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Petecress:
Chances are you will go thru the whole life of your boat and never break an AKA sheer pin. All the boats come with a spare pin right next to the original on the off chance, the original breaks.
The vast majority of sheer pin breaks (probably 90%) occur when 'helpers' are trying to get your boat on shore or on the trailer by unknowingly pushing on the AMA's, which break the bolts everytime for sure. This kind of exemplifies just how little force it takes to sheer the bolts off. This is all by design, and the very last thing you want to do is disable this safety feature.
If you don't believe me just grap the AMA while locked in the out position and wiggle it forward and back, you will see for yourself the hull bending wildly in and out. This is caused by the 3 to 1 leverage in the joint caused by where the joint is located on the AKA bar. You can easily measure all these forces with a fish scale hooked to the AMA. As an example pulling the AMA with 100 lbs of force is in reality 300 lbs of sheer force against the sheer bolt (and the ball (don't forget about that ball because it only takes slightly more force to sheer the ball off, or worse yet tear the hull in the area around the ball).
You can calculate the forces on the 1/4-20 bolt holding the ball to the hull yourself (pretty common engineering calculations (most learn all this in high school). There is one other factor that also needs to be considered, and thats the force required to fold ( what we call elbow) the actual metal tube of the AKA bar, which just happens to work out to close to the same force that it takes to shear the ball off, or rip the hull. Think of the AKA sheer bolt as a self preservation device on the boat itself (a brilliant design BTW). If by some unfortunate hapinstance you happen to hit a dock or another boat with the AMA (which happens to all of us) the AKA sheer bolt harmlessly sheers off, and allows the AMA's to harmlessly fold in with all the force now on the knuckles which would take many thousands of lbs of force to fail. This feature can literally save you from potentially thousands of dollars in structural damage to the boat and hull itself.
This is usually an oh crap moment, and most likely to happen near shore (where there is traffic, docks, and of course the shore, etc), I alway say if you get scared at this moment, just stand up, most of the time this stuff happen next to shore.
Worst case scenario is the AMA folds in and the boat tips over. First off, all small sail boats tip over at one time or another, they are all designed to withstand this, I used to have a sunfish and spent half my time righting the boat (I was a teenager, need I say more (lol)). All small sail boats tip over from time to time (just ask any H16 owner, or watch any laser, sunfish, H16, or cat race), thats all part of sailing, and knowing how to right your sailboat if it does happen to tip is neccessary knowledge and should be practiced (all small sailboats ,cats, and dingies ).
Now lets get back to the AI/TI, 99% of the people out there will never see the conditions where the force of the water against their AMA's is enough to shear the nylon shear bolt. This is typically caused by a combination of speed and the size of the waves hitting the AMA's. Keep in mind the force of water increases exponentially with speed. You can test this yourself, at 3 mph take your paddle and jam it straight down into the water, you can hold the paddle, now do the same thing at ten mph, now you have to go buy a new paddle because you just snapped it off and it sunk in the water, this is an example of the exponential force of water.
There is an extremely small number of AI/TI sailers (lets call them the one percenters) that take their boats out (on purpose) out into offshore conditions that are beyond the design intent of the vessel. The vessel has an EC 'D' rating, if you look that up it says vessels only designed for inland and protected waters (not offshore, that would be a 'C' rating BTW). Obviously the EC rating system only legally applies in Europe, but it's based on common sense (I heed to common sense).
In the US you are captain of your own vessel and can do as you please, the coast guard only asks if you are more than 2 miles from shore you comply with a few minor safety factors ( i.e.... A flare gun ( varie pistol), flares, pfd's, offshore radios, etc, ( all common sense things)), and if they pull up on you and your boat is clearly overloaded with people hanging off the railings, and the hull more that 50% submerged, they will ask you to return to shore ( for your own safety, mostly because they don't want to have to come back and fish your bodies out of the water (lol)).
I'm not saying you can't take a TI offshore, we do it all the time ourselves (but our boat is specifically hardened for offshore use, and we have the knowledge and experience in our local waters ( the Florida Keys, and So Fl) to do so.
As captain of your vessel it's pretty important to understand the potential failure points on your vessel and midigate them to the best of your ability (your life depends on it). If you don't understand what to do you have no business being out there.
All just my opinions
FE
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