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Author Topic: Grounding a mobile antenna on a kayak  (Read 1246 times)
WA1ZFY
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Posts: 4




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« on: May 23, 2009, 07:03:15 PM »

Hi:

I would like to install a tri-band mobile antenna for use with a Yaesu submersible HT. The kayak is 100% polyethylene. I think I can create an effective ground plane from copper foil. The question is: how do I figure out how much foil or ribbon to install and how can I apply it to the hull? I'd like to seal the copper against the hull with some kind of clear sealant, maybe polyurethane? Any ideas would be greatly appreciated.

Thanks and 73,

Steve
NH USA
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K0BG
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« Reply #1 on: May 24, 2009, 06:29:49 AM »

Even if you covered the whole kayak, you still wouldn't have an adequate ground plane. The best you can do, will have to be adequate, but it won't be cheap. Three-quarter inch wide 3M copper foil tape, is about $15 to $20 a roll, surplus, and about twice this new.

Personally, I wouldn't be worried about the ground plane, as much as I would worry about the safety factor involved with a decent VHF antenna. Kayaking isn't a sport for amateurs (not radio), and requires adequate personal protection. Having an antenna whip nearby to poke you in the eye when you rollover the kayak, isn't a fun thought.

Alan, KØBG
www.k0bg.com
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K8QV
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« Reply #2 on: May 24, 2009, 09:07:34 AM »

I agree with Alan. One hobby at a time. I've been kayaking, and I wouldn't have found time for radio without missing the thrill of paying attention to the kayaking. It doesn't sound safe to me either. To me it's kind of like trying to play radio while skiing or playing baseball.

As far as the "ground plane" goes, each band only needs 1/4 wave radials. Why not take a small tripod and deploy the antenna with some radials when you stop somewhere?
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KB1LKR
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Posts: 1899




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« Reply #3 on: May 24, 2009, 10:47:37 AM »

Or use the HT's factory or similar waterproof antenna.
 
Same would be true for a VHF marine HT if you were carrying one (e.g. when sea kayaking or participating in an event such as the Gloucester, MA Blackburn Challenge rowing race around Cape Ann)
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WA1ZFY
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« Reply #4 on: May 25, 2009, 12:47:50 PM »

Thanks to those who responded to my question about grounding an antenna system in a kayak. I will be using a wide and stable recreational kayak (Emotion Advant-Edge) and do not expect to be operating while underway. Also, the antenna will be stowed and not left to swing around.

I wanted to use a mobile rig instead of an HT, but I think the power source would be too dangerous in a kayak sloshing with water. Having said that, how do motorboats get away with carrying huge batteries for their starter motors?

Plus, I am thinking that a ribbon of copper which went around the hull would tie the lake or ocean in as part of the ground plane, no?

Thanks for thinking this through with me.

73,

Steve
KA1ZFY
NH USA
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K0BT
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Posts: 176




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« Reply #5 on: May 25, 2009, 01:51:57 PM »

If you still want to do this, you could mount a female BNC connector in the plastic and use four 19 inch strips of copper adhesive tape on the underside to act as a simple ground plane.  Solder the copper strips and the coax shield to a washer before you adhere the ground plane to the plastic.  Connect a rubber duckie type antenna to the BNC, and you have a simple antenna.  It won't be very efficient, but it would be reasonably safe.

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WA1ZFY
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« Reply #6 on: May 25, 2009, 02:31:05 PM »

Thanks, Bob. I am going to do a whole lot more research before I do anything. I may end up with an HT in a dry bag.

73,

Steve
NH
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KD4LLA
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Posts: 450




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« Reply #7 on: May 25, 2009, 04:25:50 PM »

Are you trying to remain in contact with another kayaker, a base camp or to a repeater?

I used to work for the USA Corps of Engineers surveying the Intercoastal Waterway in Georgia.  The Corps had Boston Whalers (fiber-glass or a composite and unsinkable, believe me, we filled one once accidentally) with a marine battery (in plastic marine battery box) for the 70hp MerCruiser.

Took a HT with me many times.  Never worried about getting the HT wet or losing it as when I did use it we were stopped.  I did use a aftermarket rubberduck, a Pryme RD-98.

One of the boats had a marine VHF and GPS data link radios in it.  Both radios used regular mobile antennas with no additional foil grounding.  Granted, we did not have optimum setup or signals, but we only needed to communicate 5-10 miles simplex--over flat terrain or water.
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N7DCR
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« Reply #8 on: May 28, 2009, 10:45:59 PM »

Having run some Class 3 and 4 rapids on the Rogue River in S.W.Oregon and the S.Fork of the American River in the Sierra Nevada foothills,the last thing I would be trying to do is transmit on an HT.I would try to keep my focus on the upcoming rocks,eddy currents and churning rapids before me,along with holding onto my paddle(not CW paddle).If you are in calm waters,this would be a different story.If an emergency or communication need did arise,a waterproof container with a HT would suffice.For further gain distance,a portable,collapsible antenna,such as an ELK 2M/440CM log periodic with a short length of RG-58 coaxial cable and an appropriate HT connector adapter would suffice for the river kayak journey.Watch out for that kayak at the bottom of the rapids!..73/N7DCR.
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KB1LKR
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« Reply #9 on: May 29, 2009, 11:57:15 AM »

"One of the boats had a marine VHF and GPS data link radios in it. Both radios used regular mobile antennas with no additional foil grounding."

Most of the short (4-5 ft) marine VHF antennas tend to center (or end) fed 1/2 wave designs, so should work w/o a ground plane, e.g. over a fiberglass hull.

An end fed 1/2 wave 2m whip (Larsen, Antenex, etc.) might be an option if you're flat water or sea kayaking vs. white water.
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KC9JCH
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Posts: 29




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« Reply #10 on: June 01, 2009, 01:52:42 PM »

Don't let these guys dissuade you.  I ride many, many miles each summer in a flatwater kayak (15 1/2 foot rotomolded Easky).  I can't usually hit local repeaters with certainty using the rubber duck on my HT, and there is little or no cell coverage in far northern wisconsin.  Frequently, the HT is my only communication with the real world.  I also use a VX-7R, love it, really is waterproof, have dunked it enough times to say so with certainty.  I put a half wave "ground independant" antenna on my boat with a plain old NMO mount through a hole in the rear of the boat.  It is far enough away that even if I were to roll (rare), it couldn't hit me.  The think works fantastic, much better than the duckie and no ground plane required.  Can send photos if you'd like, but really simple install, think the antenna is made by Diamond.
Tim
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