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Compass Marine How To | all galleries >> Welcome To >> Anchor Scope Illustrated > The Test Bench
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The Test Bench

The Test Bench

Having been asked the question over and over it seems a lot of boaters do not fully understand anchoring scope or what relationship it has to your anchor on the sea bed.

For this article I wanted to put scope into pictures. I used a short piece of aluminum to represent an anchor shank, some 12 GA finely stranded wire, my work bench and an upright jig marked off in inches to represent the water depth or bow height of the boat and black tape to represent every foot of rode. The depth was set to 12" or 12' by scale.

I used a scale of 1" = 1', or 1 inch equals 1 foot, because this was simple. The aluminum anchor shank, at this scale from pivot to rode connection point, matched my 35 pound CQR and represents about 33" long.

The wire was drawn tight to represent the rode straightening under a full load on a boat. Of course with 300+ feet of rode approaching infinite scope is nearly impossible but this is relative and illustrative only.

Most boaters only measure scope along the rode length so I therefore did not include the anchor shank length. This is why the 1:1 scope you'll see is not vertical.

To measure the angle I used my angle cube that I use for woodworking. This is a highly accurate device though very, very sensitive. I was not and am not concerned about the small fractions .05 etc. it may be off but more about the general angle to the whole number. I tried very hard to be gentle when setting the cube on the shank so as not to disturb the angle of the rode.

The shank was designed to sit 100% flush with the bench but an anchor would be buried and depending upon the design the shank might too be buried. The bottom line is the angle the rode puts on the shank at a given ratio.

Please note that this is a ratio so the scale does not matter and the angle of the rode at 7:1 would be the same if we were talking 300 feet of rode at 7:1 or 8 feet of rode at 7:1.

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