{"title":"Harken Block Loading Formulas","description":"\u003clink rel=\"stylesheet\" href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0879\/4908\/2930\/files\/om-manual-v2.css\"\u003e\u003cstyle\u003e.mpom .om-tbl.nw td+td{white-space:nowrap}\u003c\/style\u003e\u003cdiv class=\"mpom\"\u003e\n\u003cdiv class=\"om-head\"\u003e\n\u003cdiv\u003e\n\u003cspan class=\"om-tag ss\"\u003eSELECTION GUIDE\u003c\/span\u003e\u003cp class=\"om-lead\"\u003eHarken's formulas for sizing blocks, genoa leads and traveler cars: block load by angle of deflection, genoa sheet load, mainsheet load and the standard rig dimension abbreviations.\u003c\/p\u003e\n\u003cdiv class=\"om-box\"\u003e\n\u003cdiv class=\"om-row\"\u003e\n\u003cspan\u003eDocument\u003c\/span\u003e\u003cb\u003eHarken Block Loading Formulas\u003c\/b\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-row\"\u003e\n\u003cspan\u003eFormat\u003c\/span\u003e\u003cb\u003ePDF · 1 page · 2.5 MB\u003c\/b\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-row\" style=\"border-bottom:0\"\u003e\n\u003cspan\u003eLanguage\u003c\/span\u003e\u003cb\u003eEnglish\u003c\/b\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-acts\"\u003e\n\u003ca class=\"om-btn dl\" href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0879\/4908\/2930\/files\/Harken-Block-Loading-Formulas.pdf\" target=\"_blank\" rel=\"noopener\"\u003e\u003csvg viewbox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2.4\" stroke-linecap=\"round\" stroke-linejoin=\"round\"\u003e\u003cpath d=\"M12 4v11\"\u003e\u003c\/path\u003e\u003cpath d=\"m7 10 5 5 5-5\"\u003e\u003c\/path\u003e\u003cpath d=\"M5 20h14\"\u003e\u003c\/path\u003e\u003c\/svg\u003e Download PDF\u003c\/a\u003e\u003ca class=\"om-btn buy\" href=\"\/collections\/harken-sailboat-blocks-carbo\"\u003eView Collection\u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-toc\"\u003e\n\u003ca href=\"#om-block\"\u003eBlock Loading\u003c\/a\u003e\u003ca href=\"#om-genoa\"\u003eGenoa System\u003c\/a\u003e\u003ca href=\"#om-main\"\u003eMainsheet System\u003c\/a\u003e\u003ca href=\"#om-rig\"\u003eRig Dimensions\u003c\/a\u003e\u003ca href=\"#om-products\"\u003eProducts\u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-img\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0879\/4908\/2930\/files\/Harken-Block-Loading-Formulas-Cover.png\" alt=\"Harken Block Loading Formulas\" loading=\"lazy\"\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-block\" id=\"om-block\"\u003e\n\u003ch2 class=\"om-h\"\u003eBlock Loading vs Angle of Deflection\u003c\/h2\u003e\n\u003cdiv class=\"om-tbl nw\"\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eAngle of deflection\u003c\/th\u003e\n\u003cth\u003eLoad factor\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e30°\u003c\/td\u003e\n\u003ctd\u003e52%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e45°\u003c\/td\u003e\n\u003ctd\u003e76%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e60°\u003c\/td\u003e\n\u003ctd\u003e100%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e75°\u003c\/td\u003e\n\u003ctd\u003e122%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e90°\u003c\/td\u003e\n\u003ctd\u003e141%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e105°\u003c\/td\u003e\n\u003ctd\u003e159%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e120°\u003c\/td\u003e\n\u003ctd\u003e173%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e135°\u003c\/td\u003e\n\u003ctd\u003e185%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e150°\u003c\/td\u003e\n\u003ctd\u003e193%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e160°\u003c\/td\u003e\n\u003ctd\u003e197%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e180°\u003c\/td\u003e\n\u003ctd\u003e200%\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\u003cp class=\"om-note\"\u003eBlock load = line load × load factor for the angle the block turns the line. A footblock turning a sheet 180 degrees sees twice the sheet load; a deck organizer turning a halyard 30 degrees sees 52 percent.\u003c\/p\u003e\n\u003cdiv\u003e\n\u003ch3 class=\"om-h3\"\u003eBoat type\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eFormulas assume a medium-displacement monohull.\u003c\/li\u003e\n\u003cli\u003eMultihulls and boats with canting keels or water ballast carry sail very high in apparent wind – calculate with that wind speed (e.g. a trimaran with its blade jib in 25 knots true at over 15 knots boat speed, nearly 40 knots apparent).\u003c\/li\u003e\n\u003cli\u003eULDBs are tender and reef early; a ULDB will probably drop its #1 genoa at about 15 knots apparent.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-block\" id=\"om-genoa\"\u003e\n\u003ch2 class=\"om-h\"\u003eGenoa System Loading\u003c\/h2\u003e\n\u003cdiv class=\"om-tbl nw\"\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003cth\u003eEnglish\u003c\/th\u003e\n\u003cth\u003eMetric\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eSheet load\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003eSL = SA × V² × 0.00431\u003c\/td\u003e\n\u003ctd\u003eSL = SA × V² × 0.02104\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSL\u003c\/td\u003e\n\u003ctd\u003eSheet load in pounds\u003c\/td\u003e\n\u003ctd\u003eSheet load in kilograms\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSA\u003c\/td\u003e\n\u003ctd\u003eSail area in square feet\u003c\/td\u003e\n\u003ctd\u003eSail area in square meters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eV\u003c\/td\u003e\n\u003ctd\u003eWind speed in knots\u003c\/td\u003e\n\u003ctd\u003eWind speed in knots\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\u003cul\u003e\n\u003cli\u003eWind speed is squared, so it is the key variable: use the apparent wind the specific sail is carried in (a #1 genoa on a 7 m (25') boat might only see 15 knots; a #3 blade on a maxi could see 40).