Stress cracks in Stainless Steel Arch on my Hunter 306

Oct 14, 2017
101
HUnter 306 Aruba
While doing the monthly maintenance SS cleaning on my Hunter 306 arch I noticed some stress cracks. The pictures show the small hairline cracks on the support pipes (port side both) and the plate that holds the boom traveler (also port).

Has anyone experienced these type of cracks and can these be grinded out and rewelded to keep it's strenght?
 

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JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,770
Hunter 430 Waveland, MS
The Arch has the Traveler Stress on it.

Needs welding or the Boom will lift and be a big issue.

Jim...
 
Nov 6, 2006
10,093
Hunter 34 Mandeville Louisiana
All of those resemble poultice corrosion..Intergranular corrosion from being covered and remaining wet .. it looks as if the straps that went around the tube did not breathe and water remained to corrode the stainless. A stainless sleeve could be welded over the corroded area .. or a new tube installed. That can't be fixed.
 
Jun 25, 2004
490
Hunter 306 Pasadena MD
Wow! I have a 2004 306, and I've never seen anything like that. It's hard to believe! Frankly, the arch is so tremendously oversized that I can't see normal tension from the boom causing it. I really have no idea how you should handle it.
 
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JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,770
Hunter 430 Waveland, MS
the arch is so tremendously oversized that I can't see normal tension from the boom causing it.
When I took Materials Engineering our Professor told us this example.

"Take a Walnut and hit it with a Big Hammer, the Walnut is crushed."

"Take a Walnut and hit it with a tiny Tack hammer, it may take 1000 hits to break the Shell."

Jim...
 
Oct 14, 2017
101
HUnter 306 Aruba
Thanks for the feedback. Already in talks with welder(s) on island. The arch was never covered with any cables or straps. We do sail in heavy winds at times and have had the main fly across during a jibe in heavy winds that rocked the arch.
We just repaired the life line stanchion bases on port side (arch issues are also on port side) due to corrosion, the bow stanchion was made new. The slip is 90 degrees in the wind coming from port @ an average of 15Knots or higher daily. That might be the cause of salt penetration into small cracks that only get worst over time.

Will keep you posted on next steps.
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
7,770
Hunter 430 Waveland, MS
That is a stress crack , rare to happen unless Oxygen is starved from the Stainless Steel. That is why @kloudie1 suggested the strap preventing Oxygen.

Jim...
 
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Oct 14, 2017
101
HUnter 306 Aruba
Anyone have an idea as to where one can find drawings for the Arch? Looking at the possibility of making a new one. I've reached out Mike at Sailboatowners who could not help, seems the hunter/marlow team is also not an option.
 
Jan 19, 2010
12,565
Hobie 16 & Rhodes 22 Skeeter Charleston
There was a shop not far from one of my former houses that would make custom SS cargo racks for trucks. I know a guy who went to them and asked them to fabricate one for his pontoon boat and it came out fantastic. If you could find a custom auto body shop doing something similar, you might ask them to come take the measurements. And being pros in the arch/rack biz, they might have other ideas for you to consider.
 
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Likes: Brinky63
Oct 14, 2017
101
HUnter 306 Aruba
There was a shop not far from one of my former houses that would make custom SS cargo racks for trucks. I know a guy who went to them and asked them to fabricate one for his pontoon boat and it came out fantastic. If you could find a custom auto body shop doing something similar, you might ask them to come take the measurements. And being pros in the arch/rack biz, they might have other ideas for you to consider.
We have several machine shops that can get this done on island. Plan is to remove the arch next week so they can use it at the shop to make a new one. hopefully we can still use the traveler plate.
Will keep you posted. thanks for the input.