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Old 16-07-2010, 23:26   #1
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Gimbaled Radar . . . Do it Yourself ?

My boat by design likes to heel, (the first name for my boat was " Roll n' Go") , which causes problems with radar. I just lucked into a used radar set-up really cheap, but to gimbal it costs around $1000. Does anyone have any ideas about home made radar gimbaling.
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Old 17-07-2010, 00:01   #2
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When you're in conditions that's require radar ease the traveller and mainsheet? Save $1000 and sail faster. With reasonable heel angles, 20deg, a gimbal doesn't make enough difference to matter as marine radar has a very tall vertical angle. I made a gimbal once. Used it once. Made no noticeable difference. That's my opinion.
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Old 17-07-2010, 00:29   #3
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I'm most dependent on my radar in heavy fog and at night. The two times I'm least likely to be healed more than 15 degrees are in heavy fog and at night.

I've never owned a boat with a gimbaled radar, and I've never once been in a situation where I wished my radar was gimbaled.

This is cruising. If you're in a situation where you need the radar to navigate and you're healing more than 15 degrees, it's time to reef.
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Old 17-07-2010, 01:41   #4
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as far as the amount of heel it is specific the to design of boat. big fat wide fin keels like to stay level. I don't want to argue the sailing characteristics of my particular boat just want to know about gimleted radar. BTW in a 10knot breeze I am heeled over about 30 degrees doing 6 knots close hauled.....that isn't inefficient and as far a reefing...I might take replace the genny with the working jib, it doesn't effect my speed any, just brings it back to a 20degree heel.
it's not the rig, but the hull design, a friend of mine has the same hull, but rigged as a gaff rigged cutter, he does alot of water sailing">blue water sailing and has told me how much the boat heels. The second owner of my boat thought she was a bit tender so added 1000lbs of lead on the bottom of the keel, it made little difference as far as amount of heel. The boat heels to about 30 degrees and then wouldn't go any further. She lays over on her side and takes off like a bat out of hell...that is her nature, might have even been designed like that. As far as efficiency, when the boat is heeled over that much I am at hull speed. Ever boat has it's optimum heel, which varies tremendously between hull designs.
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Old 17-07-2010, 02:08   #5
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Even at a "conservative" 20 degree heel it would still affect the radar significantly, the higher up I mount it the more the affect. If I mount the radar on the front of the mast it will have to be above the top of the forestay, about 35ft off the water. The only other viable option would be on a dedicated radar mast on the corner of the transom opposite the wind generator mast (8' 0ff the deck, 11' off the water)
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Old 17-07-2010, 02:46   #6
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Ok then 30 degrees it is. You're out $1000. That's boating.

I seen gimbals with a damping gizmo. Sounds like a good idea on a boat with as little initial stability as yours.
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Old 17-07-2010, 03:52   #7
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Gimballing a radar is a waste of time and money. It improves the performance of the radar so marginally that it hardly matters. There is no improvement whatsoever for targets ahead and behind about 45į of the CL of the boat. Gimballing will slightly improve returns for targets on the beam.

But you run the risk of fatigue of the cable which is flexing with every tack. Wires are secured on a boat for very good reason - fatigue and chafe.

And finally, others have point out that when visibity is poor that's the time to slow down, stand up the boat and the advantages of gimballed radar for targets on the beam is wiped out.

For collision avoidance a pole mount is fine.

KISS and don't fall for the gimballed radar hype.
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Old 17-07-2010, 05:55   #8
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Have owned multiple stern poles, a Questus and multiple mast mounted domes. The gimbaled radar domes performance was not discernible from the stern pole, on the same boat, that I had converted away from. This was an apples to apples direct comparison as I re-used the same radar dome and display on the same boat the only difference being the gimbal vs. a fixed pole.

The best performance will come from a higher dome than most stern poles can give you especially in a sea..
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Old 17-07-2010, 14:38   #9
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G'DAy Wolf,

It depends to some degree on the specific model radar: some have much sharper vertical cutoff in the beam than others.

Specific examples: We had a Furuno 1720, which uses a flat circuit board rotor with the active elements "printed" on it. Very soft vertical cutoff. Never could notice a performance degradation when heeled. Then replaced it with an Anritsu radar. This one had a metal reflector type rotor that looked sorta like the big ones you see at airports. It had a very sharp vertical cutoff and indeed there was a deficit in sensitivity abeam when heeled more that about 15-20 degrees. Both were mounted about 30 feet up on the mast.

Cheers,

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Old 17-07-2010, 14:54   #10
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Low cost gimballed radar pole

Manually adjustable easily if you are on a pole; just takes a little extra work on the mount by a local machine shop, Ties off to a cleat attached to the pole via the two adjustment lines. Has survived over 20 years and outlasted 3 scanners. Currently has a 4kw Raymarine (for the past 9 years or so).
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Old 17-07-2010, 23:09   #11
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I have a Ray-marine SL72 Plus, don't know the particulars of it, but got it really cheap because someone wanted to upgrade to the "latest/greatest" colour display w/built in GPS and chart plotter, etc. If I do mount it on the mast it will be about 35' up, my mast is wood.

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G'DAy Wolf,

It depends to some degree on the specific model radar: some have much sharper vertical cutoff in the beam than others.

Specific examples: We had a Furuno 1720, which uses a flat circuit board rotor with the active elements "printed" on it. Very soft vertical cutoff. Never could notice a performance degradation when heeled. Then replaced it with an Anritsu radar. This one had a metal reflector type rotor that looked sorta like the big ones you see at airports. It had a very sharp vertical cutoff and indeed there was a deficit in sensitivity abeam when heeled more that about 15-20 degrees. Both were mounted about 30 feet up on the mast.

Cheers,

Jim
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Old 22-12-2013, 09:06   #12
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Re: Gimbaled Radar . . . Do it Yourself ?

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Originally Posted by wolfenzee View Post
as far as the amount of heel it is specific the to design of boat. big fat wide fin keels like to stay level. I don't want to argue the sailing characteristics of my particular boat just want to know about gimleted radar. BTW in a 10knot breeze I am heeled over about 30 degrees doing 6 knots close hauled.....that isn't inefficient and as far a reefing...I might take replace the genny with the working jib, it doesn't effect my speed any, just brings it back to a 20degree heel.
it's not the rig, but the hull design, a friend of mine has the same hull, but rigged as a gaff rigged cutter, he does alot of blue water sailing and has told me how much the boat heels. The second owner of my boat thought she was a bit tender so added 1000lbs of lead on the bottom of the keel, it made little difference as far as amount of heel. The boat heels to about 30 degrees and then wouldn't go any further. She lays over on her side and takes off like a bat out of hell...that is her nature, might have even been designed like that. As far as efficiency, when the boat is heeled over that much I am at hull speed. Ever boat has it's optimum heel, which varies tremendously between hull designs.
Hi,Have a 40ft Hinckley full keel owens cutter and she likes to heel and do best around 20 to 25 degrees.I do almost all bluewater cruising,solo.I prefer to be on deck 6pm to 6 am.With 1000ft container ships with an aft bridge,going 20 plus kts, I just assume they can't see me.Good chance there's nobody on the bridge and would,nt do anything if there was.I gimbaled my dish and used over the counter hydraulic auto hood hinges? running from my mizzen spreader down to my fabricated bracket.Whole thing cost around $200 bucks,and am really happy with it.
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