Hydrocoat Long-term Review-Last Update 7-18-17

****For updates, see the end of the page****

We finished painting our 1982 Tartan 42 with Pettit Hydrocoat today, August 21, 2013. We are using this page for a long-term review of the product and our application of it, mostly so we can track its performance and critique our application of it for ourselves, but we thought it might benefit someone else as well so here we go.

The hull had badly blistered paint on it due to poor substrate preparation on previous paint jobs. It also had a coat of VC-17 in the middle of other coats of paint, and compatibility of those layers of paint with VC-17 was of some question. We sanded down the paint to hard surfaces, removing all flaking paint and sanding the blisters down to a smooth surface. There was some fairing compound repair that had to be made to the keel and also around the prop strut. All the bad fairing compound was ground out and replaced with West System epoxy with filler. This was sanded smooth with 60 grit. The entire surface was then wiped down to remove sanding residue with water as per  Pettit's instructions.  According to Pettit's paint calculator, we needed a little less than 4 gallons of paint to do 2 coats, plus a quart extra for the waterline third coat. We were conservative in applying the paint initially in order not to run out of paint, but we found that 1 gallon did the whole boat in the red base coat we applied, so we should have probably applied it heavier the first time. We allowed the paint to cure overnight and used the second gallon the next day after moving the stands so that we could paint underneath them. (Ed note: use caution when moving stands. We had 2 extra stands under the boat which allowed us to move one at a time a foot over and paint the original position. Do not attempt this unless you have an adequate number of stands under the boat.).  After waiting the 3 hour recoat time recommended by Pettit, we applied the first coat of black, again using only one gallon with complete coverage. We let this coat cure overnight as well and moved the stands and applied the second gallon of black.

Application can be done by spraying, roller, or brush. We chose roller application for reasons of time and facilities,but will probably choose brush application the next time we use it because the brush we used in hard to access areas that the roller couldn't reach actually produced a smoother surface, one that would likely not provide as much purchase to marine life as the slightly dimpled surface that the roller application makes. We tried both a short-nap roller as the instructions specified and a foam roller and decided the foam roller provided the best results. The instructions mention a method of wetting the surface down and thinning the paint with water for a smoother surface when using the roller application, but we tried this on a small area and didn't notice much difference. One very important tip: pull the tape line between every coat and reapply before the next coat. This paint dries so hard that if you leave the tape on very long after application it becomes very difficult to remove.

We contacted Pettit's technical advice line to inquire about the compatibility of Hydrocoat over VC-17 as we had seen conflicting information online. Some forums were saying that it was compatible, the pdf instructions were saying it was compatible, but a Pettit pdf compatibility chart found online was saying that all VC-17 had to be removed prior to applying Hydrocoat. On contacting the tech line to resolve the issue, they told me that they have recently updated the compatibility chart to reflect the fact that they have discovered Hydrocoat is in fact completely compatible with VC-17.

Cleanup is one of the best features of this paint. Soap and water remove all traces, although the red was much easier to get off skin than the black was. We found we needed to wash up in the middle of the black application because once it dried it was much harder to remove. Yes, we probably should have been wearing tyvek suits even though this is a water-friendly paint, but it was 90° in the shade with absolutely not breeze so it was a survival issue.

We will be posting coating status as we progress through the next year or two to the next haulout, including results of hoisting in the slings and trailering as we move the boat to the East Coast and launch it there.

January 2014:  We have not had the boat out of the water (thankfully) or even been able to dive on it since the water is still so cold and not very clear, but as of this date there is no visible growth on the waterline or the foot or so that you can see below the waterline. Pretty impressive considering we sat still for a month in Oriental, a week in St. Augustine, and a week in Vero Beach. Hydrocoat rating: 5 stars.

February 2014: We finally had a chance to dive on the boat at No-Name Harbor. After just under 4 months there was a very fine coating of algae type growth which brushed off easily with your hand. There were also some small barnacles mixed in with that growth. There were a fair amount of larger barnacles but they were easily dislodged with a plastic ice scraper from our old car. There was considerably less growth on the bottom than I would have expected for 4 months, especially since almost 2 of those 4 months we were sitting still at a dock or on a mooring ball. At the moment we are very pleased with the performance of the Hydrocoat. Hydrocoat rating: 5 stars.

March 2014: We are cleaning the bottom ourselves in the Bahamas free diving with ice scrapers once a month. There is a typical amount of growth on the bottom, medium sized barnacles spaced every several inches, but they are dislodged easily with automotive ice scrapers. The prop shaft and prop are not doing as well and we will be looking for some other kind of pain to use on them. Hydrocoat rating so far - 5 stars.

