Be Aware of welding flaws - aluminum masts with welded pad eyes.

M

Mitch Witt

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Nov 25, 2011
14
Beneteau First 42 In Transit
I am seeing an increasing number of aluminum masts on catamarans that have one or more welding problems. This issue centers on pad eyes welded near the mast head for forestay and port & starboard stays. I have seen minor stress cracking from improper weld procedures (too hot) and I have seen catastrophic cracks through the throat of the weld due to improper weld joint design. If you have welded pad eyes it is worthwhile to take a close look at these welds, take photographs and monitor them for change. There is no logic that forgives cracks in welds. Purpose of this post is to announce the observations so that others with same type mast can be aware of this potential problem. If found it would help to hear about it.
 

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JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,745
Hunter 430 Waveland, MS
This is a guess...
There mast stays are too loose and allow mast flex in the area of highest stress.
Jim...
 
A

AWalker

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Nov 13, 2011
163
Oday 23 New River Az
Might stem from improper rig tuning was what I think he was getting at.
A couple of those look to be repair welds. The biggest problem with that is that there is no post weld heat treatment (assuming there was when the mast was made) and therefor the weld area is surprisingly soft. The original extrusion likely was in a T-10 state, then after welding is is very close to a T-0 state 10 being as hard as the alloy can be and still be malleable and 0 being completely soft. That type of weld process, MIG spray welding, done with a spool gun, is very hot by its nature. It can't very well be turned down, as it then becomes short circuit welding which causes a lack of fusion.
I am not seeing a lack of fusion, just fatigue in the heat affected zone. TIG welding would be better, but there will still be a heat affected zone that is soft.
I would think the fix would be, better rig tuning, and re heat treating of the mast after repair. Since that is not practical, I would suggest welding a plate around the repair area, then welding the eye back on. This would spread out the load over the annealed aluminum in the heat affected zone.
 
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woodster

woodster

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Sep 15, 2009
6,243
S2 9.2a Fairhope Al
from looking at those weld failures it appears to me...there was insufficient metal prep...welded without grinding the weldment
and welding on top of a anodized surface....typical production shop procedure ...find you a good certified pipe welder to do the repair...and see that his papers are current
 
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sailnoproblem

sailnoproblem

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Oct 10, 2011
619
Tartan 34C Toms River, New Jersey
looking at photo 7363 this is a TIG weld. The weld is also cold as the penetration on the mast is minimal. The weld beed is way to small. If properly done even over the anodized mast, the weld should hold.
Aluminum welds are soft, but if done properly this weld should not have cracked.
When you get it repaired take it to a reputable Tuna Tower fabricator. Do not worry about certifications, because most certs are for one type of welding, which may not have anything to do with Anodized Aluminum TIG.
Trust me I did it for over 30 yes.
 
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JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,745
Hunter 430 Waveland, MS
Oh My Gosh! SBO has an expert welding crew too. You guys are great! I have done forensic weld analysis and those pictures have a combination of failures. The crack in the center of the weld is fatigue (again my guess).
I have cautioned, in many thread, about mast tuning. Even slight continuous movements will fatigue the best welds over time.
As kids we used to wiggle a coat hanger fast enough to break the metal and the touch the break for extreme heat.
Jim...
 
M

Mitch Witt

.
Nov 25, 2011
14
Beneteau First 42 In Transit
JamesG161 said:
Oh My Gosh! SBO has an expert welding crew too. You guys are great! I have done forensic weld analysis and those pictures have a combination of failures. The crack in the center of the weld is fatigue (again my guess).
I have cautioned, in many thread, about mast tuning. Even slight continuous movements will fatigue the best welds over time.
As kids we used to wiggle a coat hanger fast enough to break the metal and the touch the break for extreme heat.
Jim...
Click to expand
The 1/2" thick pad eye needs a plate beneath it to transition between the pad eye and the thin wall mast. And yes, welding professional here.
 
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M

Mitch Witt

.
Nov 25, 2011
14
Beneteau First 42 In Transit
sailnoproblem said:
looking at photo 7363 this is a TIG weld. The weld is also cold as the penetration on the mast is minimal. The weld beed is way to small. If properly done even over the anodized mast, the weld should hold.
Aluminum welds are soft, but if done properly this weld should not have cracked.
When you get it repaired take it to a reputable Tuna Tower fabricator. Do not worry about certifications, because most certs are for one type of welding, which may not have anything to do with Anodized Aluminum TIG.
Trust me I did it for over 30 yes.
Click to expand
So have I and the problems stem from not having a written weld procedure for the welder to follow exactly for every weld. A tuna tower fab guy is no guarantee of anything.
 
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sailnoproblem

sailnoproblem

.
Oct 10, 2011
619
Tartan 34C Toms River, New Jersey
The Blue Gen said:
So have I and the problems stem from not having a written weld procedure for the welder to follow exactly for every weld. A tuna tower fab guy is no guarantee of anything.
Click to expand
true a tuna Tower fab guy is no guarantee.
 
C

Cayennita

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Nov 28, 2009
495
Catalina 30 St. Croix
I see some sugaring from insufficient shielding gas. A fillet weld done to teo materials of very different thickness. Probably no gap betwwen the two. Too much heat for such a small area. If no preheat then the welding should have been done incrementally. With MIG many welders will try to do the job in one pass.
My Catalina 30 mast had broken at the spreaders. After cutting and cleaning. 1"" holes were drilled on both sides in staggered locations and then a 3' sleeve sliped in. It was done with slug welding. 4 new spreader support plates were then welded using TIG after a little bit of preheat. Insulation blankets were laid on to slow down the cooling. After priming and painting and stepping the mast. We tuned it keeping the lowers slightly loose for better sail shape.
Raced in two regattas with a total of seven days with winds gusting over 30. No problems.
 
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JamesG161

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,745
Hunter 430 Waveland, MS
Cayennita said:
After priming and painting
Click to expand
The aluminum welds on a anodized mast, are normally NOT anodized and are subject to more corrosion.
Is this the area of priming and painting? What paint did you use?
Jim...
 
C

Cayennita

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Nov 28, 2009
495
Catalina 30 St. Croix
I cleaned the mast with acetone, then spray painted the protective coat with the same paint used on aircraft (green). Sorry, I can't remember the name and followed that with one part white in spray cans from Rustoleum. Cheap but effective. I don't know how to post pictures from my ipad.
 
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