Short Wave Sportfishing wrote in
:

Properly installed, there is no honest advantage to a 8' antenna over
a 3' antenna for small boats.

For larger boats, that's a whole different ball of wax. :)



It's not on larger boats, either. At 55' atop the mainmast of an Amel
Sharki 40 ketch, the Metz easily outperforms the 8' monsters, which must
be mounted lower.

There is a problem with these "High Gain" antennas that's not
addressed....BOATS ROLL AND PITCH.

The horizontal radiation pattern of a 1/2 wave whip, like the end-fed
Metz, looks just like a donut that has no hole with the whip sticking up
where the hole should be. Its "gain" over the isotropic source is 3 db
because of this donut. The isotropic source's radiation pattern is a
sphere. If you took that sphere and pushed the north and south poles of
it to the center, the sides bulge out twice as wide....the 3db measured
at the equator, for you cartographers in the audience. The equator is
fatter.

Now, if we took that Metz radiation balloon, the donut, and put it
between two plates in a vice, when we squeezed the vice, the balloon
between the plates would be squeezed even more and its equator would
bulge out even more as we flattened it so the plates were only an inch
apart. (Our balloon can take any pressure.) This is what the radiation
pattern looks like for the 8-9 db fiberglass colinear "whip", which is
actually a phased array of 1/2 wave dipoles inside a fiberglass tube to
hold them in place. 8' antennas have two dipoles spaced 1/2 wavelength
apart to create this donut that looks like you stepped on it and
flattened it.

Now, this gain IS real gain AT THE EQUATOR when either whip is held
pointing at zenith, straight up and down. Too bad your boat NEVER points
it there, only in passing through it. The pattern is ALWAYS
perpendicular to the plane of the whip passing through the middle of it.

So,



\ Tip of whip
\
\
\
X Boat heeled this way
\
\
\
\
Boat ^-pattern edge heeled to right

God that's awful but its the best I can think of. AS you can see, the
donut has tipped with the whip as the boat rolls. The pattern rolls,
too! All the stations off to starboard or port DON'T see the signal
caused by the EDGE of the donut. They see something MUCH less. How much
less is determined by the tilt of the donut and how squished out it is.
If it's squished hard, like the 8' whip (compared to the Metz' fat
donut), the part of the pattern pointing at the receiving antenna afar is
much less thick than the fat Metz donut.

The effect of rolling and pitching at the receiver you're trying to
impress is that the Metz antenna's signal at that far-off receiver runs a
course from our reference signal, for this explanation, down to 60% of
reference signal. The big whip's signal, on the other hand, being
flatter produces about 20% more signal when the antenna is vertical, but
the dip in signal as the boat rolls is down 80% or more because its donut
is so squished. Very little signal points to the receiver when the donut
is pitched over like this.

That's what the REAL difference between them is, at sea, in the real
world. If your VHF has an S-meter on it, watch it in rolling seas and
you can see the other guy's rolling and pitching making it roll up and
down as his donut's peak and minimum pass by you. The Metz, or any half-
wave with the fat donut, has lots less pitch/roll fading and better comms
when it really counts....precisely why the CG uses it on THEIR pitching
and rolling craft in heavy weather.

Besides, I've submarined the Metz on the jetboat a few times when the bow
became a shovel.....and it survived what would rip the fiberglass whip
right off, probably in splinters....(c;


Larry
--
Search youtube for "Depleted Uranium"
The ultimate dirty bomb......

John H. wrote:
On Tue, 25 Sep 2007 14:15:24 -0400, HK wrote:

Eisboch wrote:
"Frogwatch" wrote in message
oups.com...
Proof that this NG does some good for boaters and is not all
politics. I face the same issue in that I have an 8' antenna on my
Tolman but recently installed a bimini and have not been sure of what
to do about the antenna. Harry says his 3' antenna works fine and
clears the bimini............

I installed a 3' antenna and Icom radio on the console of a Dauntless Whaler
I had. No bimini, but I didn't want a long antenna in the way while fishing
and the short, stainless whip could be bent over under the console grab
rail, out of the way.

It worked, but didn't have nearly the range of an 8 footer mounted higher up
on a boat. As for 10 mile range? No way on mine. Maybe two at best.

