Anyone with experience using "hull shield" ultrasonic antifouling system?

[fstbttms]

Originally Posted by mvweebles

Come to think of it, given your self-proclaimed vast and successful 28 years of bottom diving, the fact that you no experience with Ultrasonics is kinda evidence they may work, certainly not that they don't work. If you've been that busy, surely you would have encountered one or two dissatisfied users who now need a bottom job, no? Maybe folks use them and no longer need a diver so your phone doesn't ring.......

Yes, undoubtedly you are right. 42,000+ hull cleanings performed over almost three decades and out of all the thousands of customers who have come and gone during that time, not a single one bothered to mentioned that they had installed an ultrasonic system and so no longer needed a diver.

It's amazing how big of a secret this anti fouling magic bullet is.

[mvweebles]

Originally Posted by fstbttms

Yes, undoubtedly you are right. 42,000+ hull cleanings performed over almost three decades and out of all the thousands of customers who have come and gone during that time, not a single one bothered to mentioned that they had installed an ultrasonic system and so no longer needed a diver.

It's amazing how big of a secret this anti fouling magic bullet is.

I see you're a flat-earth type of guy...

We see the same thing, just differently. I see a guy who states he has done 42,000 hulls over 28-years. 6-hulls per work day in San Francisco Bay Area, one of the most expensive and tech-savvy regions of the world, and who are not bashful about 1-star reviews for poor performance. In all that, you have never come across a single disgruntled user of Ultrasonics. Frankly, I find that a possible endorsement of the technology. Either users like it and don't need a diver so your phone doesnt ring; or its very early in the adoption curve which means it may or may not work for yacht applications. But it doesn't mean it doesn't work.

Bit ironic that you complain BoatTest makes bold that you cannot validate, but you make bold that no one can validate?

[HeywoodJ]

Forget "does it work?", the first question we should be asking is "is it proven safe for the marine environment, or at least safer than current bottom paint?" We all know that bottom paint pollution is detrimental to the marine environment we all love and enjoy.

We also know that the marine environment suffers from noise/sound pollution in ways that are worse than sound in air, a) because noise attenuates much more slowly in water, and b) because many marine organisms use sound frequencies far above what humans can hear. From their website:

Signal pulses in this range alter organisms [sic] cellular structure. Reproductive and dispersal cycles are disrupted.

Before we all go asking if it works and throwing them on our boats we should be asking to see the evidence that widespread use is safe for the environment. After all, we are still paying the price for TBT antifouling, that certainly worked but was not a good solution from an overall perspective. Are we ever going to learn that just because something works for what it is designed to do doesn't mean it is the right thing to do?

[fstbttms]

Originally Posted by mvweebles

...you have never come across a single disgruntled user of Ultrasonics.

It is not true that I have never come across a disgruntled ultrasonic user. In point of fact, I have. But that's not what I said. What I said is that I have never lost a customer to an ultrasonic system. Your blatant attempt to twist my words belies your inability to defend your argument.

Originally Posted by mvweebles

...its very early in the adoption curve which means it may or may not work for yacht applications.

Ultrasonic systems have been advertised to pleasure craft owners for decades. That you have been unaware of them until doesn't make that untrue. What is true however is that although they have been around for many years and remain a blip on the anti fouling technology radar and in very limited use, you are unable to explain why that is the case.

Originally Posted by mvweebles

Bit ironic that you complain BoatTest makes bold that you cannot validate, but you make bold that no one can validate?

Again, lack of an argument leads you to misconstrue what I said. But since we're on the topic, maybe you can prove to us that a social media content provider who specializes in reviewing boating products does NOT get paid to post positive reviews about the products they are given.

[HopCar]

These things have been around for a long time. There was even a system that hooked to a radio. It was suggest you play a rock channel.

[fstbttms]

Originally Posted by HeywoodJ

Forget "does it work?", the first question we should be asking is "is it proven safe for the marine environment...?

Well, UC San Diego and the Scripps Institute believe these systems are demonstrably unsafe.

https://scripps.ucsd.edu/news/ultras...rine%20mammals.

[Tin Tin]

What they should have done for that test on the power cat was to install the sonic device in one hull only. Then haul and look at the difference between the hulls.

[fstbttms]

Originally Posted by Tin Tin

What they should have done for that test on the power cat was to install the sonic device in one hull only. Then haul and look at the difference between the hulls.

Your post makes me wonder if that boat lives in a shed. I can't speak for anywhere else but the Bay Area but here, boats that live under a roof foul much, MUCH less than boats that do not. In any case, nobody with a vested interest in selling these things seems particularly interested in doing any side-by-side testing and letting us see the results, that's for sure.

[mvweebles]

Originally Posted by fstbttms

Well, UC San Diego and the Scripps Institute believe these systems are demonstrably unsafe.



https://scripps.ucsd.edu/news/ultras...rine%20mammals.

From the link: "The [ultrasonic antifouling] systems have become widespread globally on various types of ships. “Cruise ships, in particular, seem to be using this technology heavily"

Article doesnt cite actual research on wavelengths used. It makes a diffence to marine life, but suffice to say, the technology apparently works, at least in ships

Here is an actual research paper that compares low and high frequency. Low frequency waves can be damaging to marine organisms. But the yacht systems use high frequency waves.

https://www.researchgate.net/publica...c_guided_waves


"Selecting appropriate resonance frequencies for the transducers to exert a continuous, high frequency force perpendicular to the hull surface, as observed here in vibrometry analysis, causes a repelling mechanism to control biofouling without endangering sea life forms."