October 2014: We had a diver come look at the bottom of the boat before we left Cooley's Landing. We were worried that the engine intake might be blocked and wanted it cleaned before we started the engine to leave. He informed us that the bottom looked good, and that there was almost no growth whatsoever. He had to clean the prop shaft and prop, but the bottom was fine. As of one year out, we are immensely happy with the Hydrocoat's performance. Hydrocoat rating: 5 stars

November 2014: We anchored in the Marine Stadium anchorage east of Miami and for the first time in months we had water clear enough to get in and look at the bottom. Donning my mask and fins and flopping into what was a little chilly water due to a cold front, I was pleased to find almost no growth. We had been in Middle River for 5 weeks and then in South Lake about a week, and there was some green slime at the water line and very few barnacles on the hull, about 1 or 2 per square foot. The rudder has more barnacles on it, but still not many. While I was scraping I looked to see if any of the red first coat was showing from underneath, and I could only see a few places where I had scraped a little aggressively. The coating is doing extremely well and I look forward to a light sanding and a few more coats when we pull her in the summer. Our ice scraper courtesy of our St. Louis cars finally bit the dust and couldn't be sharpened any more so I ordered a plastic bladed scraper from Amazon with replaceable blades and it's a winner! You have to be careful not to scrape too aggressively but it pops off even the bottom circle of the barnacle glue that they use to attach themselves, something the regular ice scraper was not able to do. I ordered the 12" one but it comes in 24 and 36 as well. The replacement blades are really cheap.

February 2015: We had the bottom cleaned by a diver at Dinner Key in Biscayne Bay because 1) the visibility is lousy, 2) it's too cold and we don't have wetsuits, 3) it's worth $80 to have someone else do it in those conditions. The diver reported that there was a fine film of very small barnacles, very little vegetation growth and no large barnacles. This was after 1 month in Middle River and 2 months in Biscayne Bay. Hydrocoat rating: 5 stars

May 2015: We hauled the boat out at Oak Harbor Marina this month. We had cleaned the bottom at the end of March while we were in the Bahamas and the water was clear. It had minor, very small barnacles on it that removed easily with our ice scrapers. Six weeks later, at the haulout, there was almost no growth whatsoever. The spots in the pictures are the spots left after you pop the barnacles off and will easily sand off before we add the new coats. Hydrocoat rating: 5 stars.


July 2015

The paint was on the boat for two years prior to the haulout pictures posted above. Those pictures were as the boat came out of the water with no alterations. In the ensuing two weeks we prepped the bottom for the new bottom paint which we will apply just prior to being launched in the water again.

As you can see, the first red coat that we put on in 2013 is completely intact as is about half of the black coats. Very little sanding was required to make it smooth - about 12 hours altogether with 80 grit. There were numerous spots where the paint had chipped off down to the get coat because the original paint coat on top of the gel coat was not done properly. In 2013 we had sanded about half of the 10 or so coats of paint that were on the bottom, and sanded everything that was loose until we reached firmly stuck paint. Regardless, the paint underneath periodically chips off . This is in no way any reflection on the Hydrocoat, but rather the original painter who did the first paint job after it left the factory.  We sanded these spots with 80 grit until no loose material was left and then filled them with fiberglass putty and sanded them smooth.

One unexpected thing surfaced as a result of hauling the boat. I am in the habit of cleaning my galley sink drain with baking soda and vinegar since they are not harmful to the marine life. Unfortunately, it does happen to be harmful to Hydrocoat. Here is a picture of the area around the galley sink drain prior to sanding. Clearly care needs to be taken in choosing anything going down that drain. We will be putting several extra coats of paint around the drain this time.

We are extremely pleased with the quality, durability, and ease of cleaning of the Hydrocoat after the two years we have had it on. Our goal is to see if we can get three years out of this next paint job.

Update September 2016: Due to an unexpected haulout to repair some damage to our prop shaft strut, we decided to throw another single coat of paint on the bottom. After the power wash, I ran over the existing paint with a Scotchbrite pad then applied a single coat. There was no red layer paint showing at the time we hauled out and pressure washed, even after more than a year on the paint job. Hydrocoat rating: 5 stars

Update July 2017: After the haulout in September we cleaned the bottom in October, November and December. We left in January of 2017, fully intending to clean the bottom at least twice while we were in the Bahamas. The weather was so bad this year that we never got in the water once. After returning to Snead in May, we had the diver come in June for a cleaning. It had been five months since the bottom had been cleaned and there were very few barnacles on the bottom. The diver said that there was some algae growth, but after cleaning he still couldn't see any of the red bottom layers of paint. After two years on this paint job we're extremely happy with the paint.

