Latest News: Forums Technical Fitting Buoyancy Bags

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  • #19933
    jameschew
    Participant

    Hi everyone,

    I’m adapting a mkI woodie for cruising, and I’ve bought a couple of inflatable rollers which are to be used as fenders, rollers and buoyancy.

    Am I right to be thinking of adding more buoyancy to a mkI? I’m concerned that (assuming I put them in the sides of the boat) it’ll increase the tendency to invert.

    If I should go ahead, I’m not sure how best to fit them, as they would need to held low down to be effective, but there is a shortage of attachment points. I could screw some eyelets into the lower bilge stringer, but they would have to be very short screws, unless I glued on extra wood. Alternatively, I could bolt through the lower frames, and lead lines up through holes in the floorboards.

    Or maybe the bags should go elsewhere entirely?

    Any thoughts much appreciated.

     

     

     

    #20025
    john1162
    Participant

    Some people I know with inflatable Boat rollers usually pump them up when needed. Assuming your rollers are 20cm dia x 120cm long they will have a volume of about 36000 cubic cm this gives a buoyancy of about 36kg so any fixing would have to withstand this amount of force (sorry I know force is measured in newtons). If fastened each end then each fixing has to take 18kg.  I wouldn’t fasten them to the stringers. Just had a look at Force 4 boat rollers and they would give a buoyancy of 78.5 kg. That’s a lot of stress on your fixings. Over 12 stone in “real money”.

    #20031
    jameschew
    Participant

    OK thanks John.

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