From my book:
Anchoring
In the cruising guides you’ll find detailed descriptions of a great many anchorages along the way. Rather than discuss the anchorages themselves, we’ll discuss anchoring issues and technique (much of which you may already know), with emphasis on the nature of the Inside Passage. If you’re experienced at anchoring, there’s not much magic to it, but recognize that you will need to take into account really big tides, deep water, and potentially tough weather conditions. If you’re less experienced, anchoring safely is not that tough to learn – and it’s an essential skill for the Inside Passage.
Tidal range varies greatly from place to place, and from one time of the lunar month to another. When the sun and moon are aligned, or directly opposite each other (new moon and full moon), their gravitational effects add together, making “spring” tides which are especially large. When the moon is at ¼ or ¾, the “neap” tides are smaller. PNW tides can be as small as 6-8 feet, or as large as 20 and more. You could find yourself high and dry if you don’t know where the tide is when you anchor, and how much lower it will get over the whole time you’re there. Modern chartplotters with tide tables make this easy to figure out – but make sure you get it right.
We usually anchor in 25-55 feet, and put out 90-180 feet of rode. We start by listening to the weather forecast, so we know how much wind to expect, and from what direction. Then we figure the tides, and thus the minimum depth we need. If we aren’t already quite familiar with the anchorage, we make a circle 200-400 feet across, checking depths in the area where we’ll be swinging on the hook. We do this slowly and carefully, to avoid suddenly coming across a very shallow spot – particularly where detailed charting is not available. We did wreck our props on one dark day, circling too casually in 25 feet of water, and running into a pinnacle we didn’t see, only 2 feet below the surface.
If depths look OK within the circle, and we set the anchor solidly in the center of it, we’re fairly sure we won’t wind up aground. A good way to ensure we have covered the right area, and we’re anchoring in the center of it, is to zoom way in on our chartplotter. It shows the scale of the view it’s presenting, so by looking at our track we can see quite accurately the size and shape of the area we’ve checked out.
We point into the wind, come to a stop, lower the anchor, and after the anchor is on the bottom we back slowly, letting out more rode. After letting out the appropriate length of rode, we shift into neutral, cleat off the line, and let the boat put some tension on it. When the anchor seems to have set, we pull gently in reverse, while feeling the line for signs of dragging. Usually it’s easy to tell whether the anchor is well set or dragging. More often than not, it sets solidly right away. If it drags, we retrieve and re-set. The more wind we expect, the longer our rode, and the harder we pull to test the set.
If the wind is strong, and we’re not sure of the holding quality of this particular bottom, we leave the chartplotter on and zoomed in. If it’s really windy, we might leave both chartplotter and fishfinder on for quite a while. As we swing on the hook, our track on the chartplotter shows as a crescent, centered on the location of the anchor. If our position moves beyond the initial position of the crescent, we know we have been dragging. Occasionally this happens soon after we anchor, usually because thick kelp or soft mud has prevented good holding. Then we retrieve the anchor and re-set, successfully in most cases without moving very far.
Ideally we choose a relatively small cove with protection from several angles. If we know where the wind is coming from, an anchorage that’s open for some distance in a different direction may be just fine. But suppose our anchor spot is open to the west for a mile or two, and west wind is forecast – we’re going to feel it when even a moderate west wind blows. On the other hand, if we anchor where there’s only a few hundred feet of water surface (fetch) for the wind to work on, and even more so if higher ground blocks the wind somewhat, we can ride out a pretty stiff breeze without bouncing around much. This is not just a comfort issue, but also one of safety: if waves have us pitching heavily, on the upward bounce there’s much greater strain on the rode. It could jerk the anchor out of its set and allow us to drag.
We research anchorages with cruising guides and charts, and decide before we travel which ones will probably work for us. When we head out for the day we have our next stop already in mind, but always have others picked out along the way, in case weather worsens and we need to duck in somewhere. Over time we’ve developed a considerable list of anchorages that work for us, or seem that they would. With a look at our list, we can plan a day’s travel quickly, without a lot of re-reading in the guides.