i went there and logged out, then reset and it said guest; but link still werked for me. Try their
Forestry Forum homepage link and in lower left corner hit the toolbox icon; shows log weights, board feets, values, line angles etc. i can download if continually a problem i think.
Sherrill/Arbormaster Calculator is cool school toy; not so much field tool. But, it can show patterns of forces; how varying hitch height; line choice, load angle etc. as inputs can vary output forces in lines and supports etc.
The most counter intuituve reflections seem to be that changing the hitch on load height (on vertical spars you have pulley uder load) does not increase drop forces but rather sneaks s'more elastic line into equation to buffer said forces, how much changing to a stronger line raises the SWL but lowers the dampening of again the elastic response to dynamic forces and how dropping the weight in half doesn't drop loading in half in same scenario-because once again there is less elastic force buffering with the higher SWL raised. SWL and elasticity are reciprocals; higher SWL wants more tensile strength to load, higher elasticity wants less tensile strength to load(for same length rubberband/line; but more line is onption for imparting more elasticity without lowering SWL. Also more straight forwardly; but important; how on especially vertical load blocked under the height of the CG within same shape increases forces, that increase in drop is doubled by the inversion of the CG from above pulley to below-then that force doubled by the 2;1 action of the pulley on the supporting spar( my men tall cartoons call this 'quadrophenic' loading as laugh energy and easy mneumic to remember.)
It does not show overhead rigging or adjustmeants for pretensioning of line. It shows less forces in line blocking out from under a lean as compaired to pure vertical; but not how the lessor forces blocking out from under lean take the lessor forces and give more leverage on spar as transferred to the lean.
Also inter-arresting is how a redirect pulley gives 2x forces on a support; but gives mroe elastic line to absorb shocks. Whereby a 2:1 on load only places 1.5x loading on support (statically) and 3:1 places 1.33x on support statically; whereby lines are easier to hold and tighten; and also less static load on support. Loading = Load X (1 + 1/legs of line to load, so 1:1 simple redirect is load x (1 + 1/1) and 2:1 is load x (1 + 1/2). But, there is an inversion as we go to dynamic loading, at some point (depending on line length on last leg to load + return:control leg as elsatic length); the higher MA that gives hgiehr SWL; gives less easticity/ more shock loading to support.
Snarf Shock Loading Question(s)on Calculator
It seems there are continuously more and more things we know nothing about the smarter we get!