Update: February 2018: Our time working at Snead Island Boat Works had come to an end. We needed to do the bottom job and decided that since the folks at Snead Island are about the best there is in that department, that we would pony up the pennies and let them do it. The boat has never had a barrier coat on it, since there wasn't one done at the factory in 1982. We wanted to take off the 16+ coats of paint on the hull and do a proper barrier coat and new paint. When they  hauled the boat, there was still black topcoat on nearly every part of the hull. The red undercoat could be seen in the areas where the jackstands were. The yard people were impressed. The workers put three coats of barrier epoxy and two coats of Hydrocoat SR (one red and one black) with a third coat at the waterline, and used Prop Speed on the prop and shaft. This is our first experience with Prop Speed so I will post later as to its veracity. A few days later we were splashed back in. Things happened to prevent us from leaving right away. Two months later, right before we headed out for the Keys, we had a diver come check things out and he said the bottom was unbelievably clean. He used a soft brush to wipe away the grassy stuff but everything else was fine. My rating for the Hydrocoat is still five anchors.


Ryukyu said...

Tim and Deb,
How did the paint hold up to lift, trailer, lift, and stands again? I'm planning to paint mine in the next couple of weeks and think I will use Hydrocoat over my VC-17.
James (Chardonnay)

Deb said...

We were very happy with the Hydrocoat after the move. We did have some repairs to do where the stands rode against the hull but it was not the fault of the paint but of the very poor preparation done by previous owners. We didn't sand off all of the paint to the gelcoat due to time restrictions, and some of that paint that was too stuck to sand off did chip off from the stands. If you have the time my recommendation is to sand to the gelcoat. Lots of work though, but we'll probably end up doing that the next time we haul.

Unknown said...

Did you strip down to barrier coat? Did you apply a new barrier coat? I'm about to do a Fales Navigator. We are sandblasting the bottom first.

TJ said...

@Brian - we did not strip down to the barrier coat. We simply did not have the time, money, or energy to do that at this point. That was one of the reasons we picked Hydrocoat because it can go over everything including VC-17. We did sand down all irregularities well, which included some paint blisters caused by the application of a non-compatible paint over VC-17 by some previous owner. We sanded down to the VC-17 but there were still multiple layers below that. We may do a complete removal at some point, but at this point there just isn't any reason.

Carolyn said...

How's the Hydrocoat continuing to do? We met you last summer at Carlyle in mid-Ausust . . . now we have a boat in FL, stored on the Okeechobee, and we need to do the bottom before we re-launch and head for the Keys. Like the easier prep (we have no clue what previous bottom paints are on there, so the universal compatibility is a big plus, too) but have heard conflicting info on how well it holds up in southern Florida. Also, did you use the SR version (slime reducing)?

Deb said...


We are still very pleased with the Hydrocoat. We clean the bottom about once a month in the Bahamas and FL and we have yet to see any of our red undercoat appearing. We use a standard automotive ice scraper and a heavy duty scrub brush. We needed to put more paint on the bottom of the keel because we lost some in a grounding on the ICW and there is heavy growth there that is nearly impossible to remove. It's been nearly a year since we painted it so we're quite pleased at this point. We will definitely be using it again.

Jonathan said...

Thanks for this review. Did you use the Hydrocoat with the 40% copper content, or the Eco version with no copper in it?

Deb said...

Jonathan we used the regular Hydrocoat not the Eco. The Eco wasn't out yet when we did the bottom paint the first time and, to be honest, I'm afraid to change now since this is working so well.

Charles said...

Thank you for taking the time to do this review. I'm hauling my "new to me" 1994 Hunter 29.5 out in 10 days to do my first bottom job so lots of research ahead. I've done auto paint and bodywork as a hobby for years so I hope I can do this without too many surprises. Although no stranger to a respirator, I'm looking forward to the low voc content and low odor along with the durability of the Hydrocoat SR. Sounds like a win win. Do you have a recommendation for a good prop and propshaft coating? Thanks again, Charles.

Deb said...


Thank you for reminding me that I hadn't done the most recent update. You can check at the bottom of the post for the most recent notes.