Fitting Radar

[AlexL]

I am thinking of fitting a JRC 1000 MkII radar ('coz its cheap!) and was wondering how to route the cable as I will be fitting this mid season and I don't want to remove the mast. The mast will probably be coming off next winter (18 months) as some other work will be required then.
Option 1: route the cable down the front of the mast in some cheapo domestic plastic conduit and then move the cable inside the mast when the mast is removed.
Option 2: Drill a hole in the bottom of the mast, put a mouse line through and pull the cable through - however the cable will be mixing it with the halyards and I'm not sure of the structural implications of drilling a large ish hole in the mast (large enough to facilitate grabbing the mouse line and weight and to accmodate the cable + connector (if fitted) + grommet

Any comments?

<hr width=100% size=1>

 

[Oldhand]

Don't know the specifics of the JRC but the radome end cable connector is usually removable thus you should only need a cable sized hole in your mast. This would normally be adjacent to the radome as most masts have sufficeint cable exit apertures at the base.

I wouldn't recommend your temporary external solution as it will require many attachment holes in the mast. If your mast is rigged properly any permanent or temporary fore and aft bend should be with the masthead moving aft. Thus the front of the mast is in tension and the aft mast section is in compression. It is thus, in my opinion, better to place any holes required in the aft part of the mast section.

<hr width=100% size=1>

 

[cindersailor]

A rather temporary solution, and one that was applied to the JRC1000 fitted to my boat when I bought it, is to route the cable up one of the shrouds, either the cap and along the spereader, or one of the lowers, attaching with cable ties. Not very pretty but effective for a short period. I only lived with it for a couple of months and then routed properly inside the mast, not a simple job as cable is 10mm and quite stiff. I mounted a waterproof junction box at the base of the mast and joined the cable inside using conventional crimp terminals. This avoids the need to drill a hole in the deck large enough to pass the cable plug/connector (about 30mm) and still alows removal of the mast.

<hr width=100% size=1>

 

[Woodpile]

As I recall, the JRC instructions recommend you temporarily disconnect the cable from inside the scanner unit casing itself. You then fit the cable 'backwards' from helm/nav station to scanner, so you don't actually need to pass the connector through a hole in the coachroof or mast and you shouldn't need a junction box either.



<hr width=100% size=1>

 

[JamesS]

I've just fitted the JRC 1800 and dropped the cable into the front channel of the mast. I used a plastic draw tape, bit of a fiddle even going down the mast rather than up. I think I made a 13mm hole

It does share with the genoa halyard but as its a roller reefing it doesn't get disturbed too much. The cable is fairly tough and has a screen. The cable entry to the mast is protected with a grommet and a single fixing on the mast stops the weight of the cable pulling on the radome.

You will need to cut the cable so that you can put in a joint above the headlining just below the mast. I made a straight forward choc strip joint below the deck - works fine with no interference. Make sure all the screens are given a seperate join.

The biggest problem I thought would be to fit the Scanstrut to support the radome (16 rivets!) so I got the local yard to do it for me.

Hope this helps.

<hr width=100% size=1>

 

[William_H]

Just a few comments without ever having installed a radar. A coduit up the front of the mast may be ok but as pointed out allow for mast bend increasing the length of the front of the mast. Dont attach by drilling holes in the front of the mast any where near mid height as the integrity of the mast could be compromised . Try silicone or other glue that can be scraped off later. You should not have so many worries drilling a hole near the bottom of the mast as loading here is in column compression. My mast as do many others use holes about 1 metre from the base for halyards to exit other designs use larger holes to fit turning blocks near the base. Try not to make a hole in the same horizontal plane as any other holes ie go up or down by 6 inches but near the bottom. As for mounting the scanner that will need holes probably about mid way up. I don't like the idea but I guess lots of others do it. Perhaps you could use existing spreader attachment holes. Masts are however quite tough provided stays remain intact and you don't abuse them on obstacles as I seem to have done several times. good luck regards will

<hr width=100% size=1>

 

[gjeffery]

I share your concern over drilling the tension face of the mast. The problem will be greater with a fractional rig. I have been waiting fo some weeks for a well known mast manufacturer to reply to my e-mail, asking for advice.

I think that this is another indication for mounting scanners (and reflectors?) elsewhere.

<hr width=100% size=1>

 

[brianhumber]

Have done this job 2 years ago.
Ran a plastic sqaure conduit up side of mast fixed with double sided tape and a few small selftappers. Height was dictated by height of my ladder to drill and pop rivet scanner support but was below lower spreaders and deck light. However I still get 16 miles range which I never use so I would regard a high mounting as not essential. Most difficult part was reconnecting scanner to cable having threaded up from Chart Table through coachroof to side of mast. Found out I could not do this from top of ladder so had to take cable I had just put up out of conduit and connect scanner to cable at deck level then rethread back cable into conduit as I took the scanner up the ladder before finally fixing scanner up.
After all the effort was a neat job and the JRC has been excellent.

<hr width=100% size=1>

 

[LORDNELSON]

I used the front internal wiring channel of the mast for my radar. I think it would be a good idea, if you do not know the layout of the internal channels provided by the mast maker for cables, to get in touch with the makers and ascertain the location and size of the internal wiring channels

<hr width=100% size=1>

 

[Jools_of_Top_Cat]

I have just fitted an SL72 with probably a very similar cable to yours. I fitted with the mast unstepped and had it all nice and neat with the cable running inside the mast and popping out the rear to then feed to the deck gland.

Unfortunately the cable was faulty and I had to fit a replacement. When we pulled the old cable out with mouse attached it was really difficult to get the cable to feed through the bottom and top holes, near impossible, it scraped the insulator quite badly in places. You see, when fitting, with the mast base removed it was simple to put your hand up and feed it gently bit by bit through the hole, I removed the mouse as I decided the reverse action would just be too painful.

I used 5 x copper pipe clamps, the small 10mm copper ones every couple of feet down the after part of the mast, using the smallest rivets I had, 2mm. This appears so far to be holding the cable quite firm, it is amoungst my halyards but does not appear to cause any problems, it is just like the spiniker halyard which tends to spend most of its life just sat against the mast.

hope this helps....

<hr width=100% size=1>J

<A target="_blank" HREF=http://www.topcatsail.co.uk>

</A>

 

[Talbot]

You will always see 16 miles on the radar, but if your scanner was 4.5m above sea level, the target would actually have to be 25m above sea level to be visible. A 2m target would only be visible at 8 miles.

Thus height of the scanner is of some importance, but must also be balanced by weight and its effect on the AVS.

<hr width=100% size=1>

 

[brianhumber]

Absolutely agree. I was trying to suggest it is not necessary to have a top of the mast fixing for Radar to work sufficiently well but you explained it better. My height is perhaps a wee bit higher than the stern pole mounts. I find I use the following ranges the most - ships at 6 miles, small boats at 2 miles and to my surprise it will pick up lobby potmarkers in a flat sea off on the lowest range.
Brian

<hr width=100% size=1>