Join Date: Aug 2010
Location: New Mexico, USA (Heron, Elephant Butte lakes); Arizona (Lake Pleasant)
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Re: Anchoring for long term or in unprotected waters
The rule of thumb for anchor rode length should be covered in all basic boating classes, books, and presentations as a fundamental safety and seamanship issue.
In its simplest form, the rode should be about 5 to 10 times longer than than depth of the water in which you are anchored. Less rode is for shorter periods of anchoring in calmer water while you are on or close to the boat; more rode for less ideal conditions. (Different guides will argue about the exact ratio.)
Different types of anchors tend to do better in some conditions and worse in others; matching the anchor to the local bottom type and other situations can make a big difference. Which anchor is best? Ah, be sure to put on your flame-proof suit before asking this question in a gathering of sailors.
The depth used for figuring rode length this should also add the height of your boat's freeboard/how high your bow cleats or winch are above water line.
Sometimes you have to use less rode because of a tight anchorage.
Sometimes you can get away with somewhat less rode if you have an oversized anchor, heavy all-chain rode/extra weight attached, ideal bottom conditions, did a great job of setting the anchor, and have the latest super-premium high-tech anchor, and don't have stupid other boaters dragging their anchor over your anchor rode.
Or, if circumstances are nasty, you might need more and will want heavier, better, longer, more ground tackle and rode.
Having a "bullet-proof" connection of rode to boat is a big issue; your anchoring system is only as strong as its weakest link. Undersized cleats or bitts that aren't backed up properly (backing plates), sharp cleats or fairleads that can saw the rode, lack of snubbers, failure to "mouse" a shackle closed, lack of chafing gear, a wimpy swivel, etc., can spell death to your anchoring.
Reversing currents or action of wind against tide can be a problem for some anchors. Some boats travel around a lot/"hunt" at anchor; a riding sail can often help calm this. Boats that have lots of windage will be more likely to drag than those where excess stuff has been stripped away, particularly if a big blow is forecast.
A double anchor system can help in some conditions, such as dealing with tidal currents or in a tight anchorage.
Anchoring successfully is really several steps; picking an anchorage that has good protection, depth, bottom types, room, absence of hazards, etc.; then matching anchor and rode to the anchorage, communicating between helm and the person on the bow, lowering and setting the anchor properly, checking to see that the anchor is really set, setting up chafing gear and snubbers as needed, monitoring for dragging, keeping an eye on weather changes that may affect your anchorage, maintaining the chafing gear, making sure the rode isn't fouled around the bottom of your boat, etc.
All this is mostly about conventional anchoring; long-term moorings are another topic.
Anchoring for storms is sort of an ultimate challenge and is a severe test of anchoring skill and equipment.
"Your anchor drag may vary." There are quite a few ways to screw up anchoring.
Last edited by rgscpat; 12-17-2013 at 03:46 AM.