Can we use PVC core to build the mold?

Discussion in 'Fiberglass and Composite Boat Building' started by coolgps, Sep 13, 2012.

  1. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    I have found one kind of PVC core, like 100kg/m3. It is made of scrap PVC core pieces. The price is about 1/3 of Balsa, 483USD/m3.
    The compress modulus of Balsa is much higher than PVC core.
    Since i do not quite understand why we always use balsa core for mold, i used to consider price is major factor. Now i found cheap PVC core, so i want to replace balsa with it.
    Can some one tell me it is OK or not. If there is an explanation, it will be very thankful.
     
  2. rwatson
    Joined: Aug 2007
    Posts: 5,875
    Likes: 311, Points: 83, Legacy Rep: 1749
    Location: Tasmania,Australia

    rwatson Senior Member

    You seem to already have identified the answer all by yourself.

    "The compress modulus of Balsa is much higher than PVC core."

    Its the compressive strength that is the biggest factor of cored hulls, so a drop in core compressive levels makes the amount of fiberglass needed to be much higher, therefore more expensive and heavier.
     
  3. tunnels

    tunnels Previous Member

    how big is the mould you are making ?? and what the other materials ??:?:
     
  4. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    I am thinking about using it, not going to apply it on some boat molds.
    If it is going in the mold, the mold laminate should be fiber glass, 300gsm CSM, 450gsm CSM, 2mm core mat, then 3000gsm fabric beneath the core and 3000gsm fabric on the core. CSM and core mat will be done by hand laminate, fabric and core will be done by infusion.
     
  5. tunnels

    tunnels Previous Member

    How big is the mould you making ?? thats one hell of a lot of glass !!!:eek:
     
  6. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    We have made 75ft,60ft mold and are going to make 40ft,46ft mold with this laminate. BUT I always think the mold is too much strong in this laminate.
     
  7. tunnels

    tunnels Previous Member

    Have found over the many years its better to keep the mould to a reasonable lighter thickness and build a good supporting steel frame work on the outside .
    Heavy mould are really and truely a complete waste of materials and time . Do you intend to make a 1000 boats ?? even 100 boats ?? 10 maybe !!!
    What a waste of time and materials !!!:(
    I used to mould a boat that came from a mould that was light and had a strong frame and it had 120 38 foot boats taken out of that mould and was better than when it was first made its was continuously used and never had problems what so ever.
    I can take you and show you light moulds that are 40 years of age with strong steel frames and still as good as the day they were made .
    The amount of glass used to make the mould has very little to do with how long it will last . :(
    Dont waste your time and money its not worth it !!
    In two years the boat will be out of date anyway and will have to start all over again . !!!
    Have been in the glassing industry for over 40 years and a few countries and theres mould every where you go !! They are all dead dreams that some one had long ago . :eek:
     
  8. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    HAHAHA, this is what happened, but the mould was built in this way when i joined this company, it is now kind of conventional way to build a mould here. I always think those moulds were built for anti-missile :rolleyes:

    Can't help you about the job, i am just a technical guy here, not right to call in some one.
     
  9. tunnels

    tunnels Previous Member

    Truly making moulds in this present state of play with the reccession on our doorstep you got to be crazy for a start off !!! or got to much money !! Its never going to get any better than it is not for some time anyway . What kind of boats they want to make ?? power boats or yachts with mast and sails ?? either is a waste . There are overseas companies that could and would fill any order just sitting with boats in there yards already to go .If you only intend to make a very few boat then do what we just done and make a wooden mould and line the inside and that way these guys could keep plucking boats out for the next 5 years and have a mould thats just wood and because they made a pretty nice job its fair and will need a minimum of work to bring it to the standards of a glass mould .Its 90 plus feet long the one we doing hull deck and flybridge and all done in a short time . Unless you have firm orders with deposit money paid you are playing with yourslf . boats in the size range you quoating are long term to make and have ready for the water specially the bigger ones so if the mould ever go 5 boats made out of them that would be well and truely out of date in a couple of years . Like i said there are moulds all over the world doe all sized boats ! in nz there farms with old big boat moulds sitting in field and under trees and behind sheds up and down the country some of those mould could have a bill of close to a million dollars to make plugs and moulds and possibly only ever had 2 or 3 boats taken out .
    A boat designer /builder had the right idea of making a boat over a wooden plug and using that boat as the mould and we made 6 boats moulding inside it!! the boat had a steel frame outside and when we had finished the 6 th boat the steel fame was taken off and the mould that was really a boat was finished off and sold . Only ever cost the price of the steel frame and that could be used for scrap and no wasted glass and what ever makeing a mould .you have to make a plug so make a wooden former with batterns ,foam and glass the outside then off with a steel frame and finish the inside and theres your mould when orders are done ,the last boat gets turned back into a boat Power boat or yacht what ever !! The old moulds people have tried to us the mould as a boat but its never worked . Wrong glass and way to heavy !!
     
  10. tunnels

    tunnels Previous Member

    So no one really has any idea what they doing ?
    Here thats the normal way of things no one really has any idea what side is the outside .
    This company not one single person here is interested in boats big or small !!not one !! trying to strick up a conversation to do with boats is impossible no one is interested and no one knows anything .
    oops sorry the pointy end always faces the doorway so it is the front and the other end is where the stern drive goes so must be the back . :eek:
     
  11. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    You analysis is quite right. A strong mould can't be wrong in quality, although we know it wrongs in money. But the people here have a different thought, what if you built a less strong mould, maybe you will have some problems, then you are in trouble. So you make a strong mould that keep yourself out of trouble.
    Kind of political here, spend more boss's money to keep myself good is always the best way here.
     
  12. tunnels

    tunnels Previous Member

    Not really simply they dont know and dont understand . there are so many big mould laying idle in every country ive been to . Unless they are working with a boat inside they are a libility , and in times of reccession like now the are money down the drain because no one wants them !!Where i work now we have a whole shed filled with moulds all old all out of date , all a complete waste of money !!!
     
  13. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    Same here, bunches of idle mould, some even stay at beach, waiting for UV degrading them.
     
  14. tunnels

    tunnels Previous Member

    so why make more to add to the collection ?? :confused:
     

  15. coolgps
    Joined: Jun 2012
    Posts: 53
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Xiamen

    coolgps Junior Member

    We always have new boats to build, so we have to make more. Sometimes after we made the mould, my boss stopped the cooperation with the company gave our boat order.
     
Loading...
Similar Threads
  1. BOWTIE
    Replies:
    0
    Views:
    1,469
  2. Mark C. Schreiter
    Replies:
    12
    Views:
    2,250
  3. Mowgli
    Replies:
    32
    Views:
    559
  4. SummerSchool
    Replies:
    5
    Views:
    454
  5. Bzidro
    Replies:
    7
    Views:
    1,684
  6. jjhamm22
    Replies:
    8
    Views:
    3,338
  7. guzzis3
    Replies:
    26
    Views:
    4,587
  8. mojounwin
    Replies:
    8
    Views:
    4,813
  9. DennisRB
    Replies:
    7
    Views:
    3,994
  10. captndon
    Replies:
    17
    Views:
    11,453
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.