Repair a bent boom?

[AntarcticPilot]

IMHO - as I posted earlier =- trying to bend such a form back straight will make the track guide close up and really make a mess ... it needs dent pulling out .... then form put into the track to prevent it collapsing before then straightening ..... finally weld the cracks.

Another way would be to cut away bottom face ... pull dent ... insert form into track preventing collapse .. straighten - then have tapered sheet installed inside to strengthen the area BOTH sides .... then close up by welding bottom piece back in.

I've seen riggers repair masts / booms / outriggers same way.

The heat applied during welding MIGHT also anneal the metal, removing the accumulated fatigue. But I am not a metallurgist!

 

[Refueler]

The heat applied during welding MIGHT also anneal the metal, removing the accumulated fatigue. But I am not a metallurgist!

I showed picture to my mate who is a Metal Master .... his comment ....

Easy Peasy ... and he without any prompt from me described what I said ... pull dent ... support track groove ... bend and weld.

 

[rogerthebodger]

I showed picture to my mate who is a Metal Master .... his comment ....

Easy Peasy ... and he without any prompt from me described what I said ... pull dent ... support track groove ... bend and weld.

Exactly how I would do it and I have bent metal work before

The bending back and forth of wire does fatigue the metal but you are bending way into the plastic phase of the metal.

This is just straightening bent metal back to its original position

 

[Refueler]

The main item is to support the groove to prevent it closing as the bend is made ...

 

[JonathanM]

Thanks for the sensible replies. I almost gave up on the thread at the unwanted nut on the tiller comment. I thought this forum was better than personal insults. If it happens again I will report that user, most uncalled for.

The boom was like this when we got the boat. I am sure the damage happened off the boat, I just cannot see anything the boom could violently swing against in situ to do that. In spite of the bend and small crack I an sure is is sound for the job. It would be of course a totally different issue if this damage was on a mast.

I contacted the original manufacturer, that profile is no longer made so the option of buying a spare length of extrusion is not possible, and they quoted just over £1000 for a new boom with the current profile and all the fittings. That is too much of a fraction of the boats value to be viable.

We are looking for a second hand replacement boom. So far no luck. We are prepared to do alterations to a different boom to make it work, for instance the reefing lines run inside this boom, a different boom may necessitate bolting blocks on either side to run reefing lines externally. If anyone hears of a boom about 3M long for sale let us know.

The dinghy club idea may be worth a try, are you there suggesting we use a section of a damaged dinghy mast? I can't imagine many dinghy booms being big enough.

I posted the question about straightening the existing mast to see if it was possible, A simple no it is no rather than ridicule would have sufficed.

We will continue using it until we find a cost effective replacement. One option we might try is loose footing the main sail and try it like that.

The stac pack is not decided yet. We might opt for independent lazy jacks and a simple sail cover instead.

Please could you let me know if you have any success? By strange coincidence I have exactly the same problem, a bent boom on a hunter 232. Would greatly appreciate it if you manage to find a replacement or a fix.

 

[ProDave]

No we have done another season in the boat as it is, including cruising and racing, and in spite of the doom sayers the boom has not snapped or bent further.

We have also kept an eye out for a replacement boom but nothing showed up yet.

Care to post a picture of yours? (I have shown you mine your turn to show us yours)

 

[JonathanM]

No we have done another season in the boat as it is, including cruising and racing, and in spite of the doom sayers the boom has not snapped or bent further.

We have also kept an eye out for a replacement boom but nothing showed up yet.

Care to post a picture of yours? (I have shown you mine your turn to show us yours)

 

[JonathanM]

Thanks for the reply, glad the boom held up for you! I’m thinking I might take the boom to a metalworker. No cracks in mine but the bend is nearer the mast so might be more of an issue.

 

[William_H]

Just a few thoughts on booms. The load on a boom is at the end mostly downward but also sideways holding the clew. This load can be transferred to the hull via an end of boom sheet with very little load on the boom. However if as is often the case the sheet attaches at a point forward of the clew then we can get loads down ward at the sheet attach and down ward at the gooseneck trying to bow the boom down at the sheet attach. Further forward requires more sheet pressure so stronger boom.
Then we attach a boom vang which in terms of loads is a terrible thing. Trying to force the clew down with a typical 5 to one ratio of leverage required causing up bend of the boom from vang attach to clew while at the same time providing similar force pushing the boom in to the gooseneck. (fortunately busually assisted by sheet loads)
So a boom can ahve an easy life or a very hard life depending on attach geometry. ol'wwill

 

[Metalicmike]

You can get pullers to pull out the dent, that would probably straighten the boom if there are any cracks you can get them welded.

