Stability Issues on my TUG - pls help!

Discussion in 'Stability' started by jfrech, Apr 3, 2014.

  1. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    I totally agree. But I think what we should not do is replace a professional report which is expensive, with reassuring comments that have no basis.
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    If the boat has a known history of plying the same waters as the new owner intends for it, without incident, an accurate ( if that is possible) audit of the nett additions or subtractions, and what it amounts to in terms of weight, how much and how high, would be the next best thing. Of course that will still require interpretation by an experienced person, but not cost so much. But that information may not be obtainable in the first place.
     
  3. nzboy
    Joined: Apr 2011
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    Location: nz

    nzboy Senior Member

    I agree It is possible to spend a huge amount of money to find its stability now is no different to when it was built or no different to other comparable vessels .By its very nature tugs have a low centre of gravity and traditionally low freeboard .What our reader is concerned about is his personal safety if caught out in extreme conditions . In NZ there have been a number of enquiries into sinking of similar sized trawler vessels .In all cases the vessels were not exceeding their design loading and stability . But the Judge said they were in sea conditions that they were not designed for and ingress of water was a contributing factor. So we are no better off .(Design is an issue if you have 8 metre waves)The expert opinion was if these boats had watertight hatches that didn't fall off when boats were rolled(knockdown) by freak(8metre) waves and doors and windows that didn't break that there would be reasonable chance the boats would return to being upright due to their righting moment
     
  4. Capt Peter
    Joined: May 2014
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    Location: Ontario Canada

    Capt Peter New Member

    Interest in selling your new tug

    Good day JFrech,
    I'm curious if you'd be interested in selling your recently purchased tug?
    Thanks.
     

  5. Yobarnacle
    Joined: Nov 2011
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    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    Congratulations on your new tug yacht. The dimensions seem appropriate to me.
    13tons, 38 feet x 10.2” beam, 4 foot draft.
    Marine mammals vary between a 1 to 3 beam length ratio for some seals up to 1/4.5 for some whales.
    Seems you are in the ballpark.
    Great Lakes freighters typically had 1/10 ratio or even 1/11. But those are big ships.

    Something not mentioned is tugs usually have heavy built hulls. Thick shell plating and heavy frames closely spaced. It should be fairly easy to determine what portion of the hull is newer. Probably fewer frames and lighter plate.

    The heavy hull and engines give tugs their enormous stability. I recommend you NOT carry excess liquids for ballast. Lake Superior water is drinkable away from port cities.

    Free surface in slack tanks kills ships. You might want to keep your large tanks as air flotation chambers and convert some smaller tanks or voids to fuel.

    Only small water tank needed.

    http://www.seagrant.umn.edu/superior/facts

    "Lake Superior ...
    ◾is the largest freshwater lake in the world by surface area and the third largest by volume (Lake Baikal in Siberia and Lake Tanganyika in East Africa contain more water).
    ◾could hold all the water in the other Great Lakes, plus THREE MORE Lake Eries.
    ◾connects the heart of North America to a global economy.
    ◾is remarkably CLEAN and cold.
    ◾is a geological newcomer (only about 10,000 years old).
    ◾is exhibiting a trend in summer surface temperature. Per decade since 1980, surface water temperature in summer has increased about 2 °F (1 °C), while regional air temperature has increased 1 °F (0.5 °C).
    ◾is managed through a binational agreement involving Canada and the U.S., and by the Province of Ontario and the states of Minnesota, Wisconsin, and Michigan.
    ◾has rip currents that are dangerous to swimmers.
    ◾holds 10% of the world's fresh surface water that is not frozen in a glacier or ice cap. "



    Good luck!
     
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