Opium with 3 crew is lighter than Stream with 10 crew. We talk a lot of weight versus early planing. When going downwind I maintain you have no or very little use of 10 crew so Stream heavier and less optimised for planing. And since my comments, as stated, are about cruising I am not saying a boat will not be faster on a beat with both a lot of ballast AND weight on the rail. But most of us cruisers, even if performance oriented, are satisfied with good performance beating and are looking for excellence on other angles.
A boat with narrow hull and calculating with crew weight on the rail for RM and with singel rudder will be difficult to sail with small crew cruising. ...
Anders I don't want to continue to discuss this with you neither I want to piss you so it will be a quick post:
You seem to think that a boat like the Stream 40 without a crew on the rail would be slower than the Opium 39. I do not agree.
The rating of the boats has nothing to do with crew on the rails. Compare the rating of an Opium 39 with a top cruiser-racer like the Stream 40 and you will be on another order of magnitude.
You seem to assume that the Stream 40 is a narrow boat. It is not, 4.00m for a 40ft cruiser-racer is well above the average.
You seem to assume that a two rudder set up is indispensable or is a great advantage in a boat with 4 m beam in what regards performance and control. Certainly they are more convenient for cruising but just because you would need a very deep rudder like the one on the Stream 40.
Many top designer continue to prefer this type of rudder for very fast cruiser-racers and certainly they can provide an adequate boat control.lt is obvious that if they continue to design them that way is because they think they are more efficient and they use complicated fluid dynamics programs to determine the performance of rudders. It is all a question of design even if I think a two rudder setup is more efficient the difference in performance and control would be marginal. My preferences are more linked with reliability and less maintenance.
Bottom point, the Opium 39 is a great and very fast performance cruiser optimized for downwind sailing. The Stream 40 is a top cruiser racer very much oriented for top level racing and with an overall top racing performance.