Coating for weathered Marine antennas?
Doobie
Both my antennas are fibreglass and fraying? If you touch them
you would surely get a fibreglass sliver.
Im thinking varathane? varnish? to reseal them.
Ideas?
R Kling
27'Sunrunner
On a frozen Lake Simcoe :(
Canada
Capt Lou
"Listen to the live broadcast of 'Nautical Talk Radio' with Captain Lou every
Sunday afternoon from 4 - 5 (Eastern Standard Time) on the web at
www.959watd.com or if you are in Boston or Cape Cod set your radio dial to
95.9FM.
Rich Hampel
down any exposed glass fibers and spray again, etc.
HLAviation
>Both my antennas are fibreglass and fraying? If you touch them
>you would surely get a fibreglass sliver.
>Im thinking varathane? varnish? to reseal them.
>Ideas?
Depends what I'm using around the boat, sometimes I use varnish, sometimes
epoxy, sometimes Awlgrip. Anything to seal those bloody fiberglass splinters.
John Gaquin
Regards,
John Gaquin
m/v Brefnie Queen, 32' Luhrs
Bass River Marina, West Dennis, MA
Jere Lull
>Is there a coating for weathered Marine antennas?
>Both my antennas are fibreglass and fraying? If you touch them
>you would surely get a fibreglass sliver.
>Im thinking varathane? varnish? to reseal them.
>Ideas?
>R Kling
>27'Sunrunner
>
>
It's time to replace. Seems fiberglass antennas last only about 5-6
years. How we found out: Our new handheld got out a little better than
the primary when we called in a tow boat (for a nearby boat that could
hardly transmit 100 yards). We replaced with stainless steel.
--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/
Keith
is expensive!
--
__________________
Keith
"A government that is big enough to give you all you want is big enough
to take it all away."
--Barry Goldwater
Brian Whatcott
Ignoring for a moment, the junction between antenna and mechanical
mount, a conductive coating would at worst, infinitesimally increase
the bandwidth, and a dielectric coating would be essentially
undetectible. A lossy ferrite or iron powder coating, might be at
worst, lossy, but if you remember not to coat antennas with stealth
formulations, then you can pay a little attention to the important
antenna base mount junction.
A resistive coat (as most all paints, even aluminum flake paints are)
is no problem in that area, but a conductive coating that introduces a
series resistance to ground of less than say 1 kilohm for a VHF whip,
or say 10 kilohm for a long wire mount is the only cause of concern.
Brian Whatcott
On Sat, 25 Jan 2003 17:05:55 -0500, BinaryBillTheSailor@Sea++.com
wrote:
>It would be best to replace the antenna. There is no coating that can be trusted
>NOT to interfere with the antenna's proper operation. You could end up with
>reduced range, or even a damaged radio.
>
>BB
Brian Whatcott
Altus, OK
Eureka!
Keith
Fiberglass is just a "carrier" for the wire, right? If that's the case,
a coat of paint on the outside shouldn't do anything. Now, cutting the
antenna is a different story, as is getting water inside anywhere.
BinaryBillTheSailor@Sea++.com wrote:
>
> On Mon, 27 Jan 2003 00:38:25 GMT, bet...@sbcglobal.net (Brian Whatcott) wrote:
>
> >BB's note is needlessly pessimistic.
> >Ignoring for a moment, the junction between antenna and mechanical
> >mount, a conductive coating would at worst, infinitesimally increase
> >the bandwidth, and a dielectric coating would be essentially
> >undetectible. A lossy ferrite or iron powder coating, might be at
> >worst, lossy, but if you remember not to coat antennas with stealth
> >formulations, then you can pay a little attention to the important
> >antenna base mount junction.
> >
> >A resistive coat (as most all paints, even aluminum flake paints are)
> >is no problem in that area, but a conductive coating that introduces a
> >series resistance to ground of less than say 1 kilohm for a VHF whip,
> >or say 10 kilohm for a long wire mount is the only cause of concern.
> >
> >Brian Whatcott
> >
>
> How thick a coating is safe? A mil, an Inch, a foot? What paints are safe? What
> paints can you buy, and know the formulation in great detail? If a paint doesn't
> say right on the package "safe for very high frequency radio antennas", you
> should not use it. The fact is, the wrong paint could seriously detune the
> antenna. Since a new antenna is not very expensive, I don't think there is *any*
> level of risk that would be worth taking.
>
> Do you also slit open empty toothpaste tubes to scrape out the last little bit?
> At least that doen't carry much risk. Using both sides of the toilet paper is
> probably not going to be so pleasant! LOL
>
> BB
>
> >On Sat, 25 Jan 2003 17:05:55 -0500, BinaryBillTheSailor@Sea++.com
> >wrote:
> >
> >>On Sat, 25 Jan 2003 17:45:20 GMT, Doobie <letsp...@hotmail.com> wrote:
> >>
> >>>Is there a coating for weathered Marine antennas?
