Radar Question

bcassal · Posted: Thu Dec 19, 2013 7:32 pm Post subject: Radar Question

I am reinstalling radar on Carpy using the scan strut mount that was on the boat when I bought it. It has a 7 inch rise. I want to keep the 12 inch tall roof rack that I have been using to carry our inflatable kayak, spare fuel jugs, etc. I did a test fit of it all today and I like the way it has come together allowing almost all of the rack to be usable. The radar dome projects forward of the rack, but a loaded rack will obscure the aft radar view. While I am primarily interested in the radar view forward, I wonder how this will affect the functioning of the radar.

Bruce,
Carpy

T.R. Bauer · Posted: Thu Dec 19, 2013 8:32 pm Post subject:

My Garmin unit doesn't like large stuff around it much and says "error" on loading at initial startup when there is significant obstruction. So, I made an adjustable mount out of some welded aluminum to compensate when the pots, dingy, or whatever happens to be on the roof at the time. Yours may be fine and I guess you will find out....hopefully it works for you Smile

rogerbum · Posted: Thu Dec 19, 2013 8:33 pm Post subject:

Bruce, I took a look through your photo album to find pictures of your kyak rack and the radar mount. It looks to me like most of the kyak rack is made from either starboard or wood and that the cross bars to which the kyak saddles are mounted are well below the height of the radar. Correct?

I'm guessing it won't affect the radar performance much. Most radars ignore signals that come back to quickly (e.g. reflections from stuff on the boat) and if the kyak saddles are plastic, the radar will probably shoot mostly through them. I'd say test it out. You won't hurt anything by testing. Park in a big flat parking lot with an obvious target behind the boat (e.g. a building or a water tower). Then test the radar with and without the kyak saddles. See if it makes any difference.

bcassal · Posted: Thu Dec 19, 2013 9:00 pm Post subject:

The kayak racks were replaced last year with wooden crib type rack. We now carry
an inflatable. It will amount to a large lump of vinyl with aluminum paddles when stowed. I might be able to test it soon, if I get it hooked up and the snow and ice melt.
It's a Garmin 18 HD.

Bruce

thataway · Posted: Thu Dec 19, 2013 9:34 pm Post subject:

If there is no aluminum motor mount (as in some inflatables) the inflatable, should not be an issue. Keep the aluminum paddles out of the way of the radar beam. I assume that the flat surface of the blades are plastic and the handles of the paddles are aluminum--

The wood should not be an issue.

rogerbum · Posted: Thu Dec 19, 2013 9:34 pm Post subject:

The radar will easily shoot through the inflatable. As long as the metal parts of the oars are below the line of sight, it shouldn't make a difference.

bcassal · Posted: Fri Dec 20, 2013 6:42 pm Post subject:

I got the whole mess wired up today. Thanks to a day and a half of 60 degree temps, a foot of snow and ice vanished. I hauled the boat out of the shop and fired it up. The radar worked well without the rack, with the rack, and with the boat in the rack. Guess I'll be good to go!
Thanks everyone for your advise and hand holding.

Bruce
"Carpy"

Foggy · Posted: Sat Dec 21, 2013 8:40 am Post subject:

It is my understanding close objects to the radar dome or array are not "read" or reflected back to the radar unit. "Close" may be beyond the boat and some distance considering variability in boats size. Otherwise, bow and stern rails, masts, other antennae, wiring, etc (any dense material within the vertical radar beam) would show on the screen as interference or at least be unwanted.

How many radars have you seen mounted below the level of an upper helm? This seems foolish to me as I would not like to have any part of me (especially some parts) in the direct path of a close radar beam. That aside, these low mounted units would not seem to work well if home ship materials within the beam were a problem.

Aye.

localboy · Posted: Sat Dec 21, 2013 11:21 am Post subject:

I had to raise our radar. It would not shoot thru the dinghy and I had a huge blind spot off the bow about 30* in total. Once it was raised 12" it shot over and we have no issues.

thataway · Posted: Sat Dec 21, 2013 4:35 pm Post subject:

What was the composition of the dinghy? Transom--with metal? Was the Radar center at the lower part of the dinghy (just off the top of the roof?).

Thanks.

localboy · Posted: Sat Dec 21, 2013 4:57 pm Post subject:

thataway · Posted: Sat Dec 21, 2013 7:16 pm Post subject:

Confirm that it was most likely the aluminum plate on the transom. I have seen that be an issue in other dinghies. --I looked at your albums and didn't see the dinghy, but did see the beautiful radar stand!

The small metal poles are not a problem, because of the width of the scanner, and presenting a small shadow. But the flat plate, does occlude a fair amount of the energy of the beam.