Author Topic: Paint Peeling on Keel  (Read 206 times)

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sjohnson

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Re: Paint Peeling on Keel
« Reply #4 on: September 24, 2017, 12:17:16 PM »
Andy and Andrew, thanks for your replies,  We also are suspecting some galvanic action as the zincs have been getting eaten up and we even started showing some corrosion on the prop with some minor pitting.  This issue just stared in the spring, while we have had the boat for 8 years.    We did have to move to a new marina after Hurricane Matthew, so that appears to be the biggest suspect.  We already have an issolator, so it may just be the boats around us.  In any event, we will do some testing once we are back in the water.  Interlux seems to be recommending their I-2000 primer over the Primacon.  Maybe we will give that a try on the bare prepped lead.

Knoxan

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Re: Paint Peeling on Keel
« Reply #3 on: September 24, 2017, 11:41:35 AM »
I have had this issue for 3 years now. At first a strange pink growth appeared near the bottom of the keel and when removed found some lead had evaporated. Filled the void, faired off, sanded down a large area of keel and applied new barrier coat over the area- 6 coats of primacon. Continued to lose more paint over next two years. More sanding and more primacon. Spoke briefly with a surveyor who was working on my boat and his opinion was galvanic corrosion and I should review all grounding. I very rarely use a pontoon berth and shore power so its leakage around my boat. However, I do run a generator daily and suffer from severe depletion on the propellor anode. I will review all grounding this winter and am now fitting a shaft grounding brush shortly to see if that helps with the prop anode.
As with all Hylas yachts just about everything is grounded but for me and my surveyor the jury is out over whether this is a good idea. The argument is either not to ground anything or make sure if you do you include everything and then make sure it is well maintained.

Andy
True Brew H46#32

Andrew

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Re: Paint Peeling on Keel
« Reply #2 on: September 23, 2017, 05:37:29 AM »
Hi Scott,
We had something similar- bottom paint flaking back exposing bright metal on the keel and heavy corrosion on through hulls.  This could have been a stray electric current on the boat, and we found some wiring that was not as it should have been, but in the end we blamed stray currents in the marina (Spanish town in Virgin Gorda) and a badly corroded earth contact in our Shore power plug lead.  We also fitted a galvanic isolator on the shore power lead .  We have not had the problem to the same extent since, but do still sometimes get a paint blister on the lead keel which needs to be scraped back, primed, filled and painted.  Our SSB radio uses the keel as an earth, and I have heard it should have diodes isolating it, but our radio has such great range I am reluctant to change it....
Cheers,
Andrew Eagle, (Hylas 51 "Hanne Danske"

sjohnson

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Paint Peeling on Keel
« Reply #1 on: September 20, 2017, 07:16:35 PM »
We recently hauled out in prep for Hurricane Irma.  Thankfully we did not get hit hard and no damage to the boat.   When we hauled, we found that the bottom paint on the keel was peeling off in round circles varying from maybe 1 to 8" in diameter.  The bottom was just done less then 4 months previous with Petit Ultima SR 60, a paint that has been very successful in our area (Beaufort SC).  Notably the hull paint looked great, the peeling was limited to the keel and around the through hulls.  Our boat yard is speculating that there appears to be some spots were the barrier coat on the keel  may have failed (just pin holes), causing a galvanic reaction between the lead keel and the metal in the paint.  Ultimately resulting in patches of paint pealing off. 

Was wondering if anyone else has experienced anything like this and if so what you may have found for a resolution.

Best Regards

Scott Johnson
L'ame Libre  H54 - #22

 

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