Fitting a radar dome cable up the mast

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garvellachs

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I plan to install a Furuno 1623 radar dome up the mast. The cable is long enough to reach all the way down inside the mast and through the deck to the chart table for the LCD screen. However, I'm reluctant to thread it all the way through because it makes it hard to take the mast down for the winter: connecting the dome is awkward up the mast and the cable has to be extracted somehow to move the mast foot.

So I can see two alternatives: put the cable in an external conduit up the mast or split the cable at the mast foot using a plug and socket (below the deck with a gland?). What is the experience of others please? Has anyone found a suitable ten-way connector for radar? Have others used external conduit? Are there better solutions? (I'd prefer not to use a pole at the stern)
 
On my boat it was fitted by the previous owners. The cable is split but not at the mast foot. It is a foot or so longer, and goes through a cable gland into the heads compartment. It emerges inside close to the bulkhead where it connects to the rest of the cable.

The connector is a plain 10 or 12 way plastic terminal block. It doesn't have to be waterproof. The whole thing is boxed in in the heads with a teak box about the size of a small paperback book screwed to the bulkhead to keep out water from the shower.

This works fine. When the mast was stepped I took the precaution of putting a loop in the cable on deck at the foot of the mast to lose some of the drips and tied this in place with cable ties. Posher boats have a stainless swan neck.

The whole thing has worked fine for the four years I've had the boat. I got a bit of water into the teak box in the first year and so put some sealant round the cable where it enters the gland. Whether there's a better 'official' connector for the two halves of the cable, I don't know.
 
My arrangement is the same as jbweston's. My mast compression post has a covered channel that carries the (radar, wind instrument, lighting and vhf) cable runs down from the stainless steel swan's neck alongside the base of the mast. The radar cable is joined with a multi-way chocolate block connector. it was installed nearly 8 years ago and, despite disconnection to lower the mast, has been fine so far.
 
I took the end plug off and threaded through the mast, the multicore cable is about 10-12mm thick (Raymarine) it should be simple enough to pull the cable back down the mast with a string attached for when I want to re-thread. IMHO I would not cut the cable. No room for poor connections etc. I appreciate that this is not what you have asked though.
 
on both my beneteaus the cabe was cut and threaded thru a deck gland and then joined by std block connectors, no probs
Stu
 
Mine came with the cable in plastic conduit down the mast. It is not UV friendly though, and bits are falling off all the time. It is jointed in a waterproof box at the foot of the mast. I am considering drilling a couple of holes in the mast and threading it internally (with the addition of some foam for quiet nights)
 
I have installed my Furuno in way thay you have described.

I have had to take the radome twice to fix a problem. With the cable on the outside of the mast, its very easy to bring dome and cable down in one piece. Means I was able to test the radar at a workable level.

But you might hope nothing will go wrong I guess.

Good luck
 
Thanks for the quick comments - it seems people have cut the cable and used a simple joining block successfully; and conduit on the outside of the mast works if it is UV resistant. Any others with contrary views?
 
Yes it can be done with 'chocolate block' connectors but the best way to do it would be circular connectors. These are manufactured by a lot of people but Hirose does some good ones. http://www.hirose-connectors.com/products/H-MS_5.htm Next trip out to the boat i am going to gather the 5 small cables going up my mast into one 16 way circular connector, bulkhead one side, plug the other, to do away with 5 holes in my deck in favour of one properly sealed one and provide a single 'twist to lock' connection to the mast. I'll be using an aluminium bodied mil-spec connector with gold contacts.
 
Cutting and rejoining the cable has not proved a problem for me. But I was advised not to shorten the cable. Something to do with resistance being calculated by the cable length.
 
Bullet points:

1. Be sure the cable has a down loop below decks before the junction box - this throws off any water that comes through the deck gland - and it will!

2. Simple choc box connector below decks is just fine.

3. Lay in cable within the mast - this is heavy cable and prone to damage. There is no gain in strapping it to the outside of the mast - only downside. Use good grommets where the cable passes through the mast.

4. Don't be put off by claims that the radome has to be low or high on the mast. Above the first spreader - hopefully 5+ meters above sea level will meet your needs, and ensure it is easily accesssed each year for maintenance greasing.

PWG
 
I managed to install my furuno with out cutting the cable. Cable is in trunking on the outside of the mast painted to match mast and I managed to thread cable to chart table. I was told that if I must cut the cable don't shorten it and put those round pins over the bare wires to protect them from the choc block screws. The cable has a generous loop in it after the index deck gland in case I have to cut it.

And finally, when testing for the first time do it in an 'empty' area. I started mine in a marina and all I could see was black blobs all over the screen where the "reflections over powered" the screen / electronics.
 
Get an engineering firm to make a 2 metreish pole to fit on the stern and mount it there - no taking down - even mount your aeriel, GPS receiver and all round light there - much better same performance - no hassle £120 ish

or buy one http://www.scanstrut.com/ Ouch!


DON'T cut the cable - not recommended

BOL
 
Mine is also the same as jbweston's, except it goes through a swan neck and I mounted the block into a die-cast box.
I don't agree that a push fit pins in a plug and socket are better, because you will have to extract the pins from the connector to get it through the deck when you drop the mast.
A terminal block makes for a good positive connection.
 
Use a die-cast box and fit the cable shield to the box. This way the shielding of the inner cables is not compromised. It it is not shielded RFI may effect some of your instruments.
 
Thanks again to everyone for the very useful replies. I know there's a set up procedure for checking and adjusting the Magnetron heater voltage in the dome - I guess the integrity of the cable (length, quality of any connector) may affect that.
 
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