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Friday, March 19, 2010

Boat Anchor Strategy - Go Many Go Heavy

One of the most fascinating areas of this new life that I'm really enjoying the study of is anchoring. I've concluded that it is part art, science (physics, sociology, and psychology), and even a bit of philosophy. This is why there are so many different anchoring approaches because when you blend art, science, and philosophy, you find as many ways to anchoring as you do people!

I've dubbed our boat anchoring strategy the Go Many Go Heavy approach-
have as many different anchors as you practically can and go as heavy as you practically can.
For us, this manifests as having 3 different types of larger anchors (70 lbs Luke, 35 lbs Fluke, and 45 lbs Plow), plus 2 smaller anchors (10 lbs Plow and 10 lbs Fluke) for kedging.

Anchoring, to us, is everything from the physical end point anchor all the way back up to its connection point on the boat. Thus, we also consider the rode as part of the anchoring system.

We will have 2 lengths of 100 foot 5/16 inch PC/BBB chain, 2 lengths of 50 foot 5/16 inch PC/BBB chain, 2 lengths of 25 foot 1/4 inch chain, and 5 lengths of 100 foot 3 strand 9/16 nylon.

Given our load capacity, this means that we are choosing to exchange some creature comfort type stuff for more ground gear.

Our big Plow will be primary, and the big Fluke the secondary. The Luke will be pulled out when in a questionable situation (bottom type, current, or weather ambiguous situations).

Why so much? Because we intend to live a vast majority of time on the hook. The anchoring system is our insurance that the boat will stay put. Studying the load dynamics the system must accommodate, I don't feel comfortable doing anything less. It is the psychological element, comfort, that is also in play here.

When I worked as a divemaster on a boat in the Keys, I would manually set a single anchor (that is, I'd dive down with the anchor and set it by hand in the ocean floor ... it was a great ride!). In the boat living situation, I do want to dive the anchor but that won't always be an option so the varying types of anchors will help ensure we get at least one to set.

We plan on setting 2 anchors when we are staying overnight in a location, and only 1 anchor when just stopping for the day. By having a 3rd anchor on board, the big Luke, if something crazy starts to happen, like another boat starts dragging our lines, we can set the Luke to help keep us from dragging.

We have 60% of the items listed (the big and small Fluke, the big and small plow, and much of the rope). We have about another $1,000 we will need to spend to complete our anchoring system.

This is, of course, all theory as we are not yet living out on the ocean; this is our starting point strategy. Only real world experience will tell me if I've got it right! Reality, in the end, always trumps theory!


  1. Your logic is OK but setting two anchors has great dangers if the wind changes and is inconsiderate if there are other vessels anchored close by. They all believe that the vessels are hanging from one anchor and will all swing in the same direction as the wind and tide changes. The two anchancor vessel swing differently. I always insist that if this vessel comes too close it should either do what every one else is doing or go somewhere else. From my experience these vessel invariably fly the Stars ans Stripes from their stern. After a few confrontations you will revise your anchoring strategy and ensure the single pick you through over is well in and holding.
    If a vessel drifts down on you the second anchor restricts your ability to motor out of its way while still at anchor and it will take you more than twise the time to up anchor and put to sea which is the safest place in a well found vessel.
    Storm warnings do however require a different strategy for which swing room is a prerequisite.

  2. @HarryWS: Thanks for your input and experience. What you write totally makes sense when vessels are within swing radius of one another. I do believe in the adage, "when in Rome, do as the Romans do."

    Another interesting take on all this is the amount of scope and the materials of the rode (how much chain versus rope). With different amounts and lengths, the rate and distance of swing will also be different. We've been out and seen this happen (one person has a small amount of chain, but lots of rope and another has lots of chain and changes much more slowly). If the swing radius of boats overlap, but their anchor lines are different, then there still is a chance for closeness. It will be interesting when we are actually out.

    We intend to be away from other boats in general. If, however, we are the first in a particular spot, and do our style of anchoring and another boat comes along and wants to do something different, then what is the etiquette? Do we change? Or does the second boat? Thanks again for your insight.

  3. There is some good reading here for anchoring a small cat with two anchors:


    I did some math on that ground tackle setup and with some rough guesses at the weight of the chain and rode, that is a BIG percentage of your 2000 lb payload. Any thoughts on that?


  4. @Mike: Thanks for the link. I will most certainly check it out.

    You're right on the anchor strategy resulting in a very large percentage of our payload being consumed. It is a conscious choice to give up so much, and one of the drivers is the type of voyaging we plan on doing.

    Our intentions are to live on the hook 90+% of the time, and spend 90+% of the time in non-tourist areas. As a consequence, a good solid anchorage will be completely up to us. We want to be sure we have the right tools to do the job of holding our boat. It becomes a bit of an insurance play and even more of a peace of mind play.

    On the glib front, I can stand to lose 20 lbs myself to free up some of the payload. This, of course, will be offset by my growing girls.

    2000 lbs isn't much at all. We will have ourselves, ground tackle, rode, food/drink, sewing machine, and well, not much more. :)


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