board/rudder formula

[Pernicious Atavist]

dangit...i forgot the percentage leeboards and rudders should be of sail area. 86' sail...four percent? is that right? sheesh........ :rolleyes:

[BrianY]

Jim Michalak's website says the board should be 4% of the sail area. He does not say anything about rudder area - at least not anything that I can find and I'd really like to find some guidance on that

[ 01-13-2006, 10:28 PM: Message edited by: BrianY ]

[Pernicious Atavist]

thanks for the reminder, i forgot to check there!

[Lewisboats]

According to Kinney (Skene's elements of Yacht design) 8-10% of the area of the underwater profile (sq ft) should be about right for a sailboat.

Steve

[Pernicious Atavist]

10% would be 9 square feet, on a 16' booat? holy molie........

[Thorne]

Yeah but doesn't that 8-10% include the centerboard/leeboard, rudder and skeg? Making it about right if the area of the center/leeboard is 4% and the combined area of the rudder and skeg 4-6%?

(it had better be, cause my 'high-wind' rig is a Sabot mast, boom and sail, with my figures for the Chamberlain dory skiff's underwater profile easily 20% of that relatively small sail...38 sq ft I think.)

[ 01-14-2006, 04:24 PM: Message edited by: Thorne ]

[Hwyl]

Originally posted by Pernicious Atavist:
10% would be 9 square feet, on a 16' booat? holy molie........Not of the sail area, of the underwater profile

[Pernicious Atavist]

<whew> thatt's better...big skeg and the rudder will help....thanks guys

[Pernicious Atavist]

<whew> thatt's better...big skeg and the rudder will help....thanks guys