Tuning an anchor rode
Important
For almost 10 years, these pages were supplemented with some Excel® spreadsheets to allow readers to simulate their own boat characteristics and anchoring conditions. I'm sorry to inform you I have decided to remove those spreadsheets, for the following reason: Many readers informed me it was impossible to correctly open them with recent Microsoft Office® versions for Mac OS X® or even Windows® 8, because of "macro" incompatibilities! Some people suggested I should transpose the offending macros to Open Office® (or LibreOffice®). Unfortunately, I have no available time to undertake this rather involved task. Thank you for your interest in my work. Happy anchoring! Alain |
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Quiet sunset in Anse de Leoube (French Riviera)
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Most cruising yachts spend at least 80% of the time at anchor. The safety of the boat and its crew depends on a few pieces of metal and rope which hopefully will prevent the boat from running aground. When choosing a place to anchor, as well as sizing the anchoring gear, a wise skipper should not rely on luck to make sure that the anchor will hold if the weather conditions deteriorate: some physical sense and knowledge are invaluable.
Admittedly, although anchoring is based on longstanding physical laws, it cannot be completely mastered unless an in-depth (;-) analysis of the soil around the anchor is made, as oil platform engineers do.
Therefore, we will only skim the anchor problem, just stressing on the parameters that condition the performances of an anchor. We will focus on the rode behavior, with special emphasis on a generally underestimated problem: the dynamic behavior of various types of rode under wind gusts.
Note: If you feel allergic to formulae, tables, curves etc., you may skip them and directly go to the conclusions of each section!