SSB antenna on a catketch

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Michel
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Location: Enkhuizen, the Netherlands, EU

SSB antenna on a catketch

Post by Michel »

I know this topic has been discussed in the past, but I didn't pay attention then, and perhaps insights and technology are changed since then.

I have one of these catketches, no shrouds and an overhanging mizzen boom. In the next two years, I need to install an SSB transceiver antenna. I have two stainless adjustable backstays with block and tackle at the bottom. Normally, in their idle mode, they are athwart ships of the mizzen. When in use, The luff backstay tackle is set on the luff transom corner and tensioned. I know some people use this backstay as an antenna.

What I want to know is if someone has experience with positioning the balun at the TOP of the backstay and feeding the coax cable from the top of the mast down to below decks. Normally, the balun is at the bottom end of the antenna and the coax is fed in from there. This is not possible (or at least practical) with a backstay that is moved around at the bottom end. As far as my limited knowledge goes, the coax has to be included in calculating the required antenna length.

Thanks!
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

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Castaway
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Location: Lerwick, Shetland Isles

Re: SSB antenna on a catketch

Post by Castaway »

Michel,

Not quite an answer to your question, but Castaway has an SSB antenna wire running from a gland on the gunwhale to an insulator tied to the mizzen masthead. The gland is abeam the mast, and the aerial is kept in tension by a mooring line bungee, which does not impede the mast from flexing. The coax runs from the base of the aerial to an ATU mounted below the side deck (behind the cooker), and this seems to work. The ATU adjusts automatically for the aerial length, including the coax. I don't know enough about radio to tell whether your plan would have any effect from the coax radiating within the mast, or adjacent to and nearly parallel with the backstay aerial.

I get good reception, but so rarely transmit that I couldn't say whether the transmission is efficient or not. The aerial doesn't often get in the way, as we rarely try to set the mizzen ahead of the beam. The single runner and the free end of the staysail halyard are clipped to a similar bungee on the opposite side. In port they are useful handholds for boarding! The aerial is mostly used to fly courtesy ensigns and club burgees.
Gerald Freshwater,
s/y 'Castaway', (UK F35 cat ketch, centreboard, 1987)
Lerwick Boating Club
Shetland Isles, Scotland

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Michel
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Re: SSB antenna on a catketch

Post by Michel »

Gerald,

Thanks for your thoughts and information. Your point about radiation from the antenna/aerial into the coax is something that crossed my mind. But it made me think further; would it be possible to have a SSB antenna INSIDE a carbon fibre mast? That would be ideal!
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

Mike Holibar
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Re: SSB antenna on a catketch

Post by Mike Holibar »

Michel, I am far from an expert on this subject but I do work, in a small way, in the electrical field. I seem to recall that the outer wire in co-ax is called the shield and its purpose is to protect the inner wire from any external interference as it does its job of conducting the signal from the antena to the receiver. For this reason I am pretty sure that co-ax will not act as an antena its self although its length can be a factor in antena tuning. Your idea of taking the co-ax up inside the mast seems feasible to me and would be worthy of further investigation. I have no idea whether the antena could be sited inside the mast but if that were possible it would be an elegant solution indeed. I have similar concerns on the F39 and no backstays. The po only ran an ssb receiver so antena requirements were much simpler. Kind regards,
Mike Holibar
S/V Fyne Spirit of Plymouth (Freedom 39PHS-1989)
Lyttelton
New Zealand

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Michel
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Re: SSB antenna on a catketch

Post by Michel »

Mike, Gerald,

I found the solution to the problem; I don't per se need a long wire antenna because there are alternatives. An active antenna, for instance. These are 1' to 1.5' long, 1" thick sticks that can be mounted in many places. They need a bit of power however. An other alternative is Iridium, usable for both voice and data. I did not make any calculations yet, but a full email-savvy SSB transceiver set with Pactor III modem is quite an investment. The running costs may be lower than with Iridium, but an Iridium set is much less of an investment. Any observations and thoughts on this trade off are appreciated.

Best,
Michel
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

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GeoffSchultz
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Re: SSB antenna on a catketch

Post by GeoffSchultz »

Michel,

I don't have any answers for you regarding your antenna questions, but I have do have extensive experience using a SBB with Pactor for e-mail/weatherfax as well owning an Iridium phone.

First off, I don't know what your cruising plans are, so I can't speak to the usefulness of either system. Many people get toys that they install and never use.

