pulling a boat from a mold

Discussion in 'Fiberglass and Composite Boat Building' started by brokensheer, Jun 30, 2010.

  1. brokensheer
    Joined: Jun 2009
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    brokensheer Senior Member

    I have one of my 23' hulls ready to be pulled from the mold. what is your preferred way to connect to the hull to do so In the past I have glassed glass roll tubes between the stringers and so on , what do you do?
     
  2. anthony goodson
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    anthony goodson Senior Member

    Float it out
     
  3. brokensheer
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    brokensheer Senior Member

    I still need to pick it up out of the mold or am I missing something?
     
  4. Greybarn
    Joined: Apr 2006
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    Greybarn Junior Member

    There are a few ways to do it. Depending on the size of the part, you can 1) Glue on (with something like Plexus) a piece of hard glass that has a hole for a shackle and then use an overhead crane to pull it out; 2) Use a plastic wedge to get under one edge and then pry it out; 3) laminate the ends of a loop of unidrectional onto the part (leave the middle with out resin) and the loop onto the dry fabric with a rope and then pull it out; or 4) mold an edge onto the outside of the part and pry it out of the mold.
     
  5. anthony goodson
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    anthony goodson Senior Member

    No you are not missing anything ,float it first and then pick it up as you suggested. You didn't mention the water to release it in the first place that's all.
     
  6. brokensheer
    Joined: Jun 2009
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    brokensheer Senior Member

    I got ya,
    Thanks Greybarn and Anthony goodson, I have done a few one offs, I would hate to have the boat fall and damade the mold, I worry too much !
     
  7. CDK
    Joined: Aug 2007
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    CDK retired engineer

    How about a central point in the mold where you drilled a small hole and glassed on a little stud that fits your compressed air gun?
    A garden hose and water is another option, but maybe a bit messy.
     
  8. brokensheer
    Joined: Jun 2009
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    brokensheer Senior Member

    you don't want me to tell you I did drill three holes in the hull but for got to glass in the air fittings prior to gelcoating the mold,, hahaha, WHen I built the mold the plug came out of the mold just fine I am more concerned with what to attatch stuff to, Thanks Bo
     
  9. tunnels

    tunnels Previous Member

    So you have a boat in the mould and want to lift it out ??
    What is inside the hull youve made at this stage ??There should be bulkheads , stringers and even to the point of floors . Its better to pick it up with a part thats been glassed in high up at the gunwhale level .
    If you pick it up low down inside the hull it could and will simply want to fall over and turn turtle , very dangerous .
    Depending on the shape of the gunwhale thats a good place to pick it up from . Once you have the point of balance of course !.
    The more structure you have inside the hull the better it will hold it origanal shape when you lift it into a cradle !!.You can see in one of the pictures where we were at before demoulding and lifting !.
    We were making eight 36 foot match racing boats and the pictures are from what we had set up for this . Note the cradles that were made! The glass shape was taken off the plug to hold the hulls completely stable and straight till they had there decks on , glued and glass bonded and fully finished ready to be lifted onto there keels one after the other .Being match racing boat they has to be a close to the same as each other as was possible to get .
    Picture 8 boats 36 foot fully rigged with everything on and assembles with only a 12 kg variation from the heavyest to the lightest .
     

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  10. apex1

    apex1 Guest

    Float it out as mentioned already.

    And lift it from the lower structures, not from the gunwale! That is usually still a weak point at this stage.

    Engine girders and the collision bulkhead root are the common places to apply the load.

    Regards
    Richard
     
  11. Landlubber
    Joined: Jun 2007
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    Landlubber Senior Member

    "The more structure you have inside the hull the better it will hold it origanal shape when you lift it into a cradle"

    yep, also it helps to keep the shape as designed to start fitting out whilst still in the mould, if you are not in a hurry to get another one started, leave it in there for a while to cure and set up.

    As the hull will weigh bugger all at this stage, bulkheads are excellent lifting points, you may wish to crack it out and then put it back in, just move it enough to separate, that is all that is needed. We use air and water inlets and the O/H crane does the rest.
     
  12. tunnels

    tunnels Previous Member

    Its best to use water to simply float the hull without all the banging and possabilities of marking the mould or the boat with star cracks that are there and hard to see till much later !!.
    Once its floated it best to pick it up with a steel spreader bars on your crane if you have them . As is seen in the one we used a simple bar with adjustable slides that can have a lot of uses not just for one thing .
    Was also used for lifting the deck as well but in a differant configeration of ropes and belts . Because our gunwhale had a complete roll over we got a semi hook shape with a length of pipe to fit snuggly and no possablities of sliding The hull simply got lifted , one person holding it and the mould rolled out from under and the cradle moved in straight away . In the very early stages of the project i got the mould set completely level so at anystage of the manufacture there was no need to do any time consuming set up for any reason . Also the cradles the hulls were set in were made so the hull stayed level right through to the stage of fitting the deck with a lazer mounted on one wall and marks on the floor for the cradle wheels to be locked in possition and nothing changed . Simplicity and ease of assembly are the keys to making life bareable . Just to carry the theam on a little further . The rudder bearing and keel recess was also made fool proof as well ! its was impossible to get anything in the wrong place . the bearing shape was moulded over a aluminium shape sent to us from the French rudder componants manufactures . We got a aluminium shape made for the keel stub made in aluminium as well It polished up beautifly) with 3 dowls fitted ,(one at the forward end and 2 at the after end it also had spring loaded pins where the keel bolts were . These were all set in the moulds and corners coved and waxed and gel coated over and moulded as a part of the hull the hull was foam cored but cores were kept back 75 mm from places like the rudderbearing , keel stub , and where the saildrive fibreglass mounting was fitted inside . by doing our home work and setting all these things right at the begining nothing could be changed and all the keels were interchangeable for any boat all the rudders were interchangable . The thing with Moulding in all these things was there was no place for water to get on any where . The only holes were for the keep bolts and they had nylon seal rings under the washes each side . The first boat got about one cup of water because they hadnt been done up tight properly . :D
     

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  13. brokensheer
    Joined: Jun 2009
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    brokensheer Senior Member

    I have all the stringers and bulkheads installed I plan on once it float to lift it at two or four points using a spreander bar so the lift is vertical and will keep her from listing,, Thanks Folks great info!
     
  14. brokensheer
    Joined: Jun 2009
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    Location: So. Md

    brokensheer Senior Member

    I have to say the garden hose wat the ticket,, I spent a total of 1/2 hour driving wedges at the flange, allowing access for the hose and she popped free,, I am impressed!, on the next hull I will glass in some water fittings,, Thanks Gang!
     

  15. anthony goodson
    Joined: Mar 2007
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    Location: Dorset UK & Murcia Spain

    anthony goodson Senior Member

    That's the nice thing about this forum ,the advice is sometimes worth more than you paid for it.
     
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