Rigid bimini for a cruising catamaran

Discussion in 'Fiberglass and Composite Boat Building' started by citoyendumonde, Oct 23, 2011.

  1. citoyendumonde
    Joined: Sep 2010
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    Location: NEW CALEDONIA

    citoyendumonde Junior Member

    Hi everyone,

    Eventually, I did get some Airex at good price but i had to buy a lot. Previous topik: (http://www.boatdesign.net/forums/fi...ini-cruising-catamaran-34890.html#post405137I)

    Now it's time for new questions. Does everyone could tell me if there is a rule between PVC foam tickness and GRP sandwich skins? What kind of fiberglass cloth is better for a rigid and lightweight bimini? do you recomand vacuum bagging as well?

    Many thanks,

    Philippe.
     
  2. tunnels

    tunnels Previous Member

    Need to know the actual size of the top you are planing to make ??. dimentions and shape !!!. Flat ??curved ?? If its big it will need to be supported ?? shape built into a top adds strenght but no more weight so worth thinking about !!. Are you intending to ever stand on the top ?
    Have a look at the roof of a big van and see the shapes they use to gain ridgitity have to make something simular using the same principle !! Glass !!Id be looking at double bias or triaxle both sides inside and out laminated and roll peel ply over the top to make smooth and take out excess resin . :D
     
  3. citoyendumonde
    Joined: Sep 2010
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    citoyendumonde Junior Member

    Thank you for answering. Very interesting in the way I have to considere everything. I was thinking of something like flat under et curved over in order to gain thickness. The previous one was made ply wood (about 10mm) supported by 2 posts inside the cockpit. As this is a small cat (35ft) I'd realy like no post for more room. ( 1/2" inox tube) One close to helm station the other one through the table. Dimensions are about 3.5 m x 1.30m
    P1010546.jpg
    The binmini would lean on "big window wall" each side, and the center roof on front.
    This means the shape could be thinner on front and thicker aft ???
    Well, i don't know if what I say is making sense. I should better make a drawing, shouldn't I?:confused:
    Thanks again.
    PS: Yes I need to stand over when hauling down the main sail (often 2 people so about 150 kg).:mad:
     
  4. tunnels

    tunnels Previous Member

    It its only that small go find a van with a nice shaped roof about the right length and mould your self some bits off it!!!! just a few coat of wax and some pva and Take a skin off it !!!!!
    to keep it light Just use 300 gram double bias each side of 9mm foam core !!
    Will be smooth on the inside and glass finished on the outside . :p
     
  5. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    The local glass shop builds many simple rigid biminis for small sportfish centerconsole boats. I notice that they use a very thick core so that they may bury electric cables , speakers and lights.

    They build the tops on a common cambered ,one size fits all, mold then trim and detail to fit.

    They laminate the inside skin over the mold first, add core , reinforments, cable runs , cut to shape and then lay the top skin and fair. Seems to work well

    I see plenty of tri axail scraps around the shop.
     
  6. citoyendumonde
    Joined: Sep 2010
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    citoyendumonde Junior Member

    Sorry, i'm new on the forum. I am not sure to understand everything "The local glass shop" ... where? However thank you for answering.
    The same about the "van with a nice shaped roof". You mean a van with a 3.5m large roof? are talking about a truck?
     
  7. tunnels

    tunnels Previous Member

    why people never try to look outside the box over they have there heads .:confused:
    With 4 parts you can make anysize you want!! think !!:eek:
    What about a bus !!:p
     
  8. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Local glass shop refers to a 3 man boat building gang who specialize in the repair of fiberglass boats.

    This " bust your *** for fiberglass" gang is presently taking a bow mold off of a production charter boat so that they can graft a new bow section onto a sister ship glass charter boat who Tee boned the breakwater and developed the classic flat nose heaveyweight fighter look. .

    By using a van top as a FORM for a simple Bimini you are eliminating all the work in developing and building a form. Its a great idea.

    Perhaps there are other structures that you could take a shape off of to form an elegant top. The bottom of your neighbors swimming pool ??? The neighborhood skateboard ramp ?
     
  9. Sand crab
    Joined: Feb 2011
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    Location: Montana

    Sand crab Junior Member

    running electrical

    How is the wiring run in the composite structure. Is it just the wires laid in the core and then glassed over or is it run in conduit? Anybody got pics?
    Thanks BOB
     
  10. Frosty

    Frosty Previous Member

    Thats given me something to think about. My Stamoid rear deck awning is just about shot and I re sticthed it with Gortex a year ago now its knackerd again

    I was thinking of using flat plastic sheet covered with alluminum.

    But this bus roof idea needs some pontification. Now I can spend another year thinking about it, actually not I need to do something quick.

    Now!-- where to find a bus. There is one comes in at 3.15 and leaves 3.45 is that enough time? If not ille have to wait till 5 .15 till it comes back again.
     
  11. Frosty

    Frosty Previous Member

    Well Ive been out all day looking at bus roofs till I came a cross a boat factory. I know the manager so I popped in and asked if he happened to have a bimini mould lying about. We had a look around and found one, hes gnna knok a skin out in white, so ille be able to cut that up. I got him to knock out 2 becaue Ille use one for the bridge as well. 2 for 400 ringet, ( 30 us to the ringet).

    Job almost sorted and Ive been thinking about this for 6 months, I didnt want another fabric awning and this should last forever if painted with uerothane.

    So this thread has helped me --thanks for the ideas.

    You know sometimes you cant see the wood for the trees.
     

  12. pelagic
    Joined: Oct 2010
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    Location: Connecticut

    pelagic New Member

    the 60' cat Im on has a canopy shape taken from the cabin, which they used to build the mould. seems like an elegant solution...
     
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