\u003c\/li\u003e\n\u003cli\u003eGenoa lead car load = sheet load × load factor of the sheet deflection. Most #1 genoas deflect about 45 degrees; a #3 may deflect 75 degrees or more.\u003c\/li\u003e\n\u003cli\u003eLead car adjuster tackle load: about 0.3 of lead car load at 45 degrees deflection, and .05 of lead car load at 60 degrees (as printed; the drawing on the same page shows .5 × car load at 60°).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"om-note\"\u003eFor typical cruising monohulls with fixed keel and Dacron sails, sheets and halyards. For other types, ask Harken for technical assistance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-block\" id=\"om-main\"\u003e\n\u003ch2 class=\"om-h\"\u003eMainsheet System Loading\u003c\/h2\u003e\n\u003cdiv class=\"om-tbl nw\"\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003c\/th\u003e\n\u003cth\u003eEnglish\u003c\/th\u003e\n\u003cth\u003eMetric\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eMainsheet load\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003eML = E² × P² × 0.00431 × V² \/ (√(P² + E²) × (E − X))\u003c\/td\u003e\n\u003ctd\u003eML = E² × P² × 0.02104 × V² \/ (√(P² + E²) × (E − X))\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eML\u003c\/td\u003e\n\u003ctd\u003eMainsheet load in pounds\u003c\/td\u003e\n\u003ctd\u003eMainsheet load in kilograms\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eE\u003c\/td\u003e\n\u003ctd\u003eFoot length of main in feet\u003c\/td\u003e\n\u003ctd\u003eFoot length of main in meters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eP\u003c\/td\u003e\n\u003ctd\u003eLuff length of main in feet\u003c\/td\u003e\n\u003ctd\u003eLuff length of main in meters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eV\u003c\/td\u003e\n\u003ctd\u003eWind speed in knots\u003c\/td\u003e\n\u003ctd\u003eWind speed in knots\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eX\u003c\/td\u003e\n\u003ctd\u003eAft end of boom to mainsheet attachment, feet\u003c\/td\u003e\n\u003ctd\u003eAft end of boom to mainsheet attachment, meters\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\u003cul\u003e\n\u003cli\u003eLess widely accepted than the genoa formula: a rough guide only, for offshore boats of 9–18 m (30–60').\u003c\/li\u003e\n\u003cli\u003eAssumes standard roach of 7.5%. For large-roach sails such as flattops, multiply by the roach percentage – with 25% roach, multiply the result by 1.25.\u003c\/li\u003e\n\u003cli\u003eTraveler car adjuster load is generally taken as 0.2 × car load.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"om-block\" id=\"om-rig\"\u003e\n\u003ch2 class=\"om-h\"\u003eRig Dimension Abbreviations\u003c\/h2\u003e\n\u003cdiv class=\"om-tbl nw\"\u003e\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eAbbr.\u003c\/th\u003e\n\u003cth\u003eMeaning\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLOA\u003c\/td\u003e\n\u003ctd\u003eLength overall – tip-to-tip length of the boat\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLWL\u003c\/td\u003e\n\u003ctd\u003eLength waterline – length of the waterline\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDWL\u003c\/td\u003e\n\u003ctd\u003eDesign waterline – theoretical waterline length, as opposed to LWL, the actual waterline\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBMX\u003c\/td\u003e\n\u003ctd\u003eBeam maximum – width at the widest point\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBWL\u003c\/td\u003e\n\u003ctd\u003eBeam waterline – widest beam at the waterline\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eI\u003c\/td\u003e\n\u003ctd\u003eForetriangle height, top of highest sheave to sheerline\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eI\u003csub\u003e2\u003c\/sub\u003e\n\u003c\/td\u003e\n\u003ctd\u003eHeight of staysail halyard above deck\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eJ\u003c\/td\u003e\n\u003ctd\u003eForetriangle base, front of mast to forestay\/deck intersection\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eJ\u003csub\u003e2\u003c\/sub\u003e\n\u003c\/td\u003e\n\u003ctd\u003eBase of staysail triangle\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eP\u003c\/td\u003e\n\u003ctd\u003eLuff length of the mainsail\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eE\u003c\/td\u003e\n\u003ctd\u003eFoot length of the mainsail\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLP\u003c\/td\u003e\n\u003ctd\u003eShortest distance from headstay to the clew of the jib\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp class=\"om-note\"\u003eNeed a part that isn't listed? \u003ca href=\"\/pages\/contact\"\u003eAsk us to source it\u003c\/a\u003e and quote the part number from the PDF.\u003c\/p\u003e\n\u003ch2 class=\"om-h\" id=\"om-products\"\u003eProducts in this Selection Guide\u003c\/h2\u003e\n\u003c\/div\u003e","products":[],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0879\/4908\/2930\/collections\/Harken-Block-Loading-Formulas-Cover.png?v=1791298253","url":"https:\/\/www.mauripro.com\/collections\/selection-guides-harken-block-loading-formulas.oembed","provider":"MAURIPRO Sailing","version":"1.0","type":"link"}