Ultrasonic Anti-Fouling

[nox]

a few freinds of mine in Perth have put it in for about 6 weeks now, they bought it at the Mandurah boat show.

they say its working wonders for them

[nmit5903]

I'm surprised they can tell in 6 weeks unless the boat went in the water without antifoul from new and is still clean. That would be encouraging.

BoatSure have updated my system to a twin unit (I still think that 42' is to big for the single unit though doesnt explain the shocking results we experienced) but have also that it is important to remove the flow coat on the hull so that the transducer is in direct contact with the glass. The flow coat has some wax content apparantly, which gives it the smooth appearance but also weakens the signal.

I remain hopeful but have just slipped and antifouled in any case - have another look in 12 months.

[AnchorageGuy]

P.T. Barnum said it best. I hope he was wrong in your case.

[squid]

Originally Posted by nox

a few freinds of mine in Perth have put it in for about 6 weeks now, they bought it at the Mandurah boat show.

they say its working wonders for them

After the Mandurah Boat show product introduction, six weeks is not enough to prove anything IMHO, unless the boats involved were barnacle-encrusted when the devices were fitted, but now are quite clean. Was that the situation?
Certainly the photos from Sydney are under-whelming for a $4000 investment, but perhaps that vessel really need the twin installation?
It is tempting to invest in hope, but that requires abundant financial resources!
Any other recent experiences?

[sid kimbrough]

Ultrasonic hull cleaners
in reply to most of the above
A) they do not depend on audable sound. The ultrasonic waves create cavitation in the water surrounding the hull and the resultant sub-microscopic bubbles implode tearing the algal slime cell walls. No slime no other critters come to feed or fix to the hull.
B) they have been around since world war II but technology available made them inefficient and noisy.
C) current solid state technology allow piezo electric ceramic rings to be resonated at specific frequencies for maximum effect
D) this technology is available from Blue & Green Marine in the UK and will be available in Greece, Croatia and Australia from them in the next few weeks. Their system is expensive by comparison to others currently available but they are the only ones with serious testing programmes (National Oceanographic Centre, Southampton, Lloyds Register of Shipping, etc.) and UK designed and built product.

[Nordic cat]

Originally Posted by sid kimbrough

Ultrasonic hull cleaners
in reply to most of the above

Ultrasound is by implication inaudible as is infrasound (low frequency) How can a sound wave make the outer skin of a hull move if you can not find the resonant frequency? It is possible by using massive energy...

B) they have been around since world war II but technology available made them inefficient and noisy.

Piezo ceramics have been around for a very long time - the old Polaroid cameras used them for rangefinding back in the 80's

Are there any verified tests done on fibreglass/composite hulls by these institutes? If so please post them or links to them.

Lloyds Register approves equipment for installation on board vessels regarding safety issues for the use of the equipment, but does not give you a generic approval for an application - Please post the LR approval or a links to them.

I have used ultrasonic cleaning for small sensors in e.g. oceanographic applications, and they are of average to little use. Keeping a boat or ships hull clean is something completely different, and having worked with ultrasonics for 25 years - I think this kind of application is comparable to those magnets around your fuel line that supposedly improve your mileage - . In other words - useless.

I would love to be proven wrong, as any no work bottom cleaning sounds good.

Alan

[sid kimbrough]

Nordic cat, sublime, et al,
There arwe several brands of ultrasonic hull cleaners out there now for leisure craft. They all work or there abouts. Some are better that others. putting a soundwave through a hull makes it resonate. This also makes the water outside the hull resonate which is how the cavitation happens.
Early results on several vessels including the M/V Bill Conway (research vessel for National Oceanographic Centre) prove that the Blue and Green marine product works. The tests currently being undertaken are in their fifth month of a 2 year test programme with control GRP panels away from the vessel for comparrison. The results of monthly dives are written up and sent to Lloyds. This study will be finished in 2010 but I am happy to send a synopsis of the December write-up to you.
The only trouble getting the signal out is on wooden hulls and sandwich hulls. There are a couple of solutions to the sandwich hull scenario.
Commercial vessel solutions are being developed and tested but to date none are available for sale.

[sid kimbrough]

P.S.
only one UK website suggests using antifouling paint "as well". B&G are out there to eliminate the need for things going into the sea that harm the environment.
SK

[Nordic cat]

Originally Posted by sid kimbrough

Nordic cat, sublime, et al,
There arwe several brands of ultrasonic hull cleaners out there now for leisure craft. They all work or there abouts. Some are better that others. putting a soundwave through a hull makes it resonate. This also makes the water outside the hull resonate which is how the cavitation happens.
Early results on several vessels including the M/V Bill Conway (research vessel for National Oceanographic Centre) prove that the Blue and Green marine product works. The tests currently being undertaken are in their fifth month of a 2 year test programme with control GRP panels away from the vessel for comparrison. The results of monthly dives are written up and sent to Lloyds. This study will be finished in 2010 but I am happy to send a synopsis of the December write-up to you.
The only trouble getting the signal out is on wooden hulls and sandwich hulls. There are a couple of solutions to the sandwich hull scenario.
Commercial vessel solutions are being developed and tested but to date none are available for sale.

