Obviously Alex is one of the don't knows. Hope he was one of the many I roundly abused last year in various places for not hoisting one when doing 6 knots into a headwind of 2knots!!!
It's not an inverted cone, it's the right way up. If you put it with the wide end downwards then the ice cream falls out.
IRPCS talks of 'a conical shape, apex downwards'. Some places don't seem to care about it, others (particularly Belgium) are very insistent. Whether you need it or not depends on where you sail, but better to have one anyway.
I have heard it suggested that if you insist on motorsailing without a cone, then don't have a collision as your insurance company may not be too happy to pay out. However I have to admit that I'm guilty of the offence myself.
Motor sailing without a cone is as stupid and ignorant as driving at night without headlights. Then those who do it are probably the same drivers who hog the middle and outer lanes on motorways when there is nothing ahead in the left hand lane.
Yes you need one and use it well. Imagine your hard on the wind on port tack and you notice a boat with only it's mainsail up and is on starboard tack. You give way only to notice that it's motor sailing and no cone up. You'd feel pretty *&$£ed off and so will other people unless you fly a cone when motor sailing.
The harbour master regularly chases boats and enforces it in Chichester Harbour. You needn't make a meal out of it. I just tie it to the baby stay. Takes 30 secs.
Can't say I've noticed this has had much effect on the number of infractions. I sail everywhere, but I've lost count of the number of times I've had a 'moment' while trying to work out whether a vessel is motoring or sailing and so if I'm to give way or stand on. Tacking out of the harbour entrance can be quite exciting.
You're right. The whole hour's journey can be highly exciting on a busy day. Maybe that's why he's trying. With that and the radar gun, they're busy people. Saw someone taking a short cut from East Head to the Chi Bar Beacon on Saturday. Suppose they'll get the breathalyser out for that soon.
Those who don't fly one will yield when in doubt as they reckon you must know your IRPCS better and your insurance company won't drag things out quite so badly if things go horribly wrong.
It IS more seamanlike - rather like tying a bowline.