Torque Specs ?

I don't think the torque required would register much on a torque wrench anyway. One of our engineers guessed 5-10 foot lbs, but he will get back to me after checking that on the assembly line.

We design the internal brass parts... these are not from some known vendor with some sort of torque spec. and the parts are molded into plastic... you have varying degrees of flex with thickness and the plastics cured stiffness. It is the plastic that maxes out. Not the fasteners.

We use Blue Loc Tite in most cases.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thanks!... that would be extremely helpful on my end...... Especially since it's the plastic that fails before the brass.

My inner Magilla-The-Gorilla has been laying low lately - hasn't stripped or broken anything for over a year - but who knows when he might get loose ? .... -)

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2015 AI in "Dune" - "The Grey Pig"
2017 Trailex 450 Trailer
Pre-September 2015 cradles
(anybody want to buy a slightly-used AI SpinKit?)
eMail: [email protected]

Pete:
On a joint like the AKA braces, all the load bearing is the flat surface on the bottom of the brace in contact with the top of the brass insert. The purpose of the bolt is to hold the two flat bearing surfaces together so they can't move.
The only reason to over tighten the bolt would be if in normal use it tries to work it's way loose from normal strain and movement of the AMA assembly (allowing the two flat contact surfaces to slide and rock (a bad thing). It's important for the two flat surfaces to be clean and burr free. The bolts need to be sufficiently tight to prevent movement. When you use blue locktite this does two things, it prevents the bolt from working loose, and it also helps insulate the two dissimilar metals from each other, and helps prevent galvanic corrosion by not allowing the salty water from wicking into the threads. Especially on boats it's probably a good idea to use locktite on all screws, especially any stainless bolts/screws going into aluminum or brass threads. If locktite is not used the noble metal (aluminum or brass) the threads will simply disintegrate over time, or worse yet corrode into each other and sieze (then you have to drill the screws out). Over tightening the bolts serves no purpose when locktite is used.
Like I described earlier the correct torque to apply is typically related to the screw size and class of the screw itself, normal would be for the brass insert to have sufficient threads to equal or exceed ( usually expressed in x times dia to insure the bolt will always snap before the threads strip, so in other words the required torque is always detemined by the male bolt , not the female nut. In the example of a brass nut the thread bearing would normally be 2x the diameter, a stainless nut would be 1x the diameter, a plastic thread (plastec screws) might be 4x or 6x times the diameter (dependent on the type of plastic). All this crap is always all calculated by the designers and manufacturers, so your concern about using different torques into different materials is completely unfounded. You would always use the torque specified by the male bolt or screw, the female side is always higher. In other words the bolt is always designed to break first. Obviously there are exceptions, an example being the threads that hold the harken cleats into the x-bar, in this example the extruded aluminum is only so thick, and you only have 1x times the diameter female thread, where normal should be 2.5x dia, in this case if you over tighten the screw the female thread will strip before the bolt breaks, you only need to be aware of the exceptions and apply torque accordingly. The math is simple if you only have 1/2 the required threads, you can only apply 1/2 the normal torque. Nobody publishes any of this stuff as its all common knowledge to everyone and applies to all fasteners regardless of the industry or application. Hobie (or anyone else for that matter ) is not going to publish torque specs on industry standard stuff everyone should already know.
If you have an interest in all this junk (sounds like you have an intense interest (an engineer in the making (lol)) go to engineering school, or just read up on the subject. If for nothing else, your own understanding of the subject. Knowledge is power.
Hope this helps
FE

Bob, I believe the "weak link" is NOT the bracket/hull interface, but actually the ama/bracket interface. Hence my suggestion for some emery paper between the two. All the bolts then have to do is hold the bracket tightly against the hull.

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Tony Stott
2012 Tandem Island "SIC EM" with Hobie spinnaker

Tony:
Thats a whole nother matter. He was concerned about torque requirements on screws in general, I was just trying to set his mind at ease explaining how all the stuff works (all general knowledge stuff that everyone normally already knows). The sandpaper trick is a good one especially on the front x-bar (the one that takes all the load). Hobies design on that system is ok but they didn't figure in hull flex, and flexing of the plastic mast holder under load. In theory it all works but in practice the bar slides back and forth, side to side, thus the placement of the Harken blocks one on each side of the right hull brace in the factory (kind of a minor oops in their basic design) Your sand paper trick takes care of that nicely, hopefully most have done your simple fix.
FE