Fishing boat cabin rebuild - reshaped

Discussion in 'Fiberglass and Composite Boat Building' started by dzausta, Feb 27, 2013.

  1. tunnels

    tunnels Previous Member

    Tell me you logics in using 1 oz csm ?? if you hold it up to the light you can read the news paper through it . the only time such a light glass gets used usually is against the gel coat and made very resin rich ,these days people are also using Vinylester resin because of its superior qualities and its extra hardness but only for that first layer and possibly a second layer for a hull bottom on bigger boats .
    Give you a example if you lay 4 layers of 1 zo cloth and 2 layers of csm the amount of resin you will use is way over compared to using 1 x4 oz cloth and 1 x 2 oz csm . !! and thats just the glass!!.
    The other thing is fine glass in the case of impact will delaminate like pages of a book in the wind ! its list like peel ply and is totally dependant on the resin to hold it together ,where as a heavyer glass weave will hold together much much better!
    Yes core matt in 5 mm would be ok but do you understand what core matt is all about ?
    For a cabin would be ok , but never us corematt any where ever a panel moves a lot!! such as a hull bottom or simular place !!
    The worst possible thing you can do with core matt is not put on the required amount of resin it needs and must have to do what it does !!. when you start laying 5 mm corematt you will get the shock of your life as to the amount of resin it will require just to wet out each and every square foot !!specially on big areas !! core matt is alway crossly missunderstood specially 5 mm !!. Anything less than 3 mm gives very little to almost no stiffness at all !!
    You must get a spec sheet that tells you how much resin is required per square meter or square foot and that the amount you must use and not a drop less .Read it very carefully and completely understand what its telling you !!. So measure your area and the do the sums !!.

    The chinese guys where i been working could never get it right at all and i would only let them used 3 mm core matt. They always ended up with big dry patchs and air voids everywhere always on the underside where its not possible to see !!, and because they would never wet the underside first befor putting it on the job, they'd always just rely on it soaking from the top and it never works like that .
    They always insisted on letting it go hard before putting on the top layers of glass over it and had air bubble appear as big as dinner plates and could never understand why !!
    So just something to thinkabout !!
    Sorry for the late reply been busy with lots other things !!
    :)

    Core matt is designed to displace resin because of the impregnated Q cells within its self ,in a given thickness of a solid glass panel . Becasue it uses less resin than the eqivlent thickness of solid glass it acts as a core adding stiffness !so needs to be used in the middle of any glass lay up where it gets the least amount of movement from the solid glass layers each side if the laminate !!.
     
  2. tunnels

    tunnels Previous Member

    The reasoning for using sheet foam is less joins and yes is used mainly on flat areas . Cabins becasue they are high up need to be light so they dont upset the ballance of the boat to much specially in the rocking motion from side to side . Stability is what you have to be carefull of!!. The side panels would be stiff with 9mm but if there difficulty go down to 6 mm its still stiff. the forward cabin room i would try for 9mm as if you ship a geen wave over the front you dont want the roof to cave in !! and some will end up walkng on it as sure and God made little green apples !! Foam is easy to work with even in sheet form !!.
    Corners and shapes like gentel curves add strength to any panel !!!.
    Just take a look at every panel on any car !! theres is never a flat area any where ! everything has shape !! shape equals strength and stiffness without adding weight !!a curved panel is much stiffer than just a flat panel the same size .
    Have you thought about structure like a console /dashboard on one side and a panel come compartment for the otherside to act as Bulkheads and stop side to side movement of the cabin once its in place ?? even at this early stage it need to be thought about . The fixing and addition of the top and side screen will do wonders but small ridged Bulkheads will add the icing to the cake so to speak . Easy to make and manufacture just make and cut from flat panels of glass then hot glue together and glass up the backside remove from the boat and then do all you finishing and refit and glass tab into place !! or if the hull is aluminium just need flangs and pop rivit to the hullsides ,but if its glass thats easer still to glass to the hull !!
    :D
     
  3. tunnels

    tunnels Previous Member

    This is all alittle confusing !!

