Saturday, 12 September 2015

How to avoid sleepless nights rolling at anchor.


September 12 - 2015

Our second anchorage on our current trip north to the Great Barrier Reef was at Double Island Point, a spot renowned for providing sleepless nights due to swell induced roll. While the point is reasonable high, the terrain behind it is much less so with the prevailing South Easterly winds flowing over it relatively unimpeded. Meanwhile the normal South East or Easterly swell swings around the point and enters the north west facing anchorage.

The prevailing South Easterly winds and swell twisting around Double Island Point made the anchorage the perfect place to test a different anchoring technique we had read of. Advice provided in pilot guides is to anchor close to the point itself which we did, but when we first dropped our 30kg (65lb) Sarca Ex-Cel we experienced the usual persistent roll from the swell rolling around the point. (Boat image not to scale)

In his highly respected pilot guide, "Cruising the Coral Coast", Alan Lucas describes the anchorage at Double Island Point as '…one of the most uncomfortable on the coast'. Despite this reputation, many, many cruisers have to use it to await the right tide and suitable conditions to cross the nearby Wide Bay Bar.

That was the situation we found ourselves in. In our case conditions were relatively mild with under ten knots of South Easterly blowing however there was still a persistent half metre or so swell rolling beam on into the anchorage. More than enough to be uncomfortable.

It was the perfect situation for us to try a different anchoring technique involving running an extended snubber that we had read of. 

Even in near perfect weather, the swell at Double Island Point can roll your boat all day and night.

First we anchored normally in about 4 metres of water and set the anchor putting down our usual five times scope.  We instantly began to roll. Next, instead of running our snubber line off the bow over the anchor roller as per normal, we hooked a longer line into the anchor chain and ran it outside the safety lines and back to our sheet winches at the cockpit. We then slowly let out additional anchor chain. As we did this, the wind progressively blew the bow around towards the incoming swell. We stopped when we were facing directly into the swell and then rode up and over each one with no roll. The snubber line and chain we'd originally put down ended up in a straight line to the well dug in anchor sitting almost ninety degrees to the boat. Through the afternoon we were easily able to fine tune the angle by easing or winching in the snubber line at the cockpit.

(Boat image not to scale)



Here Our Dreamtime faces directly into the incoming swell while the similar full keeled ketch in front hangs to the wind and rolls with every wave.
We ran our extended snubber around the staysail winch to clear the stanchion and toe rail then adjusted our angle to the swell by easing or bringing the line in on the genoa winch.

While the conditions were quite mild, we were very happy with the results we were able to achieve using this technique. We are confident it would help when the swell is bigger. Through the afternoon a very similar ketch anchored conventionally in front of us before our arrival rolled consistently in the small swells. It was amusing to watch its skipper repeatedly come on deck, stare at his swaying masts then look across to us riding smoothly bow first over the waves. He was below when we dropped and didn't see our set up so we could almost read his mind thinking, "I should have anchored over where they are.

A couple of times through the night the wind dropped which allowed the bow to swing about a little giving us a bit more movement but we never came around beam on. It was very satisfying to rise well rested early the next morning and set off for our bar crossing. 


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9 comments:

  1. Great post Karen - definitely
    Going to try this!

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    Replies
    1. Glad you enjoyed it Sue. Let us know how it goes for you. Cheers.

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  2. Thanks for the informative photos !
    I do have a couple of questions- what do you think the upper wind limit would be for this technique, and did the boat shear about much as when normally at anchor ?
    Regards, Steve (DS43 owner....)

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  3. Hi Steve, We wish we had known of this technique when we had our 43DS, We would have loved to have tried it. She sailed about at anchor like a bitch when hooked in conventionally. We're sure this would have helped a lot. Not sure about an upper wind limit. That would depend on how good an anchor you have, the strength of the snubber line used and the cleat or winch you put it on. Because you can lay near beam onto the wind, there is a bit more load than being head to but it's worth it for the comfort of not rolling. We'd suggest you try it in light to moderate conditions first and go from there. We'd love to know how it goes for you. Overall we did love the Jeanneau by the way.

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  4. Great idea. Seems like you would get the same effect with bow and stern anchoring? Just curious if you tried that?

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    Replies
    1. It can be possibly to achieve the same result by deploying a kedge anchor but we like the simplicity of this set up. The stern anchor takes more set up in that you have to put a dinghy down to row or use your outboard to take the anchor out. Deciding the right spot to drop it to get your boat aligned into the swell can be difficult too. Then you have to get it to set properly. Cheers!

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  5. I did this in the Bahamas and got into trouble when the tide changed. Had to drop the snubber (fortunately it was tied to the chain with a rolling hitch) and tried to sleep the rest of the night on the sole.

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  6. I used to spend a lot of time at anchor in Porlamar (Margarita Island, Venezuela). The conditions there are exactly the same as you've described and I used to use a similar system with one more step. I made a "Y" with rope and attached the foot of the "Y" to my anchor chain. The other sides of the "Y" were attached fore and aft and then I played out plenty of chain. The reason for using rope fore and aft is because with chain on the bow and rope aft, as the wind increases or decreases the angle of the boat shifts due to the weight of the chain. With rope on both ends the boat remains at a more constant angle to the wind and requires less adjustment. svchama@yahoo.com

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  7. Yes it works great, I have bee doing this for a few years and have used it in pretty strong winds on my mooring, when on board, also by extending th bridles. I regularly get calls to say there is something wrong with my boat!

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