Post curing full hull

Discussion in 'Fiberglass and Composite Boat Building' started by fallguy, Apr 12, 2018.

Tags:
  1. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I want to post cure my hulls for two hours at about 150F.

    The boat will have 4 watertight compartments and an air pocket inside the beaching keel.

    What would anyone recommend for the watertights during post cure to avoid a rupture? Temp rise will be slow.

    Would it be wise to hole all of them? How big a hole? Like 1/8”

    Would it be wiser to put inspection holes in all of them?

    Has anyone ever done this inside a building? I can build a thermal chamber and run heat strips with the limits removed, but that is a little risky. Pretty much any heater will need limits removed. I’ll have water hoses on standby as I doubt my insurer would cover me cooking a bot with heaters with limits pulled, but can’t think of another way.

    Thanks.

    More generally, is there any problem when watertights expand and contract? They were built near ambient temps in a dry environment.
     
  2. gonzo
    Joined: Aug 2002
    Posts: 12,734
    Likes: 246, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    It would make sense to have an inspection plate on the compartments.
     
    fallguy likes this.
  3. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Then are they still considered watertight with orings? Or do you mean a fish eye glassed in?

    A little worried about having something rupture on post cure and a little worried about coasties.

    Thanks as well Gonzo
     
  4. gonzo
    Joined: Aug 2002
    Posts: 12,734
    Likes: 246, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    It would depend on what classification your are building for. You may find that there is a pressure rating requirement for the plate.
     
  5. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Recreational use/personal vehicle.

    Class B vessel for offshore use.

    Designer told me no holing.... I suppose I ought to check with him.

    Thanks Gonzo.
     
    Last edited: Apr 13, 2018
  6. gonzo
    Joined: Aug 2002
    Posts: 12,734
    Likes: 246, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If the plate can withstand the same pressure as the bulkhead, there should be no problem.
     
  7. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    I don’t think a fish eye would be able to withstand pressure (et al) as well.

    Consider a composite sandwich locker base. Mine are made with 18 ox biax both sides and 12mm core.

    There is no way the fish eye would not be a first point of failure under pressure, but the pressure is not a concern if the vessel is holed. The hole already exists at that point. The pressure would be atmospheric. Perhaps I misunderstand.

    I have an email into the designer.

    I can hole all the watertights before heating. The only thing I’d rather not hole is the beaching keel, but that, too, would be an air chamber getting heated from say 80 to 150, so perhaps that, too might be trouble. If the air inside the keel heats more slowly; the effect would be collapse of the keel? (I think so). Then a leak may form in an indeterminate location. So perhaps I must hole and repair to avoid any issue.

    Thanks for the dialogue. It is very helpful to have someone to discuss this with vs making a bunch of watertights fail and not know they did. I won’t be in the hot oven to watch.
     
  8. gonzo
    Joined: Aug 2002
    Posts: 12,734
    Likes: 246, Points: 63, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    If there is a hole in the bottom of a chamber, water will enter until the pressure equalizes. That pressure, plus a safety factor, is the rating of the flotation chamber.
     
  9. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Woods told me to install screw ins.

    I am not certain I understand your point.

    I think I will hole the beaching keel near the end and fill it up full with some milled fiber and cab.

    Now, about that oven...
     
  10. PAR
    Joined: Nov 2003
    Posts: 18,995
    Likes: 448, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Any time you enclose an area of a wooden structure, even a well encapsulated one, it should have a minimum of a deck plate if not planed out ventilation, if only to provide access for cleaning and preventing mildew. A buddy recently completed a daysailor with floatation tanks down each side as part of the seat boxes. The plans said to seal them up, which he did. He's now pissed he has to repair the rip out along a few of the bottom panel to flotation chamber seams, because he'd left the boat on the trailer in the Florida sun. If it's a tight chamber, you can guarantee two things; the first is the contained air will expand, so things need to give and it will develop condensation issues because of the heat/cool cycling that'll happen. With a couple of deck plates or other venting both issues are addressed, assuming they employ them as part of the operational routine.
     
  11. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    What do you mean by ‘part of the routine’?

    Is that a routine drying out? So you open the during drier weather? Right now and after cooking the hulls; theu would be at their driest.

    Here in Mn in winter the compartments will go from 90F in July to -20F in winter; so the biggest temp swings would be winter. Do the caps need to be removed as winterization? Thanks.
     
  12. PAR
    Joined: Nov 2003
    Posts: 18,995
    Likes: 448, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    If your boat has enclosed areas, with deck plates or other forms of sealing them up, once you park the boat, you open the deck plates so the compartment can air out. This prevent mildew, lets the condensation out and the free low of air will help prevent other issues too.
     
  13. rxcomposite
    Joined: Jan 2005
    Posts: 1,692
    Likes: 101, Points: 63, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Inspection plates are standard for boats for the owner to check sealed compartments. It comes in plastic or metal and is normally located on decks or upper decks. It is weatherproof rating, not rated for bulkhead pressures. You only have a boat. Only big ships have inspection plate, manholes actually, that is rated for the pressure it will take be it bulkheads or tween decks. It is semi permanent in installation, meaning there is a watertight gasket and several bolts that will take some time to remove.
     
  14. rxcomposite
    Joined: Jan 2005
    Posts: 1,692
    Likes: 101, Points: 63, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Check out West Marine for a typical one. Metals for heavy traffic areas, plastic for hidden ones. It comes in 6 to 8" diameter, white, anodized or plated. There are also hatch covers/manholes.
     

  15. fallguy
    Joined: Dec 2016
    Posts: 606
    Likes: 20, Points: 18, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Have any of you guys ever cooked a full hull? Mine would need a 34’ x 7’ high x 5’ wide oven. Heat rise inside the oven is 80F.

    So I need to insulate the oven, but that temperature is above most device limits. It will be inside a heated building; so leaning to electric heat. Then need some air movement inside to avoid hotspots. Deformation is say 170-220, but I also need to bunk them to avoid the weight collapsing the hull at the cradle.

    Anyone ever seen this done?

    I could have done each panel; that ship has sailed. Thanks for any.
     
Loading...
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.