Re: Re: M_Boats: New Boat-what anchor?
With all the discussion about anchor type and anchor size, the most important aspect was not discussed. That is the length of the anchor rode. A 10:1 ratio of water depth to anchor rode length is the optimum. Ten foot water depth = 100 foot rode. But this is the ideal condition where you have unlimited swinging room. As the rode gets shorter because of nearby anchored boats, then you need more chain. The whole object is to keep the pull on the anchor as horizontal as possible. That allows the anchor to dig deeper. Deeper = more security. The chain lies on the bottom and keeps the pull on the anchor horizontal. With a short rode, the influence of tidal range, and wakes, will cause a vertical pull on the anchor stock, tearing the anchor away from it's hold on the bottom. At that point, you are drifting through the anchorage. Connie
On Jul 28, 2005, at 10:39 AM, chbenneck@juno.com wrote:
With all the discussion about anchor type and anchor size, the most important aspect was not discussed.
That is the length of the anchor rode.
A 10:1 ratio of water depth to anchor rode length is the optimum. Ten foot water depth = 100 foot rode.
I just wanted to add one comment to Connie's excellent advice. It's actually not *that* much of a factor on an M-boat, but it's to use the distance from your anchor roller to the bottom when you're calculating, not just the water depth. When I was out cruising, the boat's anchor roller (and the snatch block for the snubber as well) was 5-feet from the water. So in a 20-foot-deep anchorage, at 5:1 scope, if you only counted the 20 feet, you'd let out 100' of rode; but in reality it would only be 4:1. Go for more scope or in deeper water and it starts to add up. Probably only adds two feet or so to your calculations on an M-boat, of course. We also had a rule of 90' minimum rode out (almost) no matter what, but again, perhaps overkill on an M. ---Rachel Fatty Knees 7' #302 Former owner, M-17 #334 Former owner, M-15 #517
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chbenneck＠juno.com -
Rachel