fixing one foot diameter hole in Ferro Hull 32 foot

Discussion in 'Materials' started by luckyscott, Jan 18, 2010.

  1. luckyscott
    Joined: Jan 2010
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    Location: Queensland, Australia

    luckyscott New Member

    Hi, I was wondering if anyone could help out with a bit of a problem i have. I have just inherited a 32foot Ferro Boat, its name is Misty Blue, it has a nice big hole in the bow about a foot round and it has been gutted and mostly finished except for the hole in the hull. What would be the best way to get the repairs done on it and is it expensive to fix up Ferro Hulls so they are as good as before the damage? I am not that knowledgeable with Ferro Cement or Yachts for that matter, but now i guess is the time to get into it seeing as i now have this boat to finish and eventually live aboard.
    Thanks
    Scotty :)
     
  2. Saylaman
    Joined: Dec 2007
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    Saylaman Junior Member

    Ferro cement damage is supposed to be easy and cheap to fix. Most ferro hulls are made up of approximately 6 mm steel rods about 50 mm apart, forming the shape of the boat, then three layers of chicken mesh are fastened to each side of these rods, inside and outside the boat. A mixture of cement and sand render is then plastered onto the chicken wire, pushed right through, trying to ensure there are no voids, this render is then simply smoothed off inside and out and painted. If the hole is cleanly formed and the rods and chicken mesh are missing from the hole, you may have to break away some of the hardened mortar around the hole to expose some of the existing rods and mesh. (this should be easy to do, hold a heavy hammer inside and a light hammer on the outside to pound the mortar away by crushing it between the hammers all around the hole, maybe 75 mm all around) Tie new rods and mesh to the existing rods and mesh, then plaster the hole to close it. There are wet-to-dry epoxies or bonding agents available for mortar, these can be used at the interface between the old mortar and the new to help with bond and water proofing. A mortar mixture of 1 part GP cement and 1.5 to 2 parts dune sand will be satisfactory to make the mortar. It should only cost a few dollars for materials for the repair. Once the mortar has been applied and has set,(it only takes a few hours) cover the patch with plastic, inside and out to allow the mortar to cure. Cement mortar needs to remain wet for at least a week, preferably longer to cure and gain strength properly. (Strength gain in portland cement is a chemical reaction between cement and water, hydration, if water is lost, the strength-gain hydration process stops)
    Good luck.
     
  3. Itchy&Scratchy
    Joined: Jul 2008
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    Itchy&Scratchy Senior Member

    look in the paper for ads entitled 'building contractors'.......

    Have fun
    Itchy
     
  4. TeddyDiver
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    TeddyDiver Gollywobbler

    Make sure not ad too much water in he mortar.. dirt moist is adaquate. Press the mortar in from both sides by "rubbing" it.. then rub more, have a drink and go back rubbing...

    Regards
    Teddy

    ps Don't forget to rub! :D
     
  5. Saylaman
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    Saylaman Junior Member

    I agree with PAR, except I don't think it will be practical to give it a generous 'feather' edge. The mortar usually only covers the mesh by about 2 mm. This is not much thicker than some of the sand particles. It will be very difficult to apply mortar to a feather that is from zero to 2 mm. Even if it was possible to 'feather' the mortar into this section and get it to stick, it would have absolutely no strength since it will be unreinforced and very thin. Unreinforced mortar has no useful tensile strength. I guarantee this feathered edge would crack along the edge of the hole anyway and serve no purpose. Epoxy adheres well to mortar. I think that after the 'patch' has hydrated for a few weeks you can successfully apply some epoxy around the edges to provide a watertight finish. If you try to cut some deep grooves around the patch to 'key' it in, you risk cutting through the outer layers of mesh and causing weakness, since the mesh is so close to the surface.
     
  6. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Can you plaster it with a mix of epoxy and short strand fibers?
     
