As mentioned, you need speed because the stabilisation surfaces don't kick in until a certain minimum IMC speed, which in the Dauphin is 76 knots. For most light helicopters, it's around 45 knots. You certainly shouldn't hover without a visual reference. You would have around 178 seconds to live, according to Australian figures. Inadvertent IMC is much more dangerous in a helicopter.
Also, as mentioned, you shouldn't be there in the first place, although you can occasionally get caught out, as the helicopter creates its own fog sometimes and you won't realise until you turn round. This is why you need to know the MSA before you take off and who to call at that altitude.
Phil
PS - VY is best rate of climb, which you get at a certain sweet spot between lift and drag, so you would climb faster at that speed. VX is best angle of climb, which would certainly be vertical if you had the power, but you would be very unwise to do that.
Last edited by paco; 29th Nov 2012 at 04:45.