Keel/Bottom

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rafontaine1
Posts: 42
Joined: Sat Dec 27, 2008 11:34 am
Location: Liberte, F36, 1986, Portsmouth RI

Keel/Bottom

Post by rafontaine1 »

In 2019 I had my marina sand and paint bottom with Micron WA. All previous years I use Micron CSC. I stay in water at least 3 years and use diver on non hauled years to clean bottom. Boat stays in water all winter and I hang a 2 in x 8 in zinc over side connected to bonding system of boat. When I came back to boat in spring of 2020 the zinc was completely gone. In July of 2020 when diver cleaned bottom he noticed a large areas on side of keel and around a few thru hulls that had what he called looked liked watermarks with large accumulation of barnacles. When marina hauled this week they noticed the following from pictures below. They immediately thought I had a bonding issue. One of my thru hulls is not bonded and had none of the effects as noted in pictures. Every thing that was bonded is shown in pictures. I checked the connection from outside the hull between each of the affected thruhulls, the strut, a bare spot of lead on bottom of keel, and between three of the exposed keel bolts to the bonded keel bolt in the bilge. All read within a few tenths of an Ohm.
Checked from the male end of the power cord from the ground pin to a thruhull and that read open with the normal diode and capacitive action of the galvanic isolator. Ground to Neutral and Hot pins of the male end of power cord were isolated just as they should be. The shaft was isolated from the bonding system since it connected thru transmission and that is not a good electrical connection to engine.
In the past when I did my own bottom I always coated any bare spots on keel and any exposed metal on thruhulls and strut with epoxy primer Interlux 2000E or similar. I asked marina to do the same and bill me for the primer. Boat was sanded one day and bottom paint applied the next. I never received a bill for the epoxy primer paint. What are your thought and what affect would be realized if one applied copper based paint directly to lead keel or bronze substrate?

Ok to jump to a conclusion my thoughts are galvanic corrosion and not elelctrolysis. Thanks to the 2in x 8in zinc that was hanging off side connected to the bonding system of boat it protected the lead keel and thru hulls. I am confident that the problem was a result of copper paint on lead keel substrate with lack of primer. The marina keeps pointing to bonding issue which I already confirmed was ok. Now the latest today was there paint guru (I think that is what he was) looked at the paint chips I pulled off the keel with a putty knife and claimed there was filler between the keel and the grey/light colerd epoxy coating (I believe what he was referring to was Interprotect 2000). I believe Freedom used epoxy sim to west sytem to fair lead keel to bilge stub. The person grinding keel today was having a tough time grinding it down to bare lead and refered to it as a dark green or grey colored material. She thought is was applied by the manfacturer which I agreed. I was able prior to marina attacking the grinding was to with a couple of putty knives force off a good percentage of the epoxy coating to which now there is only about 75% that is left to grind off. FYI I contacted Interlux and they agree one shoud never apply copper bottom paint to bare lead.
I also used a silver cell over side and checked levels to each of the bonded parts (thruhulls and keel). All were within the protected levels for their corresponding metals.

I firmly believe marina is trying to cover their butts. Which I completly understand but they are not dealing with your typical know nothing boater. I've been doing this for over 40 years and 20 years with this boat .I know my boat. I stripped her down in 2001 and rebuilt her.
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Rich Fontaine
s/v Liberte
Freedom 36, 1986
Portsmouth, RI

dwight
Posts: 63
Joined: Sun Dec 07, 2008 3:41 pm
Location: Newport, RI
Contact:

Re: Keel/Bottom

Post by dwight »

Rich

It looks like a case of stray current corrosion. The "extra" anode saved the majority of the underwater metal from severe damage. A galvanic isolator is overcome by stray current in excess of 1.4 volts. When overpowered, it can't do anything to prevent corrosion.

The isolator should prevent current flow below 1.4 volts and conduct above that. A quick test is to put a clamp-on meter on the shore power cord. If you have a reading on the meter, the isolator is not working. Use your reference cell to measure the hull potential onboard and the dock potential from the shore power ground. This will tell you if the problem in on the boat or the dock.

If it is on the dock use the clamp-on meter around the shore cord and note the reading. Clamp the shore cords on nearby boats. The one with the highest reading has an issue onboard.

Finding corrosion problems can be a tricky issue. In your case the conditions have changed by hauling the boat. Other nearby boats may also have changed. Unless the problem is onboard, you will likely never find the source.

