Tips For Deck layup

Discussion in 'Fiberglass and Composite Boat Building' started by holorinhal, Oct 25, 2011.

  1. holorinhal
    Joined: May 2009
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    holorinhal Junior Member

    I would like to hear opinions on the best method to go about relaminating this deck.

    Here is a picture of the deck that needs to be laid up and a picture of what it needs to look like.
    Notice the two rigglets that run up the center. I would also like to add a thnin 1/4 " piece of ply core to the under deck for stiffness, because the glass is only 1/8" thick.

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  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    A foam core can be lighter. To make those riblets, glue two strips over whatever core you use.
     
  3. holorinhal
    Joined: May 2009
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    holorinhal Junior Member

    Should the layup be done from the inside or the out side?
     
  4. holorinhal
    Joined: May 2009
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    holorinhal Junior Member

    so I guess I will try to put a piece of thin plexiglass coated with PVA under the deck and lay up from the outside,
     
  5. tunnels

    tunnels Previous Member

    :idea:Make the unside panel out of fibre glass and pre install a core to it instead of using plexiglass to make a former . Epoxy the panel to the underside of your existing deck all round the edges 360 degrees ! a minimum 50 mm glueing surface . Fair up the foam core then glass the outside and finish how ever you want to!!, Remember the thicker the core the more ridged it will be , A single layer of 600 gram triaxle glass each side done with epoxy would be heaps strong enough make sure the foam is H 80 grade not lower !! :D
     
  6. holorinhal
    Joined: May 2009
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    Location: las vegas

    holorinhal Junior Member

    The fiberglass hull thickness is 1/8" thick and the plan is to gellcoat the hull .
    So If I am doing the lay up from the outside, working with the first layer against the mold mounted on the uderside of the deck and working outward, What laminate schedule should be used?
    Should I start with mat and alternate cloth and mat, finnishing with two layers of mat on the very outer layers? Or should I start with woven cloth,alternating cloth and mat and finnishing with two layers of mat? to build to 1/8 it shouldnt take more than 4 layers should it?...Hal
     
  7. holorinhal
    Joined: May 2009
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    holorinhal Junior Member

    Tunnels, let Me see if I am understanding correct. Should the foam core be installed to only stick up from the hole, then sanded or faired out to the shape of the outside of the deck and then layers of glass laid over the whole outer deck? If so the core would only be about 1/8" thick , as that is the thickness of the hull glass.
    Can I use the epoxy to bond the fiberglass underside and then use poly on the outer layers? reason being is that I want to use poly gelcoat for the finnish.
    In these Eliminator tunnels, There are not usually any core material in the decks., My original plan was to put a former from under side and layup the hole , then flip the hull over ,and lay up a layer or two over the under side of the deck.
    What is the best glass materials to do the layup and in what schedule. I was planning on poly, mat and 1708 with a finnish cloth on the outer.

    Here is a picture of a mock up of what I was going to use as a backing for the layup.
    Also while on the subject, does any one have any tips for shaping the leftside to match the right? Thanks for any help....Hal

    [​IMG]
     
  8. tunnels

    tunnels Previous Member

    You can do what every you want its your choice ! just to add to what i had written originally to foam fill the hollow only with 6 mm foam and then over lay a 9 mm over the top and take it all right out to the very egde of the deck and shape it at the back to fit and run to nothing then you have a smooth surface to sand and shape and do what ever you want than glass the outside completely and take to a point where it primed even and then do the inside !!,take the backing panel out and grind sand the edges and glass it !! 1708 comes with a light weight csm on one side id put that against the foam and dont scimp on resin make sure you got the right amount of resin !!,cover and use peel ply over the both sides . Once its all hard just rip it off and you will have a good surface to Bog and fill and sand etc . :p
     
  9. holorinhal
    Joined: May 2009
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    holorinhal Junior Member

    Tunnels, if I understand you, I like the idea of what you are suggesting . However, I am a little dense sometimes. So just for clarification, are saying to make a fiberglass backing , to replace the white former I the pic above, then put a 6mm foam core just inside the cutout, then a 9 mm foam core over the entire deck to the outer edges, then sand and fair, then a layer of 1708 + peel ply, then glass over entire underside? So the foam core is sandable? Would a layer of foam over the entire outside surfac not build the deck up thicker than original?
    Sorry for the condition on my part, but sometimes I just need someone draw me a picture before it clicks in my head. I do truly appreciate the help and like the sound of your idea. Thank you .....Hal
     
