Antifouling devices

[Peter Gazzard]

Hi fellow boaties.
My question is .Has any body tried or used these sonar antifouling devices.Is it any good.Does it work and if so what are the best devices.Im gessing you would still have to antifouling paint.But how long before repainting and how much hull cleaning needed.
Cheers Peter

[haiqu]

They can extend your antifoul over several years. The Jaycar kit (Silicon Chip magazine design) is the cheapest option if you know how to build electronic devices.

Since this was posted to the multihull forum I should also mention that you'll need one transducer per hull. They also work best on fibreglass, steel and aluminium hulls; not so great on timber or ferro due to lower density.

[StuM]

Lots of opposing opinions about them here's a long thread you may like to consider:

http://www.cruisersforum.com/forums/...ing-17969.html

[Seman]

I have just installed the JayCar Sonar transducers on my cat, 48' aluminium, 3 sonar transducers in each hull. Will let you know how it goes. Just now the hulls are dirty, ready to paint next month in Trinidad.

[a64pilot]

The day that an anti-fouling device actually works will be like the day that a pill actually exists that will make you lose weight while you sleep.
There will be so much demand for it you won't be able to buy it and there will be no doubt about whether it actually works or not as every expert will be extolling its virtues and every sailing magazine, internet forum etc. will be covered in stories about it..

I don't think that day has come yet.

[Triwander]

Hi Peter

I fitted the jaycar unit to a RL28 a few years ago and it made little to no difference. You face 3 problems, the leopards have a thick solid glass underwater profile which may be outside the units specification, the ultrasonic units are not suitable for a foam/balsa cored boats and I don't believe that your sail drives would be protected by the unit.

I will not fit another one until the technology improves.

[Seman]

I hope I have more luck with my sonar, being installed on my aluminium hulls with shaft drives. I have had good reports from friends with alu boats.

[GordMay]

Greetings and welcome aboard the CF, Triwander.

[rabbi]

Two things come to my mind.
First if these units would work the big ship industry would already know. These folks spend millions on antifouling, and more for the dry dock time required. Even if these units just extend the lifetime of antifouling by a small percentage they would deploy such units on a global scale within a very short time frame.
However they don't. your chances of success are pretty much nil.

Second if I understand correctly these are devices inducing strong ultrasonic vibrations into the hull. What does a strong permanent ultrasonic blast do to fibreglass? Could this weaken the internal structure over time? I don't know.

[mghunter]

I sources some 12 volt 28 KhZ and 40 Khz units from China a few years ago for my Hunter 310

Last antifoul was in 2013. Mooring is in a dead end bay off a soccer park and canal so growth is aggressive

Just pulled up this month and the yard was surprised by the lack of growth

You do need to try and use the boat at least once of twice a month to clean the hull (you can see the brown crap washing off in the slipstream)

Mine are on a 10 second on, 30 second off cycle and when on use around 2 amps per unit for the 10 seconds each (3 fitted) (eg a lot more than the claimed Jaycar ones) and have a seperate battery setup and 80 watt solar panel to run them (used to run wind as well but upgraded the panel).

I can also hear them when swimming under the boat

So they do appear to work

regards

[fstbttms]

The fact that almost nobody uses ultrasonic anti fouling devices speaks volumes about their effectiveness, IMHO.

[mghunter]

Like climate change and alternative facts, each to their own - I also agree a bottom scrub works

I looked the commercial ones that claimed low power usage (most say they only drawn 100 ma etc) and also decided they were snake oil so built my own (< $100 each by 3 )

eg 20 watt 28 kHz transducer at 12-14 volts = around 2 amps current draw

There are lots of commercial ultrasonic cleaners/ baths etc for algae control in ponds / pools / dirt removal in car parts / jewellery / uses in dentistry so the theory does work in practice, but just not at the claimed low power consumption (eg 100 ma) for a 31 foot boat

Also the fact that you can hear them working when underwater suggests that the fiberglass hull is resonating, so I guess it is shaking the crap out of something (eg the brown (assume dead growth) slipsteam for 30 seconds when I take the boat for a run)

They will not resonate steel or wood or sandwiched hulls, so maybe there lies the issue - the hull also has to be clean and antifouled first, and the system simply prolongs that, not eliminates it

[Wood]

There is little controlled scientific data about this technology.

Here is a recent article I found:

Acoustic methods for biofouling control: A review

I would use this technology given the correct hull construction AND the manufacturer disclosing all operational specifications.

Otherwise, IMO, it is snake oil

[senormechanico]

a

Originally Posted by fstbttms

The fact that almost nobody uses ultrasonic anti fouling devices speaks volumes about their effectiveness, IMHO.

This is MY IHMO.
I have an UltraSoniTec Quad System and love it.
My knotmeter always works even if the boat has been sitting for a couple of months, whereas before installation it would be fouled in a week or less.
r
I'm on my fourth? year on antifouling with no barnacles, only a light film of brownish algae which sails off after a hearty sail. I have never even sloshed off the bottom in all that time.
If it wasn't dark and blowing snot outside right now, I would snap a photo of the waterline to prove it.

I leave the system running 24/7 fueled only by solar. 4 x 50 watt PULSED high mass transducers which draws average 6=700 ma @ 12 volts.
Just my IMHO, of course which means nothing to a bottom cleaner...

[fstbttms]

So your point is that a single satisfied user in a low-fouling region is proof that the system is effective? Bwhahahaha!