anchor scope explained with visual add.

Nice technical illustration. However,I didn't see the mention of the necessity to include the height of the bow roller from the water, as well as the depth of the water in the equation to give "Scope". Many people forget to add that in.
 
Good visuals but it's a lot of work and photographs for what can be easily calculated using simple geometry. Also, it's a bit of an over simplification since most use chain for at least a portion of the rode and the weight of the chain will result in more curvature and hence a shallower angle for a given scope. Nonetheless, it's good to see how much the angle changes for different scopes.
 
If you ever did dirt work slope and scope are the same thing. A 1:1 slope is 1 foot out and 1 foot down, 2:1 is 2 feet out and 1 foot down and so on. So having done 15 years of dirt work determining scope was easy.

It’s not a difficult concept to get your head around; Depth X desired scope = amount of anchor rode.

I think the person who put together this online scope demonstration has way too much time on their hands, it’s not rocket science.
 
I guess this may seem redundant to most of you but I need all the information I can get. Sight also showed some good tips on how to repair or put water proof hole in fiber glass.
 
localboy":1oq1d8oc said:
I think the person who put together this online scope demonstration has way too much time on their hands...
Click to expand...

:lol: I was thinking the same thing.


Depth X desired scope = amount of anchor rode
Click to expand...
K.I.S.S.
Click to expand...

I agree but I do think that it was worthwhile to see mention of the bow height and relative to the position/calibration of the depth sounder. That might not make a big difference to us in Washington or Alaska as we typically anchor in relatively deep water due to large tidal swings and fairly steep shorelines. However, those who anchor on flats in areas with low tidal exchanges (say Florida), need to consider the bow height in their determination of rode. E.g. if one's bow is 4' off the surface and one's transducer is 1' below the surface, that 5' of difference matters if one is anchoring in say 4' of water (which might only read 3' on the depth finder). In this case, 7*3 (depth finder reading) =21' but you really need 7*4(actual depth)+4(bow height)=32 foot of rode to get 7:1. Letting out only 21' gets you scope (21-4(bow height))/4(actual depth) = 4.25.

Also, those who determine the appropriate scope at low tide may find the scope has changed significantly at high tide, especially in places like Seattle with a 12' exchange or Alaska with an even larger difference in tide height. At a scope of 7:1, that 12' tidal difference can add 84' to the required rode to stay at a 7:1 scope.
 
I always go to the max scope and then add 10% more for safety, assuming I have enough swing room @ any particular anchorage. I sleep better that way.
 
Back
Top