Converting Plans from ply to steel..

Discussion in 'Metal Boat Building' started by Tug, Dec 21, 2008.

  1. Tug
    Joined: Aug 2007
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    Location: Muskoka,Ontario,Canada

    Tug Junior Member

    How would one go about changing ply and wood plans to steel..
    This is the boat i would like to convert to steel..cheaply..
    http://markvdesigns.tripod.com/boatbuilding/id16.html

    The reason for converting it would be that it would be used primarily in a rain forest enviroment and stored in a metal shipping container...

    Cheers
    Tug
     
  2. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    This is out of my league. Several Glen-L plans are both aluminum or wood and a few are wood or steel. You buy the version you want. Totally different sizes of materials and you have weight and balance issues. You really need a Naval Architect for these issues. However, if you are talking about the northwest rain forests you can totally encapsulate all your wood in plastic with 3 coats of epoxy and then those members are impervious to moisture and would last as long as steel and maybe aluminum also.
    That is my 2 bits. Hope others chime in for you. Stan

    here is an example 1958 wood boat at Vancouver. http://www.ladyben.com/SearchResultsFull.asp?VesselID=2264

    That is 50 years W/O epoxy. Insulate your metal container to prevent condensation and put in a 100 watt bulb on a timer.
    You will save lots of $$$$$$
     
  3. Guest62110524

    Guest62110524 Previous Member

    thats pretty simple BUT you would need ply house and then take you hull surface areas and using 3mm plate work out the weight of those areas, I am afraid your disp will be well over 4000 lbs with ply decks, once you start putting in some steel floors and stringers, you may well be very overweight,
    So do rough calc of weights then immsersion rate, I dont think itmll work given the narrow wl beam
    smiles its christmas
     
  4. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The Mark V design series is intended to be light, actually quite light weight so that propulsion requirements are minimal. To do this design in steel, you'll need considerable alteration to the design. Specifically, the beam and hull volume in general will need to be increased to account for the increases in weight, plus several other considerations.

    You should contact Van Abbema or other qualified designer to make these changes, as they're well above what a typical novice can accommodate.
     
  5. Matt.D
    Joined: Oct 2007
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    Location: gold coast

    Matt.D Junior Member

    U would want to go 4mm not 3mm,at least from 400mm above the water water line dowm, surverys like to see thicker steel than if u used alloy. Ease of welding without distortion also will help in minamizing ur faring time.
     
  6. Tug
    Joined: Aug 2007
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    Tug Junior Member

    This boat suits all my needs and wants other then the material used in construction...
    The length and beam need to stay the same to fit in the shipping container...
    The boat will be used and stored in a south american tropic rainforest, very high heat and humidity...
    If it cant be made out of steel because of wieght i would rather not take up an Naval Architect's time..they are busy people..
    Cheers
    Tug
     
  7. rasorinc
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    rasorinc Senior Member

    Epoxy and wood will work there also. Make sure to have lots of venilation on opposite sides of the container.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It's a very simple hull form with the rest being relatively spartan. Not a difficult design to convert, but certainly not one a novice should attempt without considerable design experience.

    Matt, you calculate plate thickness by load and corrosion resistance, it's not an arbitrary shoot from the hip kind of thing. Just making your simple change from 3mm to 4mm would add 20% to the weight of the hull. Considering the max load of this vessel, this is a huge penalty to pay, just to make some surveyor feel all warm and fuzzy. The surveyor isn't responsible for the scantlings.

    If you want this design in steel, you'll have to either find a similar slab sided (Bolger like) V bottom with modest beam (in steel) or have Van Abbema set you up with new steel scantlings or another designer pen you a design in a similar vain.

    Made just as it is, you could sheath the bottom with Dynel or Xynole fabric which will dramatically improve abrasion resistance of the areas so skinned. If proper encapsulation methods are employed, then this boat could easily survive the environment and climate you intend. You also could install sacrificial bottom runners to accept grounding and impact damage, which saves the bottom planking.

    Honesty, I think you'll have more trouble dealing with a rusting hull, condensation build up and the "55 gallon drum" effects you get when living with a relatively light weight steel hull, particularly in the climate your yacht will service.

    Tug, how familiar are you with modern wooden construction methods? Using these techniques, it will not be "your grandfather's rotten wooden boat" type of result.
     
  9. Guest62110524

    Guest62110524 Previous Member

    3mm, is and was used by some of the worlds top designers, 3mm is weight of 9mm alu
    surveyers have no say, , approval societys do, my mate had robert clark draw up a 34 foot yacht, was 3 mm, cept bottom panel, went down to the ice and UP to the ice, around the Horn , but as I said before thsi is simple to convert but will not fit your disp.
     
  10. Tug
    Joined: Aug 2007
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    Tug Junior Member

    I prefer steel for a boat...
    I believe modern wooden construction can make a boat as good as one made out of steel...but not better..
    I have made a cedar strip canoe with modern wooden construction....and am aware of the benefits and downfalls of that system...
    So i need to ask for steel scantlings...how are the scantling's different from the wood ones?
    Cheers
    Tug
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It depends on the approach the designer takes to absorb the loads. Just like other building materials, metal can used a number of different engineering solutions to solve loading issues. Wood and steel behave quite differently and have very different physical properties, so you arrange the structure and scantlings to suit the engineering solutions devised.
     
  12. Tug
    Joined: Aug 2007
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    Location: Muskoka,Ontario,Canada

    Tug Junior Member

    Thank for the responces...i appreciate the help...
    So converting from ply to steel the internal structure will not support the hull skins properly..so more structure is added....adding more wieght...
    More weight gives less payload...
    Would a bigger engine give me more payload?
    Bigger engine more wieght....plus fuel....
    Around and around we go....hmmmmm
    Would aluminium be a better choice?
    Cheers
    Tug
     

  13. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The only way to increase payload (capacity) is to increase hull volume, which is why I mentioned adjusting the beam and draft in my first post. Baring this, you can increase length. The more you load up a given shape, the more it sinks in the water. A certain amount of sinkage is expected, from a lightly loaded to a fully loaded condition. Crew, equipment, stores, etc. account for these increases in displacement. Your drive train has little to do with your load carrying capacity, unless you employ lots of power and use a lifting device(s) of some sort (foils, hull dynamics, etc.).

    Aluminum would be a better, if much more expensive route. Again, since aluminum is quite different physically then the original plywood construction, it too needs to have it's scantlings and structure addressed. An example would be that aluminum plate isn't nearly as stiff as plywood, so it'll need an internal frame work to support these panels. Welding distortion and "oil canning" are other issues, not associated with plywood methods.
     
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