Hunkering down: Adding 60 tonnes prior to strike

Discussion in 'Multihulls' started by pbmaise, Aug 18, 2014.

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

    pbmaise Senior Member

    Picture this situation that is possibility I want to plan out in advance.

    Vessel: 65ft by 40ft light trimaran

    Position: Triple mooring, 2 fore, 1 aft. Lines 75 tonnes breaking

    Conditions: winds, 100+ knots on nose, sea state, inland bay 1-2 meter

    Problem: Approaching surge will elevate bows. Wind will get under two large aka.

    Based on research several cats have turtled. 2008 Lagoon 410. Further, last year, a local 380 owner was aboard when he felt wind suddenly lift his vessel for a good scare.

    Proposed Approach: Hunker down with ? tonnes seawater in bows.

    Biggest concern: Momentum. Too many tonnes may cause lines or moorings to break.


    Notes:
    Mangroves too small and more exposed. I am behind moderate hill.
    I have heard others mention sinking as a radical solution. No.

    Based on these two reports, my planning before a storm strikes seems prudent.

    One new conclusion I came to is all 4 tramps off and not just the front
    feel free to post any experience with this topic.

    Going to sea? No.

    Questions: Good or bad idea. How many tons?

    The vessel already saw 100+ winds but had 14 lines to shore and no surge.

    Philip
     
  2. groper
    Joined: Jun 2011
    Posts: 2,467
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    Location: australia

    groper Senior Member

    Have lived in the tropics all my life, cyclones are a regular occurrence. Our procedure is to take the boat up an estuary that isn't prone to large volumes of flood water - check your local area catchments and find a suitable creek. Once we are up the creek as far as possible, so the mangrove lined creek is barely wider than the boat itself, we throw out lines in all directions. All the lines are tied into the mangroves themselves... The shallow draft of a multihull is a nice feature which allows this type of risk mitigation.

    We've had our boat through many cyclones and never had any issues like this...it's safer than leaving it in a marina...
     
  3. tspeer
    Joined: Feb 2002
    Posts: 2,283
    Likes: 251, Points: 83, Legacy Rep: 1673
    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    The way OTUSA solved this problem was to use a fresh water filled inflatable mark as a mooring buoy. The fresh water filled bag floats in salt water (barely) and adds lots of mass and a large cross sectional area for damping.

    The boat is light and free to move to the wind. But the massive buoy keeps the boat from sailing back and forth at the mooring. It's maybe not the way to go for a hurricane, but it's good for ordinary gales.

    I think for a trimaran, keeping the bows pointed into the wind is the best way to keep the akas from lifting. Can you lift or remove the rudder? Or turn it 90 deg? That would allow the stern to swing to the wind. Perhaps it's better to have all 3 mooring lines going to the bow.
     
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