Bay boat hybrid hull design

Discussion in 'Boat Design' started by PBC, Aug 17, 2020.

  1. PBC
    Joined: Aug 2020
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    Location: South Africa

    PBC Junior Member

    Plug sanded and buffed. 220-320-400-600-800-1000-1200-1500-2000 and the then buffed with a cutting compound. Busy applying 7 coats of wax.
     

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  2. ondarvr
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    Location: Monroe WA

    ondarvr Senior Member

    It's looking good
     
  3. PBC
    Joined: Aug 2020
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    Location: South Africa

    PBC Junior Member

    Thanks !
     
  4. PBC
    Joined: Aug 2020
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    Location: South Africa

    PBC Junior Member

    Update on the project. We applied 8 coats of wax and then a “mist coat “ of PVA as per Tunnels instructions. Mold released nicely and it looks like we have a good finish. Currently busy with the deck plug. Sprayed it with Duratec vinyl ester top coat - currently busy sanding from 120 to 2000 grit. Previously we had no problems with micro ballon epoxy and Duratec- but it created issues on a few places on deck. Used epoxy primer and that sorted the problem C46F1FEC-9047-4AB3-9005-5D589519FAA5.jpeg F43B5F51-8A33-4C12-9923-8300C173FB9E.jpeg 9C79DE18-76D4-4BB1-9C00-65AB8B5143FE.jpeg C46F1FEC-9047-4AB3-9005-5D589519FAA5.jpeg F43B5F51-8A33-4C12-9923-8300C173FB9E.jpeg 9C79DE18-76D4-4BB1-9C00-65AB8B5143FE.jpeg 7F456FB6-99C1-4B32-8436-2D4CB9E7ABDB.jpeg 8AE45F88-896B-400B-A5DE-190BD7929FFC.jpeg 5542951C-9910-4076-84CD-DD90CEBE05F6.jpeg EAEA90A5-5496-4761-BF7D-0BBFF2658B99.jpeg D35DB42A-7BCE-45EE-97F0-7C58FA9FC2CC.jpeg 7F456FB6-99C1-4B32-8436-2D4CB9E7ABDB.jpeg 8AE45F88-896B-400B-A5DE-190BD7929FFC.jpeg 5542951C-9910-4076-84CD-DD90CEBE05F6.jpeg EAEA90A5-5496-4761-BF7D-0BBFF2658B99.jpeg
     
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  5. PBC
    Joined: Aug 2020
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    Location: South Africa

    PBC Junior Member

    Hi Ondarvr,
    What would you recommend in terms of a print blocker. I am looking for an excellent finish- Advice here is to avoid a barrier coat due to delamination problems- and only do a skin coat, but I see you recommend a barrier coat on this forum. What product would you recommend? Should probably add- our boats are beach launched and take pounding so I need to avoid anything that has potential to crack.
    We have not finalized the laminate yet but currently the following is being considered:
    Hull will be infused with Vinyl Ester -Dion 9133 that is being modified for infusion (waiting for lab to confirm)
    Skin:
    Gelcoat
    Tissue
    1 x300g csm
    1 x 450 g csm
    Vinyl ester filler for chines
    Infuse:( hull bottom)
    1x light cloth
    4 x 850 g quad
    Thanks - your inputs are greatly appreciated.
     
  6. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    VE barrier coats work well, but you have a veil (tissue) already, which can do a great job. There are filled and compromised barrier coats that can fail when stressed.

    Infusion always complicates getting a great surface profile.

    The skin coat VE needs to be formulated to cure well in a thin laminate, most VEs don't.

    Many VE skin resins are blended with DCPD or ISO resin to improve thin laminate cure. DCPD doesn't shrink as much, so that helps too.

    If the VE skin isn't cured well before you infuse, the exotherm of the infusion laminate will create print on the surface of the part.

    The cloth in the infusion laminate is probably of no value. (That's only if we're referring to the same material)
     
  7. PBC
    Joined: Aug 2020
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    Location: South Africa

    PBC Junior Member

    Thank you!
    I will talk to supplier about a suitable resin for skin coat.
    Are you suggesting that I focus on the skin coat cure(resin type and make it slightly thicker)and leave out the barrier coat or should I do both?
    Can you define well cured for me - I can control temperature between 18 and 45 degrees Celsius . 24 hours at 30 degrees be ok ? I would need to balance this with getting a good bond between skin and infused laminate .
    I have access to Reichhold, Duratec and Scott Bader any of their products you would recommend for barrier coat ?
    Much appreciated !
     
  8. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    The combination of products and techniques are determined by the surface finish you desire.

    The typical conversation with a builder starts with them saying they want the best finish possible.

    I have them make multiple test panels with different products and techniques and then choose the finish that meets their expectations.

    Rarely do they choose the best panel.

    You can get to 85 or 90% of a fantastic finish without spending a great deal of time and money, but that last 15% can cost a fortune.

    Make panels with and without a barrier coat, plus variations in the skin coat thickness.

    Sometimes it's easier to use a barrier coat, or the barrier coat may serve multiple purposes. Many builders opt for the barrier coat instead of a VE skin coat. You can use a lower cost resin and the VE barrier coat supplies the needed water resistance. These lower cost resins typically shrink less, so print may be less of an issue.

    A barrier coat can also bury any small air bubbles deeper in the laminate so they don't have a chance to show themselves later.

    Others use a skin coat, and then some use both for added insurance that there won't be problems.

    VE resins tend to have a sluggish cure compared to other types of resin, so a VE skin resin is formulated a bit different so it will cure more thoroughly in a thin laminate. This can make the exotherm temperature higher, making it only good for thinner laminates like a skin, not for building up any bulk.
     
    Last edited: Jul 8, 2021
  9. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    I'll add that builders will frequently try to use the same resin for a bulk laminate and the skin coat.

    This works fine when using VE if cosmetics and surface profile aren't a concern.

    When a very good surface profile becomes a goal, the entire laminate schedule, production methods, and techniques come into play, along with much greater attention to detail.
     

  10. PBC
    Joined: Aug 2020
    Posts: 23
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    Location: South Africa

    PBC Junior Member

    Hi,
    Thanks -
    The intention is to build a high quality product- surface quality takes priority over resin cost. And I am committed to infusion.As a starting point the boat will be a minimum VE - I am considering epoxy only thing putting me off the epoxy is the gelcoat complication… I know you get epoxy compatible gelcoat - I’m just not sure how durable they will be. I don’t want to paint the boat after it comes out the mold.
    On that basis would you have a product/approach to recommend?
     
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