Fibreglassing over new stringers.

Discussion in 'Fiberglass and Composite Boat Building' started by valvebounce, Jul 22, 2013.

  1. valvebounce
    Joined: Dec 2010
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    Location: manchester uk

    valvebounce Senior Member

    Eventually got round to fibreglassing in my new stringers,first real break in the weather here in the Uk.
    It's a 13ft speedboat I am converting for sea fishing.
    Apart from patching cars,this is my first attempt.
    I have the resin and hardener (not epoxy)and 450 grade chopped strand mat.My concern is how to apply the resin,and the amount of time I will have before it sets.Do you pour it on,and then smooth out with a roller?Would it be best to roll the top of the stringer first and then roll the sides down,and then roll it onto the hull?(the hull is fibreglass and has been sanded down)

    My fears are that I might push the strand mat out of shape.I have the back of the boat completely out and a new transom ready to be fitted,which is handy for access.
    I started this project last year and PAR has supplied me with some sound ideas.
    Just for interest's sake,a friend of mine who is a tinsmith for rolls royce marine engines,informed me that the hull design of this boat was invented initially by Lawrence of Arabia.
     
  2. tunnels

    tunnels Previous Member

    Ok basics
    The resin you have is how old ?? if its been sitting round for some time I wouldn't use it !! it has a use by date and it separates out and the promoters that make it go hard don't work any more !!
    same with the hardened you have it also looses it ability to make the resin go hard so used together could be a disaster !! .

    I suggest you start afresh with new resin and new hardened .
    The glass sounds like chopped strand matt . again if its been round a while will crumble and fall apart . nothing wrong with it but the binder that holds the strands of glass break down and don't hold any more !

    Now how big are the stringers you have ?? can you post some pictures please before we carry on any further ??
    Inside where the stringers are and with some detail so can see what's there !!
    then we'll carry on from there ok ??
    :p
     
  3. tunnels

    tunnels Previous Member

    Taking this a little further but need lots more information .
    Your stringers are there to stiffen the bottom of the hull and just csm by its self is not really that strong and could pop loose after a short time !! so you will need a better glass to use in combination to the csm glass you already have if its still workable !!

    Again need sizes etc !!
    There is glass tape in various widths and various glass weights available that could possibly help you a lot . T he supplier will recommend what he has in stock so chose carefully don't get sucked in and end up with something that not really suitable .
    With all glass and glassing the direction all the strands are running are what give it its strength so if some of it is going in the wrong direction its doing nothing
    So after we see some pictures of what you have and whats there then will carry on !!:D

    The procedure and way to mix resin and how to use we will go into a little at a time . its really quite easy and its not rocket science but will step you through it from start to finish !!so don't be to worried !!
     
  4. valvebounce
    Joined: Dec 2010
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    Location: manchester uk

    valvebounce Senior Member

    Hi Tunnels,thanks for your reply.The resin etc I have is about a year old,but has been stored at room temperature,The chopped strand matt also.I cut the csm into strips yesterday and it seemed in good condition.The boat is 13ft overall.The section of stringers I want to cover is 7ft,there are five of them.When I got the boat there was no deck in it,and all the woodwork was rotting.There was duckboards between the lower futtocks placed directly on the hull.Basically,I have stripped the boat back to its original fibreglass shell,apart from the embedded original stringers,which were part of the hull.
    I have fitted the new stringers,and adjusted their heights to suit a flat deck.When the new stringers are covered I intend to step the deck where the bow rises for more space.
    The guy I got the resin off is a small business,and quite helpful,I will phone him and ask about the timespan of the materials.
    I have taken some pictures which I will attempt to send,I'm not sure of the procedure,so I hope you will bear with me until I get it right.
     

    Attached Files:

  5. valvebounce
    Joined: Dec 2010
    Posts: 549
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    Location: manchester uk

    valvebounce Senior Member

    Sorry about the first picture,it was on my camera and got in there somehow.
    PAR suggested I go for a longshaft outboard and raise the height of the transom,the new transom will be to take a 19"shaft.It is a tiller steer,and PAR has given me the measurement to raise the transom either side of the motor to prevent too much splash.
    I have made a start on the gunnels,which will be 3"wide when completed.I intend to fit lower futtocks into the stringers,flush to the surface of them,and not touching the hull,then fit the upper futtocks onto them and into the gunnels for support.It's a new design to the original,I just hope it works.Haha V
     
