Controlled Depletion Vs Self Polishing

[B4A]

Can anyone explain what is the difference in behavior between a CDP (Controlled Depletion Polymer) and a SPS (Self Polishing Copolymer) antifouling?

Which one is better for a cruising boat spending 6 months in the Caribbean, crossing and spending the rest of the time in the Med?

[GordMay]

“Best fouling control coatings technology” ~ AkzoNobel
➥ https://www.international-marine.com...ngs-technology


"...
The rosin-based CDP technology launched in 1960s is now the most basic antifouling coating in the industry. A CDP antifouling paint works just like a bar of soap. If you leave it in a pool of water it becomes soapy and slippery. Likewise, water migrates into the CDP paint film which in turn dissolves rosin and biocides, which leach into the sea. As insoluble stay behind in the leached layer, the dissolution rate continuously declines and the remaining coatings system becomes less predictable and effective.
An SPC antifouling coating reacts with sea water to make it soluble. The result is thinner leached layers with excellent control of biocide release. Similar to CDP coatings, water migrates into the paint film and the surface reacts with sea water ions, becoming soluble. The surface then dissolves, meaning that not only are biocides released, but the entire film thickness progressively washes off – thus solving the shortcoming of a CDP system. There are three main self-polishing copolymer (SPC) technologies currently available: copper acrylate, zinc acrylate and silyl acrylate.
Both CDP and SPC antifoulings polish away from the hull of a vessel. The coatings are applied with an appropriate film thickness to last the entire lifecycle.
A completely new family of “biocide-free” antifouling coatings called “foul-release” (FR), popularly known as “silicone” coatings, creates a rubbery “non-stick” surface which provides a very smooth, slippery surface to which organisms have a difficulty attaching.
..."

[B4A]

Thanks Gord! So what is the most effective technology for a cruising sailboat that spends 365 in the water and sails 8,000 nm a year? CDP or SPC?