SMALL CRAFT DESIGN (2) - 8m yacht hull

8meter Yacht hull drawing

Machinery & system (2) - SL ratio

DISPLACEMENT BOAT
example	-	finding SL ratio
WL	70	ft
DL	220000	Lb
Speed	11	Knt
Sl ratio =	Kts/(WL)^0.5
	1.314751
SHP=	Lb*(SLR)^3/10.665^3
	412.165	=	crusing speed		(85% of Max speed)
	484.9	=	MAX speed
	LB/HP
	533.7668
SEMIDISPLACEMENT BOAT
example	-			DispT – Displacement in long tons of
					2,240 pounds
Light vessel
WL	50	feet
DL	30000	Lb		Dis T	13.39285714
					13.4
	•DL ratio =DispT/(0.01 x WL)3
				DL ratio	107.2
	SL Ratio = 8.26/(DL Ratio)0.311
				Sl ratio	1.930142924
					1.93
	Pict
					LB/SHP= (10.665 / SL RATIO)3			168.7371
								168.7
					SHP=LB/168.7		177.8305
							178
PLANING BOAT
example					Kts = C / (LB/SHP)0.5
Twin outboard runaboat					25=150/(10890/SHP)^0.5
	WL	30	ft
	DL	10890	lb		SHP= 10,890 /(150/ 25) 2
Operate speed		25	knt
					302.5
				HP(70%)	302
				MAX	431.4285714
					431
				Twin	215.5
					215	each