When we first started sailing, we avoided anchoring our boat at all costs. It seems silly now, but at the time it was far easier to trust a mooring ball tethered to the ocean floor than our own untested anchoring skills. Easy to understand. We just didn’t want to find ourselves adrift in the ocean or grounded ashore while we were sleeping. We also didn’t want to accidentally miss anything about the process that would put us or our boat at risk.
Now after many reps behind us, our confidence in anchoring is much stronger. In addition to practice, much of that confidence can be attributed to the fact that we have a set plan in place so that we are prepared and that everyone involved in the anchoring process fully understands their role. If you have been sailing a while, this is old hat, but if you are new it can be helpful to have a written guide on what to consider and what steps are involved.
We’ve got your back! Plus, I love math, so this topic makes me a bit giddy.
What to know before you leave the marina
Successful anchoring begins at the boat check. It is important to understand the equipment on board as it relates specifically to your boat. Questions to ask:
- How much chain do I have?
- How much rode (rope) do I have after the chain?
- Approximately how many feet or meters are released by the winch (the mechanical device that helps lower and raise the anchor) per second? I’ll call this Winch Speed for purposes of our discussion. You will use this in the calculations below.
- How does the winch work on the boat I am chartering?
- What are the Draft and Freeboard distances? Since Depth Finders are calibrated from the bottom of the keel, understanding the Draft, the distance from the keel bottom to the water line, and the Freeboard, the distance from the waterline to the upper deck level, will give you the additional Distance calculation you need to get your anchoring exactly right. If your charter company can’t provide this, do your best to estimate.
- Is there anything I should know about anchoring in this location?
- Are the tidal changes relevant for this location?
If you are unable to get the “feet/meters per second” of winch performance, that is ok. You can estimate this yourself by putting a piece of tape on the chain as it first emerges onto the bow deck from its storage and then measuring/estimating the length of chain from this point to just before it falls of the bow. Then you can count the seconds it takes for the tape to reach the end of the bow and create your own “meters/feet per second” number using our good friend math. You thought those word problems would end in 8th grade Algebra? Not so fast.
The last two questions are good ones because anchoring is different everywhere. In some places like Belize, you need to be very careful to avoid the coral reef. In other places like San Francisco, there is a thick muddy bottom that makes anchoring easy but requires that you clean your chain and anchor in a way not needed in other locations.
Tidal changes can also impact anchoring choices. If you are in the Caribbean, it doesn’t matter much, but in Thailand, for example, you will want to understand the tide charts and take them into consideration as you perform your calculations. If you are anchoring at high tide, make sure your boat will be safe at low tide given your depth.
Insider knowledge is the best thing you can acquire at your boat briefing, so don’t be shy about asking questions, particularly as it relates to anchoring Intel. The boat briefing is a perfect time to gain an understanding of recommended anchorages and places to avoid.
What to know before you start the anchoring process
Before you begin the anchoring process you will need to answer a few questions intended to 1) make sure you are in a safe place to anchor and that your effort won’t leave you or your neighbors at risk, and 2) understand exactly how many seconds the anchor crew will be letting out the anchor for both the initial setting of the anchor and then for the release of additional chain and rode.
Your goal is to safely be at a 7:1 scope, or less given space available, by the time the process is complete. Your questions include:
- Do I have enough space between my boat and the others around me?
- Am I anchoring near boats on anchors or mooring balls? This is important because boats on anchor will typically perform similarly in response to the wind and current, but boats on mooring balls will not vary as much in their positioning.
- What is the Depth?
- How much chain/rode will I need to let out to set the anchor? For our purposes we will call this “Length 1” and the calculation is: Length 1 = 4 x (Depth + Draft + Freeboard)
- About how many seconds will it take to let out the chain needed to set the anchor: Seconds 1 = Length 1/Winch Speed
- How much additional chain/rode, Length 2, will I set out after the anchor is set if a 7:1 scope is desired: 3 x (Depth + Draft + Freeboard)
- About how many seconds will it take to let out the additional chain/rode: Seconds 2 = Length 2/Winch Speed
Here is an example. In your boat briefing you learned that the Draft is 7 feet, the Freeboard is 6 feet, and the Winch Speed is 3 feet per second. You are ready to anchor and you are in 15 feet of water. Drumroll please…here are your calculations:
Length 1 = 4 x (15 + 7 + 6) = 4 x 28 = 112 feet
Seconds 1 = 112/3 = 37 seconds
Length 2 = 3 x (15 + 7 + 6) = 3 x 28 = 84 feet
Seconds 2 = 84/3 = 28 seconds
When the anchor crew goes to the bow, they need to know these values: 37 seconds and 28 seconds.
What is the anchoring process?
Once you have your calculations and you have answered the questions about your proximity to other boats and the safety of the area you plan to anchor in, you are ready.
There are two primary roles in the anchoring process: the Helmsman who is steering the boat and the Anchor Crew who is at the bow of the boat with the anchor and winch. Here’s how it should happen:
- Helmsman Job #1: Aim into the wind and very, very slowly motor toward the place you want to drop your anchor, putting it in neutral about two boat lengths before so it nearly stops at the anchor drop point.
- Anchor Crew Job #1: The crew dropping the anchor will begin. As they use the winch to release the chain, they will count Seconds 1 previously determined (that is the 37 seconds in our example).
- Helmsman Job #2: While the crew is letting out the anchor and chain, the Helmsman will very slowly engage the throttle and move the boat in reverse, directly away from the anchor.
- Anchor Crew Job #2: Notify the Helmsman when the correct amount of chain/rode is released.
- Helmsman Job #3: Set the anchor by revving the engine in reverse. Slowly rev up to about 1500 rpms for a few seconds a couple of times.
- Anchor Crew Job #3: The anchor crew should be watching the chain to make sure it becomes taut. At the same time, they should get a bearing on a stationary landmark and make certain that as the engine is revved, the boat does not move in reverse.
- Helmsman Job #4: When given the thumbs up from the Anchor Crew, the Helmsman can quickly rev to 2500 rpms for final security.
- Anchor Crew Job #4: Set out Length 2 to achieve a 7:1 scope. Use the Seconds 2 calculation as you determine how much chain/rode to release.
- Anchor Crew Job #5: Attach a snub line or bridle from the anchor chain to a bow or deck cleat to relieve tension from the winch.
- All Crew: Enjoy happy hour cocktails of choice and celebrate successful anchoring.
- All Crew: Keep an eye on things and gain confidence that you are secure for the night by making note of where your boat is in proximity to other boats and land
Depending on your depth, the clarity of the water, and water temperature you can dive down and take a look at your anchor as an additional confidence-building step.
It is important to note that sometimes things don’t go exactly perfect the first time. That is ok! Just repeat the steps again until it does. If unsuccessful, you may want to change your location.
Practice makes perfect and solid anchoring skills are a critical addition to your basket of sailing skills. Plus, you get to do easy math which is fun for all, or at least will help justify your middle-school education.
Anchors away!
Lea Maxwell is the sailor and scribe behind Escape Under Sail, a web|blog project that connects new and future charter sailors with the resources, information, and motivation they need to competently and confidently sail beautiful destinations around the world.
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