You were correct to check the bonding. You also got to see firsthand how an unbonded thru-hull fitting was not affected by this problem.

I see you are in Portsmouth, RI. I specialize in electrical and corrosion problems, let me know if you would like me to take a look.

Dwight C. Escalera
SAMS (R) Accredited Marine Surveyor #1024
ABYC (R) Certified Master Marine Technician
Executive Marine Services, LLC
Newport, RI 02840
Phone: 401-369-0487
Dwight@ExecMarine.com
www.ExecMarine.com
Dwight Escalera
Accredited Marine Surveyor, SAMS #1024
former engineer at Freedom Yachts
former owner F36-71
Wakefield, RI

rafontaine1
Posts: 42
Joined: Sat Dec 27, 2008 11:34 am
Location: Liberte, F36, 1986, Portsmouth RI

Re: Keel/Bottom

Post by rafontaine1 »

Dwight
Thanks for your reply. I value your opinion on the matter.
I've been in the same slip since before owning this Freedom in 2001. Granted surrounding boats change from time to time so trying to nail down the culprit at this time is difficult. Years ago I built a test cable/box with 30 amp male and female ends to which I installed a switch in box to open the ground connection with test points across the switch to connect to a meter to measure leagkage current. The test cable gets inserted between power cord and dock receptacle. Same principle as clamp on meter but I believe a lot more sensitive. Using my Fluke multimeter I measured AC and DC stray current at basically 0 ma. The highest voltage across the open switch was 162mVac and 0.01Vdc. These are all measure with galvanic isolator in place and AC loads in boat turned on. My FLuke meter has a diode test range which applies a voltage across the test diode to check forward bias voltage of diode. Tested in both directions by reversing test leads voltage was 0.765 volts so good indication diodes are functioning. From what I recall when I checked the function of the diodes years ago this is what I was reading on a 20 year old Guest Galvanic Isolator with this meter. Voltage is a function/limited by the internal battery in multimeter.

The biggest change I can see is the marina in spring of 2019 sanded and painted my bottom and I remember seeing bare spots on keel after they sanded to which I suspect copper based bottom paint was applied since they never charged me for primer which I asked them to apply and timing between sanding, applying suitable coats of primer and painting bottom doesn't fit. Plus in the areas where corrosion was evident there was clearly evidence the epoxy barrier coat on keel was feathered and exposed lead was evident. I always prime keel bare spots, thru hulls and strut before applying bottom paint. One thru hull that I replaced at that time appeared to have copper paint right on the thru hull when I cleaned them all this year. Marina has recenlty ground down keel to bare lead and promptly applied interprotect 2000 so we are starting out fresh barrier coat on keel. They also applied same to thru hulls as I requested so we should have good isolation between the copper paint and metal parts. I am applying bottom paint this time to make sure there is no bottom paint on exposed metal. As a point of information the strut which is bonded to keel and thru hulls showed no sign of what is visible in the pictures. I personally primed that one along with prop and shaft and applied Velox Plus antifouling in 2019.
Rich Fontaine
s/v Liberte
Freedom 36, 1986
Portsmouth, RI

dwight
Posts: 63
Joined: Sun Dec 07, 2008 3:41 pm
Location: Newport, RI
Contact:

Re: Keel/Bottom

Post by dwight »

Rich

It sounds like you are well versed in the ins and outs of corrosion and have the problem well in hand. I taught the ABYC Corrosion class for several years and still enjoy the challenge of tracking down these issues.

Although I no longer own a Freedom, I built many of the Freedom models over the years. 12 years ago, when my youngest went off to college, I sold my Freedom 36 and took up competitive racing, I but continue to be a big fan.

If you would like to discuss this or any other specific issues, please feel free to contact me directly.

Cheers
Dwight
Dwight Escalera
Accredited Marine Surveyor, SAMS #1024
former engineer at Freedom Yachts
former owner F36-71
Wakefield, RI

rafontaine1
Posts: 42
Joined: Sat Dec 27, 2008 11:34 am
Location: Liberte, F36, 1986, Portsmouth RI

Re: Keel/Bottom

Post by rafontaine1 »

Dwight
I don't claim to be an expert but I did purchase years ago a copy of "Boat & Yacht Corrosion Control" by Yacht Corrosion Consultants Inc. which I use as refernce material. I guess I know enough to get myself in trouble. LOL A degree in Electrical Engineering helps.
Rich
Rich Fontaine
s/v Liberte
Freedom 36, 1986
Portsmouth, RI

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