I refer you to Jon's post below.
As someone who deals with hand helds and field VHF equipment daily for the last 20 years, I would instinctively think of 1 or 2 watts when thinking hand helds. Hence my mention earlier (Like Jon) of effective "radiated Power" or what makes it out of the antenna.
As we all seem to have said, there are a lot of variables once you introduce weather and people to an exact science ! So always I guess, err on the side of caution on your equipments capabilities!
QUOTE=Jon Brooks] The other thing with any hand held is that is standard antenna is not very efficient.
We try to make them as good as we can but its all about the "laws of physics Jim"
You are taking a 1/4 wave whip and turning it into a compressed spring.
So you have approx 450mm of wire wound into a length of 160-180mm.
The 5w is what comes out of the top of the unit not the top of the antenna.
So if it is a very poor helicoil you could end up with an ERP (effective radiated power) of a fair bit less.
It would be an average of 3db loss (so half power) I have seen tested (not ours!) that have massive loss.
So you end up with a watt or less being radiated.
Some more helpful stuff for you to chew over!!