Fitting new radar cable.

Eeyore

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I'm in the process of fitting radar. The cable from radome to display has a large connector on the 'inboard' end and several connectors on the radome end. Neither will pass down inside the mast (when the hole is drilled).

How does everyone else run the cable? Is it a case of cutting, passing one end through a deck gland and and then re-joining inside the boat with a suitable connector? Or will that affect the transmitted/received signals?

Thanks in advance.
 

grafozz

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The lesson I learned about this is drill the hole big enough for the plug to pass through the coachroof gently. i kept the hole to a minimum and when pulling it through, on taking the mast down, ripped some of the wires out of the plug ! now having big problems trying to find a new cable/plug ( JRC ) . I originally glued the cable onto the mast and although it worked got fed up with looking at it ! so last year I drilled the mast to take the plug down inside . I found rubber grommets to reduce the hole size in the mast and bonded them in with pu adhesive . now it looks tidy.
 

Eeyore

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Thanks Graham. I suppose the question I'm asking is: Is it ok to cut the cable and re-connect inside the boat at the foot of the mast?

Without doing that, it creates problems, firstly in getting the plug down inside the mast and secondly when unstepping the mast, in that the whole saloon deckhead would have to come down in order to feed the plug back from the radar display head, which is sited in the cockpit.
 

rogerdog

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The 'correct' answer is no your should not as it can result in some impedance etc issues with co-ax cables due to the ..... (yes all can be measured in a lab and looks very convincing )

The short answer (also verified empirically) is it works fine - just be very careful with all joints. I solder and then use glue imprgnated heatshrink around each individual one and another large one around the whole cable/join for strain realeaf. When joining any coax cables in there I join the centre conductors, shrink sleeve it and then use a bit of copper foil over the outside to join the braid.

The other method is simply (!!) remove each wire from the plug and pass it through then reattach plug (unless its a mounded on one !)

I would try to have the join inside protected from the weather as its a pig if water gets in it !
 

Eeyore

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No coax involved and the plug on the inboard end of the cable
is moulded on.

The cable is 12mm diameter and consists of nine colour coded wires. Could it just be a simple case of cutting the cable at the appropriate point and re-joining with gold chocolate block? (or similar)
 

rogerdog

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If no coax even easier -the simple answer is yes it will work - but the choc block style connectors are not the most reliable I prefer method stated before - longer to do - slower and fiddly but you end up with a 100% job. i have used chco block on radar for testing - but would not feel as confident as the solder and shrink sleeve method

You could always use a junction box with strain relief and a connector board inside (soldered again) its a bit easier than a bunch of wires.
 

vyv_cox

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But then what do you do when you take the mast down? It turns a biggish job into a major one, IMHO. This was one of the main reasons that I put my radar on an aft pole. Since I fitted it, about 8 years ago I think, the mast has been unstepped three times.
 

PeterGibbs

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Quote: I suppose the question I'm asking is: Is it ok to cut the cable and re-connect inside the boat at the foot of the mast?

A - go ahead. But measure twice before cutting! I think folks feel a bit queezy about cutting radar cable and surely one cannot be cavalier about this, given the sensitivity of the info flows. I cut at the base of the mast to preserve the integrity of the instrument connector: use a chocolate box and hang the incoming cable in a loop to shed any moisture that could affect the connections.

You want to sheathe/grommit the cable where it passes into and out of the mast to prevent degradation: the smaller the holes you drill in the mast the better - clearly!

A regular cable gland at deck level with one of the squeeze type rubber surrounds to make it watertight should do the trick if properly installed and bedded with sealant.

PWG
 

alan17

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I used the choc block method and the result has been fine.

Chop cable so as to pass through hole into mast then out again just above deck level then through a gland with about 12 inches spare in box on head lining under mast. Make connections using choc blocks and run cable down inside compression post then uner floor to chart table. This for a Southerly 100 following Northshores advice.

Works absolutely fine. My only worry was making the inital cut. Was it in the right place. Yes it was-no worries after that.

One further thought re type of choc block. Use the type with a metal blade in the connector that presses onto the wire not just a screw end into the wire. Available from index marine and many chandlers. Dearer but worth the extra.
 

Eeyore

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Thanks guys - that's what I wanted to hear. I couldn't see any reason not to cut the cable but wanted to make sure.

I would have liked to mount the radome on the stern gantry but after considering the weight and the shadow cast on the solar panel, decided to go with the traditional 'just above the speader' option and put up with the extra weight aloft.

It's all a compromise......why is nothing ever simple on a boat? /forums/images/graemlins/frown.gif

/forums/images/graemlins/smirk.gif
 

srm

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I fitted a basic Raymarine radar a few years ago. I passed the scanner end of the cable out through the deck glands etc, then connected them into the raydome as this needed smaller holes than the inboard plug end.
Despite the comments above I would be very wary of cutting and joining the cable as cable lengths (resistance?) different to those the set is programmed for will cause time base/range errors.
 

JayBee

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I fitted a Furuno 1724C Radar/Chartplotter to my boat last year.

The cable, as supplied, has a large moulded plug which would be practically impossible to route twice through the mast, through the deck and thence to the chart table.

Reasoning that this must be a very common problem, I decided that the cable would have to be cut and re-joined somewhere under the deck. However, not being filled with confidence, I sought professional advice - which was to do exactly that, using a chocolate box connector. The connector is located in a watertight box, with rubber grommets protecting the cable at exit and entry.

I was also advised to crimp small metal sleeves onto the conductors, to protect them from possible screw damage. I did this and the result has been 100% satisfactory.

Go ahead!
 

JayBee

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[ QUOTE ]
I would be very wary of cutting and joining the cable as cable lengths (resistance?) different to those the set is programmed for will cause time base/range errors.

[/ QUOTE ]

I suspect that this is not the case.

My radar can be fitted with varying, non-standard lengths of cable and no adjustment or programming is needed to cope with this.
 

NOHOH

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Hello Eyore.....I tackled the problem by running the cable down the front of the outside of the mizzen mast in 2 part plastic conduit....then through an ordinary Index Marine type deck gland. When the mast has to come down I simply unclip the front of the conduit releasing the cable...then unfasten the whole radome from its mounting bracket and lower it to the deck with a halyard without needing to disturb the cable or its connections. QED


Eschew Obfuscation!
 
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