Wear on H18/SX18 mast base/hinge

Yesterday was Opening Day at our Club. No one minds a little rain and mud, not when there's free coffee and good friendship and lots of work to do.

One of my buddies had fun raising the mast on their SX18. Turns out that at a critical point in the lift, the mast hinge broke. So they replaced the hinge with the one off my mast, no big deal, as I have work to do on mine before I rig. The mast is up and the boat is rigged and ready to take down to the beach...

This SX18 owner uses shroud extenders, and we theorize that in a capsize, the shroud extenders changed the geometry at the base of the mast, causing there to be a greater amount of wear from the additional sideways movement. We figure that is what caused the break.

Anyone else come across this?

We have pictures, around 1 meg each, if you want, please email me at lunnjohn at magma dot ca.

I'm not sure I would want to upgrade to extenders now.....

_________________
2015 H16, with spin,
SOLD 1989 Hobie SX18 Sail # 1947 "In Theory..."
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'

Can't see why shroud extenders would cause damage to the mast base.

Usually the mast hinge breaks if the person stepping the mast lets the mast swing out too far to the side. The cast aluminum is brittle and snaps in the thin section of the hinge.

I personally wouln't use shroud extenders anyway for fear of the mast step disengaging and having the rig dismast. There are better systems available IMO.

sm

I follow what you are saying John. When the boat was on its side the extender is released and that causes additional wear. I would agree with that conclusion as there is little clearance and with the mast leaning the step could rub, should be obvious marks on it from rubbing.

I agree with SRM as well, those things are more dangerous than helpful. A dismasted boat is worse than a capsized one by far. Maybe in a lake you could use them but in the ocean I think it would be a disaster.

Once the mast is up and the pin is removed I can't see how there is any side or twisting load on the mast base hinge, it just fits up into the bottom of the mast and is only compression loaded. If you left the pin in with shroud extenders that could cause some issues.

Its probably not twisting wear but impact instead. The extenders drop the mast several inches off to one side to allow for less righting moment. You may be thinking about shroud tensioners which are never released. John is talking about a righting system consisting of several pins and a length of wire. I have never used this type of system but it is quite possible to hit the side of the hinge on the crossbar if the angle is great enough. Only way to know for sure is to set it up on dry land and release one of the extenders.
Pin left in will do damage to the x-bar regardless of whether extenders are on or not. I saw a x-bar fold when the pin twisted it as the mast tried to rotate. Not a pretty sight!

I agree, I think there would be obvious wear on the side of the mast base hinge. There would also likely be wear on the front crossbar or on the mast step from the rubbing.

If the hinge broke right where there is obvious wear from using the shroud extender, then yes, it would be conceivable that the extender caused a problem. However, the hinges that I've seen broken (and there haven't been many) have broken at the thin section of the hinge. This is the result of the mast being raised improperly.

sm