Re: We Didn't Mean To...Drag the anchor

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Posted by Jon on July 28, 2003 at 15:19:23 from user Jon.

In Reply to: We Didn't Mean To...Drag the anchor posted by Ed Kiser on July 28, 2003 at 04:42:59:

A quick google turned up the BBC Weather's tide page for Harwich, with a range today of 3.2-3.6 m, say 11-12 ft. The range at Ipswich is 3 m. or less. Tide ranges given for Walton-on-the-Naze are about 3.1 m. today. By the moon, we're pretty close to the Springs, so I would expect the range they encountered during WD and SW to be within those ranges. Given that Jim was anchoring for a fairly short time (he thought) and using a chain rather than a rope, I'd expect that he only used a scope of about 5 or 6 to 1, since the chain helps boost holding power by translating the pull to the horizontal better than a rope, and he'd have to raise it again. That'd be on the order of 60 ft. rode using Ed's depth and changing the scope to 2.5:1 or 3:1, which is problematic even for a yachtsman-type anchor. I'm assuming Jim's uncle, obviously a competent seaman himself, had equipped Goblin with only yachtsman (stocked) anchors, not the less-capable stockless which require more scope, but conversely, would have the scope reduced less by tidal changes. We know the spare anchor was a yachtsman, and that's the one that was hanging vertically as they drifted off. The primary anchor was still in some ground contact, IIRC, when John first started trying to let out more chain.

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