SSB Radio

[BrendanChandler]

I am rigging out a Beneteau Idylle 11.5m for long distance cruising. I should be grateful for any advice on the most suitable SSB radios available. Are there any recent comparisons available in the yachting press?
I believe that an earth plate is required. Can the cast iron keel be used?
All advice gratefully received.

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[MainlySteam]

The Icom IC-M710 was the cruisers radio of choice. While still available, it has been replaced by the IC-M802 which is what I use in my own boat and I am sure will become the cruisers radio of choice. It is also especially convenient for radio amateurs. If you buy a second hand IC-M802, and I see them appearing second hand, be aware that the very first ones had some problems (low output on SSB and co-ordination with ATU problems).

You can use your cast iron keel as the earth but be aware that if your DC negative is grounded as it is in some boats (even if only to the engine because of non-isolated temp/oil sensors etc) and the radio you select has a grounded negative too through its rf grounding (many do, including the IC-M802) you may (a small may) introduce some galvanic problems that did not previously exist through unwittingly connecting dissimilar metals together electrically. If is a problem it can be avoided by placing a correct capacitor in the earth lead from your radios ATU (If you do not know how to do this, a good marine electonics technician will make one up for you at little cost - the components only cost a pound or so, plus half an hours labour if he knows what he is doing).

If you use your keel, assuming your boat is frp and your antenna is at the stern (so the ATU will be at the stern) for the ground from the ATU to the keel you should use wide copper foil to minimise impedance. It should be dressed closely to the inside of the hull so that it can itself capacitively couple through the plastic hull to the seawater outside.

John

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[ccscott49]

John, can you use those sintered bronze plates/ do you know if they are any good, I would need to fit two, one for the set and one for the ATU, would this be ok, if I use copper foil? My boat is wood, with no iron keel.

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[MainlySteam]

If you use one you only need one for the ATU - and in any event I normally do not ground the radio itself, except as happens naturally through the coaxial cable shield from radio to the ATU, that for common mode current reasons which I won't go into. I have never personally used one of the sintered bronze plates myself but some swear by them (however, some even swear you don't need an earth at all!) but I am dubious. The problem is, without direct comparison of them with another system known to be excellent it is hard to tell - if propagation is good, anything will give some sort of result and it is easy to be fooled into thinking one has a good system.

The only direct experience with them I have had is rafted up at the boat yard with a big timber/glass composite boat who was having one installed with a new SSB. After it was installed he compared side by side performance with ours (we are a steel boat) and went away feeling very dismal about what he had done. I have to say it did not, for whatever reason, compare well.

The boats I am normally involved with are all metal so there is no problem. My best approach in a timber or frp boat, assuming no large area available from a metal keel (even if encapsulated), would be to have a large copper plate of several sq.m's on the outside of the hull with a feed through the hull to the ATU and also bonded to other metal parts as the method that follows. However, quite reasonably not many of us want to do that, so my next preference would be to lay a largish area (magnitude of sq. m's) of copper foil inside the boat below the waterline to capacitively couple through the hull to the sea (physical contact with the sea is not necessary for radio frequency) and also bond that to other underwater metal parts of the vessel - that last bit only if your underwater parts are already bonded amongst each other, otherwise one has to take care that one does not introduce galvanic problems by connecting incompatible metals together with conductors. That will obviously go green and unhappy looking in time in a wooden boat with wet bilges though, but still be effective. Metal water tanks, for example, which are not physically in contact with the sea, should be included. To try that roughly set up as a first approach, even using aluminium foil temporarily to see, is relatively cheap and if not satisfied not much is lost - I would be pretty confident, however, that it would perform better than a sintered plate.

I have not done a wooden boat, but I personally would not spend my money on a sintered plate and the few I have looked at closely in that respect have done as set out above. I have seen poor comments about them but never for the solutions above. In some high quality frp boats the builders have the forethought to bond a large area of copper mesh into the layup. I may be wrong and I am sure some will say so - a good test for those that claim so is that a good radio installation should be able to work around the world at sometime of the day on most days.

John

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[ccscott49]

Thanks, John. With my boat, it would be almost impossible to put sq.m's of copper inside the hull, the construction would just not allow it. I was hoping for an easy way out, it now appears, there just isnt one. the keel band is bronze, 15 meters long and about 20 cms wide, I could concievably bond to that, also connected to a big bronze rudder, about 3 sq.m's would that do? The fuel tanks are steel, but not all below the waterline and about 15cms from the hull, any good?

