How tall is your radar mast?

downeast450 · #1 (**permalink**) 06-21-2011

I have followed the excellent advice of one of our "Downeast" sailors and built a radar mast / mount for our new Garmin HD18. It is time to install things and I am starting with a 9' pole. It is all drilled and ready to put up. I have a couple of secondary braces. I started with a 9' section of pipe and am thinking of cutting a foot off. It looks high and one less foot, provided it will be above human activity, will cut down on the moment of the dome. How tall is your stern mounted radar mast? Thanks to Rikhall! for the design. It cost me only for the welding, the section of sch40 aluminum pipe and the bolts. I scrounged the 1/4" plate from a friends scrap pile and cut it all out with a scroll saw.

Down

jerryrlitton · #2 (**permalink**) 06-21-2011

As near as I can figure it if your antenna is 10 feet above the water it will only see under 5 miles. That is too thehorizon of course. If the target is higher then it will show further out. I would try to get it as high as possible.

http://tscm.com/rdr-hori.pdf

SVAuspicious · #3 (**permalink**) 06-21-2011

My radar sits about eight feet above the deck, about twelve feet off the sea.

downeast450 · #4 (**permalink**) 06-25-2011

Thank you for the input. Since I am starting with a 9' mast I will keep it and see how I like it this season. That will put the dome almost 12 feet off the water. It is a simple change to cut off a foot and drill another base mounting hole. I am using two secondary braces and the stern rail for support. One brace runs forward and the other one athwart ship. It looks a little over done but it is a work in progress. I would rather have too much support than too little.

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Maine Sail · #5 (**permalink**) 06-25-2011

Ours is about 12.5 feet off the water and far to low for decent open ocean performance. If the damn pole was not awlgripped around it would be on the spar in a second. Stern poles are fine for bay sailing but drastically lacking for open ocean use.

Go as high as you can...

downeast450 · #6 (**permalink**) 08-23-2011

I put up the 9' mast. That lifts the dome almost thirteen feet off the water. It looks, and is, much taller than any of the sailboat radar masts in Seal Harbor. It looks like a short mizzen mast. Ha! This is the only 28' boat here with a radar mast and it looks tall for the boat. I am fine with how it looks if it gives me the eyes I need to navigate our summer fog banks with some security. It does need to be as high as possible and it is well supported. I was aboard yesterday doing the final wiring for the radar. We had a nice sw breeze at 8 to 12 knots, steady. oooooh! and I had to sit on the mooring working on the boat. The I-28 is a fairly narrow hull and flares from the keel to the rail. It is a nice shape from the transom. Much like our 3/27 racing canoe. Not slap sided or tumblehomed like the other "cruising" boats. Its hull shape and fin/spade underbody give it a tendency to wander back and forth in a steady breeze. Not an unusual thing as I watch other boats but I wouldn't miss it if there was a simple solution. How about a short light weight hinged boom off the radar mast and a stay sail? It is strong enough for the intermediate breezes that seem to enjoy leading Tundra Down on this drunken swagger. It would only be deployed when I was aboard. Has anyone seen this done? What do you think? I can build it and the sail. I think I will try it out unless I hear a good reason not to. Riding at anchor with a constant view ashore would be nice. Trimming the sail and the rudder could change the angle and keep it fairly steady I think.

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rikhall · #7 (**permalink**) 08-25-2011

For me, I think "where you sail" and the consequential amount and kind of traffic you suspect might give you a clue. We just did 850 NM and five weeks going from New Brunswick, Canada down and around the Penobscot and back. Used the RADAR quite a bit. Not many places to use it on more than 1 or 2 mile settings, lots and lots of places to use it on .5, .25 and even .125 settings.

I put it on 6 miles to "see" Grand Manan when we came up the eastern coast of Maine. Then it was back to 1 or 2 mile settings.

Just one coastal cruiser's experience and ideas. Not on the boat now to measure, but I think I have an eight foot pole.

"Never judge a skipper by the size of his pole"

(sorry, could not resist)

Rik

SlowButSteady · #8 (**permalink**) 08-25-2011

Is that a radar mast? Or are you just happy to see me?

(Sorry. But someone had to say it.....
As you were....)

KnottyGurl · #9 (**permalink**) 08-27-2011

why the pole and not on a mast mount ? I am looking to put radar on my boat as well, from what I have seen in my area they are all on the mast around the first spreader, 15-20 or so feet up.

SVAuspicious · #10 (**permalink**) 08-27-2011

Quote:

Originally Posted by KnottyGurl

why the pole and not on a mast mount ? I am looking to put radar on my boat as well, from what I have seen in my area they are all on the mast around the first spreader, 15-20 or so feet up.

A radar pole has a number of advantages -- I simplifies cable routing and ultimately removing the mast if needed someday, it provides a great place for other antennas, and it makes a dandy place to mount an outboard hoist. All in all very convenient. I'm pleased with my choice of a pole over a mast mount.