However, if you're going to do extensive cruising, a SSB and Pactor are wonderful. There are many radio nets that you'll want to follow and/or join in. If you just want to listen to weather forecasts and/or the radio nets, then a receive-only HS receiver is sufficient. You can use either system with a sound card to receive weather faxes. The weather fax software that comes with Sail/Air-mail is very nice in that it lets you schedule reception times and frequencies, and it has a nice browser.

As you well know, the Pactor is an expensive piece of hardware, but it's a one time expense and has multiple uses. SailMail, which allows you to conduct business, is a $250 a year investment. Note that you can probably find used Pactors for a considerable savings.

If you have a ham license, you can utilize AirMail for free, but you aren't supposed to conduct business. SailMail is limited to 90 minutes a week, which has never been a problem for me. AirMail usage is unlimited, but you have to compete with the other hams on the network. SailMail doesn't allow attachments to e-mails, but I believe that AirMail will. AirMail also provides for things like FTP, which isn't available via SailMail.

An Iridium phone is a wonderful thing, but it's expensive to purchase and the recurring fees are quite high. I just looked that a rate card and there was a $50 activation fee, $35/mo fee plus $1.30 to $1.60/minute for calls. If you're gathering e-mail and weather faxes on a daily basis, this can add up quickly.

Depending upon where we're cruising and the availability of phone service, I use a SSB and the Iridium. However, I haven't utilized the Iridium in several years due to cost and availability of phone and/or Internet (Skype).

Note that I can't recommend GlobalStar. Virtually everyone I know who has used it has had endless problems.

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

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Michel
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Re: SSB antenna on a catketch

Post by Michel »

Geoff, thanks, very helpful. I am contemplating (planning is too much of an expression at this time) the OSTAR 2013 transatlantic race. So my cruise will be North Atlantic and then back from New England via Bermuda and the Azores. It's four years from now, so which communication technology will be required by the organization is not known today.

About Globalstar: The major Dutch sailing magazine just did a test with the SPOT beacon, including the emergency notification of SAR organizations. They were quite positive about the communication and about the emergency reporting. The Dutch coastguard got a phonecall from the emergency organisation (GEOS?) within a few minutes.

What is known in the US about SPOT and Globalstar?
Last edited by Michel on Sat Jun 13, 2009 6:58 am, edited 1 time in total.
Michel Capel, Freedom 44 #4 1981 'Alabama Queen', NED8188, cat ketch with wishbones, home port Enkhuizen, the Netherlands, 52*42.238'N 005*18.154'E.

tanton37
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Re: SSB antenna on a catketch

Post by tanton37 »

Hi Michel.....may I suggest you take your question over to the Seven Seas Cruising Association website....they have several contributors on their forum who are well versed in everything SSB....Bill Trayfors comes to mind among others. If you can't find an answer within that group it probably can't be found!! I too am curious .....
Cheers, David

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GeoffSchultz
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Re: SSB antenna on a catketch

Post by GeoffSchultz »

Another forum that I find very useful is http://www.SailboatOwners.com. Lots of very knowledgable people over there and very active.

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

Tom V
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Re: SSB antenna on a catketch

Post by Tom V »

How exciting to be contemplating OSTAR and a trip back via Bermuda too!

Re. SSB antenna. What I have on by Freedom 44 is an SSB antenna coming down from the top of the mizzen, separate from the running back. The antenna ends about 8 feet above the deck, and a thin rope tackle with cam cleat allows me to adjust the tension.... but the truth is I keep it relatively slack and rarely adjust it. The cable itself is slack enough to allow for mast flex. It goes through the deck near the toe rail, right above the nav station. It works well for me, and has the advantage of being pretty simple to install.

The issue with using the running back, as i saw it, was I would have to disconnect the SSB whenever I wanted to use the running back... and the solution you are contemplating of turning everything upside down and having the cable come down the inside of the mast never occurred to me.

As for the SPOT... I bought one last year and am delighted with it, and it is also simple to use. Before going on a trip, I share the web page the SPOT creates with whoever I want to know and it tracks my progress in excessive detail. I'm planning to set sail next week from Bermuda for a little Nova Scotia/Newfoundland cruise and my family will be able to see where I am!

Never had to call for help with the thing and never hope to.

Tom Vesey
F44 Jackrabbit
Bermuda
Tom Vesey
Jackrabbit
Freedom 44 Hull #26 1986
Bermuda

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