Craig

[waterdog]

Steve,
Your point is one of the things I was thinking about...resistance.  Does the splice itself create resistance, or are you talking about the 'potential' corrosion that could happen in a splice that creates the resistance.  I believe if you have a good connection with shrink tubing (adhesive type), then the connection is protected from possible corrosion.

The splice certainly does create resistance.   If you are just running dc power to something with a low draw, the amount of resistance will be utterly insignificant.   It's the long term corrosion related resistance you are worried about.   

If the wires are carrying transducer signals or high frequency signals, it may matter a lot.   Drives me nuts when you buy a fishfinder or something and the manufacturer sends you a 50 ft cable with a connector on the end and strict instructions not to cut the cable.    Sure everybody has room to drag a 3/4" connector through conduit.   Here the "resistance" of the splice can be a portion of the signal being reflected back and confusing sensitive electronics. 

Higher power is another beast.    But I don't think your talking about a little crimp and heat shrink on a 2/0 cable to your windlass...

[Mike and Joanne Stimmler]

Ken,
What was the total length you needed on the radar cable to get it from mid mast to the pedestal? Did you run it through the tube of your pedestal guard? I believe the cable that came with my Raymarine radar antenna is 15 meters, will it reach?  I'm also trying to figure out what I need to get all the cables needed (radar,power, GPS antenna, transducer cables for speed and depth and auto pilot) to a NavPod. I haven't purchased the NavPod yet and I'm wondering if I can get everything through a one inch pedestal guard or go to a one and one quarter inch guard. Any ideas?

Mike

[Ken Juul]

This is just a guess, but I think the 15 meter cable ends up being about 10 ft short.  I'll try to get a better measurement tomorrow.  The radar cable will not go through a 1" tube, 1.25 maybe without cutting the cable   Measure the connector.  I didn't even attempt to run wires through the guard.  I went up the pedistal and out a whole I cut just below table level then up to the chartplotter.  Even that was hard, had to expand one of the access holes in the pedistal base quite a bit to get the connector though. Will try to get a picture tomorrow also.

[Ken Juul]

I got busy at opening day festivities and forgot to do the measurement.  Did get some pictures though.  Notice the one showing the connections at the back of the chartplotter.  No way are you going to get the right angle connector through a pedestal tube, if you are going that route you will need to cut and splice.  I had my original pedestal guard modified, cut the round hand hold and about 8-9" of vertical tube, added the angled tubes and put the cut off hand hold at the ends.  Yes I still have the plastic shift/throttle handles.  Keep vice grips handy.

[Mike and Joanne Stimmler]

Ken,

I was considering feeding the other end of the radar cable down the pedestal tube from the top of the guard. The connectors on the other end are smaller.

[Ken Juul]

That would probably be doable, radar and one or two smaller down one leg, the rest down the other.  If you are going from the helm to the mast, you will need an extension.  If you choose to do it this way you will have to a splice (terminal strip, multipin connector, etc) of some sort to connect the ends together.

[Rocco]

Mike,

I just completed a new Raymarine C80 radar installation last season.  The supplied 15m cable was approx 2 m too short so I purchased a 10m extension cable and wired as followed:

1- My MKII has a deck stepped mast and I did not want to feed the radar cable down the compression post and out through the (too small) exit at the bottom anymore.  I've also had problems with junction box connections failing in the past.  I purchased an extra ray-dome data connector from Raymarine and fished the supplied radar cable up through the bottom of the mast to the ray-dome and cut the cable to the proper length so that the factory connector sat comfortably at the bottom of the mast.  The extra was trimmed at the ray-dome end, necessitating the new connector for the internal ray-dome connection.

2- I then cut the 10m extension cable and fished it through the base of the mast and the compression post back to the bilge area below the fuel tank in the aft cabin.  The other end was fished through the pedestal guard to the same location.  I very carefully spliced the extension cable back together again, leaving about 5 feet of extra cable for any future needs.  The splicing is tedious, but not anything too difficult. The splice has multiple layers all with adhesive heat shrink tubing all covered by a final large adhesive heatshrink over the entire splice.

3- I also replaced my pedsetal guard with a 1.25" which has a lot more room for wiring.

Now I have a connector at the Navpod on the pedestal guard for the C80, and a connector at the base of the mast to connect/disconnect the ray-dome when the mast is stepped with no junction boxes in between.  I'm hoping this proves to be a reliable setup and so far it has worked fine.  I did confer with Raymarine before starting and they saw no problem extending the cable in the way that I did.

Hope this helps,
Rocco

[Mike and Joanne Stimmler]

Thanks, Rocco