Tuesday, February 10, 2009

Anchoring

Rare indeed is the time when you arrive at an anchorage, and there is no one in there ahead of you. Therefore, what you do, and how you do it can either be an example to others, or the evening's entertainment for them. Some things that we think provide entertainment:
  • Driving the boat from the bow. This is when the captain relinquishes the helm to another, and proceeds to the bow to tend the anchor. From this perch a long way from the helmsman, who incidentally is standing nearly directly over the engine, he shouts his directions. "Ahead!" "No! No, I said astern! NOW! D@#n It!"
  • Plowing the anchorage. When you have a light weight anchor (like a Danforth), the trick is to let it settle to the bottom before you begin dragging it at high speed, plowing a furrow all over the bottom.
  • Failure to pay attention to the charts and the depth sounder. By definition, anchoring has the boat in shallow water. You would think that people would know how shallow, and where, or at least proceed tentatively until they do know...
  • Failure to take into account scope and swing. This is perhaps the hardest aspect. Boats at anchor do not lie uniformly directly downwind from the anchor. They tack back and forth, thus the origin of the expression "swinging to anchor". And then there is current. Usually, unless the wind is very strong, boats will pay more attention to any tidal current present than to the wind. But this will vary depending on the boat. A sleek racing sloop, with a deep keel and low topsides will respond mostly to the current, while a high-sided powerboat with little lateral area in the water will respond mostly to the wind. Finally, because of the difference in weight, boats riding to a chain rode will be more sedate than those riding on a rope rode - those seem to slew all over the place!
I don't mean to imply that we always get it right - not so. But this is what we attempt to do:
  • I stay at the helm. Jane releases the anchor and tends the rode as it pays out. This eliminates the communication problem and attendant confusion - all that is required is a hand signal from the helm to the bow indicating: "Here." We discuss ahead of time the expected scope we will require based on water depth.
  • If this is an unfamiliar anchorage, we study the charts ahead of time, and try to determine where we will anchor. When we get there, we take a slow harbor tour, watching the depth sounder. Once we have the depth contours, we can determine the scope we need. In the bow we carry 300' of 3/8 chain for the primary anchor (a 66 lb Bruce). With this ground tackle, we use a 3:1 scope for most situations. This means that we put out a length of rode equal to 3 times the depth of water we will see at the highest tide we expect to see while in the anchorage. This takes a little guesswork because we rarely arrive at high or low tide, but the Rule of Twelfths handles it nicely.
  • I bring Eolian to a stop, facing the same direction as nearby boats in the desired location for the anchor, and signal Jane. She veers rode, and signals me when we have enough out to reach bottom. By then, I have Eolian moving slowly backwards so that the rode does not pile up on top of the anchor. When Jane halts the rode payout, we both watch for the rode to stretch out and the bow to come up into the wind (by now, Eolian will be moving broadside to the wind - for some reason, boats drifting downwind do so broadside to the wind). Finally (and this is a critical step), we both maintain watch long enough to be certain (by taking bearings on shore objects) that we are solidly hooked to the ground. Then we share a ceremonial beer.
  • Ah, but where exactly to drop the hook? This is perhaps the most difficult part. When selecting the spot, we like to anchor among like-sized boats with the same kind of rode. That way, we can expect that everyone will move more or less the same. We anchor as far from others as we can - no one likes to have to worry that there will be a "thump in the night". I estimate our swing from the scope in terms of our boat lengths, and visualize it as a circle. The I put the anchor in the center of that circle.
  • Other than during a gale when someone breaks loose, the most likely time for a collision is when there is no wind at all, and at slack water. At this time, the boats will be anywhere within the circle defined by their rode, and if the circles overlap, collisions can happen. In the way of such things, these conditions seem to happen mostly in the middle of the night.
Once we are solidly hooked, we join the others in the anchorage, enjoying the evening, the setting sun, a glass of wine, and new boats as they come in, to impress us, or to entertain us.

Anchoring in Canada is whole 'nother subject.
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