Eisboch



Mine is mounted on a vertical rail on the side of my center console.
When up, it just clears the underneath of the bimini, and the bimini
clears the top of my head by at least six to eight inches, so I am
guessing the tip of the antenna is somewhere close to 7' off the deck of
the boat. It seems to work well for me, although I rarely use VHF, since
almost everyone is on cell, even the guys I chat with who are fishing on
their boats out on the bay.

Do you have this radio: IC-M604 ?

I think I like the Metz Manta 6 stainless whip antenna. It can easily be
mounted to the console.


No, I thought the IC-M504 was expensive enough. Bought all my
electronics but the fishfinder from BOE in Annapolis. Good local prices.

John H. wrote:
On Tue, 25 Sep 2007 14:51:44 +0000, Larry wrote:

John H. wrote in
:

Anyone - Is the performance of the 5' antenna seriously below that of the
8'er?


None whatsoever. I got to the horizon on a Metz Manta 6 halfwave at butt
level in a Sea Rayder jetboat all the time.

VHF only goes to the horizon, line of sight. To get further, you must
extend the horizon with ALTITUDE. 5' to 8' means nothing.

Screw a bunch of sun-destroyed fiberglass rods. The Metz is guaranteed for
life unless you lose the whip out of it. All the USCGs boats use the Metz,
a testimonial to its rugged construction. Completely self-contained. No
ground plane required. It'll work the horizon holding it in your hand.
http://www.metzcommunication.com/manta6.htm
Great company, too.

This guy has it on sale:
http://www.northeastmarineelectronics.com/index.asp?
PageAction=VIEWPROD&ProdID=2984
$34! That's half price!


Larry

Thanks for the tip, Larry.

Another question: Most antennae seem to come with about 20 feet of wire.
Mounted on a console with the radio right there, I could get by with about
3 feet of wire. Is all the extra wire necessary?


No. You can cut the wire to the length you need.

John H. wrote:
On Tue, 25 Sep 2007 11:50:39 -0400, Gene Kearns
wrote:

On Tue, 25 Sep 2007 07:01:13 -0500, John H. penned the following well
considered thoughts to the readers of rec.boats:

With the new Key West, I'm getting a bimini. The wife didn't think the
t-top would give enough sun protection.

In one of the shots of your boat, Harry, it appeared that you have the 8'
antenna folded down, although it could have been a 5'er I guess. In any
case, what do you have, and does it interfere with the bimini?

Anyone - Is the performance of the 5' antenna seriously below that of the
8'er?
By formula, 3' vs. 8' is about 2.74 miles difference in LoS..... which
is fairly meaningless..... since we don't know the altitude of the
other antenna. For safety, I rely on the height of the local 170+ foot
USCG antenna, instead of the height of my own......

Receiver sensitivity is probably way more important than +-5' of
antenna at the boat end.... unless you are trying to DSC some guy near
the horizon....

..... sooooo.....
save that money on the antenna and spend it on the IC-M604...

PS. What would you recommend in the $200-$250 range?


M504 $277

http://www.byownerelectronics.com/st...3&cat=0&page=1

John H. wrote:
On Tue, 25 Sep 2007 09:23:17 -0400, "Reginald P. Smithers III"
wrote:

John H. wrote:
On Tue, 25 Sep 2007 09:11:20 -0400, "Reginald P. Smithers III"
wrote:

Frogwatch wrote:
On Sep 25, 8:22 am, wrote:
On Sep 25, 8:06 am, Short Wave Sportfishing
wrote:

On Tue, 25 Sep 2007 07:48:27 -0400, "Reginald P. Smithers III"
wrote:
Piffle.
Your jealous nature is so obvious.
Hats for pansies.
This from a guy who wears his hat backwards, with the rim in the
front! Cept when the boat is moving along, then he wears it right.
Proof that this NG does some good for boaters and is not all
politics. I face the same issue in that I have an 8' antenna on my
Tolman but recently installed a bimini and have not been sure of what
to do about the antenna. Harry says his 3' antenna works fine and
clears the bimini............

VHF transmission range is a function of transmitter power, receiver
sensitivity, and distance to the horizon, since VHF signals propagate
under normal conditions as a line-of-sight phenomenon.

