boat stuck in mould

Discussion in 'Fiberglass and Composite Boat Building' started by whacker82, May 25, 2012.

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  1. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    Whacker,
    The pictures you provided earlier of the damaged areas do show pre-existing bumps and scratches in the mold, so sanding the whole mold surface is warranted. As I said before this mold doesn't look to be of the best quality, so if things go well for your business this summer think about pulling a mold at the end of the season.

    When your supplier mentioned not using PVA he did so for good reason since the mold release wax he provided has silicone as part of it's formula. Your best bet is to switch to a carnuba based mold wax which will allow you to use PVA at least for the first five or six hulls. This will season and cure your wax layers to the point where eventually that's all you'll need.

    Of course the quality of the mold surface will dictate when or if that's practical or even possible. The more work you do now to insure a perfectly defect free mold surface will pay dividends for as long as you use this mold. Just take your time...go slow...and don't let the smallest pinhole get past you. After this experience you'll become a full fledged member of the glass fraternaty..sore arms and backs are required...lol.

    MM
     
  2. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    Even though the crack is sanded smooth, it is still there, and as the mold is stressed the crack will open and close. After a part or so the cracks will begin to form a ridge again, this is from a polystyrene build up (commonly referred to as wax build up) and you will be right back to where you were.

    Cracks need to be sanded out and repaired completely for them to not return.
     
  3. tunnels

    tunnels Previous Member

    you got it 100% right !! star cracks are real easy to make but terrible things to repair! the crack is the complete deepth of the gelcoat so the gelcoat has to be ground off !!! (Need to also check that the surface of the glass is not cracked as well !!) for the full size of the star which i some cases can be quite big in size!! like 100mm is just a hammer blow size so get 2 or 3 close together and you have a sizable patch , The gel right to the glass needs to go !!! so its no easly quick fix . A black marker pen and some acetone on a rag and wipe it across will reveil if theres still any cracks as the ink gets into the crack and make it stand out and easy to see !!. :mad:
     
  4. whacker82
    Joined: Sep 2011
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    Location: ireland

    whacker82 Senior Member

    ive ordered the new materials for making a boat today, and dunno what just dawned on me, why didnt i keep the boat and cut the mold away from the boat, i would have had two boats and a perfect star crack free hull, to make a new mold from.
     
  5. tunnels

    tunnels Previous Member

    So true !

    Get out of the present mould what you can and come winter then do your rebuilding and re modelomg etc etc .
    So where you at at this very moment in time??
    whats you next move ??
    :confused:

    Its been one hell of a good learning excise not only for yourself but lots other's as well !!, i hope you will sit one day and re read some of the info thats been posted by many people .
     
  6. whacker82
    Joined: Sep 2011
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    whacker82 Senior Member

    well im still sanding ive no fingerprints left in my finger tips, im sanding the stem at the moment, there was a lot of building up to be done there, most of the damage was done here. once that is done ill sand the entire mold starting from 800 grit up to 2000. that should be tomorrow, i should get the material either tomorrow or wed, so what ive decided to do is start waxing the places where the boat got stuck, and when the material arrives lay up these areas, and hopefully all going well it will release easy. and if it dose ill get cracking on making a whole boat and everything should be fine.
    its not been easy but its been some learning curve and im learning a lot that id prob never would have learned if the boat released the second time.
     
  7. tunnels

    tunnels Previous Member

    yip been there done that like most people on this site. at some time will have sanded to that point get a pair of tight fitting rubber cloves and cut the fingers off and slide then on you fingers . here i have never seen before but can buy just the finger tips by the thousand .
    2000 is pretty much a waste of time !! i never go past 1200 and them buff with a sponge pad and medium compound medium will do everything you will need . Really glossy looks terrible and sows every mark there is and more even a semi gloss is much better ans show less imperfections . china i hooked on shine and gloss and the boats look pretty!! even finger prints show up ,
    Here a big boat is a status symble all shine a glitter . doesnt matter if they have not got the faintest idea how to drive it , poncing about pushing mountainous bow waves !!, trim tabs that never get used and if they do get over the hump the backside is so deep the water tumbles up onto the boarding platform . :confused:
     
  8. midnitmike
    Joined: Apr 2012
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    Location: Haines and Juneau

    midnitmike Senior Member

    Whacker,
    Keeping the mold or the boat intact was a choice you had to make pretty early on without too much information on which might be the better option. Molds are usually more valuable considering the time and material that goes into one, and the part that's stuck is replacable.



