Rigging Calculator

[AllanKP69]

This helps you understand changes in tension, angles, and load distribution quickly.

Does the rope material used in the various centuries play a role in this? Can you post a typical formula for us? My math skills are not bad, but this looks a bit overwhelming (for me at least ) I love the formulas I use from James Lees, but they do not work for modern era vessels with wire, polyester, nylon, and Dyneema and similar rigging materials of today so new data would be very helpful.

Thank you
Allan

 

[Bob Cleek]

An even more complete set that includes sizing of masts, yards, standing and running rigging has been available since 1979 in The Masting and Rigging of English Ships of War, 1625-1860, but again, learning that the book even existed was tough compared to today.

And "Lees" is quite possibly more accurate than Monfeld, too. https://www.amazon.com/s?k=the+masting+and+rigging+of+english+ships+of+war&adgrpid=1338107332249351&hvadid=83631980935843&hvbmt=be&hvdev=c&hvlocphy=88716&hvnetw=o&hvqmt=e&hvtargid=kwd-83632734995011:loc-190&hydadcr=22629_13494482&mcid=b441f39b76303d15a963d7975f948d0a&msclkid=18889b3d596a1d1ca9eef3cd54cfe08e&tag=mh0b-20&ref=pd_sl_42fqgs6ovx_e
Of course, since Lees, Seawatch Publishing has come out with Scantlings of the Royal Navy 1719-1805 Comparisons of 1719, 1745 Establishments, Ship Builders Repository and Steel’s Elements and Practice by some guy named Allan Yedlinsky. https://seawatchbooks.com/products/...el-s-elements-and-practice-by-allan-yedlinsky

 

[Bob Cleek]

I love the formulas I use from James Lees, but they do not work for modern era vessels with wire, polyester, nylon, and Dyneema and similar rigging materials of today so new data would be very helpful.

After about 1950, I think it's safe to say, "If it looks right, it is right." but it's safest to err in the smaller direction. When the stronger synthetic materials became available, the line sizes relative to tensile strength became so small that the criterion for line often became the smallest size that can be comfortably held in the hand and hauled because the increased strength of the new line rendered size more or less irrelevant. That size would be not less than 3/8" for light sheets on smaller boats, up from 1/2" to to 3/4" for sheets on medium sized sails and around an inch for so or sailing ships. (Dimensions are diameter, not circumference.) Dyneema, Amsteel, Spectra and the others now are stronger than wire rope of the same diameter and are being used for standing rigging with modern "deadeyes" instead of wire in favor of the lines' light weight. The practice seems to be to use the older rules of thumb with the new cordage materials and consider the additional strength a happy benefit. About fifteen years ago, a friend wanted to re-rig his about 60' Edson Schock schooner. I searched all over for rigging scantlings and ended up concluding that the tensile strength of a given shroud or stay should at least be equal to the weight of the vessel, but that was way over-engineered in any event.

An interesting footnote as told to me by one of the former owner of one of the old classic ocean racing boats: Back in the mid-fifties when low stretch Dacron line became available, the ocean racing fleet, in those days famous vessels like Baruna, Orient, Barlovento, Santana, Dorade, etc, were quick to replace their natural fiber cordage with the new low stretch high test line because it became possible to impose far greater loads on the new synthetic line. The owners also started installing a lot of larger geared winches that permitted generating the higher loads the new line could carry. (The famous Barient Winch Co. was formed by the partnership of the owners of Baruna and Orient.) The advantage, of course, was that the tighter the backstays, the tighter tighter the headstays and the better the windward ability. Consequently, nearly every boat in the "big boat" ocean racing fleet of that time ended up being "pulled apart," some with cracked frames, loose chainplates, and/or leaking plank seams, by the added stress their crews cranked into them using the new stronger line. The line and the new winches created stresses that never existed when the boats were built.