    This lay up has a few problems !!
    Lets see why

    4layers of 1oz cloth
    2layers of 1ozCSM
    9mm foam core/or 5 mm core mat
    2layers of CSM
    18oz woven roving


    Because of the way you building this thing its completely back to front
    The 18 oz woven roving needs to be the innermost layer against the mould !!its the backbone to the whole layup !! its the glass thats holding the whole thing together !! Impact in 99% of cases will be outside to inside so the 18 oz woven is protecting you !!
    The 2 layers of light 1 oz csm should be just one layer of a heavyer say 450 csm under the core !!
    The core used is your choice be it foam to give lightness and stiffness or core mat easyer to lay just needs to follow the rules of wetting it out completely when laying .
    Again just a single layer of 450 csm instead of 2 light 1 oz ( which can use lots more resin for the same weight of glass )
    and the 4 layers of light cloth laid one on top of the other is absolutly dangerous stuff . in the case of damage at any time it could just peels apart so easy its absolutely scary stuff !!
    Woven glass is best laid with a light weight chopped strand matt between each layer to act as a sandwich layer and adhere to the woven glass strands much much better than just relying on the strength of the resin used .
    If you ask the suppluer they can get or might have woven roving with a 275 gram chopped strand matt already attached this is easy to work with has two layers in one so saves time cutting and lays and wets really quickly because there is no glass binders used anywhere in the whole cloth /chopped strand combination its all stitched so uses less resin overall !!.
    Any supplyer with an ounce of sense should be suggesting all these things to you to think about !.
    Core ! foam or core matt is your choice !! me i would look at using a combination of both 6 mm foam and strips of 5 mm core matt where the foam wont go round some places ,Theres really not much point in taking core matt around corners because corners done i solid glass are much better and stronger than corematt corners . Corematt becomes the shearing place in this case of hard impact will simply comes apart ,wheres as solid glass to glass layups have a much much higher shear point !! Example a side impact a panel could shear the layers and even travel to and round the corners if core matt is used , where as solid glass will only separte to the corner not round it so less damage and easyer smaller area to repair !! Is any of whats here making sense ?
    What materials you use and how you use those materials to get the best possible build from them is very important . We never plan to have accidents but its nice to know that when we built something this was taken into account already ,Just incase !! :D:p:)
     
  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    My eyes might be gone, but is there sufficient "draw" for this thing to release from the mould ?
     
  5. tunnels

    tunnels Previous Member

    silly questions get even sillyer replies

    No he intends for it to stay as one solid structure and the wooden frames will become seats with a cushion strapped on your backside . !! All the foam will be sound proofing and bouyancy if it falls over !!:eek:
     
  6. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    :eek: Sounds like it will self-right if it goes over ! :D
     
  7. dzausta
    Joined: Feb 2013
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    dzausta Junior Member

    Thought about what you said and it all makes sence! Back to the drawing board for me... I was trying to save $$ by not having to make a mold but at the same time I want to do things right and what I did so far is back to front, just can't justify to myself any more the time ill lose having to sand the part getting it ready for paint.
    So lets do this right. What I made so far I will reinforce with more csm and turn it into a mold :) I will get some 9mm core and a vaccum pump. Spray GC do my layup (use 9mm core) vaccum bag and its done ready to go. I'm excited now.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    Not so quick to abandon what you've done, imo, just make sure you are sanding lightweight fairing bog and not solid glass laminate, and it won't be that much work.
     
  9. dzausta
    Joined: Feb 2013
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    dzausta Junior Member

    When I was making the plug I added enough "draw" to make sure it comes out of the mould easy if I went that way.

    To be honest im not happy with the skin layer, what I did for the skin layer is laid 2 layers of cloth than next week i added another 2 layers of cloth to the sides only (mechanical bond). As I can work on this project only on the weekends I would be saving myself a lot of time not having to sand and paint...

    getting my painter to paint it in the end would take months.....

    Ive done so much sanding on the plug its so flat that it would be a shame not to make a mould out of it.

    Id be doing myself a favour by making a mould.
     
  10. dzausta
    Joined: Feb 2013
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    Location: Australia

    dzausta Junior Member

    Can someone please enlighten me on the timing when doing a layup. From the moment I lay a layer of FG how long do i have before I have to apply another layer to achieve a chemical bond and not a mechanical bond?
     
  11. tunnels

    tunnels Previous Member

    Just some basics to work from !!

    Ok theres not tricks just plain good old common sense as always with all things to do with glass and resins .
    First lets look at the cycle of poly !!
    to make it go hard we have to mix catalyst with it !!
    The amount of catalyst is determined by the temprature of your working conditions!!
    low temprature up the catalyst ratio!!
    hot tempatures lower the catalyst !!!.
    Simple !!
    Now there is a upper and lower limit to the amount of catalyst you can use !! most polyester resins .75% is the low point and never go below that !!!
    The upper limit could be 2.5% or even 3% but again never go above !!
    so as a starting point 1.25%to1.5% is close normally .
    To get the right ratio to suit you needs make a small brew of say 1.5% and time it from the moment you pour in and mix the catalyst !!!This is called GELTIME and something you really need to know as its amount of safe working time you all have to use your resin to wet out and hard roll your glass and clean up .
    again warm day will go hard quicker !!,cold day will go off slower !!
    Just one other thing every one forgets about is humidity !!.
    Warm day with high humidity can have the complete opposite affect and really slow the resins reaction time .
    Moisture is a killer if it gets damp enough for any resins and will do just that kill the resin completely and no amount of trying to cook with heaters will make it work !!
    so make sure the surface is completely dry where you going to be glassing , make sure your glass is dry most important !!.