Sid, the key to this is to get the hull to resonate as you say - the problem is that the resonant frequencies of a piece of fibreglass will not be the same across it due to small variations in thickness, lay-up, density etc. This resonant frequency will vary with temperature as well - but let's just say that it is possible.

What happens when you start attaching things like bulkheads, stringers, engine mounts, internal panels and the like to this panel? The anser is that it now will have not one but multiple resonant frequencies depending where you are on the panel.

Like a drum, you can vary the sound by putting a finger on the drumskin at different points....

That is why I do not believe that this will be a viable solution....

Alan

[sid kimbrough]

Alan,
The proof is in the pudding as they say. believing or not believing in an idea is one thing but this product has been on ten boats now for bwetween five and seven months and it works on all of them.
sid

[Chief Engineer]

$4,000 buys a lot of dive time.

[Nordic cat]

Originally Posted by sid kimbrough

Alan,
The proof is in the pudding as they say. believing or not believing in an idea is one thing but this product has been on ten boats now for bwetween five and seven months and it works on all of them.
sid

How about some proof then? Statements without documentation are not worth much in my book. Verified and scientific tests are.

You make the claim that this works on solid fibreglass - please show us some tangible evidence.

I feel that I understand the physics involved, that is why feel so strongly that this product is a hoax, it will never work on a whole boat of say more than 25 feet.

Alan

[Robertcateran]

I have a fair grasp of physics and the explanations for its effectiveness don't make sense to me. I am not saying that they don't work as there could be some other explanation, but it is not in any of the physics I have taught.

Maybe it is what annoys a noisy oyster.

[sid kimbrough]

As I have never blogged before yesterday I am not sure of being able to attach things to this reply but if it fails I am happy to send things as an email to anyone who asks. I have never been accused of being a hoaxter before either and certainly do not appreciate it but mabye that is the just nature of people with too much time on their hands.
This first testimonial is for a 21 year old Offshore 32 dive boat based in Weymouth
“Snapper” Hull Thur 16th Oct 08



Snapper was slipped and antifouled March 31st 08.

The Blue & Green system was fitted after the boat had been back in the water about five weeks in mid May.

The accompanied photos were taken on 16 Oct 08 before the hull was washed down.
The only barnacles evident are tiny ones on the prop and the skeg, only on metal, no sign of any on the GRP.

The only other barnacles evident are a group on the sounder transducer, (see photo). This could be due to the fact that the mastic bedding that the transducer is mounted on gas isolated it from the hull, or there is a possibility that we missed it during the last hull clean but I think this is unlikely.

I can only see two explanations for the tiny barnacles, one being that only GRP is protected or these barnacles have formed in the period the unit was switched off (approx 4 weeks) but then why are there no tiny ones on the GRP?

I have only touched up the anti-fouling here and there where the pressure washer knocked some off, this could prove helpful when we do the next inspection i.e when the the older anti-fouling is less potent.

There was no hanging weed at all anywhere on the hull, where other boats that were anti-fouled at the same time as this one clearly have growth on them. There are some areas of slime on the hull that seem to mainly be where there is anti-fouling, you can see the darker blue areas of the paint (see pics)
There is clearly mullet marks evident where they eat this dead slime.

Ron Howse
Owner

The second is a fairly new Broom 425 based in Norfolk but it travels to France a lot.

Sent: 15 December 2008 09:45
To: mike@blueandgreenmarine.com
Subject: Re: A couple of minutes ago.....
Attn:Mike Arnold.

Dear Mike,

Thanks your e-mail and look forward to meeting you in the New Year

As regards the Ultrasonic unit, the one I opted for was a combination battery mains unit which I regard as being essential for continuous coverage when moored in a UK East coast marina as levels of marine infestation have increased enormously in the last few years.
Prior to fitting, infestation over a 6 month period on the prop shafts, props, rudders and propellors was so heavy that I had lost 3-4 knots off the top speed. After cleaning down and installing your product and taking a trip down to La Rochelle and back then leaving the boat in the marina for a couple of months it was lifted out for inspection and both props and rudders were totally clean of all infestation the only visible infestation being around the inner end of the prop shafts.
The construction of the hull on the Broom 425 is such that there is a localised shielding effect which needs to be counteracted somehow, either with increased power or a through hull unit but apart from that your unit is like Ronseal it actually does exactly what it says on the packaging so congratulations and well done on a product which does not disappoint!

regds

Nigel Smeal







Blue & Green Marine Ltd. Ultrasonic anti-fouling system trial.
(1) Hull monitoring Points
December 2008


Dr Ken Collins
School of Ocean and Earth Sciences,
University of Southampton
National Oceanographic Centre, Southampton


SO14 3ZH











































The University of Southampton, School of Ocean and Earth Science Research Vessel Bill Conway (Coastal Research Vessels) is a Lochin 38 GRP twin engine vessel, overall length 11.7m, beam 3.96m, full load draft 1.3m, cruising speed 9knts.

