Mooring Swing

Your boat can swing 360* depending on wind and current. The lighter the boat (or the more 'sail area') the more it will swing. It will also swing more eratically and lay at an angle to the anchor line if the line comes off the side of the bow instead of straight off the front as with a bowsprit or anchor roller. It always amazes me when I go places where people anchor and leave their boats for the day and people anchor their 40' boat with plenty of room behind but 20' from the boat beside theirs. We have a spot near here where the bottom rises quickly from 50' to 5'. The boats in the 50' are held pretty much in one direction by the current where the boats in 5' don't have much current and are affected by the wind. You can guess the result.

1) Wind direction is seldom constant.
2) If you're tied straight off your bow you'll swing less than if tied off a cleat on the side.
3) Anything outside you boat will add to it, from growth or a trim tab lowered underneath to a person standing up on one side. Are your rudders or outdrives straight? Everything has effect.
4) Putting out a sea anchor like Pascal suggested will also help.
5) Boats move. They swing and rock. The smaller and taller they are, the more they do it. Keep that in mind when you decide how close to another boat to anchor.

A suggestion I read from a marine pool to be tied behind your boat suggests the following:

" But the most successful and simplest remedy is to try the "bridle mooring" technique. Anchor normally, and then prior to deploying the pool, establish a bridle with the anchor line that will bring the boat more broadsides to the wind. This will greatly reduce the boat from "sailing" at anchor and will allow swimming in much higher winds. Use a bridle line that is about the length of the boat. The bridle should be formed by securing this bridle line from a rear cleat or winch direct to the anchor rode. Use a rolling hitch knot to secure the line to the anchor rode. Let out an additional length of anchor rode (the same amount as the length of the bridle line) and the boat will now lie more abeam of the wind and be very stable. Lastly, deploy the pool from the side or stern.

Prior to retrieving the pool, release the bridle line from the stern and drop its bitter end in the water so the boat swings again from the anchor rode. Retrieve the pool then retrieve the anchor line whenever convenient. The bridle line will come aboard with the anchor line. In an emergency, you can quickly get out of the bridle by simply releasing the bridle line from the stern."

I have one of these pools and tried this application and it works pretty well.
It also allows more of a breeze on the rear deck.
I don't know the author's definition of " Higher Winds" but I have used this on nice days with light breezes in secluded coves with no neighboring boats to speak of........ I wish I was there right now in fact.

Prolly not as good idea in a crowded anchorage though....