`Large Sailing Yacht stability criteria following MCA LY3 Code.

 

`The MCA LY3 sailing yacht criteria requires the 'derived heel' angle be greater than 15deg (11.2.2.1)

`GHS angle limits being contextual, equil angle will be checked as SMALLER THAN, although you asked for GREATER THAN

`The alternative is then to reverse the procedure, and show that with twice the heeling moment that it takes

`to heel 15deg, the angle of heel is less than the angle of DFD and also less than 60deg.

`It uses a single-limit RA to pre-calculate the arm at 15deg, calculaters the required HMMT to heel 15deg,

`applies double that HMMT, and tests whether EQUIL is less than DFD or 60deg angme.

 

`NDAR September 2015

`This run file is only proposed as an example. It should only be used as a starting point for your own work. No warranties are made on the validity of results

 

Proj MCASAIL

 

 

clear

water 1.025

 

limit RA at abs 15 > 1

 

variable RA15, dwhl, dwhmmt, WL0, WL0MMT

 

ra /lim /noprint

Set RA15={limmarg} div 100 plus 1

\Righting Arm at 15 degrees = {RA15:3}m <--Heeling arm required to heel 15deg

set dwhl={RA15} div cos 15

\Derived wind heeling lever = dwhl = {dwhl:3} <--Derived heeling arm at 0deg

set dwhmmt={dwhl} times {weight}

\Derived wind heeling moment, {dwhmmt:1}t.m

\

\{+u}Now deriving WLO, as twice the dwhl:

set WL0={dwhl} times 2

\Wind heel lever at zero degrees = WL0 = {WL0:3}m

set WL0MMT={WL0} times {weight}

\Wind moment at zero degrees = WL0MMT = {WL0MMT:1}t.m

\

\Next page, RA curve to check:

\ - Range from equilibrium to abs 60deg or downflooding is positive

\ - Flood angle is greater than 40deg

\ - Range from equilibrium to RAzero is greater than 90deg

page

 

hmmt {WL0MMT} /c:1.3

 

solve

 

limit off

limit title 3.1.6 Withstand twice the HMMT at 15 degrees.

limit angle from equil to abs 60 or fld > 0

limit angle at fld > 40

limit angle from equ0 to ra0 > 90

heel 0

ra /lim:att /stop

\Limit (1) effectively demonstrates that angle of heel due to twice\

\the HMMT derived from 15deg heel, is smaller than 60deg and FLD\

 

hmmt off