Choosing an Anchorage

 

We've been out sailing for the afternoon and decide to anchor overnight. First we must locate a suitable anchorage. What makes a good anchorage? Many cruising guides will place anchor symbols on charts of local waters showing where they think there is a good place to anchor. Sometimes they get it right and sometimes not. The cruising guide is still an excellent place to start a search.

The best anchorages are often the ones not marked on a chart or talked about in a cruising guide. Why? Because there will be few boats there and you'll enjoy privacy and quiet.

We can use four criteria to help us choose where best to drop the hook. We'll look at each one of these in detail:

Protection from weather. This is especially important if you are anchoring near the ocean where the waves and swell generated at sea can rock your boat throughout the night. If we want a restful night's sleep we'll find a place where we can tuck into a harbor or behind an island for protection. Study the chart carefully with a mind to where the wind and waves are coming from. Few anchorages offer good protection from all directions.

Good holding. We want to find a place where we can be sure the anchor will hold throughout the night. How do we know what the bottom is made of and what kind of bottom is best? Conditions of the bottom are often noted on charts; with S for sand and M for mud usually making good holding ground. Do not anchor where the charts show underwater cables or says "foul". Losing an anchor is an expensive proposition. We talk about retrieval techniques in Anchors & How They Work.

Room to swing. Once we set our anchor and are sure it will hold there will be a natural amount of boat swing. With few exceptions, a boat at anchor is always moving. With one anchor out we may swing all the way around it to complete a circle if the wind changes direction. Care must be taken when choosing a spot to drop anchor allowing for plenty of room to swing.

Sufficient depth. We need to have enough water to anchor in, but not too much. In areas with high tidal range it may not be apparent there will be insufficient water for the boat at low tide. This is called grounding at anchor. On the other hand, too much water can be a problem. if we have the usual amount of rode to let out, say 200', we will have difficulty holding in water much deeper than 25'. So, like Goldilocks, we'll look for a place for the night that's just right.

What if we were to ground at anchor? Best consult some tide tables to see how much more tide is going out. If you anchored in 10' of water at high tide and the tidal range is 8' you've got a problem. Get out of there any way you can, perhaps call for a tow. But, if you just touch bottom at low tide it's not a big deal, just wait for the tide to come back in.

Let's take a look at a chart and see what goes into this decision making process. Here, it's a nice Saturday afternoon sailing in the northern end of Biscayne Bay. We'd like to anchor somewhere for the night and enjoy the company onboard and perhaps a passing dolphin or two.

Chart showing Key Biscayne area.

 

Above we see Key Biscayne, Biscayne Bay, and the Atlantic Ocean to the East. The least desirable place on the chart to anchor would be the East side of Key Biscayne. There we'd have large waves and a lee shore is formed by the island. A lee shore is any shore where the wind is coming from open water. The danger is wrecking our boat on the coast if our anchor drags. Ideally, we'd like to be in the lee of Key Biscayne that is; sheltered by it from the wind. So, we should confine our search to west and south of the island.

We find No Name Harbor in our cruising guide and read about it. Let's apply our four criteria for a good anchorage one by one:

  1. Protection from weather. It certainly has that as it is almost completely surrounded by land.
  2. Good holding. We don't know for sure but we could try setting our anchor and see what the result is.
  3. Room to swing. Questionable. It's Saturday night and we suspect there will be a crowd.
  4. Sufficient depth. Yes, we see the water depth is 10' at low tide.

What about aesthetics? No view. Close to trees and shrubs so probably mosquitoes. Other boats anchored very close means noise. And finally, we see this is part of the Florida State Park system and they charge $15/night for anchoring here. We decide to look elsewhere so we take a second look at the chart and find the area to the northwest of Key Biscayne is littered with cable areas and shoal water only a few feet deep but, to the southwest, we see a promising area:

Chart showing Key Biscayne area with excellent anchorage.

 

The large circle above shows a potential anchorage. There is no name for this bay and it's not listed or talked about in the cruising guide but it does look good. Let's see if it satisfies our four criteria.

  1. Protection from weather. It looks like it does provide this because we would be in the lee of Key Biscayne.
  2. Good holding. We don't know for sure but we could try setting our anchor and see what the result is. However, we do see an 'M' on the chart indicating the bottom is mud which should work for us.
  3. Room to swing. Absolutely. We measure the north-south distance for the anchorage and find it's .75 nautical miles. Even with several other boats there should be plenty of room.
  4. Sufficient depth. Yes, we see the water depth is 8'-10' at low tide.

Aesthetics? Well, there are fancy homes lining the western shore of Key Biscayne and to the northwest we see the skyline of Miami in the distance. And, as we enter the anchorage, there's a pod of Dolphins playing.

Some things to avoid in choosing an anchorage: Grassy or weedy bottoms as anchors have a hard time setting; obstructions, wrecks, and cable areas; and do avoid areas with a lee shore.

It's important not to anchor too close to other boats. When first approaching an anchorage look at any other boats anchored. What style of anchoring are they using? If you are close at all to other boats you should anchor in their same style so that all boats swing the same amount in the same direction. The first boat anchoring sets the style for others arriving later; this is known as the rights of the first boat in an anchorage. But, if you provide yourself with plenty of room to swing you may choose your own style of anchoring and you may let out additional scope for added security.

We talked about special anchorages in Navigation Lights. Be careful if you choose to use one as they may be crowded and offer a bottom fouled with old, lost anchors and chains.

Approach a potential anchorage with sails furled and under power. Motor around and take a look at things. Do the other boats look sea-worthy? Or, abandoned and neglected? Be patient and take your time sizing up the possibilities and potential for dangerous situations. And, don't forget to turn on your anchor light before sunset.

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