  7. luckyscott
    Joined: Jan 2010
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    Location: Queensland, Australia

    luckyscott New Member

    Thank you all so much for the advice and very helpfull hints, I have decided to go with getting a professional in to do the repair on the hull as its just in front of the keel and will be below the waterline. I have been told that once the repair is done (properly by a professional) that there should be no worries for many years, you all have been extremely helpfull and i thank you very much. Now i guess its time to start working on the inside and doing that up to liveable standards.
    Cheers and thanks very much everyone
    Scotty
     
  8. troy2000
    Joined: Nov 2009
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    troy2000 Senior Member

    Now you have us curious. We expect pictures and regular updates on your project....:)
     
  9. luckyscott
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    luckyscott New Member

    i would be glad to post pics but its a bit of sight at the moment:) and hopefully i wont bore too many of you with the updates :)
     
  10. masalai
    Joined: Oct 2007
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    masalai masalai

    A work in progress is always interesting, before, during and after images please... Always something new and interesting to learn...
     
  11. Saylaman
    Joined: Dec 2007
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    Saylaman Junior Member

    Some progress pictures sure would be great, even some pics of the boat in general! Do you have any idea how the hole got there? I have spent over 20 years in a concrete technology career. I worked at a concrete institute that had one of the most comprehensive concrete libraries in the world, there were numerous books on building ferro-cement boats. I studied each one. I have since left them, but still have one book they gave me. If you need info on any specific areas, let me know and I can scan some pages for you. I have given up the idea of ferro-cement because I have become passionate about multihulls and the weight of ferro is just out of the question.
     
  12. Steve W
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    Steve W Senior Member

    Par, there is not neccesarily "supposed" to be welded mesh in there,i dont know who the designer of scottys boat is but being in Australia there is a good chance it is a Hartley in which case it is "supposed" to have "cheap" 1/2" x 22 gauge galv chicken mesh", probably 4 layers each side of 5ga hard drawn wire.
    Scotty,if you contact Mr Brookes at the ferroboats website you can probably get step by step instructions ,this is not a difficult job and Par and Saylaman have it pretty much right.
    Steve
     
  13. luckyscott
    Joined: Jan 2010
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    luckyscott New Member

    Thanks for all the help and advice guys:) now i am a little worried that you guys have almost convinced me to try and attack this one myself, and Steve W your right its a Hartley 32 RORC, Saylaman: i am by no means confident with doing this as i have never worked with Ferro before and dont claim to know anything about it other than it is very heavy and very solid :) the hole was chipped away by the previous owner, he was trying to remove a small rust bleed and ended up going too far with it and left a rather large hole for me to repair. I am in two minds whether or not to attempt this one by myself or to just get someone in that knows what they are doing. Pictures will be up in the next few days guys, thanks very much again, I must say i am pretty amazed at the interest that has been shown, you guys must have salt running through your veins.
    Cheers again
    Scotty
     
  14. Steve W
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    Steve W Senior Member

    Scotty,i built a modified RORC 39 about 38 years ago,so i am very familiar with them,the 32 is a good boat,one of them did a nonstop circumnavigation back in the early 80s and held the record for a short time until Dodge Morgan broke it. One of the nice things about ferro is the relative ease of repair,like i said,contact Colin Brookes in NZ and he will be able to point you in the right direction as to doing the repair yourself or if you get cold feet and hire someone to do it you will be able to discuss the procedure with him first and determine if he really does know what he is doing.Im looking forward to pictures.
    Steve.
     

  15. Saylaman
    Joined: Dec 2007
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    Saylaman Junior Member

    I think it is the kind of job you can easily tackle yourself. If there is rust it would be a good idea to passify the rust and clean any chloride off before making repairs. Concrete admixture companies like Sika, Grace or MBT would probably have an off-the-shelf product for you. Good luck. The RORC 32 was one of the ferro boats that made the greatest impression on me. Looking forward to pics and progress reports.
     
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