The way to calculate the the theoretical line-of-sight horizon distance
is:
distance in miles = The square root of (1.5 X the height of the
antenna from the water in feet)

Since the CG is normally located at the highest possible place, you
shouldn't have a problem sending and receiving to them. You *will*
notice the difference when you are communicating with other boats.
Which could impact on the ability to get a quick response to a Pan Pan
or a MayDay call.

I personally think a Hard Top with an ant. mounted on the top of the
Hard Top would give you better coverage, without the inconvenience of
the ant. and bimini straps being in your way as you fish.

If you don't have the ability to easily walk around the boat, what is
the advantage of a CC?



When I'm using the boat for fishing, the bimini will be down. Walking
around will not be a problem.

An advantage of a CC, for me, is that I prefer to operate a boat in the
standing position.

If I were getting the boat just for my use, I'd go with the t-top, with
perhaps a three foot antenna mounted on it.

But, I expect to be pulling a lot of grandkids on tubes or skis, so the
wife has a big say.
(in my best SWF voice)

Pansy.

You wouldn't say that if you've ever taken 4-6 grandkids out on the boat at
one time!

nope and since one of my kids is in high school and none are married,
that is a good thing.

John H. wrote:
On Tue, 25 Sep 2007 14:51:44 +0000, Larry wrote:

John H. wrote in
:

Anyone - Is the performance of the 5' antenna seriously below that of the
8'er?


None whatsoever. I got to the horizon on a Metz Manta 6 halfwave at butt
level in a Sea Rayder jetboat all the time.

VHF only goes to the horizon, line of sight. To get further, you must
extend the horizon with ALTITUDE. 5' to 8' means nothing.

Screw a bunch of sun-destroyed fiberglass rods. The Metz is guaranteed for
life unless you lose the whip out of it. All the USCGs boats use the Metz,
a testimonial to its rugged construction. Completely self-contained. No
ground plane required. It'll work the horizon holding it in your hand.
http://www.metzcommunication.com/manta6.htm
Great company, too.

This guy has it on sale:
http://www.northeastmarineelectronics.com/index.asp?
PageAction=VIEWPROD&ProdID=2984
$34! That's half price!


Larry

Thanks for the tip, Larry.

Another question: Most antennae seem to come with about 20 feet of wire.
Mounted on a console with the radio right there, I could get by with about
3 feet of wire. Is all the extra wire necessary?

No, but I was told that unless you know someone who can do a new
connection as good as the old connection, (which I was told will not be
done by the average DIY or boat mechanic) I was told it was better to
just wind it into a ring use some velcro to keep it out of the way.

On Tue, 25 Sep 2007 09:23:17 -0400, "Reginald P. Smithers III"
wrote:

John H. wrote:
On Tue, 25 Sep 2007 09:11:20 -0400, "Reginald P. Smithers III"
wrote:

Frogwatch wrote:
On Sep 25, 8:22 am, wrote:
On Sep 25, 8:06 am, Short Wave Sportfishing
wrote:

On Tue, 25 Sep 2007 07:48:27 -0400, "Reginald P. Smithers III"
wrote:
Piffle.
Your jealous nature is so obvious.
Hats for pansies.
This from a guy who wears his hat backwards, with the rim in the
front! Cept when the boat is moving along, then he wears it right.
Proof that this NG does some good for boaters and is not all
politics. I face the same issue in that I have an 8' antenna on my
Tolman but recently installed a bimini and have not been sure of what
to do about the antenna. Harry says his 3' antenna works fine and
clears the bimini............

VHF transmission range is a function of transmitter power, receiver
sensitivity, and distance to the horizon, since VHF signals propagate
under normal conditions as a line-of-sight phenomenon.

The way to calculate the the theoretical line-of-sight horizon distance
is:
distance in miles = The square root of (1.5 X the height of the
antenna from the water in feet)

Since the CG is normally located at the highest possible place, you
shouldn't have a problem sending and receiving to them. You *will*
notice the difference when you are communicating with other boats.
Which could impact on the ability to get a quick response to a Pan Pan
or a MayDay call.

I personally think a Hard Top with an ant. mounted on the top of the
Hard Top would give you better coverage, without the inconvenience of
the ant. and bimini straps being in your way as you fish.

