What HF radio antenna to use?

I'm jumping back in this post with a couple of questions.

First, I'm curious as to why one needs to build a ground plane out of copper tape on a C-Dory. I thought that the ocean was the best ground plane one could get, so building a Farady cage would be counterproductive.

Second, Why would you want 50' of copper tape? RF frequencies travel on the skin of a conductor, so you need one with maximum surface area, but that only only needs to go from the radio chassis ground to a water ground, such as a metal through hull. In fact at the frequencies we're talking about, I've had good luck laying the tape on the bottom of the hull and using capacitance to sink the noise. On Our Journey, I installed a sintered copper plate, but that's overkill.

Boris
 
Still new to HAM-- just upgraded to General- so I have been considering HF on the boat.
Reading through the posts and wondered-- has anyone run copper around under the eyebrow for radials.

Thanks for helping out a "newby".
 
With copper foil/tape just under the eyebrow would not be enough. Either you want to get as much surface as possible (but the C Dory does not have a lot of metal tanks etc), tuned radials, or direct contact with the sea water (as Boris suggested). In our boat we just made sure it eventually attached to the engine, rather than adding a copper or bronze plate. If you are at rest, you can dangle a piece of foil, or copper plate attached to the foil overboard. There are some studies which show that even adding a thru hull's worth of contact will improve the signal over just the inside of the boat copper foil. With metal, the more the better capacitance ground you will have. See:

http://www.kp44.org/ftp/SeawaterGroundi ... onWest.pdf

Back to Bori's "Faraday Cage" analogy--you are not building a faraday cage, you are taking the foil/tape down to the bottom of side of the boat. If you use a heavy copper screen or mesh, again, it needs to be just above the water.

You want the ground plane to start below the tuner, antenna and radio. For me the easiest, and most portable is the double tuned whip antennas, as a dipole, (Hustler or Ham sticks, if you can find them),
 
I'm curious whether anyone has ever tried a floating wire antenna like submarines use for the low bands (160, 80...).

Probably not something you'd want to do at speed or in traffic... but at anchor or trolling speed just working on a few QSLs?

Do any of you actively work ham radios when underway, or do you mostly have the rigs on board "just in case"? I've searched through all of the ham related threads here and saw some good info, but didn't really get a feeling for how much you use them.
 
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