What happen to regular fiberglass on water?

Discussion in 'Materials' started by Shafri, Jan 18, 2011.

  1. gonzo
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    gonzo Senior Member

    The materials you are planning on using will give you a boat that is a bit heavier than modern ones, but will work OK. Also, the lamination is not as critical.
     
  2. Shafri
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    Shafri Mechatrommer

    just what i want and need to listen. thanx gonzo. perusing back the thread, i saw some peculiar jargon. E-glass, got it through googling! thanx. now... Fanie suggested the luny doc... whats the luny doc? googling showing random result, Luny Thomas, Luny Gallery, etc. etc. whats the luny doc?
     
  3. tunnels

    tunnels Previous Member

    Yes its possible and as easy as you want it to be ! Look at plywood construction And make sheets of glass on a table with a smooth finish for the outside Differant material but the techneque is the same . Look also at the stitch and tape way of bulding a boat ,same differant material but the same techneque . this can be used to build big boats not just small ones . Can even make cored panels but stop the core short of the joins and dont glass the inside till you get your panels in place and tape the joins and then completely glass the whole inside . 36 FEET power boat was the biggest boat i have built using this method did the hull and the deck and cabin all built without a mould just frames spaced at 600mm apart . Was fortunate to have everything cut on a cnc and just set them in place with the minimum of batterns longtudenly checked in to hold the frames Have used the same method to build new decks on older boats but in the 16 foot to 20 foot size . Cut paterns of the size and shape fron 3 mm mdf board and then laid them on a table and masked it out and glassed the panel to that shape and had a very small amount of wastage and cutting . The crucial parts of the whole operation are the frames to hold the premade glass panels inside of and the table to build everything on top of .As a good panel is csm 600 gram a 600 gram woven and another 600 gram csm and then core matt. This make a pretty good panel to work with and stiff but bendy !. The thickness of the core mat can be varied as to what you need . Important Never use Core matt in the bottom of a boat Balsa or a H80 density foam ok
    Also look at using a peel ply material for the outside of your panels and where there is joining . Peel ply can be a life saver and save time grinding and sanding and when you see and understand it uses it saves resin weight and make a nice proffessional looking job .
    Check out stitch and tape and read all about it !!!! Its simple and easy just you are using fibre glass premade panels instead of plywood !!!:confused::D:p:p
     
  4. Shafri
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    Shafri Mechatrommer

    Thanx tunnels for joining in. Good to know there is expert on another one-off technique here, i didnt think making fiber into panel like plywood is possible, need to study on how to get those thing together, i'm guessing it will be alike to c-flex technique. The thing (female mold) popped up in my mind, since i anticipated difficulty in smoothing/sanding the exterior hull part by one-off male mold/plug technique. With very fine female, we dont have to care much on the exterior hull when its done, yes i know sanding the female mold is not that easy either, but given the available material, i dont think sanding and smoothing with "regular putty" that i usually saw for car's body work will work in the marine, but then again, i may have not search deep enough on exterior sanding/smoothing/finishing material for external hull. i only get came accross with "gelcoat" that maker will spray first inside the female mold to become external finishing of the hull. and yet, i have to search more and where i can get this gelcoat supply and how its looks like.

    But as PAR mentioned, female mold for one-off project is crazy. Tunnels suggesting making the glass into panels, that a new idea for me thanx.
    and one thing getting in my way with both female mold and one-off technique is this (picture)
    lining.jpg
    if i have to cut the plywood mold to shape, they could bend out of shape, the profile could be screwed. i suspect it will crack when the fiber panel is bent during boat making using Tunnels technique. if i have to do like normal on land application, by shaping it later after the hull is completed, then i'm afraid the technique on land will not be applicable to the sea, since strong pounding of the wave could tear those apart off the hull. so i'm still confused :(
    maybe i should do like wood making technique, by using nails to stick that "linings" to the hull.. i dont know, i'll do that if there is no more option, by hook or by crook.
     
  5. Herman
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    Herman Senior Member

    Sprayrails is the name (question in the picture)
     
  6. tunnels

    tunnels Previous Member

    Strakes !! Where the arrows are pointing .Those are just for deflecting spray but good well designed strakes can and do help to lift the hull ! the less hull in the water the less skin friction and that means more speed !!!
    Make a good strong back to set up the frames on and you wont get twist and things going out of shape . Stitch and tape boat building check every site you can find and you will come to the conclussion i had long time ago its all the same just slightly differant no mater whick site you look at . Once the panels have been joined its is self supporting within its frame . The joys of working with panesl made on a good table is its fair and relativly smooth already befor you start , if you use a peel ply and rip it off when you need to do the priming and painting its a virgin surface and can be worked on without having to grind or sand .Just tear and paint So to speak . care and attention to detail makes a hansome looking boat . Making patterns and glass almost to the right size cuts the waste and amount of materials considerably on a whole job .
    :D
    Glass panels would be tha total length of the hull for each panel the amout of bend is next to nothing Glass panels as i discribed with csm roving csm and a core but no glass inside will bend a mile and never even look like breaking of cracking . its prestressed and becomes very fair when bent as it has no grain such as a wood panel would have with scarfed joins and hard and soft places . Mka a sample a metre or so long and see what i mean about bend and fairness . its nothing new !
     
