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 Post subject: Pitting of Centerboard Pennant Conduit
PostPosted: 15 Dec 2014 14:51 
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Skipper

Joined: 21 Oct 2006 15:36
Posts: 268
Yesterday, I removed the stainless steel conduit that guides the centerboard pennant. My initial purpose was to replace the hose that connects the conduit to the thru hull in the centerboard trunk. See the attached picture. The conduit end under the hose suffered from severe pitting. It's hard to see the extent from my picture, but in some places it was close to thru wall and was most severe at the second (outer most) hose clamp location. The good news is that I caught it in time and the pitting was confined to inside area covered by the hose. Just heads up for all you centerboard boat owners. You might want to check it out at your earliest opportunity.


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Jim Voelxen
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 15 Dec 2014 18:24 
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Skipper

Joined: 27 Oct 2006 10:32
Posts: 827
Good catch!
Obviously this anaerobic corrosion where the hose was slid over the tube, definitely something to be on the lookout for. I can imagine a slow leak at first without much indication except a bilge pump running occasionally then a more constant bilge pump, then a constant stream. I can't see where this would be catastrophic unless you did not heed the warning signs, then your bilge pump would fail when you're not aboard..............glug, glug, glug. Shocked

Think there's enough room to use a tubing cutter to trim off the corroded part then use a longer hose? I'm thinking of a repair without removal of the mast. Think you could fish the tube through the slot where the pennant leaves the mast? Maybe? Obviously, the boat would have to be on the hard, but I don't want to remove the mast if I can help it. Just thinking out loud.


 
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 16 Dec 2014 06:58 
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Skipper

Joined: 21 Oct 2006 15:36
Posts: 268
I think you're right about it's likely there would be plenty of prior indication before catastrophic failure caused by the pitting. Hose failure would be much more serious.

Regarding repairing the conduit with the mast stepped, can't be done. The conduit has a plate welded to it that is bolted to the mast step. Also, it's J shaped. It's hard enough to remove with the mast removed.

I'm thinking of 3 repair options: 1. Cut off the corroded piece ( about 2 in. ) and lengthening the hose an equal amount; 2. Leave the corroded section and just lengthen the hose; or 3. Cut off the corroded section and butt weld a new section of piping. I think all three will work but I think I'll try option 2 first. I like option 3 as well but need to find out if the the ID can be ground smooth so the weld doesn't chew up the pennant.

Any suggestions/opinions would be appreciated.

BTW, the conduit was fabricated from 3/4 in. Sch 40 ss pipe.

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Jim Voelxen
Odyssey #191
Home Port: Osterville, MA


 
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 16 Dec 2014 10:30 
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Skipper

Joined: 13 Feb 2011 21:19
Posts: 337
Location: Canyon Lake, TX
Oh, yes. Stainless Steel will rust in the absence of oxygen. This is something I need to put on the punch list for my next bottom job. This is the reason I removed all my vinyl coated lifelines and replaced them. Rust seeping through the cracks makes me doubt the strength of the underlying wire.

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I'm not a complete idiot, some parts are missing.
Subservient to no man except SWMBO
Any day without dock lines is a GOOD day!


 
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 16 Dec 2014 15:34 
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Joined: 29 Dec 2010 10:24
Posts: 191
I had the same problem which ,with a PO, nearly sank the boat in early 90's,she was luckily at a shallow dock at low tide and sat on the bottom with 9'' of water over the floorboards. I have to pull my mast anually and found my stainless tube was very badly pitted,this scared me so I 'reinvented' the system. [I took photos but they are in a hard drive which died] I visited the boat a few hours ago to de-snow and took these pics of my new tube. I purchased a 3ft of titanium,had 3'' knurled on the end [ for good grip in the epoxy ]then a 90 bend. I then heated and flared the end , I cut out the old fitting which is a stock thru hull with a flat machined of each side,then epoxied in the titanium,the mast base bracket is ss angle and g10.
Titanium is not supposed to corrode so wish me luck. I would go with option 2,longer rubber tube. Bruce


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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 16 Dec 2014 16:45 
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Joined: 27 Oct 2006 10:32
Posts: 827
Bruce,
Good idea to use titanium. Just went on Mcmaster-Carr and they have it for $70 for a 3ft section (seamless) and $116 for a 5ft.
http://www.mcmaster.com/#standard-titan ... ng/=v1wv6x

Seems like a small price to pay considering the importance level. If I pull the mast, I may do this in conjunction of other projects like mast steps, radar and possible re-wiring, maybe even a new AIS antennae??? Come on Santa, be nice to ol' Tortuga!


Last edited by Tortuga's Lie on 16 Dec 2014 16:47, edited 1 time in total

 
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 16 Dec 2014 16:47 
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Skipper

Joined: 27 Oct 2006 10:32
Posts: 827
OnlineMetals.com has it much cheaper, same stuff:

http://www.onlinemetals.com/merchant.cf ... p_cat=1353


 
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 Post subject: Re: Pitting of Centerboard Pennant Conduit
PostPosted: 26 Feb 2018 08:11 
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Skipper

Joined: 29 Dec 2010 10:24
Posts: 191
Hi Dave, the titanium is thinner wall than the stainless,I took it to my local metal fab/machine shop,they put it in a lathe and knurled a couple of inches ,then put it in a hydraulic bender,no problem,a nice smooth bend.
It’s over 40° today,off to the boat to install a new chain and cables in the steering,recommended after 10 yrs by the Edson rep. and a new led compass light. Bruce.

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