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-   -   Laying Still at Anchor (http://www.sailnet.com/forums/seamanship-navigation/66035-laying-still-anchor.html)

SJ34 06-28-2010 07:49 PM

Laying Still at Anchor
 
I have never been able to get my San Juan 34 to stay put with a single anchor setting. It will sail all over the place and, if the winds are strong enough, will eventually wrap the chain around the set and drag. I always set out bow and stern anchors at night or if I leave the boat.

The problem is that in very crowded anchorages I am always on the look-out for swinging boats. That usually leaves us in the outer reaches where it is very bumpy or crammed into some pretty tiny holes with little room for cushion in case of emergency.

Anybody have any suggestions?

Faster 06-28-2010 08:38 PM

Many boats, particularly high performance/fin keelers suffer from this behaviour. It's kind of neat to watch from above esp when they seem to swing in synch.

On some designs and in some conditions the boats can get up enough speed to literally yank the anchor out when they 'fetch' up at the end of the swing.

A riding sail greatly reduces (but will not eliminate) this action. They are available from Sailrite and are very small, very flat sails that hank on to the backstay and sheet to some point forward and centered (we've tied it around the boom ahead of the vang attachment) They really take the edge off the oscillations and can mean the difference between a comfortable sleep on a windy night or being 'jerked' awake every few minutes.

Here's a pic from a couple of years back in Martinique, with such a sail on a very skittish Beneteau 36.7

Something like this would be pretty easy to make yourself....

http://i213.photobucket.com/albums/c...Carib08201.jpg

sailingdog 06-28-2010 10:42 PM

Using a bridle and a riding sail can help. So can an anchor sentinel or kellet.

What kind of anchor do you use?

brokesailor 06-29-2010 03:25 AM

Seadog, What is an anchor sentinel or kellet?

Craig Smith 06-29-2010 05:41 AM

SJ34 what does your typical anchoring set-up consist of - what anchor, what size chain and how much, what size rope and how much.

Certain anchors are a bit vulnerable to getting themselves fouled, and you can also fine tune your rode to minimize the sailing at anchor.

A kellet is just a weight you add to the rode. They can dampen things down in the same way that heavy chain can. However they won't help all that much and are a hassle to deploy/retrieve. My guess is you're using a long length of nylon and you have a bungee cord for an anchor line. Additionally a properly set riding sail is likely to help. But if it's the rode it will be best to solve the problem rather than trying to apply band-aids.

norsearayder 06-29-2010 05:46 AM

i just used my new sailrite riding sail for the first time,it works great,stoped me from sailing which was an issue with my p32.....you can buy assembled[i did] or cheaper,they sell a kit.the12.5 sq ft works

geohan 06-29-2010 09:44 AM

What worked for us on a 30-foot sloop with a tall rig and a fin keel with a 6-foot cord, was a bridle. Bend a rolling hitch to the rode clear of the bow, lead the line aft outside all and secure. Veer several feet of rode to give a heading to one side, about 10 degrees worked well. This destroys the symetry that allows the cycling from side to side.
Another option would be to deploy a droge, to a depth of 10-feet or so, from the bow. We haven't tried a droge but it should work better than the 3-gallon pail which gave about half of the restraint we wished for. This will slow the swing speed of the bow and soften the "jerk n tack".

Geohan

RichH 06-29-2010 11:06 AM

ditto on the bridle.
A bridle that is so arranged so that the attachment to the rode drops the connection, hence the rode, to where the bow meets the water will usually significantly dampen the swinging back and forth of the bow. Of course one needs proper chocks, etc. located a 'fair distance' back from the bow to do this.
Simple speak: .... get the rode as LOW AS POSSIBLE and as close the bow's waterline as possible. Use a 'bridle' - a multi-wrapped Prussic/Prusik Hitch works much better than a 'rolling hitch'. The Prusik Knot or Triple Sliding Hitch

For a boat that wildly dances when at anchor, sometimes anchoring from the STERN will stop the 'dancing'.

SJ34 06-29-2010 11:23 AM

Craig, the primary is a 25# Danforth, 30' of 3/8 chain and 250' of 9/16 3 strand. We get the best set above 5:1 scope but the more we have out the farther it will sail.

Would love to get a Rocna someday, this beast I have now is a pain.

I will look into the riding sail. I've seen them used but I guess I misunderstood their function.

To complicate matters, our favorite anchorage is in the lee of the island. A 20 degree shift in wind on the windward side of the island will often end up being a 180 degree shift in the lee. Over Memorial Day weekend the wind shifted 180 degree about 8-10 times.

Craig Smith 06-29-2010 12:25 PM

Yep Danforths with their stocks are problematic for fouling. You will find most asymmetrical anchors to be okay in this department, we spent some time for example on the Rocna making sure it wouldn't foul the rode during force reversals etc.

You don't have much chain and a lot of what I assume is nylon, 3-strand being the worst. Watch the rope's behavior next time you're out, if it feels like it is doing too much "springing" then this is part of the problem. You need rope to average out shocks, but too much spring, especially in gusty winds, can exacerbate things.


The rode plus the boat's windage profile are the causes. You can fix the one by tuning the rode and the other with a riding sail (maybe). Thereafter you're stuck with band-aid solutions like kellets, drogues, etc, which are no fun.


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