  7. Fanie
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    Fanie Fanie

    Those strakes do more for stiffening the hull than they would deflect, although they do deflect some water.

    If you can find a distributor of the materials, it's going to be less expensive than the 'local shop'. You can also find a better veriety of materials. Chop strand is going to add quite a bit of weight compared to woven to achive the same strength of hull.

    The strands directions are also desighned for a hull to stiffen against twist, but it depends on the hull size.

    Mek or hardner or catalist is usually mixed 2% and an absolute minimum of 1.5% to the polyester resin and you need to mix it thoroughly, best to use an electric mixer.

    Maybe you should explain what you have in mind as a final boat, lenth width propulsion etc.
     
  8. pistnbroke
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    pistnbroke I try

    Ok me sceptical ....have a look at www.epoxy-resins.co.uk he has a manual on fibreglass technique you can download and look at the constrion of the boat Morgan by a first timer to see how to do it /or not if you like a bumpy finish
     
  9. Shafri
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    Shafri Mechatrommer

    That long protruding line is called Strakes or sprayline. ok thanx. I can imagine that is used to deflect spray of water coming up (if its above waterline) and add stability to boat manuvearability (below waterline).

    @Tunnels: your statement on making extra size and cut later implicitly proving the excellency of your craftmenship. When my first crafting (not FRP though, but i think the concept will be applicable to any crafting), i tried to make the exact dimension as the drawing, and later when actually installing it, i realized i'm short just by a few millimeters, then i'm screwed! its better to have extra size rather than exact, the pain of cutting it is alot less pain compared to having smaller size and struggle to death adding it later. i suspect the same to boat, only more severe.

    @Fanie: thanx for the advice.
    @Piston: thanx for joining again and for the link. i will study that, i can see more material supplied there and stitching method. Its good to have people like you, at least to kick my *** out when i do something not right ;)
     
  10. gonzo
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    gonzo Senior Member

    They are lifting strakes. They are a compromise. You get a deep vee that gives a better ride on waves, and the lift of a flat bottom. Also, the water as it exits the ouboard edges leaves a gap. That reduces skin friction. At low speeds, the whole bottom touches the water and produces lift. It is a really complicated dynamic system. I don't think anyone can calculate it accurately. There is enough data on existing designs to make a good prediction of behavior.
     
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  11. Herman
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    Herman Senior Member

    At times Professional Boatbuilder is full of discussions on spray rails, dynamic stability and the like. So indeed, experts have not reached concencus yet.
     
  12. Shafri
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    Shafri Mechatrommer

    .....
     
    Last edited: Jan 29, 2011
  13. pistnbroke
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    pistnbroke I try

    not being a suspicious person I checked this Mechatromer on Google ...thousands of posts on each a number of sites ...they dont seem to have any substance or come to any conclusion ...... just techno-twoddle......

    Now I am suspicious
     
  14. Shafri
    Joined: Oct 2010
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    Shafri Mechatrommer

    am i that important? mechatromer is my made up name, or hobby i think, a combination of mechanical, electronics, and programming. its like mechatronics (mechanical+electronics), i googled as well before putting up that "term" so i'm not clashing it with other's people right. sorry if its troubling you, i'm just nobody, or at least a normal guy, not a spy not a military. i'm just a mechatromer who want to build a boat to enjoy during my free time and go to islands to take landscape photograph. now what you want to know?

    since i've made a post, coincidantelly i just made a visit to one of "fiberglass boat building" shop near my place this morning, i can say i quite learnt something a bit, and to tell ya for the first time ever, and i mean it, for the first time ever in my life... i saw the real thing of what is called "fiberglass fabric", i'm too excited but i just keep it in my mind, i wont jump and people think i'm crazy. i tried to pull the excess out of cured resin, and you are kidding me, as i recall other site mentioned, its stronger than steel, now i know why it is used for boat building. and among other thing i learnt, they put wood in the fiberglass for transom. my imagination tells, it is where the outboard will be installed and the pushing force need to be distributed throughout the transom evenly to the boat's body and keel, hence using woods inside to avoid fiberglass tearing near the outboard grips, very clever! (sorry for the lame terms)
     

  15. hoytedow
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    hoytedow Fly on the Wall - Miss ddt yet?

    Every member is important. Knowledge is power but un-shared knowledge helps few. There will be questions which you will have answers to, and you will share that knowledge for the betterment of the forum members.
     
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