Just noticed today my maui sails aluminium boom is bent on one side where the back harness line attaches.
Can it be straightened without it breaking?
How?
Yes it can be straightened But when such material is forged (casted) the process requires cooling procedure or Stress relieving . The boom has been considerably weekend wind Unfortunately i don't believe there is any sort of cold bending of the parent metal (boom)that can produce a equal or stronger outcome.
Sure its not the dimple stretch illusion from the harness line wrapping around the "boom grip" material
Bend it back but don't go out to far ! I think the area weekend will become malleable and will bend again in a short period of time.
I have been thru consecutive ali booms now and and they don't seem to be going the distance.
No optical illusion, it is definitely bent, but still useable.
Would I be better leaving it alone?
The alloy in booms is bent and then tempered. This basically means stiff, but brittle.
That is, it will bend a bit if enough force is applied, but trying to bend it back will snap it.
It is not repairable to be as strong as it was when orginally manufactured, but yes cut and sleeve may keep it going.
Very unsafe to use it offshore, but if only on the river you may be safe. If it breaks you can take it off, flip it over and use the good side to sail back (hopefully)
I have a 150 - 195 you can have if it helps but think your Koyote is a bit longer than that?
The strength and durability of aluminium alloys vary widely, not only as a result of the components of the specific alloy, but also as a result of heat treatments and manufacturing processes. A lack of knowledge of these aspects has from time to time led to improperly designed structures and gained aluminium a bad reputation.
One important structural limitation of aluminium alloys is their fatigue strength. Unlike steels, aluminium alloys have no well-defined fatigue limit, meaning that fatigue failure eventually occurs, under even very small cyclic loadings. This implies that engineers must assess these loads and design for a fixed life rather than an infinite life.
Another important property of aluminium alloys is their sensitivity to heat. Workshop procedures involving heating are complicated by the fact that aluminium, unlike steel, melts without first glowing red.,, like all structural alloys, also are subject to internal stresses following heating operations such as welding and casting. The problem with aluminium alloys in this regard is their low melting point, which make them more susceptible to distortions from thermally induced stress relief. Controlled stress relief can be done during manufacturing by heat-treating the parts in an oven, followed by gradual cooling—in effect annealing the stresses.
Pay the extra wind Go Carbon next boom start saving and run the ali till i breaks.
If its not badly bent or kinked I wouldn't worry about it. Don't straighten it though, that will weaken it to much.
You're not exactly a heavy weight Anita so I reckon it will be fine as long as it doesn't bug you to much.
I re-straightened a bent ali boom and it didn't break where I straightened it but it did let go near the mast bracket. I got a few extra rides out of it but it did cause me some worries when it finally let go. I probably wouldn't try to re-shape it and I would keep an eye on where it attaches to the mast just in case it has been over stressed here as well.
A mate's got a north skinny boom...it's bent like spaghetti, but he still pushes it around in big conditions. I bent a X3 a few years back, went to the carpark & straightened it on a mate's bullbar - lasted a while & never broke, but my confidence was shot. Got a 10yo boom that handles 110kgs swinging off it, keep wanting to retire it, but it's the only boom I have that fits a couple of my bigger sails.
Not an expert in materials, but in my view, the best (and likely) case scenario is that a single, unusual, and very sharp pull on the back strap of the harness line has caused this, but the boom is still structurally sound. Perhaps someone familiar with metals can confirm, but a catastrophic failure would feature "buckling", also called "beercanning failure", where the tube folds onto itself, and this doesn't look too close to it.
Edit: In retrospect, this is what Subsonic said.
I'd suggest monitoring this, and if the bend ever deteriorates with use, perhaps get another boom?
to do that to your boom Anita at your weight you must have done something pretty significant i would be very concerned about not so much the arm as it isn't too bad but to create a bend like that alot of stress must have been applied to other parts of the boom and as said previously i would think the head would go next before the arm breaks but not sure how many sessions away that is
last time i had a big enough crash to bend a boom the clamp exploded at the same time
You would think if I'd done something significant to that boom I would remember doing it! It must have been in that session at Safety Bay last Monday because I'd have noticed if the boom had been bent before.
The boom is nearly two years old I think
thats probably a decent life for an ali boom if you use it pretty often
if you can't remember doing anything then the other thing i have seen happen is someone will leave their gear on the beach incorrectly and the wind will flip the sail over and in doing so the boom lands extremely had on it's clew end and then the person comes back to find their boom is bent quite possible for this to happen at SB without you knowing
I bent an aeron 3 years ago, my mate bought it off me cheap, he is still using it, it hasnt bent further. He only uses it in safe areas though, always offshore but with a harbour wall over a mile away, usually people get resuced before they get to the wall.
Keep it for backup / rigging a second sail to leave on te beach. You can always swap booms over when you use the second sail.
All fixed!
I saw Jez from 2nd wind at the river the other day and he said they'd replace the bent tube with one off theirs. Can't get new ones apparently.
I took my boom in this morning and it was repaired by lunchtime. They had to replace the back end as well as the tube because both were bent, and only charged me $70 which included a new uphaul rope which I didn't even ask for (but my old one was worn out).
Great service!
If only they fixed cars as well...
