scantling calculations

Discussion in 'Boat Design' started by abhishek, Sep 27, 2009.

  1. abhishek
    Joined: Sep 2009
    Posts: 34
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: india

    abhishek Junior Member

    how can we arrive scantlings for tugs with IRS RULES (ie) INDIAN REGISTER OF SHIPPING FOR 10 TONNES BOLLARD PULL TUG
     
  2. Ad Hoc
    Joined: Oct 2008
    Posts: 6,644
    Likes: 650, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Firstly
    You need to establish the safe working load, ie what factor of safety you are going to apply to the 10 tonnes. So, is it being used daily, once a week, once a month, once a year etc??..this determines the factor of safety you use. Anything form 3 up to 6 or more. (UK MoD use 9)

    Secondly
    You need to design it, that is draw, the bollard. You then calculate what section is required to withstand the 10 tonne load, plus the FoS. For bending (if any) and shear.

    Thirdly
    You need to establish the load paths...ie what structure is there on the deck and under the deck, to take this load.
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 476, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    They need to hire someone capable . . .
     
    1 person likes this.
  4. abhishek
    Joined: Sep 2009
    Posts: 34
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: india

    abhishek Junior Member

    can i have some formulas to find out the loads and what are loads acting on the tug.
     
  5. Ad Hoc
    Joined: Oct 2008
    Posts: 6,644
    Likes: 650, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Providing formulae wont help you unless you understand them; from my post above, this does appear to be sadly in evidence already. However, if you understand them, then you should be capable of deriving a formula of your own from simple momentum theory.

    If you cannot do this, then i suggest you employ a naval architect that can do it for you...since you are asking some very very basic and fundamental questions of design that any professional naval architect can do.
     
    1 person likes this.
  6. abhishek
    Joined: Sep 2009
    Posts: 34
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: india

    abhishek Junior Member

    thank you Ad Hoc sir, i am a naval architect, i know the static and hydrodynamic loads acting like wave induced bending moment and shear forces and still water bending moment which can give the total bending moment and the ships own weight with its buoyancy, vertical and horizontal bending moment with hogging and sagging ,but rather than these if any of the loads should we consider ? but this is really nice to share every idea ...
     
  7. Ad Hoc
    Joined: Oct 2008
    Posts: 6,644
    Likes: 650, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    abhishek
    "..but rather than these if any of the loads should we consider ?.."

    It is your boat. Only you know the SOR and duty of the boat no one else. That is therefore for you to establish where the possible loads shall come from, and then as a final check look at the Class requirements.

    If you are a naval architect and you understand how to calculate structures, then my post #2 provides you with the solution. I can't be any clearer than that on such limited information.
     
  8. abhishek
    Joined: Sep 2009
    Posts: 34
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: india

    abhishek Junior Member

    ok Ad Hoc sir thanks for ur reply..........
     
  9. gonzo
    Joined: Aug 2002
    Posts: 14,575
    Likes: 699, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    The rules should provide you with what you need. They usually specify all that
     
  10. abhishek
    Joined: Sep 2009
    Posts: 34
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: india

    abhishek Junior Member

    thanks for all the senor people especially Ad hoc sir , i have one doubt regarding the bending moments as the tug goes only in restricted ares like shallow waters only should we consider the still water bending moments and wave induced vertical or horizontal and hogging and sagging moments for calculating the scant lings.
     

  11. Ad Hoc
    Joined: Oct 2008
    Posts: 6,644
    Likes: 650, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    You have to first look at the specification of the boat. What does it say for Class notation? Then look up the Class notation and see what structural calculations, by Class rules, are required.

    It matters not whether the boat is in a river a lake or the deep ocean. You need to establish the "area of operation". From this the global loads can be established, to apply to your boat. If you are stuck, then Class rules, which you must comply with, with have the answer for you.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.