When I was still sailing 2-up I found that putting the crew on the trapeze and have her standing behind here skipper (me) would make a noticeable difference. I appeared to me that just having the crew only 0.5 mtr further back was enough to improve the ride.

While there is arguable a difference between 18 and 16 foot hulls I also notice that alot of F18 crews and even Tornado (20 foot) crews tend to adopt the same posture when sailing under spinnaker.

Wouter