Trimaran folding system attachment

Discussion in 'Multihulls' started by Will001, May 13, 2019 at 7:48 AM.

  1. Will001
    Joined: Monday
    Posts: 3
    Likes: 0, Points: 1
    Location: Lake Maquarie

    Will001 New Member

    Thanks very much for the replies, it's good to see some pictures of other boats as i also have never had a close look at how the farrier mechs are supported. Thanks Solgato.
    I will try lifting the amas on land and see if the attachments points move, hopefully this weekend.

    I'll have to remove the amas at some stage to really check what's going on in this area, but if there isn't movement when lifting the amas i might take it for a few runs before i get stuck into that. (and repainting etc.)

    I still have a list of other jobs to do. Just finished fairing and glassing the rudder, need to bulk up the attachment point for this also... and the bottom of the hull is a bit soft... So it could be a bit slow.

    In terms of bushes for the folding mechanism, I will need a bush at every point correct?
    The current design uses a bolted connection for the small top member, should this be replaced with pin and bush?

  2. SolGato
    Joined: Monday
    Posts: 28
    Likes: 12, Points: 3
    Location: Kauai

    SolGato Junior Member

    Post some photos of the upper attaching points and the pivot points so we can better access the system.

    The original Australian built Tramps use a solid axle that is machined at each end to accept bolts and uses plastic bushings. Some later versions of the boats like the OTASC and Eagle used differing methods that were probably less expensive but got the job done.

    I can tell you from experience that it’s important to make sure all the fastening hardware is in good condition and that there is no play in the system, otherwise you run the risk of failure and possibly tweaking the mechanism. A little play can cause a weak link putting other fasteners in shear. Be sure to look for signs of electrolysis and make sure all dissimilar metals are insulated from one another with TefGel of a layer of plastic, etc..

    I had an upper support bracket shear a bolt once while folding on trailer and it was pretty scary. Upon inspection, it looked like over time the bolt had stretched and eventually gave after years of opening and closing the system from the rear beam which is common practice. Had it happened on water with motion, it probably would have bent the system.

    One way to make sure everything is in good condition is to see how the alignment is when open and closed. Is everything returning to where it is supposed to? Are the bolts lining up? Amas in mirrored position same distance to hull, etc.. I would definitely replace any suspect fasteners, insulate and protect all dissimilar metals from one another, and clean and grease everything if you end up demounting the amas to work on the lower connection points.
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