TIMESAVING TIPONDESIGNING A HUIL Thecubicinchdisplacement of theboatbelowthewaterline, timestheweightof waterper cubicinchwillequalte all upweightof theboa. Fresh waterweighs.03G1 percubicinch I pounds andseawaterweighs.37037pounds percubicinch.Theallupweightof alltheparaof theboat mustbeascertained byactualweighing or calculations. Thetip to savetimeisthatinstead of drawingallof thestations andthencalculating the displacement usingSimpson's rule,isto usetheoptimum prismatic coefficient of .52in drawing stationnumber fiveof a tenstationdrawing. FOR EXAMPLE: a 35/500thatyouwantto weighsixpounds witha watertine of 3Gincfeswill needa cubicinchdisplacement of 166.15435 belowthewaterline. Theprismistheshape and volumeof theareabelowthewaterline of stationfiveorthelargeststationstretched outto 35 inches. Theprismatic coefficient isthe ratioof the volumeof the hullto the volumeof the prism.Fiftytwo percent isabouttheoptimum. Thinkof theprismasa tankwiththehullinside occupying fiftytwopercent ofthetank.Tofindtheprism divide166.1 5435by.52whichis319.52759. Tofindtheareaforstation number fivebelowthewaterline divide319.52759 by36whichis 8.8757563. Remember, if youareusinghalfstations, a goodwayto beginyourdrawing, thisnumber wouldhaveto behalfof thearea.Drawtheshapeof stationnumber fiveandadjustuntilit'sareais 8.87square inches thencontinue drawing allof thestations andlines.Thedisplacement shouldbe around thedesired sixpounds. REMEMBER: THEERASER SHOUI"D OUTWTTHEPENcIt! HAVEFUII.
HOWTOMAKEAN ORCO RUDDER Page9