> >>>Both my antennas are fibreglass and fraying? If you touch them
> >>>you would surely get a fibreglass sliver.
> >>>Im thinking varathane? varnish? to reseal them.
> >>>Ideas?
> >>>R Kling
> >>>27'Sunrunner
> >>>On a frozen Lake Simcoe :(
> >>>Canada
> >>
> >>It would be best to replace the antenna. There is no coating that can be trusted
> >>NOT to interfere with the antenna's proper operation. You could end up with
> >>reduced range, or even a damaged radio.
> >>
> >>BB
> >
> >Brian Whatcott
> >Altus, OK
> > Eureka!
--
__________________
Keith
Not one shred of evidence supports the notion that life is serious.
Larry DeMers
> On Sat, 25 Jan 2003 17:45:20 GMT, Doobie <letsp...@hotmail.com> wrote:
>
> It would be best to replace the antenna. There is no coating that can be trusted
> NOT to interfere with the antenna's proper operation. You could end up with
> reduced range, or even a damaged radio.
>
> BB
A Damaged Radio!? Bull! also doubt that the radio will even notice a change of
dielectric on the outside of the fiberglass rod. RF is certainly capable of
penetrating whatever polyurethane you put on there. And no..it *will not* damage
your radio. I have used thinned epoxy to go on the older shakespeare Am-Fm antenna
I had. Worked fine for many years. If the antenna is a VHF antenna, there will be
no back effect from coating the antenna with a poly finish.
Larry DeMers
Brian Whatcott
answers.
On Sun, 26 Jan 2003 21:02:41 -0500, BinaryBillTheSailor@Sea++.com
wrote:
>On Mon, 27 Jan 2003 00:38:25 GMT, bet...@sbcglobal.net (Brian Whatcott) wrote:
>
>>BB's note is needlessly pessimistic.
>>Ignoring for a moment, the junction between antenna and mechanical
>>mount, a conductive coating would at worst, infinitesimally increase
>>the bandwidth, and a dielectric coating would be essentially
>>undetectible. A lossy ferrite or iron powder coating, might be at
>>worst, lossy, but if you remember not to coat antennas with stealth
>>formulations, then you can pay a little attention to the important
>>antenna base mount junction.
>>
>>A resistive coat (as most all paints, even aluminum flake paints are)
>>is no problem in that area, but a conductive coating that introduces a
>>series resistance to ground of less than say 1 kilohm for a VHF whip,
>>or say 10 kilohm for a long wire mount is the only cause of concern.
>>
>>Brian Whatcott
>>
>
>How thick a coating is safe?
The design parameter of interest is the thickness/ length ratio
If this kept under 2%, no practical change will be noted.
A mil, an Inch, a foot?
For a 2 foot whip, an increase of 0.2 inch would be very acceptable.
> What paints are safe? What
>paints can you buy, and know the formulation in great detail? If a paint doesn't
>say right on the package "safe for very high frequency radio antennas", you
>should not use it. The fact is, the wrong paint could seriously detune the
>antenna.
Home build aircraft makers apply copper foil VHF antennas inside
fabric or glass fuselages.
Strange to tell, even aluminum flake paint applied to the planes
surfaces does not impede the 5 to 10 watt transmit power they use on
VHF.
If you think it is "risky" I take it this is based on your opinion. At
worst, it might be a mistaken conclusion from some practical repair.
If you have any solid data, by all means cite it.
>Since a new antenna is not very expensive, I don't think there is *any*
>level of risk that would be worth taking.
If you want to buy a new antenna, that's fine with me.
Just unnecessary to a person who is licensed to take care of ships
antennas for a living.
>Do you also slit open empty toothpaste tubes to scrape out the last little bit?
>At least that doen't carry much risk. Using both sides of the toilet paper is
>probably not going to be so pleasant! LOL
>
>BB
I squeeze down tothpaste until reasonably empty.
I refold toilet paper only if caught short.
But I feel much happier with your advice on butt-wipes than antennas.
(no offence!)
:-)
Larry DeMers
Nope, nope and nope. None of those will happen at the freqs involved here. Osmosis
requires water pressure..and many years of submersion, porosity should actually be
improved with an enveope of polyurethane over it, and reflections depend on the
impedance matching of the antenna to the transmission line and the VHF's output stage
impedances..not on a few micron thick coating on the antenna. Lower freqs. may not be so
immune however..for instance in the HF bands.
Larry DeMers
SGI
BinaryBill@Sea++.com wrote:
> osmosis? porosity? reflection of very high frequency waves?
