what makes a boat mould?

Discussion in 'Boatbuilding' started by whacker82, Jan 18, 2012.

  1. whacker82
    Joined: Sep 2011
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    Location: ireland

    whacker82 Senior Member

    just wondering about boat moulds, what are they made out of, is it some form of plastic material. and if i wanted to make my own boat mould how would i go about doing it, thanks in advance people
     
  2. DavidJ
    Joined: Jun 2004
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    Location: Canada

    DavidJ Senior Member

    I assume you mean a female mould for producing fibreglass parts. They are made out of fibreglass in much the same way the boat will be made. They are usually a substantially heavier layup and it's very rare for them to be made with high tech expensive resins or fabrics, but it is fibreglass just the same. They will also require external support and bracing which also can be made out of fibreglass or metal or wood.

    As far as how to make one there has to be tons of info on this on the net as well as good books on the subject.

    The simplest answer is:
    1) build a plug - this is an exact copy of the exterior surface of what you want the final product to be. It can be made out of anything. Foam, wood, anything. It's finished surface should be absolutely perfect. Sprayed and sanded to perfection. Any blemish here will transfer to every single part you make in the future. So fix the blemish now or fix it every time you make a part.

    2) think about how you will remove the plug from your new mould and plan your mold build strategy. Will the part require multiple moulds to get it to release? Can you just pull it straight out of one mould? Will the mould supporting structure need to be rotated?

    3) coat the plug in a release agent (wax or special chemicals)

    4) apply special mould making gelcoat to the plug

    5) apply many many layers of fibreglass over the plug to build a strong mould using best practices for doing so.

    6) build and attach supporting structure for the mould to ensure it's stiffness and allow for easier access and handling. This structure can be quite simple or sophisticated depending on the needs.

    7) remove your plug from the new mould

    8) coat your new mould with release agent

    9) spray in your pretty gelcoat

    10) apply layers of FRP as specified in your design

    11) add stringers, frames, and other internal structure and laminate them accordingly

    12) grind/sand the inside of the new boat to remove roughness

    13) spray the inside of the new boat with a waxed air dry gelcoat to give it a finished look

    14) remove your new hull from the mould and proceed to fit out.

    As you can probably tell it really isn't worth it to go the plug/mold/boat route if you are only doing a one off as you basically have to build the boat three times. Other construction methods like cold moulding are usually preferred.
     
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  3. whacker82
    Joined: Sep 2011
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    Location: ireland

    whacker82 Senior Member

    Thanks for getting back to me. When you say cold mouldind is this a new or second hand mould which just needs the boat itself to be build inside the mould? ALso if I was to have the female mould itself and I wanted to start producing boats from this mould, how do I know what weigh fibreglass would I use, how many layers or thickness should the boat be once its taken from the female mould. Is there a set thickness for European law, etc? I have been looking a long time over the internet and on YouTube for these answers but could never find them.
     
  4. DavidJ
    Joined: Jun 2004
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    Location: Canada

    DavidJ Senior Member

    Each question is more and more complicated than the last.

    If you had a second hand mould you would start your build process from number 8 in my list.

    Asking how much glass to use is like asking how many 2 x 4's do I need to build a house. The designer or engineer will specify how much glass to use. Like a house design it is determined from experience and construction standards. In general a longer unsupported span or an area experiencing more stress will require more glass. It can take several hours for a small boat to many weeks for a large ship to determine these thickness. These standards are called scantlings and you will find lots of discussion about the different ones on these forums. Check in the class society section.

    Some to look at are:
    American Bureau of Shipping (ABS):
    http://www.eagle.org/eagleExternalP...l=abs_eagle_portal_rules_guides_download_page

    Lloyd's Register:
    http://www.lr.org

    bureau veritas:
    http://www.bureauveritas.com

    ABYC, Transport Canada, Coast guard and numerous others also provide some form of construction guidance. And there are infinite rules of thumb or empirical methods as well. We could really discuss this aspect forever. The simple answer is to follow the plans. If you don't have plans then talk to a designer. If it is a simple canoe or something similar that you can design yourself then read all you can and compare your ideas to what everyone else is doing.

    Cold moulded is an epoxy fibreglass wood boat. Thin layers of wood veneer are applied over a male frame-work (mould) and sealed with epoxy and fibreglass. There are thousands of ways to build a boat. It is just one of them.

    The book "Gougeon Brothers on Boat Construction" is a standard reference for wood epoxy construction and they detail several methods.

    The following book is a good introduction to composite materials. It is presented in an easy to read style. It doesn't tell you how to actually build anything but it lays out the process very clearly:
    http://www.amazon.ca/Fiberglass-Oth...=sr_1_2?s=books&ie=UTF8&qid=1326931732&sr=1-2
     
  5. tunnels

    tunnels Previous Member

    wow you need to go visit a glass shop some where and stand and watch for a whole day just to breath the styrene and get high on building boats .
    Glass boats come in every colour of the rainbow , there glass layup an be dead simple or as complicated beyond imagination but at the end its still just a boat and they will all look the same !!.
    Why all the hype ? well everyone has they own apinion of how the job should be done . Knowing what the boat will be used for and what is exspected of it is a good starting point that you work back from as to how you would build the thing!!If you ask one simple question you will end up with 100 answers to every question and all work in varying degrees of success depending on the products you end up using !. What ever part of ireland you are in there must be a city or big town that possibly has some one building boats from glass , pay them a visit and ask questions . Do some leg work first !!:p
    .Youre not close to Sligo by any chance are you ??
     

  6. whacker82
    Joined: Sep 2011
    Posts: 146
    Likes: 2, Points: 18, Legacy Rep: 33
    Location: ireland

    whacker82 Senior Member

    i know ive got so many questions to ask, these questions have been bugging me along time, im achually doing a wooden boat building course early next month and its for ten weeks so ill be able to ask all the questions i need there, hopefully i will come out of the course with the basic knowledge of wooden boat building and glass boat building, im from charleville co cork tunnels, i must look into it surely up in cork there are glass boat builders. 11811 will be able to give me a few numbers.
     
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