[TowerTalk] [Bulk] Re: Vertical Antennas near salt-water

Thu Feb 4 14:07:22 EST 2016

Professional HF SSB installations on wooden and Fiberglass boats 
typically use a "ground plate block" mounted external to the hull in 
contact with the sea water. These are often copper with fins like a heat 
sink to increase the area of contact with the water.  Some ground plates 
are maybe 6-8, inches tall a foot long and a couple inches thick 
measured to the top of the fins. This may not be the best that can be 
done but is often what is done. I'm not sure how much degradation of the 
grounding occurs when marine growth fouls the surface of the ground 
plate but cleaning as necessary to keep the growth off is recommended.   
I used my monel shaft and bronze propeller for electrical contact to the 
sea and the engine and transmission bonded in as additional 
counterpoise.  Worked well but risked lightning going through the 
auxiliary engine and welding the shaft to the bearings or similar.

Patrick        NJ5G

On 2/3/2016 9:32 PM, Gary Schafer wrote:
> Unfortunately the article does not mention a vertical mounted OVER salt
> water. Laying a small number of radials on the sand or coral rock near the
> water is not going to give a very good connection to the salt water. That
> was apparently evidenced by the detuning of the radials.
>
> Since the skin effect of salt water is only a few inches deep, laying few
> radials in the water would not provide much benefit. You would only have the
> connection to the water within a few inches of where the wires enter the
> water.
>
> Several years ago when I lived in Florida I had a 40 meter vertical mounted
> to one of the dock posts over the water. The base of the vertical was about
> 2 to 3 feet above the water depending on the tide. I had a large bare
> aluminum plate 2 feet wide by about 6 feet long placed vertically into the
> water right below the antenna. This was the ground connection to the water.
> It only takes a couple of square feet of water contact to realize a good
> ground connection.
> The impedance at antenna resonance was right close to 36 ohms with no
> matching device. I used a small coil and cap to match to 50 ohms. It worked
> very well.
> Of course as the tide level changed so did the resonant frequency as the
> length of the ground plate to water was changing.
>
> 73
> Gary  K4FMX
>
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
>> Mike Ryan
>> Sent: Wednesday, February 03, 2016 4:56 PM
>> To: Bill
>> Cc: towertalk at contesting.com
>> Subject: Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water
>>
>> There has been a ton of talk on this subject. I myself live on a salt
>> water
>> canal in Florida and have tried various vertical antennas over the salt
>> water, aside it, next to it, etc.  There is so much MISINFORMATION and
>> downright speculation based on wrong assumptions, guesswork, and the
>> like.
>> Someone did a great article on the subject who was in fact a contester.
>> (Should that be spelled contestor, or contestee? ..you decide)  At any
>> rate,
>> if you read article which can be opened from the link I have attached,
>> play
>> close attention to the paragraph that reads
>> " ... often incorrect assumptions about verticals: ".  This is
>> enlightening
>> but the information is based on success or failure in the field and not
>> supposition which in my OPINION counts for something!  -Mike
>>
>> Subject: verticals
>>
>> http://www.k2kw.com/verticals/learning.html
>>
>>
>>
>>
>> -----Original Message-----
>> From: Bill
>> Sent: Wednesday, February 03, 2016 2:55 PM
>> To: Towertalk Mailing List
>> Cc: Chuck Dietz
>> Subject: Re: [TowerTalk] [Bulk] Re: Vertical Antennas near salt-water
>>
>> My HF2V and Butternut 6 BTV are both attached to metal posts at my sea
>> wall. Both posts go into the salt water. They work at 1:1 SWR with no
>> radials. I do have some in the water but always wonder why? Hi...
>>
>> They both perform very well and load on all bands.
>> Bill W2CQ
>>
>>
>>
>> On 2/3/2016 2:30 PM, Chuck Dietz wrote:
>>> I had a vertical for 160 on a small peninsula in salt water. I ran the
>>> radials into salt water in 4 directions and pushed aluminum tubing
>> pieces
>>> into the bottom in the salt water with the end of the radials clamped
>> to
>>> them. Awesome antenna on transmit. Fair on receive. Just need enough
>>> radial
>>> length to get to the salt water.
>>>
>>> Chuck W5PR
>>>
>>> On Wednesday, February 3, 2016, Gary K9GS <garyk9gs at wi.rr.com> wrote:
>>>
>>>> I had an interesting discussion with a friend over the weekend and
>> wanted
>>>> to get some input from the TowerTalk community.
>>>>
>>>> Imagine a 1/4 wavelength wire hanging down from a tree with the
>> bottom
>>>> end
>>>> attached to a post set into the salt water.  The antenna wire would
>> be 3
>>>> or
>>>> 4 feet above the water.  What should be done with the
>> radial/counterpoise
>>>> wires?  Should those wires go into the water?
>>>>
>>>> Or imagine a similar hanging wire that has the bottom end attached to
>> the
>>>> top of a seawall.  Again, the bottom of the antenna would be 3-4 feet
>>>> above
>>>> the water.  Should the radials run on the ground parallel to the
>> seawall
>>>> or
>>>> run into the water?
>>>>
>>>> A third situation would be a vertical antenna mounted at the end of a
>>>> pier.  Run the radials back toward shore along the pier or run all of
>> the
>>>> radials into the water?
>>>>
>>>> Finally, if the radials are in the water does it make any difference
>> if
>>>> the wire is insulated or not?
>>>>
>>>>
>>>> --
>>>> 73,
>>>>
>>>> Gary K9GS
>>>>
>>>> Greater Milwaukee DX Association: http://www.gmdxa.org
>>>> Society of Midwest Contesters: http://www.w9smc.com
>>>> CW Ops #1032   http://www.cwops.org
>>>>
>>>> ************************************************
>>>>
>>>> _______________________________________________
>>>>
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