It so happens that I have a CleanAHull double transducer unit for sale. This seems to be one of the best units on the market. You can find out more at https://cleanahull.com/.
I used this system on my Hunter 41 in Marina del Rey for a couple of years and came to the conclusion that it just didn't have any benefit. One of my transducers failed due to water inundation (the transducers are not waterproof). I received a replacement transducer but decided not to install it but instead to remove the system.
It functions and it may work for someone else in some other location.
This unit currently sells for $1499 with 2 transducers.
It so happens that I have a CleanAHull double transducer unit for sale. This seems to be one of the best units on the market. You can find out more at https://cleanahull.com/.
I used this system on my Hunter 41 in Marina del Rey for a couple of years and came to the conclusion that it just didn't have any benefit. One of my transducers failed due to water inundation (the transducers are not waterproof). I received a replacement transducer but decided not to install it but instead to remove the system.
It functions and it may work for someone else in some other location.
This unit currently sells for $1499 with 2 transducers.
I'm asking for $1100 or best offer.
Let me guess, your day job is not in consumer marketing.
How can a weak ultrasonic unit ever be considered to clean a hull?
Well, sonic works at home so. When my Admiral is yelling at me, I clean up sometimes, but ultrasonic? No way, I cant hear it!
I mean, do they think, with ultrasonic a pod of house-mate dolphins will come and wipe the barnacles off the hull?
You can clean small objects in a water tank using ultrasonic, but this will not work on that scale. BTW, it is far from Eco-friendly, it disturbs communication of animals and stresses them. We are anyway noise polluter of the seas by our depth-sounder and engines.
Hi,
I'm a new boy on the block. I've read through most of the comments on this topic. Ultrasound to control algae growth sounds feasible. From what I've read it seems some installations are effective while others are questionable. That leads me to suspect the variables which are present likely lead to success or failure?
1) Make & Model of anti fouling unit
2) Quality of installation
3) # of transponders
4) vessel size
5) construction material of vessel
6) operating parameters - periodic - continuous
7) other?
What are the chances of creating a useful data base?
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 5,433
Re: Ultrasonic Antifouling
Quote:
Originally Posted by Thunder Spirit
Hi,
I'm a new boy on the block. I've read through most of the comments on this topic. Ultrasound to control algae growth sounds feasible. From what I've read it seems some installations are effective while others are questionable. That leads me to suspect the variables which are present likely lead to success or failure?
What are the chances of creating a useful data base?
All of your criteria play a part I’m sure, but the most important criteria are fouling conditions, IMHO. Note that most of those reporting positive experiences do their boating in places where fouling is so light, in-water hull cleaning is needed infrequently, if at all. Those who say ultra sonic anti fouling systems are ineffective typically sail in places where fouling is moderate to heavy and hull cleaning is a necessary and frequent occurrence. What that says to me is that ultra sonic systems do not have the “oomph” to stop or retard fouling in these conditions.
Of all the boaters I meet where we have cruising boats in the somewhat fouling water for 6 months of the year, about 1% don't use any anti-foulingpaint.
When those with paint haul-out, a quick power wash removes all traces. There is some paint maintenance required.
When those without paint haul-out, they spend a lot of effort scrubbing and acid washing and rinsing, and compounding and polishing, and waxing to keep the hull looking original.
3 years ago, one told me they were considering changing to anti-fouling but were going to try a special wax instead. I advised that if it worked as advertised, I suspect that everyone would be using this product, (on the market for many years.) The following year I asked him how well it worked. "No difference".
Last year, one of these called me to apply a barrier and ant-fouling paint, as they were starting to develop blisters.
As I have found in the marine industry, if the vast majority do something a certain way, unless there is "new earth-shattering, proven vastly superior technology" it is not likely to be effective doing something different. There could be the odd "breakthrough" but at least 9 times out of 10, the alternative will not be as good, or everyone would already be doing it.
Hi,
I'm a new boy on the block. I've read through most of the comments on this topic. Ultrasound to control algae growth sounds feasible. From what I've read it seems some installations are effective while others are questionable. That leads me to suspect the variables which are present likely lead to success or failure?
1) Make & Model of anti fouling unit
2) Quality of installation
3) # of transponders
4) vessel size
5) construction material of vessel
6) operating parameters - periodic - continuous
7) other?
What are the chances of creating a useful data base?
CF does not have a database function that I know of... however they do have a library of documents. The only way to create something useful would be for an individual to collect the posts of value, and compile them into a document for general use. Unfortunately concerted efforts to muddy the waters has resulted in a thread where there are only a very few owner accounts, and a lot of more or less useless chatter, making this a time consuming task. I've been considering gathering such accounts from the various threads on this topic, as well as accounts external to this group, and technical information, etc into such a document.
Trying to draw meaningful conclusions from posts here kind of like trying to read or write on the beach while some crazed child in a mask and flippers is waltzing around gleefully flinging sand in your eyes.
Research on retarding biofouling using audio range and ultrasonic range frequencies has been done since the 70's, and positive results were achieved. 23 khz was reported more than once to be the optimal frequency. Striping was observed on ships with these systems due to bulkheads damping the vibration, and intermittent operation seems to be effective. Here is a PDF of a research paper on the topic.