    Just to explain the upper and lower limits of Catalyzing resin . if you unercatayze the resin it will never go hard properly and you will end up with a weak soft layer of glass. !! the upper limits is the same the resin can go just like rubber and is weak and soft and completely useless in both cases its a 100% tearout and sand and redo the job BECAUSE YOU GOT IT WRONG .
    No amount of cooking at any kind of heat will fix the mess !All make sense ??

    One last and very important thing to add is the reaction of the catalyst with the resin produces heat !! thin layers of glass laid on a cold surface so the reaction time is slow ,but if you lay 2 or 3 layers of a 450 gram glass because of the amount of resin content then this will get warm as it approches the time when the resin will gel !! this can be a good thing as the gel time and warmth make the resin go hard quicker !! the warmth is retained for a while and then the chemical reaction stops and so it cools quickly . once its cooled and not warm to the touch of you hand then its safe to glass again this could be just 1 hour !! If its still warm and you start glassing the warmth will shorten your gel time considerably and the resin in the glass you just laid will start to gel before you finished getting the glass wet out properly !!
    I use a egg timer and set it 5 minutes before the known gell time of the resin for waht ever catalyst ratio you using so i have 5 minutes to get finished before the resin gels and i have time to clean everything properly !!
    Everthing is a matter of timing !! knowing what you can do with the product you using . When wetting glass i always use a 150mm wide medium nap mohair roller to apply the resin . Its quick, its easy ,gets the resin on and pushes it into and through the glass in a short time . the soaking of the glass fibres is important then hard rolling to get the air bubbles out of amongst the glass fibres .
    So if you havent glassed for 24 hours or more hen a light sand with 40 grit sand paper is a good ideal just to scratch and scuff the glass so you get a better bond when you start glassing again .
     
  12. dzausta
    Joined: Feb 2013
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    dzausta Junior Member

    I've learned this lesson the hard way. I thought the resin has cooled down enough but soon I found out that it hasn't :)

    Ok so I have 24 hours to work with if I want to achieve a chemical bond?

    The reason I ask is; I would like to do my layup in a way to achieve a chemical bond through the whole leminate but I can see myself running into an issue when i go to lay the foam core. As it is a rigid foam i wont be able just to lay it down flat than glass on top of it. I am thinking that I would have to go about it this way;

    Starting from GC I would lay down my glass layers than a very wet layer of CSM than my 9 mm perforated foam core than peel ply and the rest and vacuum bag it. (how long would i have to fait before applying a new layer?)
    From there, lay the rest of my leminate schedule and bag it again.


    Am I on the tight track ?
     
  13. tunnels

    tunnels Previous Member

    Just had a thought have you done any bagging before ??
    do you know and understand how it all works ?? if you dont know say so and dont guess , its not the hard but theres lots to take into account . most of all do a sample and understand properly what you are doing
    You sound a little excitable , slow down take your time and do a little thinking along the way .
    Like i discribed some where its the gel time you need to know !! most important !! 1.25% you could be getting 30 minutes of time to use your resin !! if you need a little more time drop to 1.0% of catalyst weigh the resin and its 10 ml per 1 kg of resin !! Be accurate with all you measurments dont guess and do get in a tizz!!
    You need to lay 1 csm and wet it out thorougherly with resin then a cloth over your mould then wet and roll then both with a hard roller to get the air bubbles out of the glass . then let it go hard . do that all over the whole mould !!Leave for 3 hours and then lay a wet cloth and a csm over the top and then your prefitted and cut to shape foam then bag it down !!one section at a time !!do small areas at a time Alway know what you gel time is for you resin always have a timer or a big clock on the wall or what ever.
    People only get into trouble when they dont think . !!:idea:
     
  14. dzausta
    Joined: Feb 2013
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    dzausta Junior Member

    Im doing my research on vac bagging atm, i understand theres a lot to take into account and I wont be starting anything unless I'm confident that I have the right information. I understand that small details can be very important and vital for success, that is why im asking all so many detailed questions. There is a lot of information out there on glassing but nothing compares to experience, thats why I greatly appreciate all your help.
     

  15. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Just finish what you started to do imo, you are not going into the fibreglass fabrication business. I am getting weary at the thought of it !
     
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