Choosing a Bottom Paint for Dummies

Posted by Darrell Nicholson at 01:35PM - Comments: (6)

It's easy enough to choose the most effective paint from our semi-annual bottom paint reports, but that paint might not always be the best for your circumstances or location. For this reason, Practical Sailor always recommends a variety of paints, each suited for a specific preference or situation that a sailor might face.

Unless you’re prepared for more prep work than a light sanding, the first step in selecting a bottom paint is finding one that’s compatible with what’s on your hull now. All of the manufacturers in our test will provide guidance on this, either over the phone or on the company website. If you’re voyaging internationally, Interlux (under the brand International Paints) offers the widest distribution, simplifying finding a match.

Generally, you can repaint a hard paint with either a hard or soft paint, while a soft ablative paint will need more sanding or a “tie-coat” primer when being coated with a hard paint. Bare fiberglass or metal will require a primer, and aluminum components like saildrives need a special copper-free paint that won’t induce potentially disastrous galvanic corrosion.

Twice each year, Practical Sailor reports on its comprehensive bottom paint tests.

Before plunking down nearly $100 or more a gallon, consider where your priorities lie.

Simple application: With no unpleasant solvents, water-based paints are easy and safe to apply.

The environment: Driven by new and pending legislation regulating copper, this is a fast-growing field. In recent tests, the copper-free blends from Epaint have proven the most effective. This is good news for owners of aluminum boats, which are incompatible with most copper-laced paints.

No paint buildup: Over time, ablative paints wear away; hard paints generally form thick layer cakes.

Quick recoating: Hard paints can take a second coat sooner than ablatives, although some of the newer co-polymer ablatives can be recoated after four hours or less. Thin-film Teflon paints for racing boats can dry in a matter of minutes.

Haulout schedules: Some  paints (typically hard paints) lose their effectiveness if not launched within a certain time frame, or if the boat is hauled out and then relaunched without painting. Some paints you need to lightly sand or scuff to reactivate before relaunching.

Trailerability: Some ablative paints are designed to resist abrasion from trailering. Most hard paints will trailer well, but not all are meant to dry out.

Color: Pettit Vivid, Interlux Trilux, and Blue Water Kolor offer broad palette choices. Typically, the low-copper paints (Epaint being an exception) offer more color choices. If potency is what you're after, some makers suggest black, although our panel studies are inconclusive regarding this. Some brands (such as Pettit) put a little more copper in some of their red paints.

Want to be a part of our bottom paint testing program? Fill out this quick survey so we can share your experience with other sailors. 


Comments (5)

Wait! Look objectively at this biofouling problem & goal of preserving our waterways & seafood-- the options to investigate are lower-cost barriers/membranes that float around your boat (with fresh water next to hull) &/or include a sump-pump so that your boat floats dry & *un-painted next to your dock. Of course, cruising away from your dock > 2 weeks might require toxic metals/poisons on your hull. John Reeves Va.

Posted by: John R | April 2, 2013 10:02 PM    Report this comment

Something that PS hasn't spent much time discussing is how the boat is really (and honestly) used. Most ablative paints need to be moved through the water regularly to remain effective and not "slime over". The rule of thumb a paint rep gave me was a minimum of 4 kts for a half hour every week. That has proved out on my own boat. On the other end of the spectrum, if your boat runs hard and fast for extended periods, your ablative may wear off earlier than expected. As you point out the paint needs appropriate to the location, the boat hull material, the use, and the duration between haul outs. One final note is that in the water scrubbing of bottoms coated with pesticide based antifoulants is restricted in some areas. Further, the wash water generated during power washing of bottoms must also be managed appropriately, it can contain significant and toxic levels of metals. Most yards and marinas must collect the wash water for proper treatment or disposal. Boats with "foul release" coatings can be scrubbed in the water and power washed to your hearts content making them the greenest choice of all but certainly not feasible for many boats, including my own. I have had good luck with a couple metal free paints, adhering to the rule of thumb above, in the cold water and short season of mid-coast Maine.

Posted by: Pam P | March 26, 2013 12:17 PM    Report this comment

I often read that hard antifouling paints are preferred for racers.
Does somebody know how much faster my boat would go if I use a hard paint vs. an ablative one ?
Woul dhte improvement be in the order of 10% ?
Thanks for helping.
Ed Lentz

Posted by: Voilactus | December 5, 2011 2:22 PM    Report this comment

Generally, if your paint is fending off hard growth for 2-3 years, you are doing well. You can add some endurance to the Interlux Micron paints (and most ablatives) by putting three coats on the hull and four on the leading edges and waterline--or even four coats on the whole hull. Just make sure you allow enough time to dry between coats. If you clean the hull, start with the least pressure--a soft t-shirt-- before moving on to sponges, and/or a 3M scrub pad. Avoid removing any of the antifouling coating.
Switching to a newly introduced paint can be tricky. We've seen some of these new formulas fall flat, or go through a few different iterations before the maker finally settles on one that works. There are plenty of good paints with long track records that we have more reliable data on. Our latest bottom paint report is due out in a couple of weeks.

Posted by: Darrell | September 6, 2011 10:10 PM    Report this comment

My Pearson 26 is on the Potomac near Mason Neck, well upriver (fresh water). I've been using Micron Extra and have regularly gotten 2 to 2 1/2 yrs. between jobs (2 coats, with 3 coats on the bow and front of keel).

This year I'm trying West CCA (? the ablative that did well in the Practical Sailor recent tests) to see if the lower cost gives similar longevity/performance. Increased haulout intervals do help bring down the cost factor.

Posted by: JON C | August 31, 2011 3:19 PM    Report this comment

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