Block Loading Formulas
I thought to suggest the following link which includes a chart of load factors for blocks at various angles of rope lead deflection which may be of use: http://www.mauriprosailing.com/Harken/harken-loading-formulas.htm The way I read the chart, if a block say has a 1000 swl, and the angle of rope deflection is 180 degrees (such as the back-and-forth series of blocks between the traveler and the boom), then max safe rope tension is 500 lbs (1000 lbs swl / 200% = 500 lbs). But if the angle of deflection is say instead 45 degrees, then the max safe rope tension would be 1316 lbs (1000 swl / 76%) and at 30 degrees the max slw would be 1923 lbs (1000 swl / 52%). So for your 300 swl cheek block, say 45 degree deflection for the lead from the mast based back to the cockpit, you can safely exert almost 400 lbs tension on the halyard and about 2700 lbs tension before the block fails. The above examples assume that I have interpreted the chart correctly, but the concept makes sense when correlated from what I remember from Freshman Physics class 30 years ago. Best that you work through the description section and the link and chart yourself as well. rardi
I thought to suggest the following link which includes a chart of load factors for blocks at various angles of rope lead deflection which may be of use: http://www.mauriprosailing.com/Harken/harken-loading-formulas.htm The way I read the chart, if a block say has a 1000 swl, and the angle of rope deflection is 180 degrees (such as the back-and-forth series of blocks between the traveler and the boom), then max safe rope tension is 500 lbs (1000 lbs swl / 200% = 500 lbs). But if the angle of deflection is say instead 45 degrees, then the max safe rope tension would be 1316 lbs (1000 swl / 76%) and at 30 degrees the max slw would be 1923 lbs (1000 swl / 52%). So for your 300 swl cheek block, say 45 degree deflection for the lead from the mast based back to the cockpit, you can safely exert almost 400 lbs tension on the halyard and about 2700 lbs tension before the block fails. The above examples assume that I have interpreted the chart correctly, but the concept makes sense when correlated from what I remember from Freshman Physics class 30 years ago. Best that you work through the description section and the link and chart yourself as well. rardi
