Re: [Paddlewise] VHF range vs power

Fred Brown wrote:
> 
> So, I've read some stuff that marine VHF (150-160MHz) is only good for
> line-o-site.  Burch says max typical line of sight is 10mi. (he wasn't
> clear on statute or nautical).  My question; Aren't those 1W max (vs 5W)
> handheld "waterproof" tranceivers sufficient and save $100?

I think the figure you quote from Burch must be to a power boat or
something much taller than another yakker on the water.  I have not
checked my copy of Burch, but I believe yak to yak is closer to 2-3
nautical miles MAX, with a LOT of variation, depending on the swell
condition.

I suspect what you are really interested in, however, is whether a 1W
VHF unit will reach another similar unit at 10 miles.  In my experience,
if both VHF's are the typical handheld units (with rubber ducky
antenna), and both TX - and RX - holders are standing at water level on
the beach, somewhere around 8 - 10 miles is the limit for 3W (or 5W)
units.

Sometimes, I have been *unable* to make contact at a lesser distance,
when there were seemingly minor obstructions between TX and RX. 
Confounding things further, I once made contact beach-to-beach at 4.5 -
5 miles, *over an intervening 150-foot-tall island,* certainly not
line-of-sight.  I have never gotten through to another handheld at 12
miles or greater, *under the conditions typical of marine VHF use.*

We had a debate about VHF's on this list a couple months ago, with folks
experienced in amateur radio (HAMS) attesting to much greater ranges,
*but not with "off-the-shelf" equipment.*

Thus, I doubt the 1W units are worth much, on the water, to summon aid. 
And, a 3W (or, 5W) VHF might not be successful, either, depending on how
far away the RX antenna is, how far above the water it is, etc.

At the end of the debate, I said I would do some systematic field
testing under "battle" conditions and report back on what the practical
limit was for off-the-shelf equipment, but that will have to wait for
summer.

-- 
Dave Kruger
Astoria, OR
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