NEC-LIST: Monopole above soft water

Hello,

A relative of mine complains of poor results while attempting to track a
small buoy floating on softwater lake at VHF.

As far as I can gather, the antenna is probably a monopole, and the lower
part of the antenna is formed by the immersed buoy.

I've given her already a couple of tips on how to improve reception, but
I'd also like to have a look at the situation with NEC2, to see if I should
expect shadow for a distant observer close to ground.

Qualitatively, the soft water's surface should be something of a magnetic
wall, forcing the tangential H field to zero (if my brain hasn't turned to
mush). So I suppose that a vertical monopole may behave quite differently
than one would expect on say, salt water.

So here are my questions :

1) Is NEC's ground model applicable to something like softwater
(epsilon~=80, relatively low losses)? I've never used SOMNEC before, so
this is something new for me.

2) Modelling the immersed part is impossible with NEC2, but I consider
testing two things :

a) Model a monopole just in contact with the water's surface, like NEC2
allows (I'm only interested in the radiation pattern, not in calculating
the input impedance).

b) Instead of a discrete contact, have a network of short radials
converging to the base of the monopole.

What do think above approaches? Can one neglect the underwater component of
the buoy, or is my approach pointless?

3) Do you know of any literature on this or a comparable problem? (eg:
propagation studies on inland navigation).

Thanks in advance,

Alexandre

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