Spreader Height for radar installation? CD30

[JimNewton]

I am about to install a radar on Alcyone and trying to determine the cable length I'll need. Does anyone know the height above deck of the spreaders? Better yet, the full length of cable I’ll need?
I’m planning on mounting the 18” Furuno dome just above the spreaders, run the cable to a termination box at the foot of the mast (inside). Than run another cable back to the cockpit and up the pedestal. The standard cables come in 10,15, 20 and 30 meters.
Thanks,
Jim

[ldemers]

You don't want to cut that cable, unless you have a lot of experience in electronics, where you would have learned how to handle coaxial cable, which is inside the main cable.

Thats one reason why I put my radar on a pole on the port stern quarter, and routed the wire to the nav station...without cutting it.


Larry DeMers
s/v DeLaMer
CD30c Sailing Lake Superior

[Larry M]

When I had the radar installed on the mast I had the cable exit the mast inside of the headliner and then cut. We had the cut spliced through a terminal block before running the cable aft to the nav station. This was done to provide a method to quick disconnect to make removing the mast easier if we ever decided to transport the boat.
I would agree with Larry that a pole mount aft would of been easier (either a stand alone or questa type on the backstay).
If you go with the ast mount don't forget to secure the cable in the mast to stop any slapping.

[JimNewton]

Thanks Larry, I was aware of the potential complications of cutting the cable and have chosen to have a professional do the install. I’ve done most of the electronics to date, but these one I’m getting help on.
Jim

[Tom]

Inside that coax calbe that Larry mentions there are many, many very fine wires (at least on the Raytheon), it can be cut but a tricky job even for a pro and it seemed to me that it opens you up to a corrosion problem. What I decided to do on my installation was run a pvc tube down the inside of the mast to hold the radar cable and also all the wires to the deck light, steaming light etc. Then they exited through a hole I made at the base of the mast below the cabin sole. The wires to the lights I brought to a terminal bar in the well at the bottom of the mast. The cable for the radar I put inside flexible one and half inch tubing and ran it under the cabin sole back to the galley and brought it up under the sinks. Inside the sink console I ran it over to the bulkhead and then up to the overhead and the display unit all in one continuous run with no splices. Out here we only pull the mast every 15 years or so and it isn't a problem. If you're in an area whereyou have to pull the stick every year this probably wouldn't be practical. Wires slapping inside the mast can be very annoying at anchor and I think you'd be well advised to install some kind of restraining device for the wires while you're at it. FWIW

[Louis Gerhardy]

I recently completed installing a JRC 1800 radar - chart plotter on my CD 30. I used a back stay mount for the 18" radar dome and have been very pleased with the operation and looks of the set up. I have had it bouncing around in some fairly wild wind & waves and all is well withi it. The installation was quite straight forward and took 8 to 10 hours for me, an amature, to do.

One of the advantages of the back stay mount is it is unnecessary to cut the co-axial cable. I fed it through the starboard dorade at the stern of the boat along with the GPS cable. The fitting that connects to the radar display fit through all the little passages under decks and over the ice box where the display is mounted on a swing arm. I did need a hole saw to cut out a piece of wood in an inconspicious place below the electrical panel through which I fed the cable. The display swings out into the starboard side of the companion way for viewing from the cockpit. My unit came with 30 ft. of cable connected to the dome with the display fitting alreadey made up to the cable. If you use a mast mount you will need to taqke down the mast to install a conduit for the radar cable as well as put some new holes in the deck.

Good luck with your installation.

[Cathy Monaghan]

Hi Jim,

The length will be determined by both where you install the scanner and where you install the display unit.

If you recall from last year's Maine Cruise, Realization's radar scanner is mounted about 2-feet below the spreaders and the main display is at the helm. Our PC can be hooked up in the nav station as a second station.

You should recognize Bucks Harbor, ME in the photo. Note the location of the radar scanner. The object that appears just below the port spreader is the radar reflector.

<a href="http://www.capedory.org/images/misc/rea ... .jpg"><img width="540" src="http://www.capedory.org/images/misc/real_radar.jpg"></a>

The staysail just clears the scanner when we tack. I'm not sure, but in order for the staysail to clear the scanner on your CD30, you may need to mount it similarly -- a couple feet below the spreaders. This means that your deck light in it current position will be useless, so you'll either have to move it or just install a new one below the scanner.

Anyway, take a look at the photos that you took of our boat during our sail to Pulpit Harbor, you may have some where you get a better idea for positioning.

By the way, Bruce and I installed our networked Raymarine system ourselves (actually, I did most of it myself). I used the 15 meters of cable that came with the unit and had to purchase an additional 10 meters. You won't need more than that since your mast and boat are shorter.

We installed an electrical box on the bulkhead inside the cabin, in the head actually, beneath the mast step of our deck-stepped mast and the cables are connected within that box via a terminal block. This is the only way to install a mast-mounted radar if you still want the capability of mast removal.

Hope this helps.

Cathy
CD32 Realization, #3
Rahway, NJ
Raritan Bay

[Chris Reinke]

Jim - When I installed my Raytheon system a few years back I ran a single antenna cable from the scanner to my nav station. I then purchased an "extension cable" from Raytheon which had a female receptacle to accept the antenna cable, and a male connection on the other end which installed in my display. I ran the extension cable from the nav station up to my helm. This provided me with 2 mounting options for the display. I can easily mount it at the nav station and attach the antenna cable. Alternatively, I insert the antenna cable into the extension and the display gets installed at the helm.

Perhaps you can purchase a sealed extension cable which would allow you to break the cable when removing your mast, and avoid the labor expense and potental problems of splicing the cables.

[David VanDenburgh]

Just be aware that the radar manufacturer will have a maximum cable length beyond which you cannot go and get reliable performance. 20 or 25 meters is often the max.

Also be aware that the connectors between two lengths of cable are often bulky and may not fit through the hole in the mast or the woodwork that the cable runs through.