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repairing dent on the mast

7K views 14 replies 9 participants last post by  chkeno 
#1 ·
Hello,

I unstepped the mast of my 30 years old, 29 ft boat for inspection and maintenance. When I removed the spreaders, I found a dent right under the spreader base, as seen in the pictures. I own the boat for two years only and I can't think of anything that could have caused that since I bought it. It was caused by a previous owner, so I don't know what is the history of that dent

My question is: is it something to worry about? Is the mast structurally weaker in this section? What can I do about this problem?

I talked to a rigger here who told me this is nothing serious and by enlarging the base of the spreader so that it spreads the load on that region the problem is solved. I'm not so confident about that, so I would like to hear more opinions about the issue.

Someone suggested me to fill that dent with epoxy mixed with fiberglass powder, is that a good idea?

I appreciate your opinion on the matter.
 

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#3 · (Edited)
That's pretty nasty looking , and with no compression tube, someone was cutting corners. I would say get a tube welded in , and get that plate your rigger was talking about . Before you put the plate on sand it all down real good and use 3M marine filler . And then pray . On second thought get a new mast , and no one gets hurt, hopefully .
 
#4 ·
Can't help but to say that I just found myself in the exact same situation with a Catalina 30 I bought 3 months ago. A not so trivial dent (larger than yours) at the spreader. Rigger told me to sleeve or replace. I'm looking for a used replacement. Good luck. I feel your pain.
 
#6 ·
I would straighten that one of two ways. make hardwood end grain mandrel and slide it into the mast. while someone pushes it down or up past the dent you would tap the outside with a body hammer. I have done this a few times and it is the best way. the other more redneck way would be to tap the dent out from the opposite side with a punch thru the existing holes. then I would install a larger spreader place bent to match the curve of the mast. also add a spreader bar between the plates. it is an easy one to fix
 
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#8 ·
I would straighten that one of two ways. make hardwood end grain mandrel and slide it into the mast. while someone pushes it down or up past the dent you would tap the outside with a body hammer.
Hello overbored. I'm thinking of straightening the dent. I'm not sure I understood your method. What is the purpose of the mandrel? Is it just to support the mast wall while tapping directly above it? Or should it be a tight fit inside the mast, and pushing it under the dent would push the dent upwards?
 
#7 ·
Thanks everybody for the answers.

bassmanss: ouch, sorry to hear that! I still have hope that I can salvage this one. I don't have money to buy another one right now, probably even a used one (I'm buying new standing rigging as well, not cheap).

I'll keep an eye out for bargains though, who knows.

I'm having the rigger build a bigger base as well as a support which braces the mast. Regarding the compression fitting, it's a great idea, I'll look into it. Should it be made of aluminum or stainless steel?

overbored, you mention an interesting technique for removing the dent. I didn't think it was doable until now. I'll look into it.
 
#9 ·
I use the mandrel to hammer against the same way you would do car body work. the mandrel need to fit the contour of the inside of the mast but not to tight . only needs to fit tight where the dent is. I used a long 2x4 to push the mandrel into the mast. taped it in until it hit the dent. had another person tap it in as you tap on the outside of the dent. it is combination of both the mandrel pushing it out and the hammering on the outside. that moves the metal. first one I used very hard wood with the grain going across the mast. the second one we used a mandrel made out of Delrin plastic. and we left the Delrin in the mast as a spreader. that mast did not have internal halyards or any wiring
 
#11 ·
Aluminum doesn't like to be bent and bent back. It fatigue cracks very easily. That method will make it look nicer, but isn't going to return it to it's original strength and may make it weaker than it currently is.

The plate that bridges this sounds like a better solution to me. Talk to another rigger and see if you get the same advice.
 
#12 ·
Find out who the mast manufacturer is and get their opinion. What brand of boat is it? Do you know what brand of mast it is?

Alex_W is correct aluminum does not like to be worked and can/will fatigue easily. If that mast breaks and comes down you will be spending money on a lot more that just a mast; all rigging (running and standing), sails, roller furling, fiberglass repairs, hospital bills, higher insurance premiums, etc.

You do not want to wind up with this:
Roof Security lighting Steel Metal Street light
 
#14 ·
Alex_W: Yes it is an Isomat mast. Not sure what happened. Went sailing on a high wind day 18-20 with 30 gusts. Coming back into the marina and one of the crew points up and goes "is that supposed to be bent back like that?"

The manufacturer and surveyor say it may have been a defect in the weld that just finally failed 19 years later.
 
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