pW2
Active Member
Once again my apologies.
The graph for the 46 ft boat confirms my experience with my 40 ft boat, and also seems to confirm the formula printed by the AYRS.
From the graph I would expect the hulls to have a length:beam ratio of about 10:1 giving an AYRS max of about 27 knots ( I´m guessing of course) which compares with my max of 22 knts. With my boat I can get to 50% max without any trouble more than that and the strain starts to show. The most I´ve ever managed was 75% max (17 knts) when she was much lighter than she is now and conditions were absolutely perfect.
If you want to go fast you need very narrow hulls, a huge power to weight ratio and lots of overall beam to make use of the power, under sail that is.
It takes a hull 60 ft long with L:B ratio of 30:1 to get to 30 knts, just. And a hull of 120 ft with much the same ratio doesn´t get to 40knt.
Unfortunately I´ve lost all my AYRS puplications along the way because it would be interesting to compare the maximum speeds given by their formula with the actual speeds obtained by the 60 and 120 ft boats
The graph for the 46 ft boat confirms my experience with my 40 ft boat, and also seems to confirm the formula printed by the AYRS.
From the graph I would expect the hulls to have a length:beam ratio of about 10:1 giving an AYRS max of about 27 knots ( I´m guessing of course) which compares with my max of 22 knts. With my boat I can get to 50% max without any trouble more than that and the strain starts to show. The most I´ve ever managed was 75% max (17 knts) when she was much lighter than she is now and conditions were absolutely perfect.
If you want to go fast you need very narrow hulls, a huge power to weight ratio and lots of overall beam to make use of the power, under sail that is.
It takes a hull 60 ft long with L:B ratio of 30:1 to get to 30 knts, just. And a hull of 120 ft with much the same ratio doesn´t get to 40knt.
Unfortunately I´ve lost all my AYRS puplications along the way because it would be interesting to compare the maximum speeds given by their formula with the actual speeds obtained by the 60 and 120 ft boats