Proa-Cement

Discussion in 'Boat Design' started by DrCraze, May 14, 2010.

  1. tugboat

    tugboat Previous Member

    sorry its just me again drcraze--but i have been following this project with zeal and enthusiasm. i Think what you have accomplished is awesome-..i think that you have silenced the critics. somethign not easily done...

    since i have only actually seen a few fc crafts- i am very curious---for instance--if you hit the hull with a hammer could it withstand that kind of impact??...What was your admixture?
     
  2. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    Whats awesome, the proa or the fact that the critics are silenced:p

    If you hit the hull with a sledge hammer as hard as you could it would dent the ferro-cement and if it did cause a leak it would be a manageable leak, just a trickle. I speak from experience on that one:!:

    My mix design is 1 part cement 2 parts sharp plaster sand(sand should sound crunchy when you compress it in your hand) I then use max dosages of water reducer and super plastisizer and short strand fibers. I use a pozzolian too but it isnt necessary if modern admixes are used. Once mixing begins I add Polar Set to counter the extended curing cycle the reducers cause. Without the Polar Set my mix takes over 24 hours to make its initial set!
    Do not, I repeat do not use any accelerant other than Polar Set. All other acclerants cause premature oxidization of the steel.
     
  3. tugboat

    tugboat Previous Member

    yes i will be doing some fc slabs to test..and a couple models. i will be using mesh--i am dying to find out how she handles!! i re-read your weights--thats truly amazing you got it that low...!!
     
  4. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    Well hes getting fatter:p the bulk heads and inner keel laminate added another 40 lbs and after the decks go in he'll be around 350lbs. I am doing a leak test at the moment and he holds 560lbs(254kg) of water with 12inches(304mm) of draft. The ama is underway now and is designed to hold water ballast, If anything it will be fish hold:D

    Cement is proving to be a far greater material than any other so far. What other material can be totally immersed in water or left in the sun with zero protection from coatings? Or is self sealing, it really is!

    Think of all the Etchell owners Ill be passing in my local club. Can't wait to tell them its concrete. Being ousted by a stone age craft being bad enough:p
     
  5. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    Finished the sail plan for the proa. Would have liked to have more than 100sqft of sail but this should be suitable for the local conditions. Light winds here 25 knots that gust to 35-45 knots. It gets interesting that's for sure.
    I may add roach to the leach with battens after this trial run.
     

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  6. rwatson
    Joined: Aug 2007
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    rwatson Senior Member

    What is the point of a 400 pound 18 ft multi hull sail boat, except to show it can be done?

    You will get a hernia manhandling it around the beach, and it will sail and float like a waterlogged duck.

    I would rather have spent the extra money on lightweight materials and got a Proa that does what it was designed to do - fly like a butterfly.

    You may want a slightly bigger rig to get a bit more performance under sail.
     
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  7. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    The point of this build is to practice with the material before going big. I agree about the size of the rig and have since increased the plan to 140 sqft.
    As for the weight on the beach I deal with boats 3 times that, all it takes is a little preparation.

    Launch day is coming fast so we will see how this sled performs. Will it fly like a butterfly or hurtle like an axe?
     
  8. DrCraze
    Joined: Apr 2010
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    DrCraze Junior Member

    Finished the foam form work a I will be finishing the mesh work today. The goal is to have the hull done this weekend.
     

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  9. ancient kayaker
    Joined: Aug 2006
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    ancient kayaker aka Terry Haines

    It should be bullet-proof at least!
     
  10. DrCraze
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    DrCraze Junior Member

  11. NoEyeDeer
    Joined: Jun 2010
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    NoEyeDeer Senior Member

    Mate, you're nuts. Good on you. :)
     
  12. ancient kayaker
    Joined: Aug 2006
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    ancient kayaker aka Terry Haines

    Agreed. He fits in well here, don't you think?
     
  13. tugboat

    tugboat Previous Member

    Dr Craze- i just found a product called fer-a-lite which apparently has been around for 20+ years- this stuff is amazing it is stronger than FC, light as composite and can be troweled on in increments-no one shot pours!! you gotta see this stuff! would have made your boat half the weigth or less....i still love thta you did it!! proves lots to me...
    the fer-a-lite could have been 1/8th inch thick...
     

  14. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    whats happening with the boat ? - its ages since the last post
     
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