SSB Ground - Any Dynaplate Users?

[Cap'nJeff]

Hi Folks,
I''m installing an SSB soon and must create the antenna ground. I''ve read about installing copper foil for a capacitive ground and using fuel/water tanks - sounds like a chore. It''s tempting to go the quick route and install a Dynaplate but I hate drilling any hole below the waterline. Other cruisers tell me that the Dynaplate will not be very efficient if it geta any algae growth on it.

Are there any dis/satisfied Dynaplate owners out there?

Thanks in advance for your help.

[kimberlite]

jeff,
i believe you need a 100 sq foot counterpoise consisting of copper foil. dynaplate is a good ground but will not suffice. its a bitch adding all the copper but it is necessary. mc master carr has nice wide THICK copper for this job.
what radio did you buy?
eric

[serengeti]

Dear Cap''n Jeff,

From the east cost of the United States, we routinely talk via our SSB with cruising friends in Europe, Central America and South America. For our ground plane, we use a Newmar Ground Shoe, size 6x18. This type of ground equates 100 sq/ft of copoer and foil laid throughout your hull. When checking in to various cruiser''s nets, we are repeatedly told that we have a very strong signal.
Recently we spoke personally with Gordon West rearding this type of ground, and he concurred that all that copper strapping was no longer necessary with modern-day equipment.
So, based on our experience, we encourage you not to bother with all that copper. Drill those holes in your hull, it ain''t so bad, and install a dynaplate. You''ll be glad you did.

Regards,

Sue and Larry

[tmcahn]

be sure to attach the dynaplate as close to the tuner as possible--also attach your water/fuel tanks with copper foil to the ground system--i''ve done both and have an excellent signal, tmc

[jack_patricia]

Hi, Jeff...

Here''s a specific answer to your question & also some differing opinion from what you''ve already received:
1. We were forced to rely primarily on a Dynaplate for our counterpoise on a previous boat. We too got consistently good signal reports but that often means little (see below) and I''m sure that we could have had better xmit performance if we''d access to more mass below. So...it will work but isn''t THE answer.
2. Newmar usually makes good stuff, and perhaps the ''shoe'' is comparable to a Dynaplate, but most likely not ''the'' answer, either.
3. Signal reports for one install method are - regretably - a terrible way to determine how to install your system. This doesn''t have to do with the honesty of the reporter, but rather the typically poor form of signal reports offered on Marine SSB. (I''ve yet to hear one Marine SSB user give a report based on the one common baseline method - RST - that''s in use, so who knows what ''good'' is?) Ham operators are usually better about this only because they tend (at least in some cases) to know something about radio operation & procedure. So...my point is that its tough to know which choices to make based on what I or someone else will tell you about how great our radio works. (OTOH, I have a GREAT radio installation...!<g>)
4. Here''s the approach I''d recommend for your counterpoise. Start simple, running 4" or wider foil (sold by the foot by Defender; good price) in the bilge from the tuner, forward to whatever largest metal mass(es) you can reach that are not in turn tied into your 12V negative ground. (Read each piece of that sentence, again). Don''t overlook using your lead keel, as encapsulated lead keels can often be reached by drilling a hole down thru the fiberglass cap and then using a lag screw to tie it to the foil. Be creative. E.g., one great additive source of a counterpoise are the half-oval stainless strips on rub rails. If you fell you must install a dynaplate at this point, you may not be trying hard enough. Now - after the inevitable teeth-cutting problems as you learn how to work your radio - determine with the help of multiple knowledgeable signal reports, on different days, how good your counterpoise is. Ask around: your boat may be in a bit of an rf black hole (e.g. St. Pete''s marina has this reputation; so does Satellite Beach near the USAF base); adjust its location when doing this, if you need to. Only after you''ve done this initial level of install, consider adding to your counterpoise.
5. People often confuse rf ground (counterpoise) with 12V negative ground, thinking they are essentially the same. This can lead not only to rf running all over the boat''s electrical system, squirting out in funny places, but it can seriously degrade your transmit or receive ability. I recently helped 2 boats fix huge problems caused by them diligently tying these two systems together thoroughly. That''s why I caution you to stay clear of using the engine, metal tanks (which are most likely grounded), etc., at least initially.

Good luck! You''ll no doubt find SSB adding immeasureably to your boating pleasure; the effort is worth it.

Jack Tyler

[yandina]

How the dynaplate works.

The theory is that the porus surface of the dynaplate provides a very large surface area contact with the water - many times the area of the plate itself.

The truth is that the resistance of the seawater down through the crevices is so high in comparison to the copper to seawater interface that it doesn''t provide any added advantage over a plain copper plate of the same size.

I don''t imagine that green marine growth diminishes the effectiveness very much, although barnacles may have sufficient insulation to reduce the surface area.

I believe that Practical Sailor did a test on dynaplates and found them no more effective than an equivalent copper plate.

If you have a metal keel, even if enclosed in fiberglass, this is the best and easiest ground to use.

[kellysails]

Jack,

If one was to keep 12volt grounding system and counterpoise separated, how would you ground the negative side of 12 volt power to the radio set? I would assume that if you used the 12 volt grounding system for power it would end up bridged to the counterpoise system via the radio. But I assume that you need use the 12 volt ground in order to complete the circuit to the batteries.

Regards,

Craig

[thekeip]

This debate comes up way more often than is necessary. If you have the time and energy, and a reasonably clean area onto which you can affix the necessary foil, then by all means do it. Any of the techniques described here work. I have gotten used to laying down the foil or sheet with fiberglass carpet tape...the adhesive is unbelievable...but your hull must be clean. No diesel oil. Yes, you will get predictable results consistant with the effort you put into the installation.
Having said that, installing a Dynaplate will give comparable results. Maybe no better, but definitely no worse either. If your boat is on the hard, it is usually very easy to pick a place close to the tuner where you can connect, once again, using copper foil or sheet. BTW, get your copper in whatever form you like from a roofing supply store, not WM.

Dynaplates last virtually forever, probably longer than the boat and certainly longer than the strips laid in the bilge. Marine growth does not affect the grounding characteristics of the plate one iota, though it may make you feel better if you had it scrubbed with a wire brush when your bottom is cleaned. It is a fact that it's thickness might slow you down if you race, but not much.

I don't have a horse in this race other than I install SSB's and I don't like call backs for poor performance. The bottom line is that you can't use performance as the criterion on which you make your decision.

Howard Keiper
Berkeley

[kellysails]

More great info Howard, thanks,

So do you subscribe to the practice of keeping counterpoise and 12 volt grounding separate? I can certainly see why RF leaking into the 12 volt grounding system would be a problem. Boy, building separate systems sounds like a lot of work and engineering.


Regards,

Craig

[thekeip]

Hi Craig....

Yes indeed, I do.
I know it's fairly common practice to make the engine and any other convenient mass of metal below the waterline part of the counterpoise system, I just don't like to do it if other options are open.

howard keiper
Berkeley