Picture below is comparison of one surface without UA on left and the other with UA after 32 days. Attachment 272549

[HeywoodJ]

Originally Posted by mvweebles

...."Selecting appropriate resonance frequencies for the transducers to exert a continuous, high frequency force perpendicular to the hull surface, as observed here in vibrometry analysis, causes a repelling mechanism to control biofouling without endangering sea life forms."....

The manufacturer of this device says specifically, in their advertising literature, that it harms sea life by “alter(ing) cellular structure” and disrupting reproduction. They say nothing about the range of these effects, or how that might change with several hundred of the devices concentrated in a marina.

Biofouling management is far easier on vessels that are underway, at significant speeds, on a regular basis (cruise and cargo ships). What may work for them does not necessarily translate to recreational vessels sitting stagnant in a marina, and, for a large part, constructed of very acoustically different materials.

[mvweebles]

Originally Posted by HeywoodJ

The manufacturer of this device says specifically, in their advertising literature, that it harms sea life by “alter(ing) cellular structure” and disrupting reproduction. They say nothing about the range of these effects, or how that might change with several hundred of the devices concentrated in a marina.



Biofouling management is far easier on vessels that are underway, at significant speeds, on a regular basis (cruise and cargo ships). What may work for them does not necessarily translate to recreational vessels sitting stagnant in a marina, and, for a large part, constructed of very acoustically different materials.

The manufacturer states UA (ultrasonic antifouling) devices will not reverse fouling, rather it prevents formation of it, which is why you still need bottom paint. If true, it's a prophylactic measure, not a curative one. 'An ounce of prevention' as the old saying goes.

Sounds like your concern is the opposite of the from Fstbttms the bottom diver. Your concern is [i][u] UA works too well.

[sailorboy1]

I don"t care about protecting the marine environment and life attached to my boat bottom.

This introduced an interesting thought to the normal bottom cleaner replies; maybe the reason he doesn"t seen them in operation and working is that it does so the boat has no reason to pay him

[CaptTom]

Thanks, @mvweebles, for posting that link. It does look like a fairly in-depth research project, although I'd want to know more about the funding source and goals of the study.

Unfortunately, it's focus seems to be large, steel-hulled ships. So right out of the gate it's application for small, fiberglass hulls seems uncertain at best.

One thing it does make clear is that there's far more required than just banging on the hull in some single frequency. This excerpt gives a hint at how much effort might be needed to figure out a system for any given boat:

Multiple transducers can be used cooperatively to form an array that optimises antifouling performance. The topology of arrays is of high importance due to the effects of nodes and anti-nodes, which cause destructive and constructive interference respectively at different positions in the interference pattern. Transmission frequency is another important factor as the change in frequency can change the magnitude and dominant direction of vibrations and also the position of the antinodes which then degrades the effectiveness of antifouling [9]. One of the main problems is that the efficacy of acoustic biofouling prevention decreases with distance from the transducer as the waves are attenuated as they propagate [10].

Assuming this technology would work with fiberglass, and assuming a use case similar to commercial shipping (i.e.; underway a lot, not sitting in a marina) then maybe a marine engineer could design a system which worked on a specific hull. I could see a future where new boats came with this as an option, factory-installed. Then, after those are proven, maybe there could be enough experience about what works and what doesn't to justify retro-fitting my boat. I'm quite sure I won't live to see it, but I won't discount the possibility that it could happen.

[mvweebles]

Originally Posted by CaptTom

Assuming this technology would work with fiberglass, and assuming a use case similar to commercial shipping (i.e.; underway a lot, not sitting in a marina) then maybe a marine engineer could design a system which worked on a specific hull. I could see a future where new boats came with this as an option, factory-installed. Then, after those are proven, maybe there could be enough experience about what works and what doesn't to justify retro-fitting my boat. I'm quite sure I won't live to see it, but I won't discount the possibility that it could happen.

I'm in about the same place. I've tracked this technology for a while. 5-years ago, I put it in the same category as Algea-X. But I think that's unnecessariy harsh

I found this decent comparison from PBO in the UK. They do side-by-side comparison over a 5-month season. Overall verdict is 'meh.' Provides some protection and makes removal of slime easier, but far from a magic bullet.

https://www.pbo.co.uk/gear/ultrasoni...ted-hull-72549

[fstbttms]

Originally Posted by mvweebles

I found this decent comparison from PBO in the UK. They do side-by-side comparison over a 5-month season. Overall verdict is 'meh.' Provides some protection and makes removal of slime easier, but far from a magic bullet.

https://www.pbo.co.uk/gear/ultrasoni...ted-hull-72549

Thanks for digging this up. This is the best test of the system type that I have seen. Similar boats, all in the same location and all with the same age anti fouling paint. Even a couple of control boats. Maybe the pictures don't do it justice, but there seems to be very little difference in fouling between the boats that had the systems installed and those that didn't. And this is in the UK, where fouling conditions are much less robust than in places like southern California or Florida. If ultrasonics can't do the job in relatively cold, sunless regions like the UK, how well do they perform in places where fouling is a serious concern?

They don't perform well in places like that. That's the whole point. 12 months without cleaning and it's almost spotless in a place where you normally need to have your hull cleaned 25+ times a year? Give me a break.