Changing Antifouling Bottom Paint from VC-17 to Micron CSC

VC-17 is great for fresh water but since Wild Horses will be spending her full-time future in salt water, she needs an antifouling paint that is less ablative than VC-17.  We DO NOT want to be in the business of hauling the boat out of the water every 3 or 4 months to apply new antifouling.

Hence, “change antifouling pain to something saltwater friendly” got put on our projects list.

Note to anyone thinking that this is a fun weekend project.  It is not.  It is not quick, easy and is nowhere near fun.  But getting some tips on what to do and what not to do, helps.  Here is our experience.

The major steps, in a nutshell…

1. Remove all VC-17
2. Apply a new coat of epoxy
3. Apply new coats of antifouling paint

​Crap, that sounds too easy.  Let’s unpack it a little.

Removing the VC-17

Sandblaster or DIY?  We went with DIY to keep the project within our budget and to control our schedule.   

• The advantage of getting a company to sandblast the boat bottom is that it can be done in a day, with no effort from us.  The disadvantages are (1) removal of good foundational layers of epoxy, (2) scheduling – sandblasters are busy and we were advised that our boat would have to be “fit” into their schedule (3) cost.  We were quoted $2,000 CAD for the sandblasting plus we would have to pay our marina $500 to move our boat to the sandblasting area of the yard. 
• DIY removal of the VC-17 took more of our time and effort but it was more cost-effective (see table below).  We also saved about $1,000 CAD in additional epoxy (4-5 coats) that we would have had to apply back onto the boat if we used the paid sandblaster.

Condition of hull after applying paint stripper

Close up view of remaining VC-17 after applying paint stripper

Mike sanding off the remaining VC-17

Applying epoxy and antifouling

• It is critical to start with a good base.  By removing the VC-17 ourselves, we could see that our hull was near perfect.  No cracks and no signs of osmosis (gelcoat blisters) or other fibreglass failures.  We also were able to ensure that we removed very little of the existing epoxy coats on the boat.
• Even though the existing epoxy coats were maintained, we still needed to apply one additional coat of epoxy.  Interprotect guidelines recommends applying your first coat of Micron CSC to the hull when the epoxy layer is still tacky.  This ensures that the antifouling paint is bonded to the epoxy and won’t peel off.
• Of course, the boat in her cradle is supported by boat pads, the hull under which also needed to be epoxied and painted.  We solved this by completing all epoxy and painting coats for the rest of the boat first.  We then attached jack stands to the hull so we could lower the cradle pads.  Being cautious, we only lowered half the pads at a time.  This increased our painting time but, more importantly, decreased our stress that the boat would move in its cradle.
• We applied three coats of antifouling paint using black, then red, then black.  Every other coat added in the future will be black.  The idea being that the red coat will serve as our “hey, you need to add antifouling paint” notification.

Wild Horses with a new coat of epoxy

First coat of antifouling

Second coat of antifouling

The finished product!