Redoing mold

Discussion in 'Fiberglass and Composite Boat Building' started by barnaclebill, Aug 1, 2010.

  1. barnaclebill
    Joined: Aug 2010
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    Location: new jersey

    barnaclebill New Member

    New member here. I have been in the marine industry since 1986. Worked in the family dealership and took it over in 1996. We have always focused on Johnson and Evinrude outboards and never and I mean never did any figerglass work.

    Now I had someone give me a old mold for a 16' boat. I know nothing about boat buliding but will try anything once. I am redoing the outside supports first before I tackle redoing the inside of the mold. I am told the more time I spend on the mold itself, the less time I will spend on the finished product that comes out of the mold. The oitside I am om ok with redoing but the inside and the actual lay up is another thing. I will be asking alot of questions along the way. In return I will be happy to help out anyone that has any Johnson or Evinrude outboard questions.

    Here are a few pics of what I have.
     

    Attached Files:

  2. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Is this going to be a one time boat build, or do you plan on building many of them? The reason is because if you only plan to make one boat the work done to the mold will be different and less extensive than if you plan to stay in production with it.
     
  3. tunnels

    tunnels Previous Member

    Re vitalizing an old mould !!

    Ok lets start with what you have done already!!
    Without seeing or knowing the thickness of the mould be very carefull when glassing on the frame that you have made , Do not have quick brews of resin for the glassing as the nice surface you thought you had could end up with pull marks and go wavey from the new glass .
    Has the mould had water sitting in it for a long period of time ??
    If so there a possability it could have contracted osmosis and maybe have small lumps on the gel coat surface . Now be careful these will shrink back to there origanal smooth surface if you are able to gradually dry them out . If you go ahead and sand them flat then as they dry and shrink you will end up with dimples (hollows ) and back to sanding again and the possability of sand through the surface to the glass fibres behind and then you have even more problems !!
    Like i said leave them and let them shrink back on there own !!. The orange will be tooling gel so its going to take some careful sanding . I would be using a small circular random orbital sander electric or air driven and starting with 320 grit for a quick get rid of the grap off the surface sand , then if all is clean and sweet move on to 600 grit and spend some time with that to get the surface smooth ,then on to 800 grit and 1200 grit wet sanding with a little dish washing liquid in the water !!
    The soap helps to degrease and dewax the surface as you are sanding !
    The main areas would be the sides of the hull just round the chine and a good way down the bow and the transom . These areas are the ones seen the most so if the bottom hasnt got a 110% good shine its not so critical .
    Buff and polish to the finish you want .
    Use a good brand mould release wax and Wax the mould at least 6 times with a good hour or more between coats of wax Just let one person do it and it will be a continuous job !!wax on wax off and shine!!
    For the first 2 boats i would also spray a very fine coat of Pva release agent over the whole mould and let it dry just before the gel coat goes on .
    To get the hull out of the mould release just the flange and use water to float it out very gently .
    No banging and thumping just nice and easy with the old mould !!!
    It will have spent who know how long outside in the weather somewhwere and the resin and the gel will be quite brittle so hitting the mould and or the finished boat is not a good thing to do ,you could get a lot of star cracks appear and they gradually get worse the more the mould is used. For the second boat wipe the mould dry , then another light but well rubbed coat of wax and spray another light coat of Pva again , the 3rd boat you should not need to pva just a light wax . Most repaired moulds its best to re break them in again with but with Caution !!. A light well rubbed wax each time should give you a product that will come out of the old mould nicely the way i discribed using water !!
    Treat it with respect and reap the rewards of your carefull work !!. :D
    Have you soursed materials and a laminate for it yet ? What about the deck and the interior and transom has any thought gone in that dirrection yet ??
     
  4. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    Welcome.

    You were told correctly. I had a kit car mold once with a spot that wouldn't polish as shiny as the rest. Sure enough, the bodies had the same dull spot, but at least the bodies would polish up.

    Make sure you're keeping the mold perfectly square as you reinforce it on the outside. As far as the inside goes, you can't "repair" a mold--you can only "patch" it. The gel coat should originally have been about 18 mils thick, so you have a little room for sanding and polishing. If it's just dull, buy an entire pack of 220, 320, 400, and 600 wet-and-dry sandpaper. Wet sand BY HAND with the 220 and 320; with the 400 and 600 you can use an air-powered pad sander. Follow with polishing compound until it's like a mirror.

    If you go through the gelcoat, you can patch it, but keep an eye on the parts that come out of the mold. I've seen entire molds resprayed, sanded, and polished. I've also seen "second-generation" molds where a part was pulled (usually from a pretty tired mold), then prepped, then a second mold made.

    EDIT:
    Or, y'know, do what Tunnels said. I get the impression he's had his hands on more sandpaper, and in more rubber gloves, than I have. Well, maybe not MORE...
     
    Last edited: Aug 1, 2010
  5. tunnels

    tunnels Previous Member

    Almost forgot !
    When you lay up the hull make sure the mould is level across at both ends!!Once you put in the floors and other stuff inside and its all glassed in place if theres a twist its there for life and no amount of magic wand waving is going to get it straight again . !! A glass boat is like a square plastic container without a lid !!once the lid is put on suddenly it is ridged and stuff !!:p
     
  6. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    It's a good thing barnaclebill has both of us advising him. See my previous post, second paragraph.
     
