I've sailed on a Hurricane a couple of weeks ago. The differences at a top mark rounding without launching a spi:

- Single: I have to round the mark, ease the main sheet, release the traveler a bit. 3 controls: 2 hands. All that from the wire. 10-15 seconds.

- Double: We have to round the mark, ease the main sheet, release the traveler a bit, ease the jib. 4 controls, 4 hands. 5 seconds.

Same thing at the low mark.

What about a tack? Well:

- single: I have to round, get in, sheet out a bit, get back on the wire, sheet in again. 2 control, 2 hands. Plus a wire swap.

- Double: Round, no need to sheet out as the jib will pull you out (jib's on self tacker, nothing to do). 1 controls, 4 hands.

Add a spi and the nightmare begins:

Single: Sheet out main, ease traveler, head downwind, make sure lines are clear, let go of the tiller praying for no sudden gusts, pull spi up, grab tiller, sheet in main, maybe traveler, sheet in spi. Too many things to do, not enough hands.

Double: add two hands, and maybe sheeting out two inches of jib. Boat is under complete control while the spi is going up with someone holding the main and the tiller.

Anything goes wrong on the boat? Line fouling? Need to tie a knot somewhere? Well, when solo you have to stop. Duo, you just send your slave^Wcrew to fix it while taking it easy but still screaming at 12 knots...

So yes, I think solo sailors are at a disadvantage. Not to mention that with a crew one can drive hard while the other can keep his eyes out for tactical moves.

Accounting for that in the rating? I'm not sure it's possible. How do you quantify it?