by KCStudly » Mon Mar 09, 2015 3:22 pm
It boils down to a leverage issue. The opened and closed length of the strut, and its pressure rating, versus the arc of travel you want for the hatch (opened and closed positions) and how that relates to the fixed mounting point of the strut. Also, if the angle of thrust of the strut is not optimized to the hatch angle, the available thrust can be misdirected (vector force relationship, in other words, the strut force may be applied inefficiently, perhaps more towards ripping the hinge and less towards lifting the hatch).
And then there is the weight of the hatch and its center of gravity with relation to the hinge. A steeper more vertical hatch will be easier to lift initially than a longer hatch that is laid out flatter.
A longer strut with longer throw will put less stress on the hinge and mounting point because the force is directed closer to the hatch CG than it would be with a shorter strut with shorter throw, which has less mechanical advantage due to the leverage of the hatch.
It would be much better to do a mock up and some research and try to get close, rather than trial and error. There are are many fine examples of builders who clamped scraps to the insides of their galleys to work out the weights and geometry, and check for interferences; and even more examples of people who ended up with extra holes in their walls and hatches, along with extra hassles exchanging struts for differently rated ones.
KC
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