chrism
regular
Reged: 14/08/2002
Posts: 10
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Can I use the iron keel on my boat as a ground for ssb instead of those expensive coper plates? Failing that why can't I just dangle a copper braid over the side .....yours in blissful electrical ignorance Chris
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KellysEye
regular
Reged: 23/07/2006
Posts: 626
Loc: Trinidad
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Copied from a site about SSB:
"No Pain, No Gain. Think Metal Surface Area. The RF ground installation is different for every boat but the basics are the same. You want to attach all big metal items on the boat together with copper strap and end up with a minimum of 100 square feet of metal surface area. Starting with the Automatic Antenna Tuner, the tuner should be mounted close to the feed point for the antenna which means it is usually mounted aft. From the tuner, copper strap will run forward and attach to the engine, any (and hopefully all) metal tanks and a keel bolt (any one will do). Getting the copper to metal toerails and the stern pushpit along with the lifelines can be of tremendous benefit. When incorporating the pushpit and lifelines, extra care must be taken with the route of the antenna feed wire."
To put that in another context, the best ground is to have a steel boat. Next best is to run copper bow to stern along the bottom of every bilge attached to any metal along the way. Do that in both hulls of a cat and the signal is awesome.
Copper braid over the side won't work - it's all about surface area.
Edited by KellysEye (02/05/2008 20:56)
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Eeyore
regular
Reged: 05/10/2007
Posts: 89
Loc: Marmaris, Turkey
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Following recent investigations (and fitting of SSB ground plate), most 'experts' are of the opinion that the SSB should be grounded alone. All the other fittings should be linked together and grounded to a sacrificial anode......but other 'experts' tell you not to link all metal fittings as this can speed up the galvanic corrosion of bronze skin fittings, SS prop shafts etc.
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Free gangway is now open.
www.yachtrhumbdo.co.uk
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whipper_snapper
regular
Reged: 09/08/2006
Posts: 1177
Loc: Kenya
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I agree with almost all KellysEye says. I think the message is that for most boats an expensive grounding plate will add little or nothing except perhaps simplicity of installation.
But I have a dynaplate on mine! Because it is a wooden boat with almost no metal permanently immersed; in fact 2 seacocks is it. I could run copper up and down the bilges and I know that would be at least as good as the dynaplate, but it is practically very difficult to arrange.
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oxman
regular
Reged: 25/07/2007
Posts: 127
Loc: South Coast UK ..................
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Forgive my ignorance but how can attaching all metal objects improve the grounding - surely the contact to water is the most important factor - I have been advised that attaching to a seacock is therefore adequate (although I have yet to test this!!).
2nd question - when talking about a "copper Strap" - how big a strap is required or can a decent domestic 6mm earthing cable from your electrical wholesaler do the job?
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Everyone is entitled to my opinion!
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jerryat
regular
Reged: 20/03/2004
Posts: 3096
Loc: Nr Plymouth
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Entirely agree. The grounding for the ATU should be taken to a sintered plate or, far preferably to a cast iron keel using 75mm wide copper foil tape. This will provide a fantastic counterpiise.
Linking metal components together is a definite no-no AFAIC, and these should be linked back to an anode and not form part of the counterpoise system. The best situation is, of course, to connect the tape to the hull in a steel boat - gives superb results!!
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jerryat
regular
Reged: 20/03/2004
Posts: 3096
Loc: Nr Plymouth
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Quote:
Forgive my ignorance but how can attaching all metal objects improve the grounding - surely the contact to water is the most important factor - I have been advised that attaching to a seacock is therefore adequate (although I have yet to test this!!).
2nd question - when talking about a "copper Strap" - how big a strap is required or can a decent domestic 6mm earthing cable from your electrical wholesaler do the job?
There is absolutely NO need for the metal ground to be connected directly to the water, indeed you will get excellent results by glassing in a copper mat on the INSIDE of your hull. I recommend connecting to a keel bolt simply because most boats have one. A seacock, on it's own is next to ueless as you need surface area to provide the necessary counterpoise to the aerial.
As I noted in an earlier post, you need to obtain some copper tape about 75mm wide (50mm will do) and just a few thousanths of an inch thick - you can tear it easily by hand. It's expensive in this country, but you don't need much. Because of the relatively low surface area copper 'wire' or cable is nowhere near as effective.
Fold the tape over on itself a few times at each end to give it some mass, drill it, and connect directly to the grounding bolt on your ATU (automatic (aerial) tuning unit). Glue or otherwise fix the tape into position along the bilge or adjacent woodwork to your nearest keel bolt, sintered plate or copper mat and connect it.
That's it, though you may wish to do as I and others do and paint it. This will provide excellent protection against early corrosion. The tape is, of course, very thin and therefore vulnerable.
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chrism
regular
Reged: 14/08/2002
Posts: 10
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And what about the aerial? I found something about a halyard aerial at http://www.ropeantenna.com/ which sounds a) cheap and b) effective,,
Any body with experience?
Chris
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whipper_snapper
regular
Reged: 09/08/2006
Posts: 1177
Loc: Kenya
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What boat ?
For most monohulls, an isolated backstay is the answer. Some people hoist a wire as needed, but it seems bizarre to have system that you can't use while sailing. Again, I don't take my own advice and I am about to instal a whip because my boat has running backstays.
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Captainslarty
regular
Reged: 12/08/2007
Posts: 2012
Loc: Currently La Coruna Spain
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Hi
There is much confusion and old wifes tales etc re ssb grounding.
Dynaplates are not much cop, period.
Copper strip is 'ok' and I am sure the manufacturers make lots of money from it. 
YES, you can get an excellent ground by connecting to the keel.. no worries.
I use a single bronze through hull for the ground.. with a 23 foot whip antenna. superb..
If you want to add more metal, then you dont need copper plate or strip, use 6 mm cable, connect each item VIA a 0.1 uF disc ceramic capacitor to produce an RF path and block and dc hence no worries from galvanic interaction.
I service and repair SSB and radio equipment, including new installations and problem solving old ones.
A heck of a lot of ssb noise issues are simply land noise (No worries at sea !), battery chargers, fridges and other euipment. If you can get hold of an old RDF its a great tool, I use one to detect RF interference. works a treat..
Also, use a good quality atu.. the SGC SG230 is the mutts nuts.
Have fun, and gud dx.
Joe
G4XRZ
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PM me for info re SSB's etc. Bought, sold, repaired, fitted and optimised.
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