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post #69 of Old 03-16-2019 Thread Starter
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Re: Water based anti-fouling in the Chesapeake

Good news, everyone! Irgarol (aka NCN; aka (4E)-4-(Cyclopropylimino)-N-(2-methyl-2-propanyl)-6-(methylsulfanyl)-1,4-dihydro-1,3,5-triazin-2-amine) is finally available to bottom paint manufacturers again, and reappearing in their updated formulas.

NOTE: Some environmentalists may not consider this good news, since Irgarol's effects on the environment are a concern due to potential distortion of the bottom of the food chain.

You can find this slime reducing additive in many paints, including Pettit Ultima SR60 and SR40. Petit had compensated for the loss of Irgarol by raising copper content to 65% and 47.5% (respectively), and (I think) adding some PTFE, presumably to resist adhesion of slime. Now they appear to have gone back to the old formulas with 60% and 40% copper content, and 2% Irgarol.

At the moment Pettit shows product data sheets for BOTH Irgarol and Irgarol-free versions on their website, presumably because both versions are still out there in the supply chain:

Pettit | Ultima SR-60 (Note two TDSs for the two formulas)

Pettit | Ultima SR-40 (Note two TDSs for the two formulas)

You may want to check the label of whatever you buy to make sure you know what you are getting. Maybe you prefer the new/old formula with Irgarol, but maybe you prefer the interim formula with higher copper content. This is a good reason to buy this stuff from a brick-and-mortar store, since you'll know exactly what you are getting.

I am sticking with my inexpensive AkzoNobel Nautical Proguard Ablative paint ($90/gallon). I stumbled onto this paint almost by accident when I bought my boat. Herrington Harbor put it on a completely clean bottom (PO had stripped it), and it worked better than I expected. The main benefit I've seen is that it has adhered very well with virtually no chips coming off at all (which was a problem with my prior boat). I know from experience what a pain it can be to battle adhesion problems, so I'm playing it safe and sticking with the exact same paint to ensure that I have the maximum inter-coat compatibility.

As for Pettit's "orphaned" formulas of Ultima paints without the Irgarol that were sold from 2016-2018, I do not believe that Practical Sailor ever tested them. Perhaps Drew can chime in and let us know.

Rick S., Swarthmore, PA
USCG Certified Captain, OUPV and 50 Ton Master
ASA Certified 101/103/104/105/106

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2001 Catalina 34MkII Tall Rig Wing Keel Breakin' Away, Universal Diesel M35B, Mantus 35 lb. anchor, sailing out of Rock Hall Landing Marina

Last edited by TakeFive; 03-16-2019 at 11:24 AM.
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