Found a crack in my boom

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ReggieK

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Hi Guys

Last weekend we noticed a crack in the boom. I reckon it is at a critical stress point where the boom strut attaches.
Anyone any ideas as to whether this would be repairable or am I looking at trying to source a boom?
Would you sail with this? There's still a lot of meat on the boom, it's also not a large boom so I'm hoping it would be o.k in light to medium winds.
Funds are tight at the moment and announcing I need a new boom to the "War dept." would cause world war III
 

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ReggieK said:
Hi Guys

Last weekend we noticed a crack in the boom. I reckon it is at a critical stress point where the boom strut attaches.
Anyone any ideas as to whether this would be repairable or am I looking at trying to source a boom?
Would you sail with this? There's still a lot of meat on the boom, it's also not a large boom so I'm hoping it would be o.k in light to medium winds.
Funds are tight at the moment and announcing I need a new boom to the "War dept." would cause world war III
Click to expand...

Er - type of boat? Size of beam? Amount of cracking? Photo?
 
The crack means that area has been flexing.I would remove the rivets and make a different arrangement for the fitting namely cutting off the inside plate and weld a much longer one to the tang.Then I'd make a corresponding plate that would slot over the tang on the outside and sandwich the aluminium in between the two when riveted in place.I would also put a few more rivets in.Plenty of Duralac too.
 
Definately repairable.
I would suggest as per 30boat above except I wouldn't cut off the inside plate and weld a longer one on.
This is because I would have to get someone else to do the welding.
Instead I would remove the fitting. Bond on a longer plate to the boom with a slot for the fitting. And then rivet boom, plate and fitting together.
 
The crack between the rivets is contained by them, but it looks as if cracks are also propogating outwards from the rivet holes, and they will cause the boom to fail completely if they continue to develop. Whether or not it can be repaired I don't know, but it is possible that welding the cracks, accompanied by fitting a patching plate to spread the stress generated by the vang fitting would provide at least a temporary solution. A better solution would be to see if you can source the aluminium section, and re-use all of the boom fittings, in which case fitting a plate to spread the load from the vang over a greater length of boom would be a good idea from the outset.
 
I wouldn't fancy a repair. The fact that the crack extends past the rivet holes is bad. Cutting and sleeving would be OK but not welding/plates etc.
 
Thanks for your answer 30boat. Just to clarify your solution ( you're talking to a complete eejit here when it comes to this type of repair)
You're saying to make a larger plate and pass it up inside the boom, having cut off the old plate. Then a similar plate on the outside and rivet together?
I can't work out how they managed to get the original plate in situ and have no idea how to get another one up inside and actually rivet it. Anyone know what type of operative would do this kind of work?
 
ReggieK said:
Thanks for your answer 30boat. Just to clarify your solution ( you're talking to a complete eejit here when it comes to this type of repair)
You're saying to make a larger plate and pass it up inside the boom, having cut off the old plate. Then a similar plate on the outside and rivet together?
I can't work out how they managed to get the original plate in situ and have no idea how to get another one up inside and actually rivet it. Anyone know what type of operative would do this kind of work?
Click to expand...
Yes,that's what I was thinking.The fitting must have been originally slid into place through one of the ends of the boom before fitting the boom end fittings were fixed in place.It shouldn't cost you much to have a new plate welded to the old tang.
I'd think that if the new plate extends about 30% of the length of the old one at both ends you should have a pretty permanent repair.8 rivets instead of 4 should be enough.The inside plate would benefit from being radiused to avoid the stress imposed by a sharp edge against the boom wall.Even better if you could make the inside plate to bend at the sides to conform to the shape of the boom,the stresses would be much more evenly spread.But that's probably overkill.
 
Thanks for all the replies
I think I am in trouble, I don't think I am capable of doing this type of repair, if indeed a repair is even desireable.
Looks like this Saturday's sail will have to be put on hold, forecast is for decent wind too, b*gger!
 
Could you end-for-end the boom section as a temporary fix to get the stresses in different places? Just a thought....
 
If this is an Etap 21i, I have seen one with a broken boom at the point the kicking strap was attached (it just folded up).

The rectangular section boom looks much lighter than boats I have owned of the same size (more like an old dinghy section.

I think a thick doubler or channel section along the bottom of the boom for 600-800mm would do.

Whatever you do I would not sail with the kicker tensioned!
 
ReggieK said:
Thanks for all the replies
I think I am in trouble, I don't think I am capable of doing this type of repair, if indeed a repair is even desireable.
Looks like this Saturday's sail will have to be put on hold, forecast is for decent wind too, b*gger!
Click to expand...

Before you despair, try to ask Vyv Cox, he is our forum expert on metals.
 
Nigel_Ward said:
If this is an Etap 21i, I have seen one with a broken boom at the point the kicking strap was attached (it just folded up).

The rectangular section boom looks much lighter than boats I have owned of the same size (more like an old dinghy section.

I think a thick doubler or channel section along the bottom of the boom for 600-800mm would do.

Whatever you do I would not sail with the kicker tensioned!
Click to expand...


Actually, the kicker doesn't exert a great amount of pressure, as the boom strut restricts the amount of tension. If anything the problem is the strut, which is pretty rigid
 
Would I sail with it. YES but only on a light wind day and I would not pull down hard with the kicker.

Definitely repairable. Any good ali welder will do it. You need to drill small holes at the end of the existing cracks, V and weld the cracks then add a reinforcing plate maybe with triangular shaped ends to avoid a stress point. I had a similar problem on a 38 footer, had that done in 1993 and as far as I know it is still holding.
 
TQA said:
Would I sail with it. YES but only on a light wind day and I would not pull down hard with the kicker.

Definitely repairable. Any good ali welder will do it. You need to drill small holes at the end of the existing cracks, V and weld the cracks then add a reinforcing plate maybe with triangular shaped ends to avoid a stress point. I had a similar problem on a 38 footer, had that done in 1993 and as far as I know it is still holding.
Click to expand...

Thanks for that. I'll see if I can unearth an ali welder
 
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