freeboard

just wondering.. how is freeboard established?. i have read a reasonable amount on design and basic guidlines and for the most part, the aspects that make a hull look decent and sail good are fairly well defined. but i have never read or seen any "rules" that define freeboard by a hulls length or use beyond the general parameters of windage and asthetics. do any rules exhist that would give a designer an "ideal" range for a 16ft. sloop vrs. a 22ft. yawl, or any other type. i do notice tha most boats that are coastal rated will have more freeboard than the same size boat for inland waters, is there a maritime code defining how much? thanks in advance...capt'n ron

 

More freeboard will give the boat more ultimate stability. The floatation of the upper part of the hull help on the recovery after a knockdown.

 

Good guideline for freeboard is ISO12217, that specifies freebord for ocean, offshore, inshore and sheltered boats, also depending on emerbency flotation, deck, etc.

 

thanks for the answers guys. i learned about ISO12217 just minutes after posting my question. i guess i'll have to get that paper. the boat i want to build has, for it's size, it seems to me, relatively high freeboard. i would assume it's because it's designed for coastal sailing and/or to get head room in the cabin. my use of the boat will be completely on inland protected waters. i have redrawn the boat the boat with 4 inches less freeboard and it still has more than boats like the hartly 16 and glen l 17, two boats of similar displacement and and physical dimenions. it looks 100% better,outwardly, the only expense is a loss of headroom in cabin, which still results in 34 inches above the birth. the hull sides are relatively up right and vertically parrallel from station to station with just a touch of twist into the bow. in redrawing the profile, i simply took 4 inches out out the side panel hieght, keeping the same chine and sheer offset points at each station. this will result in the expanded panel having more rocker in it than original, and the fitted panel have just a bit more(5/8 inch) flair angle from chine to sheer, which should stiffen the boat a tiny bit. i realize i lowered the cg of the profile some, but that can only be good, am i correct? i can't see any reason why it won't work, i'm sure the rig and structure will handle the proportional increase in sail effort. the redraw didn't change anything at all at the water line or below, un heeled as lwl puts the chine just on the water and i realize there will be a small increase of area at extreme heeled angles, but at 20 degrees, it is minute as the 5/8" increase in flair is over 22" of hieght at the lowest sheer hieght, so the change in angle is very small at that point. or all practical purposes i can't see any reason why this change won't fly, does anyone see something different? thanks in advance....ron