Thanks to Hudson for pointing out an error I’d made in a formula on my
spreadsheet.
I’ve corrected (I hope) the comparative figures for the BCC - the
indices that changed included Length/Beam and the Comfort Factor (the
formula I’m using is CR=disp / (.65 * (.7 * lwl+.3 * loa) *
beam^1.33)).
The following figures are, I hope, closer to the truth:
Ballast/Displacement (design): 0.33
Ballast/Displacement (cruising gear): 0.25
Displacement/Length (design): 345
(medium displacement)
Displacement/Length (cruising gear): 417
(heavy displacement)
Sail Area/Displacement (design): 18.63
Sail Area/Displacement (cruising gear): 16.35
Hull speed Vhull: 6.87 knots
Velocity ratio Vmax/Vhull: 1.07
LOD/Beam: 2.78
(a measure of fineness of the hull; fine hulls have ratios of 3.0-4.0
and higher but beamier hulls sail flatter and have more interior room)
Beam/LOD: 0.359
(a measure of form stability: hulls lower than 0.350 are tender; those
much higher are as stable as a barge)
Ted Brewer’s Comfort Factor (design): 37.0
(racing designs are less than 20, cruisers 30-40)
Ted Brewer’s Comfort Factor (cruising gear): 45.0
Capsize Risk Screen (design): 1.62
(above 2.0 is undesirable for offshore cruising)
Capsize Risk Screen (cruising displacement): 1.52
Roll Acceleration (design): 0.04937g
(above 0.06g is undesirable for offshore cruising; malaise starts at
0.1g, 0.18g is intolerable)
Roll Acceleration (cruising displacement): 0.03585g
Roll Period (design): 3.9 seconds
(less than 4 seconds = stiff, more than 8 secs = tender)
Roll Period (timed, with cruising gear): 3.8 secs
Period/Beam (design): 6.96
Cheers
Bil (BCC 116)
Bil Hansen
Post: 5 Lintang Pantai Jerjak, 11700 Sg Nibong, P Pinang, Malaysia