Has anyone used POR-15 on a rusting iron keel?

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  • Norman Bernstein
    Liberaltarian
    • Nov 2004
    • 25217

    Has anyone used POR-15 on a rusting iron keel?

    The cast iron keel of my boat has sprouted a fair amount of rust break-through... it's a 2005 Jeanneau, which is built with an iron keel that was covered with gelcoat at the factory. Over the years, as one would expect, the gelcoat has crazed and cracked, permitting rust to break through the coating. In previous years, I've sanded it and covered it with bottom paint, but this year, the rust has really taken over, so I'm going to have the keel soda-blasted down to bare bright metal, and plan to immediately apply a zinc phosphate coating, followed by two coats of POR-15, a rust-preventative paint, to be used as an undercoat for my regular bottom paint.

    I was wondering if anyone had experience with POR-15, and could offer any tips?
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."






  • Bob Adams
    Senior Member
    • Sep 2000
    • 12085

    #2
    Re: Has anyone used POR-15 on a rusting iron keel?

    I've used it on my cast iron heat exchangers. I just chipped the loose rust and applied. Held engine enamel well enough. I dunno about antifoul.
    You must be the change you wish to see in the world."
    Mahatma Gandhi

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    • Iceboy
      Frozen Member
      • Feb 2001
      • 2743

      #3
      Re: Has anyone used POR-15 on a rusting iron keel?

      I've used it on several trailers with no issues at all. I don't recommend getting it anywhere you don't want it though. It has to wear off of your skin.
      The best helping hand you will ever receive is the one at the end of your own arm.

      Comment

      • willin woodworks
        Senior Member
        • Jan 2011
        • 3345

        #4
        Re: Has anyone used POR-15 on a rusting iron keel?

        Anything with a name like POR-15 has to be overpriced...I cleaned a rusty iron keel with sanding discs and a wire wheel and hit it with two heavy coats of Rustolem Rusty Metal Primer. Waited a week and painted it with Petit Hard Ablative anti foul and it worked a charm. Rustoleum is cheap and readily available.....just my two cents worth...

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        • Bob Adams
          Senior Member
          • Sep 2000
          • 12085

          #5
          Re: Has anyone used POR-15 on a rusting iron keel?

          Originally posted by willin woodworks
          Anything with a name like POR-15 has to be overpriced...I cleaned a rusty iron keel with sanding discs and a wire wheel and hit it with two heavy coats of Rustolem Rusty Metal Primer. Waited a week and painted it with Petit Hard Ablative anti foul and it worked a charm. Rustoleum is cheap and readily available.....just my two cents worth...
          It's really not that pricy, and it cures with moisture. Harder than Rustoleum too. I like and use Rustoleum, just sayin.
          You must be the change you wish to see in the world."
          Mahatma Gandhi

          Comment

          • John B
            Senior Member
            • Aug 2000
            • 31703

            #6
            Re: Has anyone used POR-15 on a rusting iron keel?

            Its single pot . I've used it it on cars and for the boat gearbox etc but I would be looking into a two pot system for a job like that.

            Comment

            • David G
              Senior Member
              • Dec 2003
              • 89688

              #7
              Re: Has anyone used POR-15 on a rusting iron keel?

              I've used it on several things, including a boat trailer, and an outdoor table. Quite pleased with the results, but the smell bothers me the way very few solvents do.
              David G
              Harbor Woodworks
              https://www.facebook.com/HarborWoodworks/

              "It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)

              Comment

              • Garret
                Hills of Vermont
                • Apr 2005
                • 48618

                #8
                Re: Has anyone used POR-15 on a rusting iron keel?

                I went the hard way: hit with air hammer until shiny (the keel - definitely not me!) & then coat in epoxy. I mean air hammer - a needler wouldn't touch it. I did it in roughly 2'x2' patches - based mostly on how long I could stand the vibration, tyvek suit, mask, ear defenders & face shield. The bottom of the ballast was particularly fun. I'll need to do a couple of small sections after the next boat move because the blocking covered some.

                We'll see how it stands up.
                "If it ain't broke, you're not trying." - Red Green

                Comment

                • jeaustinsail
                  Junior Member
                  • Nov 2014
                  • 5

                  #9
                  Re: Has anyone used POR-15 on a rusting iron keel?

                  I used that approach on my Tanzer 22's iron keel (boat is long since sold). From what I read in preparation, it was extremely important to seal the keel as soon as possible after blasting, sanding or whatever technique you use to get to bright metal. For that reason I had the first coat of primer on it within an hour of sanding it down. Kept the boat 3 or 4 years after that sealing, and the POR 15 did the job for me.

                  Comment

                  • ShoestringMariner
                    Senior Member
                    • Jul 2014
                    • 281

                    #10
                    Re: Has anyone used POR-15 on a rusting iron keel?

                    DO NOT USE POR on smooth, fresh metal. It needs a tooth to adhere such as rust or sandblasting. It will come off in sheets otherwise. Clean cast iron is still too smooth even.

