Layup process????

Discussion in 'Fiberglass and Composite Boat Building' started by jyoung, Aug 21, 2010.

  1. J3
    Joined: Jun 2010
    Posts: 60
    Likes: 1, Points: 0, Legacy Rep: 16
    Location: MI

    J3 Junior Member

    Can you please explain this in more detail? I'm not clear how faster or slower changes how the layers would be overlapped/"interlocked" for this "24' flat bottom" (my only/limited experience with this size project is with "slower" one layer at a time.)

    Edit: thanks for the PM - I appreciate the details. I understand the idea of interlocking by overlapping layers; I don't understand how exactly a one-shot method would not overlap layers and be manageable. But it seems a moot point now as it appears no one here was actually advocating something other than a one-layer-then-the-next strategy for hand layup; only don't stop, keep going until it's done for best chemical bond. Sorry to the OP if I've muddied the waters with my misunderstanding of "one go" in post 2, but hopefully it will make it crystal clear for anyone else reading this later on.
  2. apex1

    apex1 Guest


    you should use the professional terms when you are talking business!
    The novice J3 has got the idea. You have not.

    The layup schedule and pattern was not part of the thoughts and advice on doing it in "one go". It is therefore moot to talk about.
    No matter if you do the job spread over a year or a day, schedule and pattern are the same.
    But the chemical bond is not. (let alone the extra labour to clean and sand)

    So, as recommended by Sam Sam and me, it should be done in a continuous flow, without any major brakes in the process, and according to the open time of the used matrix.

    I guess all readers have got that meanwhile, except you, the "specialist".
    You contradict for contradictions sake, not to provide serious and valuable advice.

    Your stubbornly repeated attacks against me, don´t make your contribution here much better. And it is YOU who is the unknown value here, not me.

    All the pro´s on this board know each other to some extend, not few of us work together.

    As the owner of my yards and shops I do not work on the shop floor one might assume. But I do not sit in my office, I sit on my (or my competitors) yachts.***
    And even if, whats wrong with the office job? Do you have a status problem? Have you been hurt by the "white collar" fraction? Fired again and again?

    Most of my peers here work in their offices, almost all have had their time on the shop floor.

    I have restored a dozen museum ships with my own hands, have built in wood, wood Epoxy, GRP, and steel. Though never a complete boat all by myself.

    I hold a commercial master license unlimited, sailed the world more than three times round, owned and operated 6 vessels newbuilt to my spec.s.
    But what does that mean?
    Can you read any expertise out of that?
    Then leave it.

    And now please reply on my question to shine with your "knowledge":

    Polyester with carbon?

    ***look how I enjoy my "office job"

    Attached Files:

  3. SamSam
    Joined: Feb 2005
    Posts: 3,899
    Likes: 200, Points: 63, Legacy Rep: 971
    Location: Coastal Georgia

    SamSam Senior Member

    There is a chart here in post #8. Take note where it's from ( From Ken Hankisons book " Fiberglass Boatbuilding For Amateurs" at Glen-L Marine). The book will go an awful long way helping folks build their own boat.

    With the layup described above- 5 layers 1 1/2 oz mzt, 1 layer 3/4 oz mat and 1 layer 18 oz WR, the nominal thickness would be .277", probably thick enough depending on reinforcing structure, ribs, stringers, etc. Probably strong enough although mat makes the stiffest but weakest layup.

    With the laminate schedule above, the gelcoat I would spray on late in the afternoon and let it set up overnite. Gelcoat is a whiney *****, it's best not to provoke it by rushing the process, it will kick you in the nuts.

    This is all to do with polyester resin. Polyester isothallic resin is much better than orthothallic resin.

    I assume the mold is like a Carolina Skiff 24 at a convenient height to work on. Three people is best, 1 to laminate from each side, 1 to mix batches of resin and get the rolls of precut fiberglass. 2 people can do it. 1 can do it. 3 is best.

    In the morning 1 resin rich layer of 1.5 mat is carefully put in with a slow curing (less hardener) resin and allowed to setup so it can't be disturbed, usually a little while after peak heat. The first laminate set up helps stop print through, resin rich offers a little more water resistance. The edges of mating pieces of mat are torn so they mesh like fingers more or less and leave no lapped ridges with lines of resultant bubbles.

    When set, nubs and stubs are scraped off. The layup will generally go from side to side. I'm going to change the schedule slightly. I'm going to eliminate 1 layer of mat and the 18/7 stuff and substitute a 24/13.5 product. (Woven fiberglass is weighed by the sq yard while mat is weighed by the square foot (don't ask me why) so the 13.5 is a 1 1/2 oz mat.) I'm going to divide the layup into two sessions with minimal time between sessions.

    The first is two layers of mat. One can be layed up in the whole mold dry. Say you have glass 4' wide. Starting at the stern, you heavily wet out the mat for a space about 4 1/2' feet towards the bow. Then you put on the second layer of mat from side to side and lightly wet that out. (It is difficult to wet out 2 layers of 1 1/2 mat at one time.) Then you take a 6" METAL bubble buster roller and roll out all the air bubbles and consolidate the two layers. Keep repeating that process until done. These layers of mat don't have to be torn, as far as I'm concerned they can just be butted together with no laps, but others see it differently.

    If for some reason you have to stop in the middle of a layup, DON'T stop in the middle of a piece of glass. If a piece of glass that is half wet and half dry is allowed to set and cure, when layup is resumed the divide line will be full of lumps and air and partly saturated glass. Rip or cut the glass and finish with a wet edge.

    The next session (after scraping and cleaning up nubs, etc) might be a little tricky. If I remember right you can't wet out 24/13.5 stuff from the top and if you can't get it all wetted out, you have to lift it up and get some resin under there somehow. It's easier to just be kicked in the nuts and go home than to do that. So I'll just use seperate 1 1/2 oz mat and 24 oz WR. The mat can be layed out in the whole hull dry as before and the the WR applied as before in 4' wide pieces with a 2-3" lap. It's debatable whether the last layer of mat is needed or not. It can give a smoother finish and protect the WR weave. I've done it both ways. If you want to put it on it can be done in the second session, starting with a narrower piece (3") to get the seams staggered with the rest of the layup, and then 4' pieces used from then on. Try and keep all seams staggered between layers.

    Metal bubble buster rollers are best as you can't clean them up perfectly and eventual accumulations of resin between the grooves make them useless. At that point, they can be set on fire with a propane torch and all the resin burned out, cleaned up with a wire brush and put back to a 'recently virgin, hardly spoiled at all' state.
    2 people like this.
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