Radome or 24” Open Array Antenna

Larry K

Looking to install Radar on my 22ft cruiser and was wondering if anybody had any thoughts between 24” Radome or 24” Open Array Antenna? The Furuno #1742 comes either way.

Larry K (Odyssey)

Luna C · Posted: Thu Jul 15, 2004 1:21 am Post subject:

I have the raydome on my CD-22 and it works great. Cost, and in my opinion, it will hold up better on frequent trips down I - 5!

DaveS · Posted: Thu Jul 15, 2004 3:19 am Post subject:

Speaking of Radomes and I-5..............We received our new custom made Radome cover in the mail today. It is made of the same material and in the same color as our camper back. I ordered it in the hopes of protecting the Radome from accumulating all those bugs as we travel on I-5. (I always envision looking at the radar screen and seeing those bugs Bat

splattered on the dome Disgust

,instead of other vessels).
In answer to radome vs array, it seems to me that more protection from damage is offered with the dome (as the dome encloses the moving parts) and it certainly works well. Apparently there is better "target discrimination" with an open array as those antennas tend to be longer, (maybe someone more knowledgeable than me about the subject, can chime in).

Sawdust · Posted: Thu Jul 15, 2004 6:46 pm Post subject:

Larry K,

The 2 ft. open array antenna has a 3.5 degree horizontal beam width, the 24" radome has a 3.9 degree horizontal beam width. (the wave guide is shorter in the radome)

The narrower bandwidth of the open array gives a little better picture (better discrimination) and significantly better operation in heavy rain.

Depends entirely on how you plan to use the radar which one is better for your application. Most of the C-Dory gang use the dome and find it quite adequate. If you operate in heavy weather I'd recommend the open array with an increase in power to the next model Furuno (forgot -- think the 1733).

If you want more on the subject give me a pm.

HTH,

Dusty

Sawdust · Posted: Thu Jul 15, 2004 6:57 pm Post subject:

My pm email address: lester.lampman@comcast.net

Sea Angel · Posted: Thu Jul 15, 2004 7:01 pm Post subject:

I think you will find there are two disadvantages to the open array. [1] Weight.... This can be checked by looking up the antennas in any of the main parts supplier books; i.e., BoatUS, Boaters Worlds or West Marine. [2] Long term reliability due to exposure to all elements, especially if put on the highway.

The power difference for the 4KW isn't much different for the two antennas. The array has the advantage of a narrower beam width and thus great range, though you most likely will never need it, except to look at the WX. The narrower beam width will allow you to descern between 2 target positioned side by side. As an example, lets take a flashlite and pointed it at 2 mirrors facing you with a space between them. As the beam passed from the first mirror on the right, to the mirror on the left; some light will be reflected back to you -unless you focus the beam to be
narrower to the point that all the light passed between the mirrors. Any light [RADAR energy] that comes back to you will be seen on the monitor. The is what the open array does. It has gone from abt 3.9degrees for the 24" dome to abt 1.9degrees for the 24" open array.

Hope I did not get too carried away... Go for the dome. You will be happier in the long run..... art

Sawdust · Posted: Thu Jul 15, 2004 7:33 pm Post subject:

Not to worry about exposure to elements with the open array. Most of my customers with open array systems were AK fisherman operating in typical AK weather, many pulling king crab. My 85 ft. charter boat had a 4 ft. open array Furuno and was often operated in heavy weather (breaking salt seas)... never a problem.

Going down the concrete, just turn the array aft - not to worry.

But the radome is certainly adequate for what we do with our C-Dories most of the time. I'll admit I've lusted a bit for a large open array when I've been caught in heavy rain (it DOES rain up here in NW WA) -- but with the latest technolgy in the small units -- very little practical difference. My Raytheon dome is way cool.

Rusty Dusty

Larry K · Posted: Fri Jul 16, 2004 12:11 am Post subject:

Thanks for all the input. I use the boat mostly to go back and forth to our cottage on Fawn Island and it's the fog and heavy rain that I need help looking through. I don't pull the boat out of the water except in the winter and then I don’t go very far on the road.

Thanks again

Larry K
.

Chuck S · Posted: Fri Jul 16, 2004 9:17 am Post subject:

With an antenna height only a few feet off the water the horizon is well within the range of even a minutely powered radar, so "range" won't be better or worse with either antenna. Nor will more power help ya either with this very limited line of sight. Yeah, you can blast out those watts, there's just no targets for them to bounce off. The distant ones are all below the horizon.

-- Chuck

Sawdust · Posted: Fri Jul 16, 2004 11:10 am Post subject:

It's not range you are looking for, Chuck.

Heavy rain, such as our Pacific NW "damp", antenuates the transmitted signal so badly that the more power, the better. Even with all of the new gadgets, playing with all the knobs still gets you a whiteout -- and the targets you really care about -- those within a thousand yards or so, are not there.

If I could afford a 4' open, with max power, I'd have it -- even if it would look silly on the CD. When the weather is predicted to be like that we all stay home -- but weather predictions up here are like guessing the mega lotto numbers.

The six mile range is the most I ever use, and that's just to check the shipping lanes to see what tankers and other big guys are coming down the chute. The narrow beamwidth does help when trying to break out the kayaks and paddle boats, who enjoy playing in the heavy Deception Pass current in the fog. Gets your attention when one pops out of the soup a boat length or two ahead of you and you're in 7 or 8 knots of current.

Stay home? Naah. When the fish are on a roll, every day is fog day - and low vis. Charge!!!!!

Dusty

Luna C · Posted: Mon Jul 19, 2004 4:41 pm Post subject:

I don't want to offend any old schoolers, but the radar/GPS overlap is quite cool. Came across from the San Juans in the fog using this feature for the first time last week - it was great. The routes and way points make traveling back and forth, or any where, no problem as well. The radar keeps track of boat traffic as you travel. Charts and compass on hand of course!

Sawdust · Posted: Mon Jul 19, 2004 6:47 pm Post subject:

This old-school guy sure agrees! The radar overlay function is very comforting in low vis. And particularly nice if you are in a strange area and don't recognize the radar returns.

I've got a number to stand in the take-a-number line, so when the battle at EQ abates, I'll get the radar to go with the rest of the cool toy.

Dusty

Sawdust · Posted: Tue Jul 20, 2004 11:43 am Post subject:

100 percent agree! I too have used this stuff since there was a radar and everything you say is right on. No shivers like the twitchies you get when you are playing bumper boat with a target 1000 yards away and it fades away in the stinking rain clutter! You know the rules, but does the other dude?

No right answer indeed. My 24" Raynav dome does a great job most of the time and when it doesn't -- I stop, get on the horn, and have a latte. The radar I'd put on if I could afford it costs nearly as much as the boat!!

Dusty