Position of a tow hook.

Discussion in 'Boat Design' started by Crashimir, Jan 31, 2011.

  1. Crashimir
    Joined: Oct 2006
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    Crashimir Junior Member

    Greetings to everyone.
    I need advice.
    I am making project for a inland water harbour tug and I wonder if anyone could help me in finding best position for tow hook.
    tug is 14 meters long and 4.5 meters wide.
     
  2. gonzo
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    gonzo Senior Member

    It depends on the design. You have to calculate, for example, what the pivot point of the tug is. Also, calculate how high you can make the hook. Depending on the pull, there will be a maximum angle of turn before the tug capsizes. etc.
     
  3. ned L
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    ned L Junior Member

    I wouldn't suggest putting the tow point forward of the prop or you can get into real trouble.
     
  4. mark775

    mark775 Guest

    The towpoint should be further forward for maneuverability and as low as possible. As Gonzo suggests, there is a point beyond which the boat will start to get squirrely. A minimum of 25% forward, though, to handle harbor towing. If you don't go this far, it will be a dog.
     
  5. gonzo
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    gonzo Senior Member

    I've seen some tugs using steerable pods, like the VolvoPenta type. It changes the design quite a lot.
     
  6. mark775

    mark775 Guest

    Well, my only experience with those (pods) is KAMEWA Aquamasters on a real tug and our tow point was still clear up behind the cabin.
    Alert.jpg
    Notice the tow pins aft for making the long haul tow more stable. For maneuvering, the pins retract.
     
  7. mark775

    mark775 Guest

    "Why Knot Make a Large T slot Channel Like you find on a Bridgeport Machine and have a sliding towpoint that the Capt can move dependining on the tow wieght and sea conditions?" - because there are unGodly forces involved and the towpoint needs to be anchored to something solid, like the keel. This will not be something just bolted to the deck. Also, the harbor tug never needs long tow capability, only to pull..in THAT direction.
     
  8. Landlubber
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    Landlubber Senior Member

    Why Knot Make a Large T slot ...thanks Mark, nearly died when i read that one.....
     
  9. gonzo
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    gonzo Senior Member

    We should also mention that their are general purpose and specialized tugs. That would show in the SOR
     
  10. michael pierzga
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    michael pierzga Senior Member


    You might review the design catalogue at Alnmaritec. They have many harbor, working boat, plans on line. This is a 5 ton bollard workboat.


    http://www.alnmaritec.co.uk/downloads/alnDB_68.pdf
     
  11. waikikin
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    waikikin Senior Member




    That seems pretty close to the truth Mark, from the small(very) involvement I've had in towage etc, sometimes these beautiful machines sound like a wounded dinosaur when the jobs just gotta go that way, truly some of the most impressive vessels on the water. Regards from Jeff.
     
  12. Submarine Tom

    Submarine Tom Previous Member

    You'll want to learn about and thoroughly understand "Girding".

    -Tom

    P.S. Google: girding tug
     
  13. mark775

    mark775 Guest

    Tom, I watched those videos and, after some years on escort/tether tugs and shiphandling tugs, for the life of me cannot figure out how they got in that untenable position (Nor, of course, why they would have ports/doors open). Seldom does one consider oneself "lucky" when a line parts...
     

  14. Crashimir
    Joined: Oct 2006
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    Crashimir Junior Member

    Thanks mark and gonzo. You have been of great help.. Tow hook was originally planned to be between 25 and 30% from stern. And positioned about 1,5 meter from waterline.
     
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