thinwater
Well-Known Member
^^^ I made this effort with ABYC. The truthful answer was that the details of the basis for H-40, Table 1 has been lost to the sands of time, when the men who did the research passed on. The tables remain valid in the sense that boats designed based on them have had acceptable service. The best understanding is that the working load limits are the maximum they observed anchored at long fetch in relatively shallow water but in non-breaking conditions, chain with no snubber. I did such testing and got values that suggested this might be right. It is intended to be worst case for the conditions, something any sane sailor would try hard to avoid. You anchored in an open rodestead, too close to shore, and a front passed with you trapped.
The windspeed (ABYC) is the maximum (gust) measured at 33 feet. However, the spikes are mostly related to the optimum synchronization of wave sets and the catenary coming out of the chain, so the extent to which this is influenced by gusts is less than certain (it is not a wind-load-only number--that would be much easier to measure).
So far as I know, there is no generally accepted way to estimate rode tension for recreational yachts. Too many variables. I recorded rode tensions over a range of about 400%, at one location, on one day, just by changing the rode type.
The windspeed (ABYC) is the maximum (gust) measured at 33 feet. However, the spikes are mostly related to the optimum synchronization of wave sets and the catenary coming out of the chain, so the extent to which this is influenced by gusts is less than certain (it is not a wind-load-only number--that would be much easier to measure).
So far as I know, there is no generally accepted way to estimate rode tension for recreational yachts. Too many variables. I recorded rode tensions over a range of about 400%, at one location, on one day, just by changing the rode type.