Vicprop - Prop Calculator for Displacement and Semi-displacement Hulls
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3/10/2015 Vicprop Prop calculator for Displacement and semidisplacement hulls http://www.vicprop.com/displacement_size.php?action=calculate 1/3 . Data Input Waterline length in feet: 28.87 feet Beam at the waterline in feet: 8.98 feet Hull draft in feet (excluding keel): 2.95 feet Vessel weight in pounds: 2204 lbs Engine Horsepower: 250 HP Number of engines: 2 Total Engine Horsepower: 500 HP Engine R.P.M. (max): 5000 RPM Gear Ratio: 2.08:1 Shaft R.P.M. (max): 2404 RPM Number of shaft bearings (per shaft): 1 Desired speed in Knots: 30 knots Horsepower Calculations This will calculate the maximum horsepower and torque available at the prop(s). Total available horsepower at the engine(s): 500 HP Total available torque ft/lbs at the engine(s): 525 ft/lbs Horsepower loss of 3% per gearbox: 15.0 HP Horsepower loss of 1.5% per shaft bearing: 7.5 HP Total horsepower available at the propeller(s): 477.5 HP
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Transcript of Vicprop - Prop Calculator for Displacement and Semi-displacement Hulls
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3/10/2015 VicpropPropcalculatorforDisplacementandsemidisplacementhulls
http://www.vicprop.com/displacement_size.php?action=calculate 1/3
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DataInputWaterlinelengthinfeet: 28.87feetBeamatthewaterlineinfeet: 8.98feetHulldraftinfeet(excludingkeel): 2.95feetVesselweightinpounds: 2204lbsEngineHorsepower: 250HPNumberofengines: 2TotalEngineHorsepower: 500HPEngineR.P.M.(max): 5000RPMGearRatio: 2.08:1ShaftR.P.M.(max): 2404RPMNumberofshaftbearings(pershaft): 1DesiredspeedinKnots: 30knots
HorsepowerCalculationsThiswillcalculatethemaximumhorsepowerandtorqueavailableattheprop(s).Totalavailablehorsepowerattheengine(s): 500HPTotalavailabletorqueft/lbsattheengine(s): 525ft/lbsHorsepowerlossof3%pergearbox: 15.0HP
Horsepowerlossof1.5%pershaftbearing: 7.5HPTotalhorsepoweravailableatthepropeller(s): 477.5HP
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3/10/2015 VicpropPropcalculatorforDisplacementandsemidisplacementhulls
http://www.vicprop.com/displacement_size.php?action=calculate 2/3
Totaltorqueft/lbsavailableatthepropeller(s): 1043ft/lbs
Speed&PowerCalculationsBasicdisplacementspeedandhorsepowerrequiredDisplacementhullspeed(1.34Xsqrtofwaterlinelength): 7.20KnotsMinimumhorsepowerrequiredatpropeller(s)forHullspeed: 4.8HPCalculationsbasedondesiredspeedandavailableHPHPrequiredatpropeller(s)fordesired30knotsspeed: 316HPEstimatedmaximumspeedwithexisting500horsepower:Thisisthespeedwewilluseforthepropellersize. 34.38Knots
AtthispointitisimportanttonotethatallofthecalculationsabovearebasedonfullRPMandHP.MostenginesareratedtorunatapercentageofthierfullRPM.Thisiswhatwilldetermineyourmaximumcruisingspeed.Thepropellersizingcalculationsbelowarebasedon90%offullRPM.Thisgivestheenginesomereservepowertoallowforvariableloadinginthevessel.
PropellerSizeNumberofblades Diameter(inches) Pitch(inches)2Blade 18.7 X 22.03Blade 17.8 X 21.84Blade 16.8 X 21.4Thepropellersizesshownabovedonotcontaincalculationsforcavitationorbladeloading.Ifyoufindthattherecommendedpropelleristoolargetofityourvessel,youcantryincreasingtheshaftspeed.Failingthis,youcanreducethediameterandincreasethepitchattheexpenseofyourpropellerefficiency.Theruleofthumbis1inchofdiameterisequalto11/2to2inchesofpitch.
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3/10/2015 VicpropPropcalculatorforDisplacementandsemidisplacementhulls
http://www.vicprop.com/displacement_size.php?action=calculate 3/3
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