To sand or NOT to sand!

This post is so serve as a help for whether or not you want to embark on the adventure of sanding the bottom of your boat. It also has a bit of “Boat wisdom” in it.

These are my thoughts and hopefully they will help you to decide whether or not now is the time or…maybeee put it off next year.

I got Frigg up after having her for 2 years; previously owners took good care of her but admitted that every year they pressure washed the bottom and applied a fresh coat of self polishing anti-fouling on her…after at least 5 seasons her anti fouling dress was heavy, peeling off in thick layers. It was a sad surface to look at and reminded me mostly of moon surfaces and I´m pretty sure there was at least 0,5 knots lost somewhere in there. I did a test with a small screwdriver and scratching in areas of the anti fouling to check for paint adhersion. Need a say that with no pressure at all Frigg got more naked to the primer!

I called a paint company that have a wide assortment of marine paint. Send them a mail with images of Frigg’s underbelly. The advice was actually surprisingly funny. “Piss in your pants and paint another new layer on top now; but during the next season most likely you will have more growth and bigger areas of flaking anti fouling. Or you could do the right thing and strip the anti fouling right off and start a new treatment”… So what to do? Kevin San, You must Peel off, Sand down, Peel off, Sand down. I started a journey that would yeild surprises and some interesting labor.

The off Process.

1. Peel/Scrape. Get a good scraper, I got the Vacuum Pro Scraper, and scraped away. Surprisingly this was the easy part. Took me almost 7 hours to peel every side of the hull. Once you find the way that works for you, then peel away. I figured out that I had to use all my body to make long strong strokes, from top to bottom.
2. Sand. Sand Sand Sand. Get the best monster sander on the market. I went for the Bosch GEX 150 Turbo and got a hold of 40 grit high end bulk Sanding pads. A little tip. For the fun of it i tried the neighbors orbital sander. A good quality orbital from a respected manufacturer. The Bosch creamed it, eating away matter 3-4 times as fast. Rent or spend the money on the best sander there is on the market; everything else would be a waste of time and not make an already sour job better. I scanned the web to find out that the Bosch GEX 150 Turbo  and the Festool Rotex 150 are the king of the Orbital Sanders.
3. When done with sanding. Poke a hole in all the blisters, defects, weird looking thigs, flakes, and so on….everything you can find.
4. Filling. Fix all of the above with epoxy filler. I went for West System 105 epoxy resin with filling additives. This made me able to control the viscosity of my filler and depending of the fillers…the strength of the repair.
   

   Old paint blister

    

5. The sharp eyes will note that i did not remove all the primer down to the fiberglass. I really didn’t see the point to remove good and sound epoxy primer, just to add time and money on new. I double checked with the previously noted paint company (that most likely supplied it earlier) and they agreed with me. If it was their product, just leave it. Grit it with 80-120 grit paper and then recoat with an epoxy primer.
6. When the bottom is as smooth as she can get, then comes the sweet part. PAINTING!

The on Process

1. This is the best part. Adding to project instead of removing. Let me digress for a bit. Admittedly I’m a nerd and aware of spending money; you can buy a lot of great epoxy primer products premade from various suppliers, but i thought…”Could i make something better and cheaper”? I was using West System 105 epoxy for the filling and building part and tada, they actually had a recipe for what i needed. What I needed was an “Epoxy Barrier” to keep water out from the laminate. I dont’t want to diss suppliers but I got the advice from a paint inspector once. “Read the VOC content”! Volatile organic compounds is the vapors that dissipate when the product dries/cures. The higher to VOC level, the less of the good stuff you actually get left. For example a good paint will have around 40-50%. Rolling back. Epoxy barrier from Supplier A had a VOC at 51% and West Systems Barrier Coating Recipe had 7%. Wait….what!?  So this means when you roll on your coat with Supplier A almost half is going to disappear and with West Systems only 7? Yep! Using good old math this means that you need roughly 2x as many layers with supplier A’s epoxy barrier compared to West Systems. Also, VOC are freakingly annoying if there is a fault in over coating intervals. You risk trapping VOC’s inside the previously layer and that will cause blisters….. I digress but I do love the West System product and if you are curious about what I used above; then read West Systems own guide on Barrier Coating. Go to section 5 in the Gelcoat Blister Guide
2. After a long day with adding 3 generous coats of WS epoxy with 422 additive ( I already had a good layer of Epoxy Barrier from another supplier on the hull. Originating from the previous owner) we waited for the last hours of the day. Just before the sun set and the dew started to sneak into the air. Then we applied the anti fouling. I went for a Hard anti fouling as a base layer. Which anti fouling is better then the other is an entirely different discussion. The Anti fouling, that cures fast, was applied in the last moment of the day to seal of the Epoxy coats that was still curing (can take up to 10 hours). This was done to ensure a chemical adhesion and to stop the Epoxy from creating Blush. A waxy film on the surface of cured Epoxy.
   

   Frigg with 3 layers of West System 105 with 422 Barrier Coating additive

   

3. That was pretty much it. Next was 1-2 more layers of anti fouling. In total i’ve spend 7 days with 8 working hours. The hull measures 28 m2 roughly.

 

The mental part

It is not hard, annoying, dirty…period! If you think like that it will be! I’ve been approached by quite a few people during my work saying this is the worst about having a boat. The worst job they know. They have soo much sympathy for me right now.

Hell, I really enjoyed it! I had good music in my ears when it was just monotone work. There is something about fixing something you hold dear; it doesn’t matter that it gets nasty, dirty and so on…As long you don’t let the mind turn sour.