There really is no question that it can work. It would seem that the ability of the surface to vibrate at the necessary frequency would be a critical factor (my opinion). This could vary wildly with boat construction, and may explain why people are having very mixed results with GRP boats. Carbon fiber for example, might have a good ability to carry these sound waves at the necessary frequency, while perhaps a chopper gun boat may have more of a dampening effect. Any structure will tend to have resonant frequencies, and those frequencies are likely to be in wildly different ranges, and that could be a huge factor. If the optimal frequency is 23khz, but your boat hull does not resonate at that frequency, then it would seem to me that the system would need to be "tuned" to a frequency where it would resonate to have any effect at all. That means that what works for my boat, may not work for yours, or vice versa. It also means that even if you tune the oscillator to a resonant frequency to the individual boat, one will probably work better than another. It clearly is not a simple matter of just installing two transducers, and an oscillator / amplifier. It seems like kind of a "no brainer" that a sandwich boat hull is not going to resonate at a useful frequency.
It appears to me that manufacturers of these products for yachts are selling a one size fit's all package, and not doing the engineering, or even advising on the engineering to make their systems work on the individual boats. That is a huge mistake, and the result is that boat owners will not trust them even after they correct this.
As a lifetime businessman, I long ago learned that word of mouth was my best friend, and that one dissatisfied customer can do a LOT of damage..... I go to great lengths to prevent that one dissatisfied customer from ever existing.
The system on my boat sweeps through a band, not just one frequency.
I think that's a pretty common practice............
Here is a link to a fellow who more or less built his own system using the Jaycar transducers on an aluminum boat.... he makes some useful observations, one of the more significant ones is the fact that the Jaycar transducers are potted in soft rubber.... which he removed to achieve direct metal to metal contact and far superior sound wave propagation........
Yes. I built the prototype presented above in the second half of 2014 and commissioned it in early 2015. In New Zealand waters, we get little creatures we refer to as snapping shrimps because of the sharp crackling noises they make as they crawl under the hull. While they initially dislike the taste of fresh antifouling and always wash off with boat speed, it doesn’t take them long to get comfortable once the boat stops and the music starts. When I powered up the ultrasonic system, their noise started fading away and, after a while, the hull was much quieter, other than for the faint clicking sounds produced by the transducers. It suggested that the vibration was indeed propagating throughout the underwater hull and this appeared positive. Hard Growth
The system has now operated continuously for 3½ years and it essentially eliminated all of the hard growth on the hull: no more barnacles and coral-like formations. Barnacles migrate through the water as tiny larvae, attach to the hull and then start growing a shell. When the water is choppy, I can sometimes see some larvae beneath the waterline; a few days later they are gone. They simply can’t live and develop against the hull plating any more. The only place where I sometimes find a few grown-up barnacles is at the very aft tip of the keel bulb; there appears to be a dead spot there. The effectiveness on the rudder is slightly less, obviously because of the bushes. In particular, the very leading edge seems more vulnerable. Weed Growth
When it comes to algae fouling, there doesn’t appear to be any silver bullet there: the antifouling still has a role to play. Once it has completely worn away, the hull can get colonised by algae and even sponge-like growth, but this is always easy to peel off. I was never able to distinguish any difference in fouling nearby or away from the transducers; the effect over my hull appears uniform. This was not the case on a 66′ aluminium fishing vessel fitted with two Jaycar kits. In this case, the owner told me that growth was visibly reduced over a large radius around each transducer and their effectiveness then faded away with distance. He said his boat needed four transducers. Because the effect on my hull appears uniform, it is more problematic to evaluate performance with regard to algae growth. In the first 9 months or so after painting, the antifouling normally keeps the hull free of weed anyway. However, if I dive and clean the hull once the antifouling is essentially gone, slime won’t form again for at least a few weeks, but only over areas that were 100% clean. Even when neglected, my hull has never become as fouled as I had seen it before, so the system may somewhat hinder algae growth, but this assessment is somewhat subjective. If left long enough without any care, the bottom does eventually end up filthy and this has been the case with all ultrasonic antifouling “solutions” I have directly heard of. Ultrasonic Antifouling and Antifouling Paint
All up, the system eradicated the barnacle problem and it is immensely valuable to me for this reason. In the absence of hard growth, the surface is easy to clean, stays smooth and it can be recoated with minimal effort each time. It extends the intervals between haul-outs for me provided I dive and scrape off the soft growth from time to time once the antifouling is a year old or so. I experimented with applying significantly more paint to the keel and rudder (it is a moderately ablative formulation) and I must say that it has allowed cleaning underwater for much longer without running out of paint. This old and thicker antifouling is not as effective as a new coat, but these surfaces still perform noticeably better than the areas of the hull left with nothing. Before I installed the ultrasonic system, barnacles would attach to the paint as soon as it lost some of its effectiveness and then the surface couldn’t be cleaned without effectively removing most of the paint in the process and my conclusion was that applying a thick coating primarily benefitted the paint company. This is no longer true. I would undoubtedly get better results again if I could use a cuprous oxide-based antifouling, which is both stronger and longer lasting than aluminium compatible products.
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