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[Guest]

Post deleted by danfoley

 

[MainlySteam]

I would definitely go for the bronze keel band and the rudder - a conservative guess means you would have 5 or 6 sq.m of bronze as a ground which I would be confident is as good as most else you would be able to do. If the rudder stock is electrically connected to the blade (which I assume almost certainly it is) one could test the setup cheaply by making a temporary earth connection to that. That is assuming that no more easily accessible bolts come through to the bilge from any part of the keel band or rudder fittings - but, whatever, try and make the ground connection from the ATU as short as possible and unless it is very short use wide sheetmetal copper strip for the connection.

With a wooden boat one can do that by mounting the ATU lower down in the boat (but not below the waterline), but keep in mind that everything from the ATU antenna connection upwards will be part of the antenna and is a burn hazard if accessible and touched (it, probably obviously, should also be kept away from other cables and metal objects too). As an insulated conductor below decks, where there is no UV, for the antenna up to the deck, I have used the centre conductor and its insulation stripped out of the large dia coaxial cable (eg RG8 or URM213) as it is sturdy but you must remove the copper shield from it. Otherwise use GTO-15 or whatever is commonly used there.

The engine is also something that is often recommended for connection into the ground system, but I would tend to try without it first and if that works add the engine for good measure. That way, should you find that use of the engine interferes with its instruments, etc, you have the cause isolated and can just undo the engine connection again.

John

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[MainlySteam]

Thanks for the comment Brian. That is well worth knowing.

John

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[ccscott49]

The connection from ATU to rudder, would be about 4 feet, as the ATU would be in a stern locker, with a big whip on the transomsticking out at an angle of maybe 20 degrees. the connection to it, would be less than 2 feet. I would physically connect the keel to the rudder, with a copper strap, as I cannot rely on the bearing, as it is greased. Would a flexible big battery strap do, to connect rudder and keel band? this would undoubtably be the easiest and cheapest way. Thanks for all your advice, just what I needed, somebody to tell me SIMPLY what to do.

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[MainlySteam]

The conductor to connect the keel strap and the rudder need not be very big - something like a battery strap sounds fine as long as it is galvanically compatible with the bronze. For the copper strip down from the ATU to the rudder make as straight as possible - if a right angle bend is required narrow edge on so to speak (rather than a bend just requiring a bend across the width of the strip) I think that folding the strip over on itself to get the bend is satisfactory.

If you use the arrangement that is outlined I would think you would end up with a good solution and if you find that you have problems with the radio or interference with other equipment, I think that you could be confident enough to look for problems other than your earthing for the cause. Because of the proximity of the antenna to the rest of the boats electrics, and for other reasons, interference is common (both ways in fact) - but that is to worry about if it happens.

John

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[ccscott49]

The antenna, being right aft, will not be near any other elctrics. I think I can arrange a very straight path to the rudder stock, so thats the way I will go. Thanks again John for all your help it's much appreciated.

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[Talbot]

I am starting to fit out my cat for long distance and have been advised that SSB would be a better bet than Iridium, from what you have been discussing so far on this thread:
could I use my two stainless water tanks as the ground, they are in the bilge below the waterline, but not actually touching the outer hull (they are abt 5ft long and 2 ft wide)?

What licensing would I need to have Tx/Rx SSB?

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[BrendanChandler]

Hi John,

I have read this exchange of correspondence with great interest. I have isolated the back stay for use as an ariel.
I do not know the physical size of the ATU so am not sure where in can be stowed.
As I wish to use the keel am I correct in thinking that the ATU should be placed as near the keel as possible eevn though this moves the ATU further from the aerial?

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[Roberto]

<<the ATU should be placed as near the keel as possible eevn though this moves the ATU further from the aerial<<

the atu should be fitted as near as possible to the *aerial*: on the atu you will find (among power, ground and transceiver coax input connections) an output lug for the antenna; your effective antenna will start there, meaning that radiation begins at the ouput lug. I suppose you do not want radiation in the bilge...

And also: from the atu output lug you need a thick section feeding cable to connect to your backstay, your physical antenna length then will be from the upper backstay insulator to the atu lug.

