Small Boat AnchoringBy Tim Murphy
Published: April/May 2014
Five steps to simple, reliable anchor sets on small boats.
4. Pay Out The Proper Scope
Your anchor holds best when the load on it is horizontal, not vertical, so you'll have to let out enough scope to accomplish that. First, add the depth of the water to the height of the bow above the waterline. Now, multiply that total by 5 (for a 5-to-1 scope), and pay out that amount of rode for a "lunch hook" when you'll be aboard in calm conditions. If it's windy, or you might go ashore for a bit, pay out at least a 7-to-1 scope.
If you're anchoring in water 10 feet deep and your bow is 5 feet above the waterline, water depth + bow height = 15 feet, which means that for a lunch hook you should put out 75 feet of rode (15 feet x 5).
For an overnight stop, put out 105 feet (15 feet x 7). When you calculate scope, don't include the chain at the anchor end of the rode unless there's more than 6 feet or so; the chain's job is simply to weigh down the anchor.
5. Set The Hook
Once you've let out ample scope, let the boat settle back on the anchor to straighten out the rode. A gentle breeze or a mild current may be sufficient for this step. If it's absolutely still, use the engine with just a touch of reverse. Pause and take a good look around, especially abeam; note your position relative to other fixed objects.
Now put the engine in SLOW reverse. You can expect to move slightly astern as the anchor and rode set themselves and stretch out. Soon, though, the boat should settle in a fixed position. (If at this stage the boat is still moving astern, your anchor may be dragging; pick it up and drop it again.) If the boat's position is fixed, you should see prop wash near the stern, and your anchor rode should be straight and taut.
To thoroughly set the anchor, with the engine still in reverse, increase the rpm. If the boat stays put, you can rest (relatively) easy, knowing you're hooked. Check your swinging room again, assuming that the wind or current might come from any direction. Have some fun.
When it comes time to move on, you'll need to apply a vertical load to your anchor rode to break the anchor free. This means moving gently forward with the engine, and if you don't have a windlass, gathering aboard as much rode as you can by hand.
Beware to keep the rode out of the propeller and rudder, and communicate the position of the rode with the person on the helm if visibility is blocked. Once the rode is directly below the bow of the boat, take a turn on a cleat. Then, signal the helmsperson to put the engine in SLOW forward. The anchor should break free; if it doesn't, apply a little more throttle.
Once the anchor is free, go back into neutral. Bring the anchor and rode aboard, taking care not to damage the hull, and rinse off any mud. Coil and stow the rode, and you're ready for your next anchorage.
Writer and editor Tim Murphy, coauthor of Fundamentals of Marine Service Technology (ABYC, 2012), lives in Portsmouth, Rhode Island.