Help, How do you triple anchor? Storm coming.

Discussion in 'Multihulls' started by pbmaise, Mar 21, 2015.

  1. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    I am trying to hug close to a hill to my North and beach to my East.

    Problem: The more chain I let out the bigger the waves and winds I am exposed to. For a week a heavy weight hung from the chain helped nicely. However, When the vessel turned a 360, the CQR did not reset.

    My goal is to keep my stern pointed towards that hill. If winds are highest from East the bow must be able to turn to East. If heavy waves come in from West, I need to have bow swing West.

    What didn't work is approaching close to hill, dropping anchor then playing out line.

    I heard of a triple point anchoring method. However find no sketch.
    Ideas?
    Details,

    Hill to North
    Beach to East
    Reef to West
    Coastline to South
    Good holding if anchor set
    5 meters water and Sandy bottom
    expected winds 40 knots
    Can run engine to maintain position into stronger winds


    Equipment to work with
    100 meters chain, CQR, Bruce, light anchor,
    2 55 gallon drums with sand I can hang off anchors
    2 empty drums can fill



    Thanks
     
  2. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    PS I have already tried a

    Bahamian mooring

    with two anchors set 180 to the Hill.

    I found a description at:

    http://cruising.coastalboating.net/Seamanship/Anchoring/Two_Anchors/index.html

    I can try this method again and split the lines going in each direction into a V to use 4 anchors with each weighted down with a 55 gallon drum full of sand. Or perhaps one Kellet on one side and a buoy on the other.

    To solve the 360 issue a fifth anchor to my North?

    One disadvantage of this site is distance to hill in the North. In the Mactan channel I finally settled boat with 3 anchors to port and two lines to starboard going to shore.

    PS My vessel is never left unmanned specifically because of anchoring concerns.
     
  3. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    I concluded the main problem is most of my chain, when under load, rests on the sandy ground because the water is so shallow. Letting more chain out gives no added weight and minimal resistance to slide along the bottom.

    A single kettel has done little to help.

    However, I have now the idea of placing them in series

    Boat--->Bridal-->Kettel-->Buoy-->Kettel-->Anchor

    In this type of configuration in oder for load to reach the anchor, the Boat must pull with enough tension to raise the two kettels and sink the buoy.

    Regarding the problem with the anchor failing to reset in sand, I am thinking modifying anchor. I have also wanted to incorporate zinc annodes.
     
  4. teamvmg
    Joined: May 2008
    Posts: 124
    Likes: 3, Points: 0, Legacy Rep: 22
    Location: christchurch,uk

    teamvmg Senior Member

    Drive it up onto the beach to the North.
     
  5. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    That option is for small multihulls. Mine is 65ft by 40ft with a fixed rudder going 2 meters below water line. If things get too hairy I cut all anchor and flee. This issue is just solving the 30-40 knot winds experienced away from storm central.
     
  6. waeshael
    Joined: Mar 2013
    Posts: 8
    Likes: 1, Points: 0, Legacy Rep: 14
    Location: charleston

    waeshael Junior Member

    Hope you weathered the storm. For the next time, here are some ideas I have used on a monohull during more than 5 years at anchor in winds to near hurricane force. Your windage is obviously high, and this provides the power needed to bury a CQR anchor. The engine cannot bury a CQR sufficiently to give more than 200 lbs of holding (guesstimate), so we depend on the wind forces to do the burying. The boat will drag as the CQR buries. It likes a 7 degree slope or less to bury. To bury it two feet under in hard sand requires about 20 feet of drag downwind.
    Most boats have the center of windage ahead of the CLR, so that the boat prefers to lie to the wind with the stern into the wind. Test your boat by letting it drift without sails up and see how it likes to sit. If the boat sits in the water its natural way then it will yaw very little at anchor, as the wind will keep pushing the mast and stays downwind. Use a bridle, of course to help keep the boat from yawing, and to reduce the wear on the rode.

    In shallow water (below 100 feet) you should use mostly nylon rode to give you stretch to deal with the wave action. Use chain only to prevent the rode from being damaged by the bottom, so perhaps the last 12 feet or so. Anchor only in hard packed sand, as nothing else apart from clay will hold the boat in a blow.

    As to the anchor: Must be the burying kind, and must be pulled into the bottom at the angle determined by the anchor designer. For CQR it is 7 degrees, and you can get this with a 10:1 scope. Some anchors such as the Fortress can work at higher angles (read the specs.)
    Multiple anchors: Best to have a single anchor that can hold the load, as it is very difficult to bury two anchors, and impossible for three. Even a 35lb CQR can hold more than 2000 lbs pull before it drags (in hard sand.) But if you must use more than one anchor use two anchors than can share the load being pulled in the same direction.
    A Bahamian moor is not useful for storms.

    Very important is that the rode must be stretchy to reduce shock loads on the anchor system. You may need it to stretch ten feet, or so. Use a nylon rode (new) of a diameter that will stretch. If it overstretches as the wind reaches hurrican force (i.e. beyond the manufacturers recommendation) you will need to replace it after the storm is over, but it will have done the job of saving the vessel. Most anchor systems fail at a shackle, or at the deck due to damage to the anchor cleat or roller. Use much larger shackles than you think are right. Wire the pins/screws on the shackles. Use a large eye for the loop in the rode, so that it will not bend under side loads at the anchor.

    Anchor where the fetch is under 5 miles, not in an open bay.

    I have left my low windage sloop at anchor in several places sometims for as long as three months and in occasional near hurricane force winds.

    I am an engineer, sailor, and have studied the nature of sand for holding, and developed an application to predict the forces during a blow, and the type of anchor system I need. It is a rather specialized program running under Filemaker Pro, so probably not useful to anyone else.
    I have written something for sloops on my waeshael.com web site. Click on Ocean sailing and then look for stern anchoring.
     
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  7. pbmaise
    Joined: Jul 2010
    Posts: 115
    Likes: 5, Points: 18, Legacy Rep: 80
    Location: Cebu the Philippines

    pbmaise Senior Member

    Thank you waeshael for your most excellent reply.

    Yes I weathered and okay.

    Your reply should be booked marked. In particular you cite 7 degrees necessary for a good setting of a cqr is a mind opener.

    With too much chain in the water the anchor just drags on its side on hard sand. With too little, it won't dig down.

    I finally set the cqr manually by swimming down to it and digging it in. I worked it back and forth till it dug deeper. I then covered it with a small mound of sand.

    The two 55 gallon drums filled with sand worked beautifully. One was set on the chain at the bottom and one hung just below the waterline at the bow. The one on the bottom dug a trench and attracked a lion fish to take up residence. The one at the bow had to be lifted clear out of the water, and one on the bottom out of its trenchn before the anchor saw one pound of pull.

    I slept well.

    I have moved anchorages and now have soft mud. I didn't yet set kellets, however after dragging twice in moderate winds I switched to my Bruce. It is holding even with the boat doing a daily 360.

    The local sailing community recommends I order a new anchor brand name ...... that is being copied by a local machine shop.

    Considering.

    Here is my current weather forecast

    FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 100 NM EITHER SIDE OF A LINE FROM 7.4N 144.2E TO 8.4N 140.6E WITHIN THE NEXT 12 TO 24 HOURS.

    Lifes more fun in the Philippines.
     
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