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

[neilpride]

Following the grounding of the Exxon Valdez tanker in 1989, the United States introduced the Oil Pollution Act of 1990 (OPA 90), making it mandatory for all tankers calling at ports in the United States to have double hulls.

They must also be watertight, I can't imagine 100 of those basketball-sized transducers scattered over hundreds of meters of steel.

[skipperpete]

Originally Posted by Lee Jerry

I have no idea how limited their use is or isn't. But the point is, that even if their use is limited, that is not (necessarily) an indication that they don't perform well. That would have to be demonstrated, not just claimed. It could be that, or maybe it's some other reason. Maybe poor marketing. Maybe people are bad at finances. Maybe something else. Maybe some of all of it. Again, how popular something is has no bearing on whether or not it works as claimed.

I don’t think there’s any doubt that ultrasonic antifouling works, Kongsberg has been using the “Sonihull” system on KaMeWa propulsion units and sea chests as well as on offshore structures since 2020, these applications would probably be large steel structures and a company like Kongsberg would have done a lot of due diligence before opting in. Maybe ultrasonic antifouling is not yet well adapted to smaller Grp hulls. [ATTACH]

[Pete7]

Originally Posted by neilpride

They must also be watertight, I can't imagine 100 of those basketball-sized transducers scattered over hundreds of meters of steel.

How big

[neilpride]

Originally Posted by Pete7

How big

Big !!

Also can't find real cases in double hulls because of its complexity, in single hulls it can be for certain areas, oil rigs i think they have been using it for years.

[Lee Jerry]

Originally Posted by skipperpete

I don’t think there’s any doubt that ultrasonic antifouling works, Kongsberg has been using the “Sonihull” system on KaMeWa propulsion units and sea chests as well as on offshore structures since 2020, these applications would probably be large steel structures and a company like Kongsberg would have done a lot of due diligence before opting in. Maybe ultrasonic antifouling is not yet well adapted to smaller Grp hulls. [ATTACH]

I agree it works. But not sure why you say not well adapted to smaller GRP hulls.

[BBill]

Originally Posted by Lee Jerry

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).

What is absurb is your comprehension of my post. No way did I imply ships arent affected by growth. The reason is they are moving all the time. During my time on a ship we only stayed tied to the dock long enough to load/unload. The props and engine also continue turning while tied to the dock. A long stay was 24 hrs and that paticular ship (SS Steel Scientist) was 4 yrs between drydock and that was for collision repairs with a barge. If you are going to quote me at least fully understand what I said.

[Lee Jerry]

Originally Posted by BBill

What is absurb is your comprehension of my post. No way did I imply ships arent affected by growth. The reason is they are moving all the time. During my time on a ship we only stayed tied to the dock long enough to load/unload. The props and engine also continue turning while tied to the dock. A long stay was 24 hrs and that paticular ship (SS Steel Scientist) was 4 yrs between drydock and that was for collision repairs with a barge. If you are going to quote me at least fully understand what I said.

Yes, I'm sure I'm the only one who missed getting all of that above from this:

Originally Posted by BBill

Come to Florida and experience closer to 30C (86F) as the water temp in winter and 90+F in summer. I live there...on the water. All I know about southern California temps is from surfing there and it was way colder than Florida.

I remember those electronic devices and they go back many decades...1960s-70s for me. You will have to look hard to find one but in reality probably wont find one anywhere in Florida. If they actually worked we would have them here by the 1000s and in every marina. Technology may have made them better now but it sounds like an old idea that someone has reinvented. As far as they are supposed to work on ships...I was in the merchant marines in the Viet Nam era and those ships went yrs and yrs between haul outs and had very little growth.

How could I miss that they are "moving all the time" and "only stayed tied to the dock long enough to load/unload" when you only mention them after others have first?

How could I miss that "those ships" actually meant only "that particular ship" that keeps the props "turning while tied to the dock?"

I do so apologize. I'll try to do better in the future.

[Pete7]

Looks like its a £700 (price plus import duty) science project to fit just one transducer. Problem is whilst we have is barnacles they aren't the biggest problem, its fine grass like weed, or in the case of my next door neighbour long fronds of kelp

Therefore, for those reasons, I am out until I see hundreds of reviews saying its the best thing since sliced bread.

[Offshore58]

Save your money.
Just paint your bottom

[fstbttms]

Originally Posted by Offshore58

Save your money.

Just paint your bottom

Oh, ultrasonic anti fouling doesn’t replace bottom paint. You still need to do that no matter what.

[Lee Jerry]

Originally Posted by fstbttms

Oh, ultrasonic anti fouling doesn’t replace bottom paint. You still need to do that no matter what.

Yup, what it replaces is your diver. you don't need to call him (or her).

[fstbttms]

Originally Posted by Lee Jerry

Yup, what it replaces is your diver. you don't need to call him (or her).

You'll let everybody know when that happens, won't you?

[Lee Jerry]

Originally Posted by fstbttms

You'll let everybody know when that happens, won't you?

You mean like it did for this guy three years ago:
https://www.cruisersforum.com/forums...ml#post3756417

[fstbttms]

Originally Posted by Lee Jerry

You mean like it did for this guy three years ago:
https://www.cruisersforum.com/forums...ml#post3756417

Oh, you got me. A single anecdote from a boater in cold, low-fouling, brackish water is proof that these systems are replacing human divers everywhere. Yet somehow, I'm just not too concerned. But you keep us posted on future developments, mmm-kay?

[Lee Jerry]

Originally Posted by fstbttms

Oh, you got me. A single anecdote from a boater in cold, low-fouling, brackish water is proof that these systems are replacing human divers everywhere. Yet somehow, I'm just not too concerned. But you keep us posted on future developments, mmm-kay?

I only pointed to the latest one. You know there were others, in both threads. The actual number doesn't matter, because it'll never be enough for you.

Does anyone know if Hull Shield or Sonihull are public companies? I may need a new investment opportunity.