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osirissail · 04-06-2011, 08:25

Quote:

Originally Posted by Jim Cate

. . . Well, first consider that in a deck stepped mast the loads in the subject area are nearly all compressive. To me this means that there is little stress on the welds, and that they are not an issue at all. Second, consider that there are no signs of cracking or distortion in the photos, which indicates to me that there have been no problems in the past usage of the mast, . . .
Jim

Good choice of modifiers - if - the boat has backstay adjusters then the mast can be stressed in the "shear" axis. That may have caused the fracture that was subsequently repaired. There are a whole lot of "maybe's" involved here.
- - The suggestion to "dye penetrant" check the mast from above to below the weld will reveal if there are any micro-cracks from an over-stress situation. Finding those would be cause for a major reduction in the selling price of the boat.

Sand crab · 04-06-2011, 08:29

Found it. I saw this awhile back. Here's a pic of " typical mast splice" complete with spotwelds. Notice the word typical as in it is done regularly by these guys who are pros. So nothing to worry about as long as it's done by the right people. As far as all the x-raying and proctology I say hogwash. If the repair has stood the test of time and use then it's fine. But I said that already.
Custom Projects
Scroll down to about the middle of the page and you can click on the pic to enlarge. BOB

Eric50 · 04-06-2011, 09:12

Quote:

Originally Posted by bangkaboat

Well, not interested in a dick measuring contest.

Mee neither...but it sounds we are already in.

I've seen UT show gas pockets 40mm long, almost width of bead in weld that was visually sound & would've shown no flaws w/dpt.

Well, when you start to have such size of defect on a weld the size of the one pictured, you don't need any particular NDT technique to know that the weld is completely wrong...but it would be surprising to find such flaw on this weld, wouldn't it?

If you know anything about welding aluminum, you know the strength in comparison to the parent material.

The only way I know how is the strength of a weld, is to perform test coupon and test them at a laboratory...otherwise this can only be an opinion.

No, the addition of a collar won't cause cracking, provided done right.

: yes as any weld done right...like the one pictured as well, for example.

Now, talking about aluminium welding, I have more often seen people doing wrong, than doing right, with this material.

So, taking the risk of weakening a sound weld and mast as the original seems to be, by adding a collar welded by a "so call" professionnal welder" that will probably initiate more problem and cracks than to leave the mast as it is currently, not to mention an over stiffness that might not be adequate at this location.

Sand crab · 04-06-2011, 09:37

If you Google image "splicing masts" then you will get lots of pics. Don't try "welding masts" because it wants to do welding masks. How do I know this? You guys can see that this is a fairly common job. For a pro. BOB

bangkaboat · 04-06-2011, 10:58

Quote:

Originally Posted by bangkaboat

Well, not interested in a dick measuring contest.

Mee neither...but it sounds we are already in.

Ok, well, I've been welding since I was 11, formally welding/fabricating/doing lab work since 1978, took a couple of years in the navy in early 80s, more lab work(metallurgy) & welding/fab work 84-87, lvl 2 weld inspector certification in '87, time off for Asia, coast guard, then welding/fitting/fabrication from mid 90s through 2008 in shops, drydocks, shipyards.

Quote:

Well, when you start to have such size of defect on a weld the size of the one pictured, you don't need any particular NDT technique to know that the weld is completely wrong...but it would be surprising to find such flaw on this weld, wouldn't it?

No, that was my point. The flaw I mentioned was only found when testing the hull of a 95' trawler yacht. The welder is a good friend with a lot of experience, a "go to" guy in the local drydocks/shipyards, very experienced welding Al. This is why below-waterline welds on Al boats are 100% tested, unlike steel hulls.

Quote:

If you know anything about welding aluminum, you know the strength in comparison to the parent material.

The only way I know how is the strength of a weld, is to perform test coupon and test them at a laboratory...otherwise this can only be an opinion.

A welded joint of any description in Al is never close to the parent material in strength. You know this. Therefore, in comparison to a single extrusion, a welded spar is compromised.

Regardless, what wound you up seems to be my comment on dpt. It wasn't my intention to offend you, but dpt isn't going to tell the OP whether the joint has complete penetration & fusion & whether, or not, there are below surface gas pockets. fair enough?

daddle · 04-06-2011, 11:41

Quote:

Originally Posted by bangkaboat

...in comparison to a single extrusion, a welded spar is compromised.

My spar builder, after sleeving, riveting, and welding my broken spar on a previous boat said two things:

* The weld is mostly just cosmetic. The sleeve and rivets do the work.

* It will never break there again.

I think most long Aluminium masts are made of two pieces. I know my high performance very heavily stressed mast is. Spliced about 10 feet above the deck.

So maybe ignore your weld, inspect the rivets. Sorry welding experts...only cosmetic...

Sand crab · 04-06-2011, 12:14

Hey Daddle, How long was that spliced mast? BOB

four winds · 04-06-2011, 12:53

Quote:

Originally Posted by Sand crab

Found it. I saw this awhile back. Here's a pic of " typical mast splice" complete with spotwelds. Notice the word typical as in it is done regularly by these guys who are pros. So nothing to worry about as long as it's done by the right people. As far as all the x-raying and proctology I say hogwash. If the repair has stood the test of time and use then it's fine. But I said that already.
Custom Projects
Scroll down to about the middle of the page and you can click on the pic to enlarge. BOB

I took an impromptu tour of the JSI facility a few weeks ago, while searching for some Edson long clevis fittings. Very impressive operation. The mast shop was doing a buildup as I walked through with the employee. The operation taking place looked just like the mast pictured here and it wasn't a repair, rather a new mast of considerable length.

I commented that it takes some skill to do what the worker was doing, and was told he's been doing it for 12 years now. And it's a common technique on long masts (and repairs too I'm sure).

I wouldn't be concerned in the least about the mast in question here. If it was painted no one would be the wiser. Anodizing is probably a better finish technique anyway.

bangkaboat · 04-06-2011, 15:23

So, what we don't know is whether; it was a repair or the result of the manufacturer joining two extrusions, the process used was TIG or MIG, it was a one-off or welded by someone who has done many.

As for the suggestion that the weld "is mostly just cosmetic", no, it is a structural weld that is under dynamic loads. Certainly, the sleeve & plug welds make an enormous difference, but the quality of that welded seam is crucial.

I suggest that the OP find out the details of the mast. If he can't get the answers, I suggest he have it inspected. The cost is small, compared to the cost of purchasing the boat. I always try to err on the side of caution, especially when someone is asking for advice, & make no apologies for that.