>>I thought the jib was only an advantage over a unirig when reaching and that up wind it didn't make much difference.

That dependent on how you define the comparison. And no this is no joke. There are three ways of looking at it :

-1- First is trivial, If both are sailing without a spi then the sloop is definately faster around the course.

-2- The unirig has the same overall sailarea as the main+jib combined of the sloop and both sailing with spis. With the right mast height (not too high) the uni will sail just as fast or slightly faster upwind than a sloop rig. While reaching the roles are reversed.

-3- The uni-rig has a the same sailarea as the mainsail of the sloop and both use spis. Here the sloop is faster upwind, faster on a reach and about as fast on downwind legs.

So the question is from what point are you looking at your boat ?

If you have a boat and want to go faster than removing the jib is not going to help you. That will only make you slower. If you boat is a uni-rig and you have righting moment left unused and want to go faster than putting a jib on is most efficient. At least more efficient than putting a larger mainsail on the same mast. If you are prepared to totally modify the rig than completely new mast and mainsail combo could make you faster around the course if you get the ratio's right. However the gains are dependent on windstrength and you could well find you gained in light air something that you are lacking as a result in heavy air.

No matter how you look at it, one can always put more sailarea on a boat when it is a sloop rig than you can on a uni-rig. On courses that do not require high pointing this means more speed. And on courses that do require high pointing this means that more speed compensates for lower sailed angles to some extend. It dependents on the ratios where the compensation is partially or more than enough to fully compensate.


>>Going down wind with a spinnaker I'm not sure a self tacking jib makes much difference vs. a uni rig - as the sail area tends to be rather small compared to the main and spin.

That seems to be the case.

>>That said, they also look after themselves when gybing and tacking so I'd rather have one for the all round flexibility when distance racing.

And that is where the sloop is best.

Wouter