If you don't have the ability to easily walk around the boat, what is
the advantage of a CC?




When I'm using the boat for fishing, the bimini will be down. Walking
around will not be a problem.

An advantage of a CC, for me, is that I prefer to operate a boat in the
standing position.

If I were getting the boat just for my use, I'd go with the t-top, with
perhaps a three foot antenna mounted on it.

But, I expect to be pulling a lot of grandkids on tubes or skis, so the
wife has a big say.

(in my best SWF voice)

Pansy.

You wouldn't say that if you've ever taken 4-6 grandkids out on the boat at
one time!

On Tue, 25 Sep 2007 11:50:39 -0400, Gene Kearns
wrote:

On Tue, 25 Sep 2007 07:01:13 -0500, John H. penned the following well
considered thoughts to the readers of rec.boats:

With the new Key West, I'm getting a bimini. The wife didn't think the
t-top would give enough sun protection.

In one of the shots of your boat, Harry, it appeared that you have the 8'
antenna folded down, although it could have been a 5'er I guess. In any
case, what do you have, and does it interfere with the bimini?

Anyone - Is the performance of the 5' antenna seriously below that of the
8'er?

By formula, 3' vs. 8' is about 2.74 miles difference in LoS..... which
is fairly meaningless..... since we don't know the altitude of the
other antenna. For safety, I rely on the height of the local 170+ foot
USCG antenna, instead of the height of my own......

Receiver sensitivity is probably way more important than +-5' of
antenna at the boat end.... unless you are trying to DSC some guy near
the horizon....

..... sooooo.....
save that money on the antenna and spend it on the IC-M604...

$500! Damn! Do I really need that for an 18' boat that will probably never
get out of sight of land?

On Tue, 25 Sep 2007 14:15:24 -0400, HK wrote:

Eisboch wrote:
"Frogwatch" wrote in message
oups.com...
Proof that this NG does some good for boaters and is not all
politics. I face the same issue in that I have an 8' antenna on my
Tolman but recently installed a bimini and have not been sure of what
to do about the antenna. Harry says his 3' antenna works fine and
clears the bimini............


I installed a 3' antenna and Icom radio on the console of a Dauntless Whaler
I had. No bimini, but I didn't want a long antenna in the way while fishing
and the short, stainless whip could be bent over under the console grab
rail, out of the way.

It worked, but didn't have nearly the range of an 8 footer mounted higher up
on a boat. As for 10 mile range? No way on mine. Maybe two at best.

Eisboch




Mine is mounted on a vertical rail on the side of my center console.
When up, it just clears the underneath of the bimini, and the bimini
clears the top of my head by at least six to eight inches, so I am
guessing the tip of the antenna is somewhere close to 7' off the deck of
the boat. It seems to work well for me, although I rarely use VHF, since
almost everyone is on cell, even the guys I chat with who are fishing on
their boats out on the bay.

Do you have this radio: IC-M604 ?

I think I like the Metz Manta 6 stainless whip antenna. It can easily be
mounted to the console.

On Tue, 25 Sep 2007 14:51:44 +0000, Larry wrote:

John H. wrote in
:

Anyone - Is the performance of the 5' antenna seriously below that of the
8'er?



None whatsoever. I got to the horizon on a Metz Manta 6 halfwave at butt
level in a Sea Rayder jetboat all the time.

VHF only goes to the horizon, line of sight. To get further, you must
extend the horizon with ALTITUDE. 5' to 8' means nothing.

Screw a bunch of sun-destroyed fiberglass rods. The Metz is guaranteed for
life unless you lose the whip out of it. All the USCGs boats use the Metz,
a testimonial to its rugged construction. Completely self-contained. No
ground plane required. It'll work the horizon holding it in your hand.
http://www.metzcommunication.com/manta6.htm
Great company, too.

This guy has it on sale:
http://www.northeastmarineelectronics.com/index.asp?
PageAction=VIEWPROD&ProdID=2984
$34! That's half price!


Larry

Thanks for the tip, Larry.

Another question: Most antennae seem to come with about 20 feet of wire.
Mounted on a console with the radio right there, I could get by with about
3 feet of wire. Is all the extra wire necessary?