In article , rickman
wrote:

On 4/25/2017 12:07 PM, Fred McKenzie wrote:
In article , rickman
wrote:

On 4/24/2017 3:39 PM, Michael Black wrote:
On Sun, 23 Apr 2017, highlandham wrote:

On 23/04/17 04:03, Jeff Liebermann wrote:
quote =====
When you're on the water line, antenna height does make a big
difference. Prepare a roll of coax cable setup as an RF extension
cable. Attach connectors and adapters so that they fit the radio and
the antenna. If in trouble at sea, lash the antenna to the top of a
pole or oar to gain altitude. A separate antenna, such as a common
ground plane or coax sleeve antenna at the end of the coax cable would
make a better antenna than a rubber ducky.
unquote =====

A simple alternative to the J-Pole antenna would be a ground plane
antenna made of welding rod material on an SO-239 socket with a 4 hole
square flange with a vertical quarter wave radiator and 4 hinged
radial elements,the latter under 45 degrees when in use .
The SO-239 socket would be connected to a PL-259 connector and a
suitable length of coax.

But on a kayak? It won't do much good lying on the kayak, and unless
you get it high enough (which has problems in itself), you'll poke your
eye out.

Why not go for something that doesn't need horizontal radials.

Actually I gave this antenna some thought. If the radials were attached
by some sort of hinge for example a heavy braid, they could fold up
while still being electrically attached. The antenna could slide into a
tube when not in use. It might be a bit complex to rig up, but this is
the sort of thing I can give some thought to and maybe come up with
something workable.

Back to the J-Pole! You can make a light, flexible J-Pole out of 300
Ohm twinlead. Feed it with RG-174 cable. Use some kind of oar or pole
to raise it when needed.

I wouldn't know where to begin in sizing the components.

I did a quick search for 300 ohm j-pole. The first result was:
http://www.lowra.com/antenna/flexjpole/twinlead.pdf

Fred