Final blueprints

Discussion in 'Option One' started by gonzo, Sep 8, 2003.

  1. gonzo
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    gonzo Senior Member

    The aft sections can provide sufficient initial stability.
     
  2. BrettM
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    BrettM Senior Member

    Will,

    Have you done any detailed weight estimate ie Weight & LCG ?(VCG not so important)

    I suspect your wl may be in the wrong place. Doesn't appear to be much boat in the water?
     
  3. Willallison
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    Willallison Senior Member

    Brett,
    The displacement as shown is 1450kg (our target for O-1 was around 1500)
    LCB (and hence LCG if boat is to float 'level') is 63.4% of LWL.

    No detailed weight estimates have been done as yet as we are still to make final decisions about build materials. As I have almost no experience in designing appropriate cinstruction details, I was rather hoping someone might chip in with some suggestions....
     
  4. BrettM
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    BrettM Senior Member

    Will,

    Take a stab at it anyway. You will probably need to take a lot of guesses but you you can update it anyway on a spreadsheet. Construction wise - Take your best guess at the shell material apply it to all your surface areas and add at least 50% for stiffening etc.

    Add 10% to everything at the end as these things always get heavier. Don't really know how this happens it just does...
    Best to know earlier than later.
     
  5. DTVM
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    DTVM Junior Member

    What size wake will this hull design produce?
     
  6. gonzo
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    gonzo Senior Member

    What is the length of the boat. An 8 cylinder gas engine with drive is about 550 kg. It doesn't leave much for the rest of the boat.
     
  7. Willallison
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    Willallison Senior Member

    DTMV - I don't know any way other than using past experioence with vessels of similar form, or tank testing to estimate wake height. Someone else may have access to the very complex computer programmes that predict these things - but not me!

    Gonzo - LOA is (currently) a shade under 30ft. Power is to be o/b - approx 100hp will give max speed of about 25knots - so figure weight <200 kg
     
  8. Dutch Rub
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    Dutch Rub Junior Member

    ......Im still lookin for this thing to be at least 50 foot long......... if I had a semi with a 671 in er, I know I could tow it down to the river..........
     
  9. gonzo
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    gonzo Senior Member

    It is possible to keep the weight of the boat to 1450 with durakore and lightweight plywood. The interior needs to be very basic too. Maybe nidacore or other honeycomb core for all the bulkhead and interior construction. If the boat floats so high, the beam is too wide for the displacement. Either flatten the bottom section or narrow the beam. Also, the max beam may have to be a bit further aft if we put an outboard.
     
  10. Willallison
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    Willallison Senior Member

    I ran a weight schedule on a model I did for O1 early in the piece (an open 'express' style with the head located down with the berths). Based on using corecell or similar for all the construction, weight for the basic structure (excluding furniture) came in a just over 1000kg. Add an engine, tanks and a few other bits and 1500 will soon come and go - but with a little careful thought, we might just keep the (dry) weight to the target 1500kg.

    Waterline beam is only 2.02m (6' 7 1/2 ") and transom deadrise is 12 degrees. Other than it might be rather tender at rest, why do you see the boat floating so high as a problem?

    To make things a little clearer, this is a lift of the waterlines (DWL in blue) - do you still think we should move max BWL further aft?
     

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  11. gonzo
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    gonzo Senior Member

    I think with and I/O it would be more stable because the engine is low in the bilge. An outboard is top heavy and will raise the CG. The beam is narrow by modern floating box standards but will give a nice ride. I think it looks fine.
     
  12. rlewis
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    rlewis Junior Member

    Hmm, it has been a while since anyone showed interest in this. HAs anyone tried working in GRP? I am inclined to try to build this thing using C-Flex, I'm not sure why foam core is better, it seems to me lkike C-flex would be sitffer, stronger, and lighter.

    Anyway, I'm assuiming GRP would need a plywould frame with ribs and/or bulkheads. Did anyone work this out? What about the transom?

    Actually, if anyone knows of free plans somewhere for a planing hull in GRP at abouut 30' in length that is really what I am looking for. I know there are lots of resources, I just can't find plans for a GRP planing hull of that size. The hull and the transom are the critical parts I think, the transom needs to be engineered for an outboard of about 100 hp.

    Thanks in advance.
     
  13. rlewis
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    rlewis Junior Member

    Thinkgs I really nead are, if I use C-flex, how many layers do I need on the inside and outside of the hull? How may bulkheads, and what thickness? Are we talking about 1" marine plywood for the bulkeads? I could go nots and put in lots of ribs but that would probably drive the weight too high. I need enough strength and stiffness so it doesn't pull apart in the water, but need to make it light enough so that it will plane.
     
  14. Willallison
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    Willallison Senior Member

    Free boat plans are very few and far between - quite apart from the fact that that's how designers earn their living, I would think that possible liability issues would make many nervous about supplying plans with no control over them.
    Having said that, I sincerely hope that over time O-1 can be brought to completion. The concept allows for construction using a variety of sheet materials - whether ply, cored FRP, or even aluminium - some of the construction details will need to be altered, but otherwise it's simply a matter of doing the scantling calcs.
    As far as your question regarding scantlings, get a copy of Elements of Boat Strength by Dave Gerr - you can work them all out yourself and gain a better understanding of how things should be done in the process
     

  15. rlewis
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    rlewis Junior Member

    Hmm, thanks. I just saw that book. I think that is what I need.

    However, the basic elements should be a standard, like how much glass to use and how many bulkheads. If someone worked this problem out fo O-1 it would be a great place to start. And, since the idea is to produce the plans for O-1, it would be a great resource for everyone.

    Maybe if I get the book I can work it out. If I do I'll post the plans here.
     
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