>
> BB
>
Brian Whatcott
>On Mon, 27 Jan 2003 18:13:44 GMT, bet...@sbcglobal.net (Brian
>Whatcott) wrote:
>
>>Binary Bill asked some technical questions, and I interspersed some
>>answers.
>>
>
>>Home build aircraft makers apply copper foil VHF antennas inside
>>fabric or glass fuselages.
>>Strange to tell, even aluminum flake paint applied to the planes
>>surfaces does not impede the 5 to 10 watt transmit power they use on
>>VHF.
>
>
>If you have any solid data please cite it. When you say it does noty
>"impeded" it, are you really just saying that it "seems to work fine,
>or do you have measurements of the SWR before and after the aluminum
>flake paint was added to show there was *NO* effect?
>
A google search on "antenna" in rec.aviation.homebuild will provide
the kind of third party pilot/builder feedback you are probably
looking for.
But for a really solid example, take a look at what the defense biz
can do when it really, REALLY wants to absorb signal, cost no object.
Check out the absorbant skin depth on a stealth plane.
If a quarter inch of anybody's paint would do the job, believe me,
they would be using it.
>Shakespeare Marine (who makes a lot of marine atennas) suggests you
>can paint their antennas to "color match", but not with any paint that
>is metallic or containing lead. They do not suggest painting an
>antenna that has worn through the original coating.
>
>BB
Hmmm....as an example of the riskiness of painting antennas, you cite
an antenna maker who recommends using a color coordinated paint film?
A lead-base paint might well make a difference to performance if you
painted it over the antenna to mount junction.
But I spelled that out, I hope?
But I have already written more than enough: it's not important that
you come to believe my point of view. It's your choice, after all.
Respectfully
Steven Shelikoff
>A very different application with entirely different criteria. No relevance
>whatsoever to this discussion. You can be sure that every branch of the armed
>forces REPLACES worn out safety equipment, and keep it in spec at all times.
>They would not slop paint an antenna that was so worn the fiberglass was
>exposed.
Speaking of the military, I can tell you they have "Do Not Paint" labels
around the VHF antennas on their aircraft.
Steve
Brian Whatcott
wrote:
>>But I have already written more than enough: it's not important that
>>you come to believe my point of view. It's your choice, after all.
>>
>
>potentially cause someone harm or death. Bottom line: A VHF antenna is far too
>important to screw around with.
>BB
I see that we can agree on two things, and both forcefully advocate
them:
1) it is foolish to accept advice from a well-meaning, if unqualified
person....
and
2) if in doubt, antenna replacement will usually do no harm, if done
correctly.
I take it, you would agree?
Larry DeMers
I am an E.E., and have been involved in HF and VHF comms for most of my life.
Believe what you want, but simply recoating a fiberglass antenna with epoxy resin,
which the body is made of, does nothing to change the dieletric constant that the
antenna body represents. This being so, there will be no reflections from this
overcoating, afterall, it is replacing about the same thickness coating that was
originally there, but that has succumbed to UV, and flaked off. To have a
negative impact on your range (which is the only possible negative effect here by
the way..no earth shattering transmitter finals melting down as you suggested, nor
any other catastrophic occurances), the antenna would need to provide an RF
impedance mismatch to the transmitter final amp. Since the antenna was coated
essentially with what it lost originally, to UV, there should be little or no
differences in the impedance match witht he transmitter final amp, thus no
additional reflections to worry about, and you will enjoy the same quality of
transmission as before the repair.
Now I suspect that this is way over your head, given your apparent over concern
with this topic, so maybe we need to let you worry yourself on this point, and let
others know that it is not a problem to lightly cover a fiberglass antenna with
more epoxy to prevent the fiberglass shards from jabbing you.
Larry DeMers
BinaryBillTheSailor@Sea++.com wrote:
> On Tue, 28 Jan 2003 00:26:17 GMT, bet...@sbcglobal.net (Brian Whatcott) wrote:
>
> >On Mon, 27 Jan 2003 14:32:46 -0500, BinaryBill@Sea++.com wrote:
> >
> >>On Mon, 27 Jan 2003 18:13:44 GMT, bet...@sbcglobal.net (Brian
> >>Whatcott) wrote:
> >>
> >>>Binary Bill asked some technical questions, and I interspersed some
> >>>answers.
> >>>
> >>
> >>>Home build aircraft makers apply copper foil VHF antennas inside
> >>>fabric or glass fuselages.
> >>>Strange to tell, even aluminum flake paint applied to the planes
> >>>surfaces does not impede the 5 to 10 watt transmit power they use on
> >>>VHF.
> >>
> >>
> >>If you have any solid data please cite it. When you say it does noty
> >>"impeded" it, are you really just saying that it "seems to work fine,
> >>or do you have measurements of the SWR before and after the aluminum
> >>flake paint was added to show there was *NO* effect?