  6. tunnels

    tunnels Previous Member

    ok now we are getting places !! the stringers look like about 50 x 50 timber
    the top corners will need a radius because the glass will not wrap around there at all and you will end up with great long air bubbles either on top or on the sides !! so a 10 mm radius would be your minimum to work with
    where the stringers are 100 mm wide down each side needs to be ground back to bare glass with absolutely no paint or gel coat or any thing at all should be there , the glass needs to wrap over the wood and go out onto the bottom a minimum of 70 mm each side to bond to the hull . this is really important !! ok !!!,all clear on that !! Secondary bonding is a problem so the better the surface you bonding to the better and longer the stringers will stay in place and do there job for !!
    You say the resin is a year old then DO NOT USE IT !! GET FRESH RESIN AND FRESH CATALYST !!!
    Ok what ever the measurement is from one side up and over to the other side then that's the width of glass you will need . my suggestion is to use double bias that already has a layer of chopped strand matt attached to one side !! ,measure the total length of all of the stringers and that's how much you need , its possible to get the right width of glass in a roll form so you just cut the length you need as you go . it could be about 300mm wide at a rough guess but if its not available there's another way to do it !! that will work and could be easier and will be stronger !! don't forget to add enough to go out over the ends as well .
    the csm you have already you can lay first and the double bias with matt over the top of your csm . the chopped strand on the double bias should be facing up , . My suggestion is you use a smapp paint roller to apply the resin now this will roll down and wet out nice and cleanly but will still have to be rolled out with a medium sized hard laminating roller to get the ir bubbles out with ! is best to lay the scm you have and don't spare the resin make it really wet and shiny looking then apply the double bias matt side up and roll yet more resin onto it as well again don't spare the resin its easier to press the thick glass into a wet csm layer so the resin come up and through the tick glass .

    if you never done any of this type of work before then do a small area first till you get the hang of what its all about . Do not catalyse the resin till you are completely ready to start . get the correct ratio of hardener to work to and do a small test panel and remember how long it takes to start to go hard , its called gel time ideally you should be getting 30 minutes of work time with about 35 minute before it starts to gel !!
    If in doubt stop clean all your gear and rethink what you did wrong and deal with it and restart again .
    fast brews of resin are really a no no , reason is first the resin shrinks with the heat it produces and ends up pulling away from where its supposed to be and second and most important the bundles of glass fibres really never ever get a chance to wet out properly and so a percentage of your glass is really doing nothing and the strength you thought you were getting isn't there . . on the other end if the resin is to slow sure it soaks but never reach's it full potential hardness and so its soft and all the heating in the world will not make it go properly hard !simply work within the gel time that you get with the right amount of catalyst , 30 minutes should be plenty of time to do what has to be done , in stages
    if you do it in short strips then the overlap join should not be less than 60mm one over the top of the other . send some close ups of what you got before you start . !!
    Its a piece of cake !! :D
     
  7. valvebounce
    Joined: Dec 2010
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    Location: manchester uk

    valvebounce Senior Member

    Thanks Tunnels,much appreciated.I'm not clear on what you want the close ups of,is it the stringers or the materials?
    We have just had a thunderstorm,and the boat was uncovered,so I thought with it being already wet I would hose it out.Glad I did,the bits of flaky paint and rubbish all washed out.As you can probably see it's an old boat,and had a lot of coats of paint,some being house paint I think.I know it is essential to have it immaculate and dirt free,so I have decided to jetwash it,which will probably lift off most of the old paint.
    When the interior is complete I intend to paint it with some epoxy two part paint,(aircraft quality grey)which I have managed to aquire.
    Thanks once more,I'll keep you posted on the progress.
    I hope it is a piece of cake.Haha
     
  8. valvebounce
    Joined: Dec 2010
    Posts: 549
    Likes: 11, Points: 18, Legacy Rep: 124
    Location: manchester uk

    valvebounce Senior Member

    I have cut two new transom pieces out ready to fit,they are glass coated 3/4" marine ply,which I intend to laminate and screw together to make the transom one and a half inches thick.I intend to fit the outer piece first and glass it in,then add the inner with a coat of f/glass resin inbetween and screw them together.Would epoxy be the best material to use when fixing it to the hull,or would resin and hardener suffice?The bond with the fibreglass coating on the ply seems very strong when applied with resin and hardener.
     
  9. FibrSupplyDepot
    Joined: Sep 2013
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    Location: Fort Pierce

    FibrSupplyDepot Fiberglass Supply Depot

    Whenever re-glassing stringers, bulkheads, transom or deck, make sure to coat the wood first and let the resin soak in and dry, then sand the coat lightly before applying any fiberglass. the reson is if you don't coat the wood first and you glass right over it, the wood will soak the resin out of your first layer of glass and it will delaminate a lot easier. always use fresh resin and hardener.
     
  10. FibrSupplyDepot
    Joined: Sep 2013
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    Location: Fort Pierce

    FibrSupplyDepot Fiberglass Supply Depot

    Never use resin by itself without fiberglass, its like using concrete without the rebar.
     
    Last edited: Sep 28, 2013

  11. valvebounce
    Joined: Dec 2010
    Posts: 549
    Likes: 11, Points: 18, Legacy Rep: 124
    Location: manchester uk

    valvebounce Senior Member

    Great advice,I have epoxied the gaps,and used glass and resin for the fix.
    Thannks for the interest.
     
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