    I feel for you...sanding in a mold is a laborious process, and there aren't many shortcuts that I'm aware of. Hardwood sanding blocks help save on the fingers but they have their limitations on curved surfaces. I often use foam sanding blocks (sold for sanding sheetrock) to get in the corners, curves, or radius and wrap a piece of sandpaper around them for the different grits I need. Having done this more then once I still think I prefer working on the male plug (boat hull) more then the female mold...they are in my opinion easier to fair especially in areas like the stem where you're working.

    I'm not sure doing partial layups is advisable...they might seem like a good idea at the moment, but in the end you're just wasting time and material that can be put to better use. I know there's a temptation to see if all your hard work is paying off, but stick to your plan and finish the whole thing at once.

    As the mold surface get's closer to the finished stage your inspection level for defects has to also increase...if you can feel "anything" with what's left of your finger tips...that's a defect. If you can see anything with the naked eye under various angles of sunlight...that's a defect. If the sun has gone down and you're still working, then worklights can help to cast shadows and show up something you might have otherwise missed. I also use magnifiers to help me spot problem areas that I couldn't see or feel. No defect is too small to ignore...if you do...well you'll have a problem.

    Once you're satisfied that you've done everything possible to get that mold in shape...you're almost there. A good waxing goes a long way to making your project a complete success, and this is where you have to practice all those Zen like qualities you've picked up by sanding. Force yourself to apply just one coat of wax per day for a week..that's right a whole week. If the conditions are right you might do two coats a day...one in the morning, and one at the end of the day. If you feel like you're wasting time, and you want to do more, then practice spraying PVA on something and pull samples from that. Since you're going to want to use PVA on your first pull now's the time to get aquainted with the stuff. You can try brushing, wiping, and spraying to see what method you prefer. Once you're happy with your application method and your mold has had that week of waxing you're ready to move on.

    I know how tempting it is to just forge ahead and start pulling parts from that mold as quickly as possible...just remind yourself how much work you've had to do to repair this mold. It's not worth it!

    MM
     
  9. whacker82
    Joined: Sep 2011
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    whacker82 Senior Member

    im going to pass on the pva, as was advised by the supplier, i cant find any of the silicone free wax anywhere. the supplier was addament that there was no need for it, as the wax they supply has all the additives to eleminate pva.
    im going over it and over it and keep spotting the odd dimple that i had missed so my sence of detail is at its highest now since im this close.
    ill take your advice on doing one coat a day be no harm lot of work gone in now.
    but im going lay up glass where the damage was caused, if another boat gets stuck im gone under, so its not going to be worth the risk. i need to know to save me from worrying.
     
  10. variverrunner
    Joined: Dec 2009
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    Location: New York, USA

    variverrunner Junior Member


    Whacker,

    What do you mean "im going lay up glass where the damage was caused"?


    Please look harder for the silicone free wax and use PVA. You will be doing yourself a huge favor. IMHO.

    Allan
     
  11. whacker82
    Joined: Sep 2011
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    whacker82 Senior Member

    the boat got stuck in one of the stringers and where the stem meets the keel so im going to lay up these two areas like i was doing a boat, wax it, gel coat it, and glass it. if it pulls away easily i know im in the green to start a new boat.
     
  12. variverrunner
    Joined: Dec 2009
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    Location: New York, USA

    variverrunner Junior Member


    Whacker, sounds like a pretty plan.

    You will probably find that you will need to redo some prep work around your test area, but having more information about the release will be worth it, IMHO.


    If I was you, I would lay the same amount of glass as you will in your actual boat.


    I could look into shipping you some Wax from the States, if that would be helpful. You might ask Herman where to find it on your side of the Pond.


    Good Luck!

    Allan
     
  13. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    The correct method is to just spray (brush) the entire thing with gel coat and then pull it, this will let you know if it sticks anywhere, and if it does you just need to sand down a few spots of gel coat. This results in no damage if it sticks.
     
  14. variverrunner
    Joined: Dec 2009
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    Location: New York, USA

    variverrunner Junior Member


    Ondarvr,


    Wont the gel coat flex and release easier in areas of minimal draft, than it would in the actual fully laid up boat?


    Allan
     

  15. whacker82
    Joined: Sep 2011
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    Location: ireland

    whacker82 Senior Member

    is this it??

    [​IMG]
    Honey Wax is a unique, high gloss paste wax for use by the reinforced fibreglass molder as a mold release agent. It is compounded with the purest grade carnauba wax, plus special binders and spreading agents. Honey Wax creates a durable wax surface that remains intact for multiple pulls. Honey Wax reduces man hours due to its exceptional ease of application and buffing. It is an excellent mold release agent providing reproducibility, glossiness, and a hard releasing film which are important to the fabricator. It is easier to apply than other processed waxes; the residual film is also more durable and resistant to abrasion.
     
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