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Re: Was John Walker a Competent Seaman?

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Posted by Adam Quinan on March 11, 2019 at 07:07:53 user Adam.

In Reply to: Re: Was John Walker a Competent Seaman? posted by Magnus Smith on March 09, 2019 at 04:35:42:

The tidal range between high and low water at Harwich varies between a little over 13 feet to about 7 feet depending on whether it is a spring or neap tide. I don't recall Ransome telling us which it was.
For a chain rode, it is normally a 3:1 ratio between scope (length of chain laid out) and the water depth. I am not sure how deep the location where Goblin was anchored but if it was fairly shallow, then a 10 feet change in depth could be a significant reduction in the holding but unless Jim Brading was very careless and did not lay out enough scope the anchor should not have been straight below the Goblin even at high water. However, the reduction in holding power of an anchor reduces as the scope to depth ratio reduces so high water is the most likely time for its efficacy to fail.

Secondly, the change in the direction of flow as the tide turned would change the direction of pull on the anchor. One of the ways of "tripping" an anchor is to pull it from a vertical or from a position opposite from the one which it was originally laid. In this case as the ebb tide took the Goblin downstream. she would have been pulling the anchor from the opposite direction so making it more likely to break free.

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