Scantlings for cement (IE Books?)

Discussion in 'Boat Design' started by F.H.B., Apr 24, 2012.

  1. F.H.B.
    Joined: Dec 2009
    Posts: 27
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Utah for now

    F.H.B. Junior Member

    Hi, all. I am wondering about cement scantlings. There are a lot of books on Amazon about cement boat building, but by the title it seems more about building than designing. Can anyone recommend a good book on design? I'd perfer calculations but even a reference that says this thickness and steel for this scantling of plywood/Alum/Steel would be a better start than I have now.

    Cheers,
    - J
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Designing ferro boats (cement) is exactly the same as any other hull shell material choice. You calculate the loads and capacities you need, then develop a shape, arrange the masses, in hope that everything balances out nicely on launch day.

    There is no book that will hand hold you through the process "first do this, then do that" type of thing. There are many books that do explain the processes, calculations and principles necessary.

    My suggestion is you offer some more detail into what you're attempting to do. If trying to design a ferro hull shell, then the first thing is a reasonable understanding of hydrodynamics and basic structural engineering. The book store on this site has many texts of these subjects, this may be a good place to start, but be warned, these are "easy" reads and you're not going to be designing a yacht by the end of the week. Jay Beniford has a very good book on ferro design considerations.
     
  3. MikeJohns
    Joined: Aug 2004
    Posts: 3,176
    Likes: 198, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

    Continuing on from Paul's post

    There are scanting and layup guides that were produced by both Class societies and Flag state authorities.
    As far as I'm aware Class societies no longer publish scantlings for ferro cement. But you can find a lot of rules if you search. I know our (Australia) 'USL' covered ferro design and Lloyds Register was approving plans and supervising construction at one stage here.

    I'd have some engineering material too that I could scan and email to you.

    But I'd have to ask; these days with such good paint systems for steel why Ferro ?
     
  4. MikeJohns
    Joined: Aug 2004
    Posts: 3,176
    Likes: 198, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

    Here's an example of hull layup, this is from 'USL'.
    All class rules are/were very similar. It's a good indication and enough to show how much steel is actually in there since the matrix exhibits brittle failure under very low tensile stress.
     

    Attached Files:

  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 472, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Mike, I think the real issue here is if the original poster is capable of understanding the engineering dynamics involved, not to mention the hydrostatic elements. I'd be cautious about posting scantling generalities or averages, even if class specific. With the thought they might be the very bone they get up and run with, forgoing the realities of the engineering involved, which can be considerable in a ferro build.
     
  6. MikeJohns
    Joined: Aug 2004
    Posts: 3,176
    Likes: 198, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

    Hi Paul,
    I could point him at some scantlings that would be idiot proof. I can also give him some first principles engineering material but he's need to talk the talk to understand them :)

    As I've said before I had a ferro ketch years ago. It's now on the bottom after bumping into Australia (under later ownership). Relevant to this thread the engine beds built to approved scantlings disintegrated after a few years under load and vibration.

    But it isn't very sensible to build in Ferro these days the finished hull has zero value and is crippling in time to build. That should be enough to put anyone off !
     

  7. pdwiley
    Joined: Jun 2008
    Posts: 1,002
    Likes: 86, Points: 48, Legacy Rep: 933
    Location: Hobart

    pdwiley Senior Member

    It doesn't appear to be putting Tugboat off...... but then again I'll believe he's done it when I see the finished hull and not a second before.

    PDW
     
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.