SPOT Assist

[BigLew]

An answer to your range problem is on the Orion(?) emergency flare packaging. They produce a "range of visibility chart there to illustrate how the curvature of the earth's surface effects the range of visibility of the different flares they offer. Using the "line of sight" guide of VHF transmission range you can easily interpolate what your VHF range likely is, assuming optimal equipment condition.

Good luck.

PS. They might reproduce the chart or one like it in the West Marine catalog. Come to think of it there might be a VFH range chart there for radio range purposes. Take a look and I will do the same, if I remember to do so. If I get an answer, I'll let you know.