Scope


Scope is the ratio of anchor rode to the depth of the water, plus freeboard (the the height of the deck above the water) and any rise


of tide. A scope of 5:1 or 7:1 is considered normal. This means that if you are going to anchor where the water is 10 feet deep, your freeboard is 2 feet, and the tide will rise 3 feet, you should pay out 105 feet of rode (10 + 2 + 3) x 7 or 15 x 7 = 105. Charts provide the water depth at a low level called Mean Lower Low Water (MLLW), and the tide tables will tell you what the change will be during the period you are anchored.


1 2 1 2


Scope is the ratio of the length of your anchor rode 1 to the depth of the water plus freeboard and allowing for any tidal rise B.


Is your anchor holding? It’s good seamanship to make sure your anchor has a secure hold on the bottom. Navigation apps have an anchor alarm feature that will signal if your sailboat moves more than the distance you select.


Another, non-electronic method is to locate two objects abeam (perpendicular to the middle of the sailboat) that are aligned. The objects can be on shore, such as a fence post or telephone pole or floating, for instance, a buoy. Do NOT use moveable objects, such as another boat! If the objects abeam remain in alignment, your anchor is holding. If the wind shifts, select new objects.


l Approach - Properly plan your approach.


l Mooring - Properly tie to a mooring.


l Anchors - Properly deploy, set and retrieve the achor.


l Scope - Calculate proper scope based on depth.


l Check Holding - Determine if the anchor is holding with a GPS or sighting if the two objects are aligned.


The Danforth (or fluke type) anchor is very common. It is strong, lightweight, holds well in mud and sand, and is easy to store.


Table of Contents 84


SKILL EVALUATION


Chapter 7 | Ancillary Skills & Situational Awareness


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