60 feet steel sport fisher with enlcosed bridge

Discussion in 'Boat Design' started by Capt. Bahi, Jul 22, 2015.

  1. TANSL
    Joined: Sep 2011
    Posts: 7,369
    Likes: 699, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Capt. Bahi, about the thickness I would advise some caution. The thread to which you refer is the year 2005. In that year was not yet in force ISO 12215-5, which is 2008. This standard, which is currently applied in Europe for pleasure boats and in some cases for boats under 24 meters in length, it sets minimum thickness, regardless of the derivatives of the design pressures. If you want to design your boat according to any international standard, I'm afraid you should start forgetting thickness of 3 to 4 mm.
    Have you consider, for example, the effect of corrosion on a plate of 3 mm. In a few years, you are going to be without plate, It will have been transformed into cigarette paper.
    My opinion, and I would not want anyone to feel offended, is that reading the threads of this forum is impossible to design a boat the size of yours.
    I saw with curiosity in your budget that the price of the steel material is less than the labor to build it. Have I misunderstood?
     
  2. Capt. Bahi
    Joined: Jul 2015
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Egypt

    Capt. Bahi Junior Member

    Frankly speaking, I'm still confused concerning the plate thickness, and I hear, from professional owners & builders, different opinions between the two extreems 3mm & 12mm. I don't want to end out with neither a weak hull, nor a heavy boat. So, I'm still studying...


    The current steel price, including transportation, is @EGP 5,200/ton × estimated 20 ton hull = EGP 104,000. While the labor total cost is @EGP 2,500/ton × estimated 20 ton hull = EGP 50,000.

    I got the same offer from two of the top builders.
     
  3. gonzo
    Joined: Aug 2002
    Posts: 16,790
    Likes: 1,714, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Is the labor cost for a bare hull? What is the estimate for: gas for cutting torches, cutting abrasive wheels, grinding wheels, welding rods and other miscellaneous?
     
  4. Capt. Bahi
    Joined: Jul 2015
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Egypt

    Capt. Bahi Junior Member

    All inclusive
    We are discussing construction & cost, while I requested for design assistance!!!!
     
  5. gonzo
    Joined: Aug 2002
    Posts: 16,790
    Likes: 1,714, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    It appears way too low for materials. Also, the design will determine amount of plates, stiffeners, etc. which in turn determines the total length of the welds. You don't have enough data yet to calculate costs. Construction methods and costs are part of the design.
     
  6. TANSL
    Joined: Sep 2011
    Posts: 7,369
    Likes: 699, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    The design does not include the total number of plates, stiffeners, nor welding meters.
    A project includes an estimate of the value of the boat which is very different to the cost of building it in a shipyard. A project might include the market value of certain things, not its cost.
    A design takes into account general construction method, never construction methods and costs.
    I think we are confusing things and, therefore, making the Capt. Bahi get some wrong conclusions
     
  7. Heimfried
    Joined: Apr 2015
    Posts: 535
    Likes: 139, Points: 43, Legacy Rep: 37
    Location: Berlin, Germany

    Heimfried Senior Member

    If the the goal of the design process is a boat, which really can be build, it seems not a bad idea to keep an eye on the costs.

    But to design just for design is nice also.
     
  8. gonzo
    Joined: Aug 2002
    Posts: 16,790
    Likes: 1,714, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Good, knowledgeable designers include a materials list. The cost estimate for parts can be easily calculated from that. A designer that can't calculate the total weld length and the size/shape of the plates can't calculate building time either.
     
  9. Capt. Bahi
    Joined: Jul 2015
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Egypt

    Capt. Bahi Junior Member

    Any question related to design, I'll make sure to get you the answer, but I need to understand the reason behind it, in order to learn.
     
  10. gonzo
    Joined: Aug 2002
    Posts: 16,790
    Likes: 1,714, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Your post is about a sport fishing boat. They have a pronounced flare forward and tumblehome aft. The only way to produce that shape is by cutting strips of metal and pre-form them on and English wheel or an anvil. The amount of welding and fabricating is several times that of other kinds of boats. The design process, if done by a Naval Architect or knowledgeable designer will generate the size and shape of the plates, structural members and at least some construction details. The cost and time duration of the build is calculated from that data. Experienced builders can give a reasonable time and cost approximation when they have built a similar boat in the past. I think that you need both to get the build done withing budget and in time.
     
  11. TANSL
    Joined: Sep 2011
    Posts: 7,369
    Likes: 699, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Of course but perhaps the cost depends on, for example, the shipyard in which the ship will be build which, in many cases, may not know the designer. The designer can know the costs of materials and some other things but may not know, for example, the share of overheads that a shipyard will apply to their products. You can calculate the welding meters but you can not know what position to be welded or that machine and therefore the cost of welding.
    I am not referring to you when I say that loose talk, to give the feeling of hearing a case, it is very easy but to say useful things it is harder.
     
  12. TANSL
    Joined: Sep 2011
    Posts: 7,369
    Likes: 699, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    That is not correct.
    I do not know what shipyard you're talking about but I have not seen one that built this way. I know there may be shipyards doing so, but say that is the only way to do it, is not correct.
     
  13. Capt. Bahi
    Joined: Jul 2015
    Posts: 16
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Egypt

    Capt. Bahi Junior Member

    The cost calculations were made by each of the two professional builders, each one separetly, after seeing the same boat photo in the begining of the thread here. Both of them advised that the boat will be ready to sail within 6 months, not more.
     
  14. TANSL
    Joined: Sep 2011
    Posts: 7,369
    Likes: 699, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    I do not know what kind or size of boat you talking but for larger boats, say, 6 m in length, the basic project (not the development project) never includes the parts list.
    I want to clarify this because Capt. Bahi could probably, with help, make the basic project of his boat but, imo, perform the development project (construction drawings) is not possible.
    The construction period of a boat can be estimated by many technicians, though not designers. Calculate the cost in man-hours of a boat can only be done by shipyard technician specializing in this subject. I speak, of course, of similar boats to 18 m sport fisher. Not speaking about 6 m or "catamaran" built with two drums.
     

  15. gonzo
    Joined: Aug 2002
    Posts: 16,790
    Likes: 1,714, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    I disagree. Knowledgeable designers can calculate cost and include a list of materials. If they can't understand the position of welds and the schedule, they are unable to do the engineering for them. This is not complicated, only tedious.
     
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.