  10. tunnels

    tunnels Previous Member

    use what you have and cover with plastic sheet then lay the first sheet foamfitted neatly unside the hole then the second layer of 9 mm covers the whole deck right to the very outside edges ,all sides and front and back
    It looks big area in the photo but in reality its not that big . It all has to be stuck together of course !! a layer of 300 gram csm between the two layers of foam prime the two surfaces of the foam and lay the glass also right to the edges including the part of the glass deck dont scimp on resin make sure you have lots of air bleed holes in the top layer and make sure resin bleeds throught the all the holes and not just in places .
    Vac bag would be the way to go . totally seal up the underside and bag from the top then you sure if getting 100% no air between ! :p
    In the middle where the hile is you will have close to 14mm of core the rest is just 9 so when its finished you should be able to stand on and only get a little flexing up and down . will need some bracing from behind once thhe glassinng is done so the scraps of foam covered with glass should do the job !!:p
     
  11. holorinhal
    Joined: May 2009
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    Location: las vegas

    holorinhal Junior Member

    What type of foam core do you guys suggest to use and what source to buy from. Please give me specifics names for the type of material.
    Is the foam shapeable by sanding it?
    If I put the foam all the way out to the edge of the deck, covering it completely, do i bond it with epoxy, then shape?
    If I cover the deck completely, will it not increase the hight of thedeck, and change the shape?....Hal
     
  12. tunnels

    tunnels Previous Member

    If you worried about height of the fore deck then use a thinner foam !!!
    why use epoxy ??
    I would use polyester for the whole job !! quicker easyer and its what the boats made from !.
    Glass wont stick to any surface thats not sanded if its in anyway shiney it will come off later for sure .
    Its foam !!its easy to sand use the H 80 grade divinecell or any of the other foams that are harder .
    Handle the sheets with care they will break and shatter if you hit them !!
    You going to need to Vac it all to get good bonding and make sure its all stuck every where :D.
     
  13. groper
    Joined: Jun 2011
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    groper Senior Member

    If it were me, i would grind the top and bottom edges around the cutout section you need to replace for bonding later - go right to the edges of the raised section for ease of fairing.

    Then i would cut a peice of 3mm or 1/8" thick "lantor coremat" and place it onto the backing plate you have installed in your previous pic. You wet this stuff out with resin and it becomes a like a high density foam core that weighs 1/2 of what a solid laminate does. As soon as this is wet out, proceed with laminating a single layer of 1708 or similar glass fabric right to the edges, then cover this with peel ply and roll out all the bubbles etc let it cure.

    Then remove the temporary backing plate you installed and proceed with bonding the foam core to the inside (youll have to get creative on how to hold it up there). A foam stringer is probably an easier option... the foam is called divinycell or corecell or airex 80kg/m3 or 5lb /cuft density PVC or SAN foam. Relaminate the inside around 2inch lap to the old laminate with the 1708 again. Bond the stringer on after if you choose to go that route...
     
  14. OFFSHORE GINGER
    Joined: Nov 2011
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    Location: Mich

    OFFSHORE GINGER Junior Member

    Hal , there is more then one way to skin a cat and my theory on this subject is.................................to keep it simple stupid , and the reason for this opinion is because when a person is doing a repair of this nature it can often be very overwhelming at times when two many ideas are flowing like water which seems to drown a person which in your case actually should be a walk in the park because of your past experience . Hal , just curious what type of material are you using for the backing that is shown in your pics ?
     

  15. holorinhal
    Joined: May 2009
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    Location: las vegas

    holorinhal Junior Member

    Attie, I think You are absolutly righ, about keeping it sinple. Maybe I have been over thinking a simple old school tried and true process.
    The backer that is in place now is a 1/8" piece of melomine, that has a vinyl like facing one one side. I am planning on waxing it for a release agent.
    I have used this material several times with good results. It easily conforms to the shape of the part and is fairly siged witha little bracing.
    Thepiece that is therenow is just mocked up, I need to pull it back out becouse I want to install the stringers first and use the hole th make access to the under bow portion of the stringer fiberglass work, easier.....Hal
     
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