[TowerTalk] How close to salt water is close enough?

[Patrick Greenlee]

Once upon a time a long time ago in a city far far away(San Diego) I took 
about an 18 month sabbatical, got a commercial radiotelephone lisc,  and 
worked as a marine electronic field engineer. I worked primarily on VHF, 
SSB, RADAR, SONAR, and Sat Nav on 10 million dollar tuna boats with helipads 
on their pilot houses.  Salty air and salt spray are your enemy.  fresh 
water can be your friend and rinsing salt off of things can be a good idea. 
Dissimilar metals corrosion can eat a hole in aluminum where you have 
attached a ring terminal or otherwise wreak havoc on connections between 
multiple metals. It is imperative that moisture be kept away from anywhere 
dissimilar metals are in contact.

Telescoping aluminum tubes held with clamps (a mainstay of many antennas) 
need to be well protected. There are compounds sold for that purpose. For 
added protection you can overcoat the clamped joints with a good silicon 
rubber (RTV), not the kind that smells like vinegar as it cures.  GE 50 year 
silicone caulk or equivalent is good stuff.  You want to make good 
electrical connections, use liberal quantities of the "nox" brands of oily 
anti-oxidant, wipe off the excess and coat generously with RTV.

Another type of corrosion to be concerned with is oxygen deprivation 
corrosion. Google it to be informed and avoid related pitfalls.

Your informed efforts can result in life extension for your sky wire stuff 
but the bottom line is that salt air will most likely shorten the useful 
life of your expensive equipment.  Most ham gear is NOT engineered for a 
marine environment. Electrical and mechanical performance of most ham gear 
is degraded all too rapidly if you don't take steps to improve the 
situation.

I swallowed the anchor at the turn of the century and moved inland 1400 
miles.  Had I stayed on the coast I would be experimenting with powder 
coating and similar processes for protecting exposed metallic components and 
their connections.  We lived on our sailboat for 9 years and I used the 
insulated backstay for a random wire antenna with a manual tuner.  As the 
backstay was high quality stainless steel it was not a corrosion problem 
(and not the best possible antenna either although I worked the world. 
There will generally be more maintenance in a marine environment.  Products 
like coax seal are worth using liberally wherever it can be applied if 
needed.

Good luck whichever way you decide to go.

73,

Patrick AF5CK


-----Original Message----- 
From: Mike & Coreen Smith VE9AA
Sent: Friday, May 17, 2013 10:17 AM
To: towertalk at contesting.com
Subject: [TowerTalk] How close to salt water is close enough?



Wife and I are looking at waterfront properties in VE1/9/VY2/VO1/2.  Ideally
I would like to locate my antennas inland (in the trees)

a little ways to (hopefully?) minimize(??) salt water corrosion and/or
'potential' problems from neighbours.



If I was to locate a yagi up 40' of tower, (or say a Butternut vertical 10'
agl) or even a 6m yagi on a short tower inland does it matter?



Let's say the rocky land itself was 20' ASL and 400-500' away from shore, is
there any benefit seen in being "close" to salt water or is all the benefit
(whatever that may be) seen only if the salt water is nearly underneath the
antenna?



Currently, I work all bands from 160m thru 6m.



Comments on corrosion prevention appreciated also.  I've always lived inland
and my only experience with salt water was 3 weeks in 1996 as CY0AA, in
which the salt air corroded all of our aluminum antennas making them look
very old.



Thanks much,



Mike VE9AA



Mike, Coreen & Corey

Keswick Ridge, NB

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