New project, is my planning sound?

Discussion in 'Fiberglass and Composite Boat Building' started by groper, Jun 19, 2011.

  1. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Hi, im new to the forum and in the planning stages of building my first boat. Whilst this is my first attempt at a complete boat, i do have extensive experience with fibreglassing and vacuum bagging smaller parts.

    I wanted to run my planned process past the more expereinced composite boat builders to validate whether the building process itself could be improved to minimize the labour involved.

    So here is an overview of the plan so far, we will go into more detail later, i just want to give you an overall picture at this point;

    The boat is a 10m hard chine sport fishing powercat, drawn up professionally by a naval architect, with a small amount of accommodation in the hulls and a center cabin with small galley and saloon area.

    The material will most likely be endgrain balsa core with glass laminate and epoxy - i maybe persuaded into using PVC foam core, but its balsa at this stage.

    Firstly i plan on laminating both sides of all the hull bulkheads first under a vacuum bagging setup on a large melamine table 24ft x 12ft. Depending on the bulkhead sizes and resin open time, i will bag multiple bulkheads in one "shot". This process will be repeated for many other panels needed throughout the build including full length hull sides, hull bottoms, deck panels etc - the design/engineering of the boat is suited to pre cut DUFLEX panel type construction - ill just be making my own 'panels' so to speak, made up on a flat table mold using a vacuum process.

    I will then stand the bulkheads upside down "on station" on a strongback and tape the inside hull panels to the bulkheads, bilges and bottom wingdeck into position leaving outside hull panels off for access into the hulls after faring the bottom sides and turning the whole thing over.

    I will then build the cabin, finish the internals and then add the external hull sides before faring and painting etc... thats the plan so far anyway...

    Now the devil is in the details, so ill elaborate on a few of the finer points...

    When laminating the panels on a melamine table, i can get a near perfect finish on one side and peel ply on the other side, so i plan using the smooth side on the outside hull surfaces and other relevant areas to have a nice paint job finish. Skill in acheiveing this nice finish is tricky as often air bubbles get trapped under teh core material and if too much vacuum is applied or laminate is too dry you get pinholing where the laminate will still need to be bogged afterward - if you get it right tho, just a light scuff and its ready to paint without any further work.

    All the exposed edges of the panels will be filled with epoxy bog prior to laminating. Also any hardware mounting areas will be routed out and epoxy bog filled at this time aswell. So when the panels are laminated and then released from the table, i can simply trim and sand back to a finished solid epoxy edge - such as an internal bulkhead walkway cutout etc. and any mounting hardware can be drilled and mounted straight away - door hinges or cleats etc.

    I thought about recessing all the balsa core edges prior to laminating about 1mm deep with a router to allow for any tape joins making faring them out much easier, however i cant think of a quick way of doing this and would seem quicker to simply bog and fair the raised tape joins afterwards... any ideas on this?

    Id love to hear of any improvements on this process and of course any potential problems i may encounter. If i have been a bit too brief, i can clarify any points further, just let me know.

    Good sailing...
     
  2. Scrumble
    Joined: Aug 2008
    Posts: 27
    Likes: 3, Points: 0, Legacy Rep: 75
    Location: Darwin, Northern Territory, Australia

    Scrumble Oram 46'C MS Builder

    Composite Building - re New project, is my planning sound?

    G'Day Groper,

    Congratulations on getting into building and solid planning about the build process itself. You seem to have a similar attitude to me in trying to avoid building in work for yourself. I too agonised over how to simplify the fairing of taped joins etc. One thing for sure is that there is a lot of processes and techniques you will require that are not easily available to amateur builders.

    I have some comments to offer;

    If you are sure that you will save costs by laminating you own cores, please be aware that variables in your own process such as humidity, temperature, contaminates and core moisture etc. may cause you grief. Also there is a huge amount of time required to make your own panels and I know it is your time but it will tie you down for a long time which has its own cost additions.

    Do you have a relatively benign environment to work ie climate and more particularly "the shed"? I could go on and on about this as it has been the bane of our project.

    The open core edges can't be filled with "Bog" unless you are going to wrap a tape laminate around the edge. "Bog" has lightweight, low strength micro balloons etc with a little silica glue powder. In the serious cut-outs through bulkheads it is important to use at least a glue powder mix with a high percentage of silica. In my project we prefer to fill with a uni laminate to create a little beam around each cut-out which also has the advantage of not wrapping and creating a neat 90 deg edge. You can lay up extra glass when doing this for fasteners. We like a fastener to go through glass reinforcement as even glue core can crack, chip under vibration and/or load.

    You would be best to just fair the tapes than to spend a lot of time and effort rebating a fragile core. Remember, just enough bog is good, you can always put a bit more on, but it takes time, heavy work, and the possibility of damaging laminates if you just bog every where and then try to get it fair. This brings me back to pre laminated cores, they are very fair when a joining method such as Z joins are used.

    I think a lot of builders think that my fastidiousness is a waste of time but I am mindful of a number of production boats that have had bulkheads and beams dislodge and/or start to break up in seas that make the boat work.

    I hope you will find some use of my comments and wish you well for your build. Will you be documenting it?

    Regards,
     
    1 person likes this.
  3. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 123, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    thanks for your input Tom,

    i referred to all types of epoxy with powder modifiers as "bog"... im aware of the different types and where they are to be used. The ability to create my own panels without open core edges (by laminating them with the solid epoxy glue margin already around the core edges) is going to save alot of time fiddling and finishing panel edges... simply trim off the green glass and sand back to final solid edge, done. I was wondering why ATL didnt do this for the duflex panels - apparently they offered this at one point but due to lack of demand they stopped???

    The other appealing part of making my own panels is having one side of the panel "ready to paint" so to speak.... a light scuff to key is all thats required- save any tape joins... No filling the entire exterior panels with a coat of bog first...

    All the panels i make will be cutout and laminated in the workshop/shed, then the boat itself will be assembled or consolidated from the panels in a temporary shelter in the "backyard". Should only be taping and sanding etc outside... setting up the shed and laminating table(s) with glass on rollers at one end is something ive been thinking about carefully. I dont anticipate the laminating of the panels to take all that much time in fact. I think cutting all the cores will take some time tho, i may transpose the drawings into autoCAD and get the cores precut by CNC router if i feel the need... not sure on many things yet...
     
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