Dent in aluminum mast

That's the spirit Ad Hoc. Hanson Rivet out of Pacoima, CA is a good source for quality supplies (WWW.hansonrivet.com). I'd add an inch in the vertical dimensions of your patches. I have a Lindenberg 26, just picked it up for a song and dance this summer. It will easily kick the Aloha 27's transom off, but it's a different package of design compromises, as I'm sure you know. Lets see some pictures when you get her re-splashed, say with the 150 up and the crew lounging around sipping wine and eating chunks of cheese.

 

No surprise you've received a lot of disinformation from the resident "experts".

Without seeing the damage it is impossible to say, but it is entirely possible that you could just fix the step area and go sailing. My mast has a much bigger dent in it than that, and the boat is now 30 years old. The mast was dented before the boat was built.

I think the section you mention sounds a bit overkill for that boat, so even more reason to not worry too much.

Have you considered drilling a hole in the impact area of the dent and using a dent puller hammer to try and pop it back?

If you do externally reinforce the area it is best to cut the patches into an elongated diamond shape. Use Monel rivets, and coat them in Alumelastic or other anti-seize. Structural rivets are better than normal pop rivets.

3M makes a lot of different adhesives and they have a good one for bonding aluminum to aluminum. We used to call it "the green stuff", and it is great in shear as well as tension, so it was good for full length internal stiffeners in bendy rigs. You can call 3M and they'll tell you what to use for your application. Maybe you can find what you need on the McMaster-Carr site.

Many older masts aluminum masts end up with some corrosion at the base, and it is normal to add external re-inforcement to that area. You are right on in that regard. If you don't have material that fits well to your section you can tack and bend an alum strip all the way around.

 

Ad Hoc, i was planning on using type 316 SS rivets in a 3/16"diameter with some goo to prevent corrosion probably about 16 per side,so they wont be too close.
Paul, my gut tells me i could probably get away with just repairing the base as you suggest but since i have such perfect material available for the external stiffeners i may as well do it,the curvature of the side of the J35 mast is a perfect match,i do like your suggestion of the elongated diamond shape,this would tend to reduce point loading at the ends of the stiffeners, i think i may do that and make them a bit longer as Par suggests and will look for monel structural rivets.Thanks for the tip on the green stuff,i will contact 3m and see what it is.
Par, so you are a Lindy owner too eh,i bought mine on Ebay a couple of years ago for a song also and its still waiting for my attention,mine is hull #4 and has a double spreader keel stepped mast instead of the B&R rig.
Steve.

 

I have the double spreader rig too, It came with a whole new set of everything, gauges, winches, rigging and fittings, literally everything, including new toe rails. The guy died in the middle of a redo and it sat for 10 years, now the wife wants to get remarried, but "it has to go". Hanson has some nice self sealing stainless rivets that I like on rigging.

 

Aloha to you all.

My Columbia '33 is on the hard, in the yard. She's patiently waiting for bottom paint and some interior repairs (thank you termites...). That was the project list until the mast was dropped; while being stepped it rolled over, as the mainsail was still on the boom, creating a high cg as the mast was being tilted forward. The torque created by the heavy boom rotated the mast and snapped the starboard plate off of the tabernacle and the mast came down on the forward hatch cover denting it and tweeking a few degrees.
(I wanted to remove the boom to lighten the assembly, then step it, but the boatyard insisted on leaving the boom attached as SOP, to maintain "mechanical advantage", but that is not what I'm writing about. I just want to fix it.)

The damage (x) is about 2 and 1/2 feet from the bottom, below the winches and gooseneck. 38' is the total length. The extrusion is 7 1/2" by 4", the circumference 19 1/2". According to a mast sections chart in my book (From a Bare Hull), this appears to be S-203, 7.50 x 4.00, .140 thick, 3.214 lbs/ft, 16.672 IXX, 6.818 IYY, Alloys 6061-T6 or equivalent.

Obviously, I want to heat/pound/straighten, or cut out dent, or cut off above dent, to remove dented metal. Then I will need to "sleeve" on another section of mast, the length of which depends on how much I cut out or cut off.

Intuitively, a close-fitting internal sleeve of identical alloy, and a 2 1/2'+ section of matching mast extrusion will allow me to maintain integrity with regard to both strength and dimension.

I assume the sleeve will stiffen that area where it is installed, so this may create a weak spot at each end of the sleeve if shearing loads are introduced (ideally there will be no acute, shearing loads focused there or I've bigger problems...). It seems the tabernacle/base of the mast is immoveable anyway, so obviously can't flex there to absorb shear loads. I watched the taberbacle welds fail as the mast rotated and tilted forward.

SO, MY QUESTION:
*****1. Is there an extrusion out there that is intended for sleeving this size/shape of mast? It seems the manufacturer of this mast extrusion would sleeve mast sections and therefore manufacture a sleeving stock of ideal dimensions, and a section of S-203 to maintain rig dimensions.*****

2. Other options:
-obtain an identical mast, ideally scounged from a similar boat
-obtain a complete rig, similar to hers, complete with boom and sails
(for these first two, I would have to be lucky enough to find a similar vessel and not closely watched... ha ha. Columbia 33' owners beware)
-Build a "tall" tabernacle to allow removal of the dented section while maintaining rig dimensions.
-Change to keel-step configuration with an 8' extrusion of S-203
-Shorten the mast by 2 1/2 feet (as 3 chainplates were damaged, I'll be removing them and relocating chainplates to the outside, and I could likewise shorten shrouds and stays...and sails, yuck)
-scrounge another mast, probably a longer, fatter one and cut down to 38', similarity would limit the amount of mods required.

These above are just ideas. I'd rather stick with the parts she's used to, and I'm used to, so am leaning towards the sleeving on a 2 1/2'+ section to the base per my question 1, but if you know where I can find a used rig in good shape I will happily scrounge. It is very satisfying to "recycle", breathe life into idle equipment and get it back out onto the water again.

Thank you,

Patrick B


Base Masthead
____x_________________________________________________________
) ] damage is low, below the winches and gooseneck

 

You can weld a patch to the outside if the looks don't bother you.

 

Can one weld such a mast ?

If the damage on the high is so small it seems more a case one wants to cover it up. If you sleeve it with a thin allu and have it welded professionally one would hardly see it.

If the foot gets sleeved and welded it would strengthen the lower which was maybe weakened by bending back into shape part. Alu bends two ways, the one you can bend back and no damage, the other where it already craked and will break if strained any more but does not show up so prominently. Which is what you have to decide.

 

The mast is repairable, but welding wouldn't be a recommendation, unless plugs. In most cases, the repair either is cut away or the mast cut "over and under". If the dent is in the small side, it's locally cut and patched, possibly with an internal sleeve. If it's a good size dent (it doesn't take much of one to compromise the section) it's cut over and under, a sleeve inserted and usually glued and screwed in place. Sometimes rivets are used and sometimes plug welds.

You can do this yourself, but I strongly recommend you have a pro do it. Contact Dwyer mast(dwyermast.com), as they've bought up a lot of the old tooling for now discontinued sections, yours may be one of them.