                    Comment

                    • The Bigfella
                      Banned
                      • Oct 2006
                      • 11600

                      #11
                      Re: Has anyone used POR-15 on a rusting iron keel?

                      Originally posted by ShoestringMariner
                      DO NOT USE POR on smooth, fresh metal. It needs a tooth to adhere such as rust or sandblasting. It will come off in sheets otherwise. Clean cast iron is still too smooth even.

                      Yep. I've had both good and bad results with it. Don't really know why some worked, some didn't....

                      Comment

                      • Norman Bernstein
                        Liberaltarian
                        • Nov 2004
                        • 25217

                        #12
                        Re: Has anyone used POR-15 on a rusting iron keel?

                        Originally posted by jeaustinsail
                        I used that approach on my Tanzer 22's iron keel (boat is long since sold). From what I read in preparation, it was extremely important to seal the keel as soon as possible after blasting, sanding or whatever technique you use to get to bright metal. For that reason I had the first coat of primer on it within an hour of sanding it down. Kept the boat 3 or 4 years after that sealing, and the POR 15 did the job for me.
                        The outfit that does the soda-blasting tells me that they will be able to bring the keel down completely to bare, bright metal. There's no way that I could do the same with sander, grinder, or any other tool... for one thing, my bad back would give out long before the job is done. This soda-blasting is expensive... but if the entire project works, it will solve the problem for longer than I'm likely to own the boat.

                        My intention, with the assistance of the contractor, is to get the zinc phosphate converter onto the bright metal within an hour of soda-blasting. According to the POR folks, that will do the trick. I then have to wait until the keel is completely dry before coating with POR-15, using two coats... the second applied in about an hour, after the surface is barely tacky. Total cost for the zinc phosphate converter and POR-15 was $138.

                        After that, I'll apply my usual bottom paint: Pettit Hydrocoat, the best damn bottom pain I've ever used. It's half the price of a solvent paint, and after a season's worth of use and a quick power wash, it looks virtually as good as the day I applied it. With no solvent smell, and easy water wash-up, it's a no-brainer.
                        "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."






                        Comment

                        • Dave Hadfield
                          Senior Member
                          • Apr 2000
                          • 7458

                          #13
                          Re: Has anyone used POR-15 on a rusting iron keel?

                          You need to watch for condensation too. If the keel is cold, and the air is warm and moist, there will be a film of water on it seconds after the media-blasting stops.

                          Comment

                          • Norman Bernstein
                            Liberaltarian
                            • Nov 2004
                            • 25217

                            #14
                            Re: Has anyone used POR-15 on a rusting iron keel?

                            Originally posted by Dave Hadfield
                            You need to watch for condensation too. If the keel is cold, and the air is warm and moist, there will be a film of water on it seconds after the media-blasting stops.
                            That's certainly true, but there's not much I can do about that... supposedly, the zinc phosphate converter is the thing to ameliorate that problem. I do have an agreement with the contractor, to insure that the whole thing is scheduled so that I can be there, with the requisite products, as soon as he's finished the job.

                            Moist air, by the way, is actually an advantage, since POR-15 is a moisture-cured product. If it's very dry, it might take a long time for the first coat to 'tack up' sufficient to apply the second coat.
                            "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."






                            Comment

                            • BrianM
                              Wood-And-Boats
                              • Sep 2002
                              • 1237

                              #15
                              Re: Has anyone used POR-15 on a rusting iron keel?

                              Originally posted by Norman Bernstein
                              The outfit that does the soda-blasting tells me that they will be able to bring the keel down completely to bare, bright metal. There's no way that I could do the same with sander, grinder, or any other tool... for one thing, my bad back would give out long before the job is done. This soda-blasting is expensive... but if the entire project works, it will solve the problem for longer than I'm likely to own the boat.

                              My intention, with the assistance of the contractor, is to get the zinc phosphate converter onto the bright metal within an hour of soda-blasting. According to the POR folks, that will do the trick. I then have to wait until the keel is completely dry before coating with POR-15, using two coats... the second applied in about an hour, after the surface is barely tacky. Total cost for the zinc phosphate converter and POR-15 was $138.

                              After that, I'll apply my usual bottom paint: Pettit Hydrocoat, the best damn bottom pain I've ever used. It's half the price of a solvent paint, and after a season's worth of use and a quick power wash, it looks virtually as good as the day I applied it. With no solvent smell, and easy water wash-up, it's a no-brainer.

                              I'd add a simple step Norm. After the POR-15 (converter), then slather a good thick coat of Coal Tar Epoxy.... Then the bottom paint. The protective skin left by POR-15 performs well in the environment it was devised for (car fenders!). The coating is very thin. The Coal Tar Epoxy will give you a bit of a shock absorber between any contact on the bottom paint and the underlying metal.

                              This combo worked great on my iron keel in all the spots I was able to get down to bare metal and bottom paint (red vinyl) sticks REALLY well to the epoxy.
                              Last edited by BrianM; 04-20-2017, 12:36 PM.

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