Let me quickly start by saying the notion that ships do not have issues with
hull biofouling is just patently absurd. It’s so ignorant that it doesn’t warrant further response. I mean, you see some stupid stuff on the interweb, but that’s the best in quite a while. But anyway...
As far as the effectiveness of ultrasonic antifouling (in general, not the brand in the OP), just based on this thread the conclusion has to be YES it CAN
work. This is clearly demonstrated by the following posts: #75 by hezi973, #79 by norton, #85 by fstbttms (yes, I’ll explain), and #107 by molly1. There are others too and also some links. Are these people wrong, lying, shills for the industry? I take them at their word. YMMV.
This is not to say that any particular
installation WILL
work. As with any system or product, there are a myriad of ways that things can go wrong: poor design, improper
installation, wrong setup, etc., etc.
Also, some of you seem to have some unrealistic expectations. If you require no painting and no growth for decades on end, you’re living in some fantasy world. If we come back to earth and use some common sense and a reasonable definition, like maybe something in line with what the vendors actually claim it does, then again yes they work. I believe those claims are (IIRC): used in conjunction with appropriate
bottom paint, it will inhibit some growth and retard other growth, resulting in reduced bottom
cleaning, reduced haul outs, longer
paint life, and what growth there is cleans off easier. I think those posts (and others) demonstrate that performance.
Here's post #85:
So you admit the systems are installed in sea chests; do they work there? Or are the owners wasting their
money? If they work in sea chests, why wouldn’t they work on the
hull? It’s the same
water and the same organisms. The only significant variable might be less sunlight in the piping (at least compared to the WL and sides, less so the bottom). Why, specifically, would they not work on the hull if they do work in the sea chests?
I posit that they could/would work on the hull but
commercial vessels are probably not using them for hull protection for some other reason(s), like say, simply because it isn’t economically beneficial. Here are a few possibilities for why this might be:
- Ships have to dry
dock on a fairly strict schedule (varies depending on vessel type), so if you can’t benefit from the potential extended time between haul outs, you’re missing one of the major cost saving opportunities provided by the ultrasonic system.
- If you have a
paint system that already provides “adequate” protection between these dockings, that benefit may be reduced too. (Even if maybe it could help reduce growth somewhat and lower
fuel consumption in between.) As previously mentioned, many
commercial ships are operated continuously and are only in port for cargo operations, thus allowing the paint to function properly with regular “scrubbing” at sea.
- Some ships are big. That means the ultrasonic systems would have to be “big” too (lots of transducers, lots and lots of cabling). In addition to the up-front cost, the weight might translate to
lost cargo capacity (so even if relatively small, could add up to be significant since it’s on every voyage), thus negating some of the other savings. Not sure how the system scales.
- Some vessels aren’t too concerned with frictional resistance, so wouldn’t benefit nearly as much. For example, a harbor tug whose primary mission is high bollard pull, and even when transiting “at speed” is only doing about 10 kt and digging a large hole in the
water while doing so (i.e. has proportionately higher wave making resistance).
These are just a few I thought of now; I’m sure there are more. Regardless, none of them mean the ultrasonic system "is not capable," just that the benefits are reduced or negated, so the economics don't work out as well. It's quite possible that there are some commercial vessels that could benefit (irrespective of that first bullet).
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