> >>
> >
> >A google search on "antenna" in rec.aviation.homebuild will provide
> >the kind of third party pilot/builder feedback you are probably
> >looking for.
> >
>
> So, you don't have any credible data?
>
> >But for a really solid example, take a look at what the defense biz
> >can do when it really, REALLY wants to absorb signal, cost no object.
> >Check out the absorbant skin depth on a stealth plane.
> >If a quarter inch of anybody's paint would do the job, believe me,
> >they would be using it.
> >
>
> A very different application with entirely different criteria. No relevance
> whatsoever to this discussion. You can be sure that every branch of the armed
> forces REPLACES worn out safety equipment, and keep it in spec at all times.
> They would not slop paint an antenna that was so worn the fiberglass was
> exposed.
>
> >
> >>Shakespeare Marine (who makes a lot of marine atennas) suggests you
> >>can paint their antennas to "color match", but not with any paint that
> >>is metallic or containing lead. They do not suggest painting an
> >>antenna that has worn through the original coating.
> >>
> >>BB
> >
> >Hmmm....as an example of the riskiness of painting antennas, you cite
> >an antenna maker who recommends using a color coordinated paint film?
> >
>
> They do NOT recommend painting antennas to patch a failed factory coating. Once
> the factory coating is breached, you buy a new antenna. This is a safety item,
> remember? It's really not there for looks. It may have to save your life. My
> life is worth more than buying a new antenna every few years. Jeez, you're
> irresponsible.
>
> >A lead-base paint might well make a difference to performance if you
> >painted it over the antenna to mount junction.
> > But I spelled that out, I hope?
> >
>
> Shakespeare, who MAKES antennas, says you are wrong about this. You asked for a
> source other than my own personal opinion and I supplied one. You have yet to do
> the same.
>
> >But I have already written more than enough: it's not important that
> >you come to believe my point of view. It's your choice, after all.
> >
>
> It is also my choice to point out when someone posts dangerous advice that could
> potentially cause someone harm or death. Bottom line: A VHF antenna is far too
> important to screw around with.
>
> I hope that if you follow your own advice, it doesn't cause you problems.
>
> BB
Chuck Chunder
"Larry DeMers" wrote in part...
> Hey BB,
>
> Now I suspect that this is way over your head, given your apparent over
concern
> with this topic, so maybe we need to let you worry yourself on this point,
and let
> others know that it is not a problem to lightly cover a fiberglass antenna
with
> more epoxy to prevent the fiberglass shards from jabbing you.
Well said, Larry -
But I bet he'll still carry on...
"Blind are those who WILL NOT see..."
Chuck
Jeff Morris
http://www.shakespeare-marine.com/antennas/ant-faq.htm
------------------------------------------
Can I paint the antenna, and with what?
Shakespeare's antennas can be painted any color you wish. But, make sure not to use any paint
containing metallic chips or lead bases.
Can I repair the antenna if the fiberglass becomes frayed?
Yes. Simply wash the antenna with soap and water first, and allow it to dry completely. Next, paint
the antenna with polyurethane or a lead free, non-metallic paint. Then lightly sand the surface with
400-grit sandpaper. Additional coats of paint may be added, but are usually not really necessary.
--------------------------------------------
FWIW, I would replace the antenna.
--
-jeff
"Assumptions shall not be made on the basis of scanty information" ColRegs, Rule 7(c)
<BinaryBill@Sea++.com> wrote in message news:n23d3vsiggjiop442...@4ax.com...
> On Tue, 28 Jan 2003 07:43:33 -0600, Larry DeMers <dem...@sgi.com>
> wrote:
>
> >Hey BB,
> >
> > I am an E.E., and have been involved in HF and VHF comms for most of my life.
>
> Your credentials, if real, do not exceed my own.
>
> One more time, since you seem really quite slow to grasp this...
>
> A VHF antenna on a boat is a critical piece of SAFETY EQUIPMENT. If
> you want to take risks with your life, then be my guest. However, when
> you advise others to do something stupid, and with the potential to
> cause harm, expect reasonable and responsible people to correct you.
>
> BB
Terry K
BinaryBillTheSailor@Sea++.com wrote:
>
> On Sat, 25 Jan 2003 17:45:20 GMT, Doobie <letsp...@hotmail.com> wrote:
>
> It would be best to replace the antenna. There is no coating that can be trusted
> NOT to interfere with the antenna's proper operation. You could end up with
> reduced range, or even a damaged radio.
>
Rubbish!
Any UV (exterior) paint would do. Scrub uff the slivers, with
sandpaper, don't breathe the dust, or get it in your socks, etc.
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