The hull was last treated with antifouling paint in summer 2007. It was lifted and pressure washed in June 2008 the again in August prior to this trial.

Two inboard transducers (port aft and starboard forward, corresponding to monitoring points 3 & 10) were fitted by Blue and Green Marine on 14th Aug 2008. 16 external photographic monitoring points have been selected adjacent to hull features to enable re-location underwater. They also include points such as the rudders and prop shaft supports which are mechanically remote from the ultrasonic transducers and thus likely to be less efficiently protected by their action.




8

3


1

2

7

6

5

4

Port monitoring points

16

9


13

14

15

12

11

10

Starboard monitoring

1. Hull monitoring
The Research Vessel Bill Conway was put back into the water on 18th August 2008. This monitoring series of

photographs was taken underwater on 17thDecember, 4 months later.
All the photographs are taken with a frame fixed to the camera to ensure a fixed area 18 x 14cm.
The locations of the 16 monitoring points are described in the August 2008 report.

Growth on the bow (points 8&9) and much of the starboard side (points 9- 16) reported in October and November appears to be at a similar level.

2. Settlement plate study
A vertical rack of 4 of monitoring plates (clear polycarbonate, 36 x 15 cm) were deployed on the same day as the vessel was replaced in the water. These are suspended from pontoon furthest from the vessel with the shallowest 15cm below the surface and the deepest 120cm below the surface.
The object of this study is to provide a control for comparison with the hull monitoring study. Plates will be left in place for the duration of the study to demonstrate the settlement that could occur on an unprotected surface. One plate will be replaced each month to reveal the type of organisms settling on a clean surface during the previous month. Below are the observations from the plate after 1 month.

Both sides had a patchy diatom film, clumping in places, concentrated along edge on dark side.
The only epifauna noted was one small (5mm) jelly blob, probably Botryllus, on dark side.

3. Pontoon monitoring
The possibility that the ultrasonic antifouling system may have effect beyond the vessel is
being tested by monitoring the growth on the pontoons where the vessel is moored.

Five pontoon concrete float vertical surfaces (A-E) have been selected for routine photography
And study, the closest (B) being 1 metre away from the port transducer and E the furthest (>10m distant).
No decline in the colonisation at the closest point (B) has been noted.

4. Vessel cruising speed
The vessel cruising speed is being routinely monitored to check if any growth on the hull is affecting its performance. With sophisticated navigation software and differential GPS the course
The speed through the water can be readily determined. This has remained at 9.4knts. (both
engines at 2200 revs ) through the first four months of the trial.

5. Overview
The port ultrasonic transducer has been working throughout the trial and the minimal growth on that side of the vessel’s hull shows that it has been effective. The problems with the starboard transducer during the first 2 months of the trial have presumably led to the establishment of a thin diatom & filamentous algal film on the south, sun illuminated side of the hull. This growth has not increased subsequent to the remounting of the starboard transducer in October and there are Some signs of decline in this growth but whether it is due to winter, seasonal decline or the
correct functioning of the transducer is difficult to discern.

The (mainly starboard) growth to date is only thin algal/diatom film and has had no effect on the vessel’s performance. The control panels which have been in place since the start of the trial have a dense 2cm thick faunal growth which is not apparent anywhere on the vessel. The long term control panels will be studied in more detail in January.

It is not clear if the ultrasonic system can shed the already settled film on the starboard side. To address this small areas of the starboard hull will be cleared of its film during the January monitoring dive,



















































Hull monitoring points, 1(top left), 2(top right), 3(lower left), 4(lower right).





Port rudder, point 1 Port shaft bracket, point 2


































Port side, Point 3 port side, point 4




















Port side, point 5 port side, point 6



Port side, point 7 port side, point 8







































Starboard side, point 9 starboard side, point 10























Starboard side, point 11 starboard side, point 12

Starboard side, point 13 starboard side, point 14, shaft bracket








































Starboard side rudder, point 15 stern, point 16





















Control , settlement plate, no. 1 settlement plate no. 2

[Hud3]

Sid,

Copying text with photos embedded doesn't work as you would hope. If you have links to the articles on another Internet site, copy and paste the link into a new post by clicking on the "Link" button above the new post text box. It's the icon with the earth with a chain link. Paste the URL into the popup, and you should be good.