 

[Refueler]

You can get pullers to pull out the dent, that would probably straighten the boom if there are any cracks you can get them welded.

A reasonably competent Metals guy should be able to pull that .... its creased - but not too bad.

Will' H mentions loads on a boom ... the load of concern here is the 'folding' one ... as the main loads up - it tries to fold onto itself ... basically the ends come together ... bit like a hammock to give a rough idea.
This causes the boom / foot of sail to try and collapse as the wind pressure increases.... sheet position of course makes a big difference.

 

[rogerthebodger]

The issue you are going to have, is the crease at the bottom of the picture.

The way I would tackle that is with a hydraulic jack from inside the type that panel beaters us inside the tube.

The other way would be to cut the crease out and the either weld an insert plate or cut the crease out by cutting the boon in half and joining back together sleaving the joint inside the boom

 

[ProDave]

You can get pullers to pull out the dent, that would probably straighten the boom if there are any cracks you can get them welded.

Can you give an example please.

I am trying to figure how you can drill a small hole then get something through that that is then able to get a purchase and then pull what could be a considerable force. i.e something that will go through a small hole then expand so you can pull against it.

I have thought of just drilling an tapping a thread but I would expect that just to strip the thread if you try pulling on that.

 

[rogerthebodger]

Dent Puller Set 10Lbs 9 Piece With Sliding Hammer - Highveld Garage Equipment CC - Shop

Look for a dent puller with slide hammer

Bodywork Dent Puller for sale | eBay

 

[ProDave]

Dent Puller Set 10Lbs 9 Piece With Sliding Hammer - Highveld Garage Equipment CC - Shop

Look for a dent puller with slide hammer

Bodywork Dent Puller for sale | eBay

I can't honestly see any of those working. Many seem the just be suction cups or small hooks that would go through a small hole. Neither of those is going to pull a dent out of a boom which I am sure will take a lot more force than pullling a dent out of a thin car panel.

 

[rogerthebodger]

I can't honestly see any of those working. Many seem the just be suction cups or small hooks that would go through a small hole. Neither of those is going to pull a dent out of a boom which I am sure will take a lot more force than pullling a dent out of a thin car panel.

This is why I considered a hydraulic jack from inside.

On you boom you need a press to straighten the boom first before you consider how to remove the dent.

The one real issue is th crack on the left side of the first picture

 

[PaulRainbow]

I can't honestly see any of those working. Many seem the just be suction cups or small hooks that would go through a small hole. Neither of those is going to pull a dent out of a boom which I am sure will take a lot more force than pullling a dent out of a thin car panel.

I can say, 100%, neither of those will work.

 

[oldbloke]

If it's the outboard end I wouldn't worry to much about it just be gentle when gybing. If it's the inboard end I would swap the fittings round so it's on the outboard end.
That said , I would still keep an eye out on Ebay, a friend broke the boom on his Swan 44 and got an exact replacement within a month

 

[earlybird]

I think that any DIY intervention will still leave a battered looking boom and has a risk of further weakening it by extending the crack. If you succeed in finding a replacement, or possibly paying for a good professional repair, the cost can be offset against improved boat re-sale value.

 

[Beneteau381]

Can you give an example please.

I am trying to figure how you can drill a small hole then get something through that that is then able to get a purchase and then pull what could be a considerable force. i.e something that will go through a small hole then expand so you can pull against it.

I have thought of just drilling an tapping a thread but I would expect that just to strip the thread if you try pulling on that.

I would drill and tap a couple of holes, use a piece of angle iron drilled at the same distance as the tapped holes, and tighten it all up, a few judicious hammer blows? Alu is a strange metal, a good propane gun can provide enough heat to allow movement. Then a plate over the repair using the tapped holes and pop rivets should be ample?