  7. tunnels

    tunnels Previous Member

    Yeah you just reminded me !!
    Its looking a little way into the future mind you !!

    I made Tunnel boats a while back and it was one of the big problems the company had was not getting a twist in the hull/boats !!

    Last big important job we used to keep the hulls in special cradles and use a lazer at each end to get everything absolutly 99.999% aligned and straight and level .

    :D
     
  8. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Does Barnaclebill also have the top mould? Or is there no top mould?

    If you want to pop just a couple of boats, why bother with the outside of the mould? It looks used, but not too bad? Is the structure compromised?

    As for the inside, there are many different sandpapers on the market, I like the Mirka stuff (Abranet, Autonet and Abralon). But basicly it is all the same system: clean up, sand (depending on the surface quality begin with 400, 600 or even 1000) and go through the sequence untill you have reached the highest number. (for Abralon this is 4000). Then polish. There are many polishing systems.

    This will, if the mould is not too bad, make for a very nice inside.
     
  9. barnaclebill
    Joined: Aug 2010
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    Location: new jersey

    barnaclebill New Member

    Thanks for all the replys. Have not done any work to it as been busy with paying jobs.

    There is no top mold deck. I found out it was called a Bayrunner and was made on and off from apox 1973 to the late 80's. It was offererd with three bench seats or a small center consel.

    Yes there is some blisters. I was gonna sand them but maybe I will wait to see if they do shrink back down.

    Im just looking to pop out about 5 boats a year during the slow times to help keep us busy with something to do.

    I know the outside was probley fine for what I am doing but I just dont like the looks of old supports. I think I have a form of OCD.

    I will try anything once and its something I always wanted to try. If I find out its not my thing then I will store the mold and when my kids get older maybe they will want to play with it. I will store it the proper way and not just sitting sideways outside.
     
  10. tunnels

    tunnels Previous Member

    The blisters !!! What you can do is get a very small drill bit and just break the gel coat on one of the blisters to see if water comes out of it and how much !!
    The sun is a good way to dry the blisters !! The color of the mould will draw the heat and make the moisture come out as it expands . The water thats behind and pushing out could be between the layers of glass rather than just between the gelcoat and the glass. If the mould was made of E matt csm the moisture gets into the fibres via the binder that holds the bundles of glass fibres and causes the water to travel along its length and so gets into the glass layer . :confused:

    If possible let nature do its thing and save doing lots a small repairs .

    Would be nice to find some pictures or a old boat and see what the origanal deck consisted of ,Or simply make a complete new deck from mdf board and skin with glass and paint etc etc eand make a mould off it .
    Hulls over the years dont change that much its mainly decks and interiors , motor wells etc .
    Keep in touch with what thought s you might have ,we are all here to lend a hand !!
     
  11. Herman
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    Herman Senior Member

    This boat might not have a deck mould at all, just rolled with topcoat inside, and some benches and a console mounted. The bottom will probably have some core inside, to reduce flex.

    If you plan on storing the mould, do yourself a favour, and put at least a layer of gelcoat, and a layer of mat in the mould. This will protect the mould surface from many mishaps (moulds are great to store other stuff in...) and water.

    Whenever you feel like it, you can either laminate a boat on that first layers, or pop it out, and then you have a perfect mould which does not need any rework, with only a minimum of effort.
     
  12. tunnels

    tunnels Previous Member

    Hi
    After a closer look at the gunwhale yes it has had a deck on it , It would have been there to strengthen up the side and stop it from going in and out !!
    Its also had a internal floor that could have sat on the step in the side of the hull closest to the bottom ! The roll over gunwhale would have had a side decks about 4 to 6 inchs wide and gone down inside a ways in places like the rear and up near the front may have even had a set up at the front with a small fore deck . The shape of the hull lends its self to being a nice wee boat if modernised . Because of its potentual for speed and fishing i would do a solid glass lay up for the whole boat but a internal frame with storage down the centre plus a couple of stringers . The centre could also have a underfloor fuel tank but a place for and aft of the tank for ropes and all sorts of stuff . Have you any idea of the motor you would put on the back ?? How big is this boat anyway ?? :confused:
     
  13. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    It looks like a typical rolled gunwale boat, no deck mold is used with this type. The floor (if it has one) is just set on the hull, with few, if any stringers, just foam under it isn't unusual. Seats can be just about anything you want, bench, pedestal, or none.

    The interior seats, platform, storage compartments, etc, can be fabricated with plywood and glassed over (OK), fiberglass flat stock (better), or molds made for each part (best), this makes it easy to customize the layout for however the boat is going to be used.
     
  14. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    I believe there is also generic seats, consoles etc available. Or ask any manufacturer for some parts.
     

  15. hyboats
    Joined: Jun 2010
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    Location: Sydney

    hyboats Junior Member

    Engine question

    Why now X shaft engines are more and more popular ?
    :p yersterday my friend asked me this
     
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