So the cable from the atu to the backstay should be as short as possible, and should not run near to grounded parts of the boat, otherwise part of the radiating energy will be lost into ground.
If for example your lower backstay turnbuckle is grounded, it is better to keep the connecting cable separated from it: while it runs parallel to the lower section of the backstay (the one not between the insulators), it should pass through a serie of spacers (ex 10cm long, 1cm diameter pvc pipe) that avoid too close proximity between the antenna feeding cable and the uninsulated backstay.
Arches, radar poles and all metallic struts aft pose similar problems but can be adressed with proper positioning of feeder cable.

hope this helps

rob,m0ita

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[beneteau_305_553]

I connected my ICOM 710 earth to the keel with 6mm2 copper cable and added an annode to each side of the keel and bonded between.

Worked well with being able to speak to herb (Canada) while crossing biscay and speak to the canaries from uk east coast.



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[MainlySteam]

As has been said, the antenna will start at the antenna connection on the atu. In a timber or plastic boat as long as the atu is above the waterline the antenna will, in itself be alright, but remember that the part of the antenna inside the boat needs to be kept clear of grounded and metal objects, and cables. The antenna should not be run horizontally through the boat for the purposes of minimizing the distance from the atu to the ground (in your case the keel). Your atu should be placed at the stern of the boat (usually mounted on the inside surface of the transom is the most convenient) and the ground conductor taken forward from there through the bilge to the keel.

If the lower part of your backstay is not grounded ie the chainplate is just bolted to the fibreglass hull with no connection to the sea or your keel, then the antenna coming up off your tuner can just be taped to it - however, I have known cases of voltage breakdown of the insulation on the antenna wire burning through to another wire closely dressed or sufficient voltage being induced on it to become a light burn hazard when transmitting (as it is uninsulated) so you may wish to space it off just as described in another post as if the chainplate was grounded. If the chainplate is grounded (it usually is not) then you must space the antenna feed from the atu away from the chainplate and stay as described in the other post.

John

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[BrendanChandler]

I connected my ICOM 710 earth to the keel with 6mm2 copper cable and added an annode to each side of the keel and bonded between.

Thanks for that Richard.
How did you attach the earth lead to the keel?
Was there much wear on the anodes?
What do you mean by "bonded between"?

Brendan

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[BrendanChandler]

Hi Talbot,

As I understand it, there are 2 choices.
We can either do GMDSS Long Range Cert which would qualify us to use the Marine SSB channels or
we could do Ham qualifications which are at different levels each level allows use of certain frequencies at certain signal strengths.

As I understand it, the new ICOM M802 has both SSB and Ham frequencies available, it may be necessary to have a dealer 'enable' the ham frequencies.

I wait with interest for advice from those in the know as I need to decide on the route to take.

Brendan

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[Roberto]

Brendan,

there are several differences between marine and amateur radio uses/qualifications

Amateur radio is far more comprehensive, it usually takes a few month study, either at a local amateur radio club or by yourself, after that you have to pass an exam and can get your licence and callsign. Personally, as a newcomer a few years ago I did not find the subject too difficult, there are just many things to learn but really anyone can do it. The subjects are also quite interesting.
You may want to look at rsgb.org site for additionl info, especially for morse qualification (12 word per minute were needed for High Frequency band access, now I think regulations have changed and surely it is much easier, maybe not needed any more ?).

Marine ssb LRC can usually be had in a week study. Obviously, if you go through the amateur licensing then you will find the LRC very basic indeed.

Now, suppose you have your radio "opened", with both accesses to amateur and marine bands receive - transmit.

No problem in listening to both bands, you can tune to amateur or marine frequancies and listen to them.

Very different thing for transmit : if you do not have a amateur callsign, you will hardly find any radio amateur willing to talk to you, not that they are discorteous but if talking to a non licensed person, hams would be in breach of their licence and possibly lose it.
Quite a few sailor are hams, try listening to 14.303MHz at 0800 and 1800 and you will have an idea. If you plan to sail in the atlantic, caribb or pac then I strongly suggest a ham license.

Personally, I have both licenses and found that usually marine band shore stations are much less stringent in terms of regulations, many boats simply talk to them using their name. Also, there are less opportunities to talk to shore stations: usually for repeating a weather report, or make a telephone patch.

In an distress or emergency situation or in the middle of pacific ocean.. I think authorities would probably close an eye

imho of course

rob m0ita

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[Boatman]

Colin,

Don't use sintered bronze plates, anyone I know who has tried them ends up with dismal transmition distances and quality.

There is a very detailed description of the alternative earthing options on the Icom site in the US can't find the URL at the moment, but worth downlaoding the whole book in PDF format, lots of useful tips even if bias towards ICOM gear. (Nothing against the gear I love it)


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