Preventing or reducing anchor swinging

[Lancer28]

UPDATE - POST #43 HAS MY COMPLETE TRIAL RESULTS AND SHOULD WORK ON (sail)BOATS 40' and UNDER I TESTED ANCHORS AND TECHNIQUES BOTH!!!



I didn't even think about this until the other night when I was out on the hook in 20ft of water and we had a huge wind storm come along pushing over 45 mph and gusting to 65.

Earlier in the night, the breeze was from the west, so I set my anchor and a 7:1 scope properly and went to bed. Well, at about 3AM we get these retardedly huge wind storms from out of nowhere, and I was woke up from a great sleep by the lid on the anchor locker slamming down on the deck and the sound of the rigging whistling. Not too fun, I think. I don my pfd and foulies over my boxer shorts and run upstairs to the cockpit.

I climbed out to the cockpit and turned on the gps and set the anchor drift alarm for 200 feet, thinking that if I busted that ring, it was slipping out and would need to be reset. I then rethought this idea because the line on the 7:1 was pulling strong, so I reset the alarm for a 100ft circle. I was clearly shooting left to right and back quickly on the gps screen, but not falling backwards. When I got to the far side of either swing, the boat would hang then she would sloooolwy creep over to leeward, then fly back to the other direction.

I went back to the bowsprit and dropped out another length of anchor rode to increase the line to over 220 feet according to my rode markers... This was out of sheer nervousness and when I am thinking of a semi-survival situation, I like to have to think I can do something else to help me stay safe. Remember, it was dark, I was dazed from being jostled from my sleep, cold, and now starting to get wet. Not the best of times on a boat, and why I was "fiddling" to try to help myself out. It's almost like if I'm productive during a storm or another problem, I can feel like I am doing something to better the situation so I do little tasks like re-check everything or so fotrh.

Well, I never slipped, but I was getting annoyed with how much the boat swings at anchor. I was all alone, so could not have someone to help me set up to hove or heave-to. I could not have time to start the engine, then run to the bowsprit and haul up the anchor before I was pushed the 1/2 mile to shore by the wind.

I was considering throwing out the para-anchor behind the boat to slow the creep-creep-creep-then fast swing to port then creep-creep fast swing to starboard garbage... is this a correct assumption? Can I put it out to slow this swinging, or should I use something else???

I really don't want to drop two anchors off the ship, I singlehand about 90% of the time and I need as little interruption to geting underway as fast as possible when conditions get worse than my anchor can hold. Is there something better I can drag or tow to reduce this? I keep hearing that people have tow-warps? What is this for and what are they?

Some details -

7800lbs, 30ft boat, full keel, 4 feet of freeboard, 1 foot of cabin over the deck, bare poles under anchor

rode is 10ft of chain, 400ft of 3 strand

12kg Scottish Bruce anchor. (nope it has never slipped...)

Winds often exceed 40mph in shallow (under 30 feet) water, so it gets VERY confused out there I'm confused too, should I just never sleep on the hook out there, and pay the slip fees, or is there a remedy?

Thanks,

Robert

[TrueBlue]

It may help to have more chain - 10 ft seems short. We have 200 feet of chain - but you should have at least enough to hit bottom. A double loop bridle on the anchor chain and a reefed mizzen will also help control swing - to an extent, or in your sloop rig, perhaps even a small staysail off the backstay.

[sailingdog]

I would recommend going up to at least 30' of chain. 10' is pretty short for a boat your size, but it also depends on the anchor. Certain designs, like the Fortress, set better with less chain...

To reduce the boat kiting, you might want to either install a bridle or try anchoring from the stern. Don Jordan, creator of the Series Drogue, has an interesting paper on anchoring from the stern, which you can read here.

Another, less radical, option is to add a line to pull the anchor rode off to the port or starboard quarter, so that you're not dead into the wind, but in the position that you would be in if you were hove to. This is recommended by the Pardeys IIRC.

[sailortjk1]

Others have gone with a riding or anchor sail.
I am not sure, (because I don't use one,) what the limitations are as far as wind speed.

[Wayne25]

I have never done this myself, but if I was in those conditions I would try a small anchoring sail as described in this month’s issue of "DIY Boat Owner". It’s Issue #2 2007, page 41. Probably see it on line. They describe how to set the sail up to stop the very sway you describe. The anchor sail technique is also described in many other articles and books. Try a search for more info. Maybe you can find a set up done on a boat like yours.

Wayne

[labatt]

Are you sure the winds were 45mph-65mph? With a 7 to 1 three strand rode, you were awfully lucky not to drag. As others have mentioned, the amount of chain you have is so short I would actually discount it, unless you were running a Danforth or Fortress style anchor. With a rope rode like you have, I would normally overnight with 10 to 1 out and more for a storm. Outside of that, a riding sail or bridle would lessen the shifting (OK... I have nothing else to add). I would definitely get a lot more chain. That alone may decrease any "oscillations" you may have on the hook.

[camaraderie]

With a long nylon rode and gusty winds, you are gonna have a slingshot effect anyway as you can easily get a 20% stretch. A riding sail can help a bit as can a bridle on the bow or a central sampson post to keep the pull linear and in line with the keel. More chain may be desireable from a holding standpoint (depending on your anchor) but as long as the majority of your rode is nylon, you are going to have considerable stretch. I would not add chain to avoid swinging...only to provide more secure holding.

[Rockter]

The problem with carrying too much chain, like 200 ft, is that the ship will be down by the bow and will tend to nod a lot. My 36 ft, 10 ton ship is noticeably bow-heavy with all that chain in the bow, and there really is no other place to put it. Maybe 50 ft of chain would be more manageable, and the rest rode. I know not.

I have not used the anchor for, like, 6 years, so maybe it's time to go back to lighter tackle.

The swinging is a matter of physics... the boat tries to pay off weather, then gets tugged back, to repeat the show the other side. Maybe a stern para-anchor would help to slow the swing.

[astraeus]

My boat will hunt a lot at anchor even in light winds. I have used an achor sail for wind gusts of up to 35 knots. Even in these conditions, the boat tends to be much less "restless", although I have noticed a moment of heeling when the wind shifts direction.

[sailingdog]

Rockter--

Erring on the side of heavier with your ground tackle is rarely a mistake.