Ultrasonic Antifoul Test

A full bottom paint is US$7000 including PropSpeed. The antifoul is now 2 years old and its barnacle season over here. Divers came today and charged US$250 plus a bit more to change the anodes. I considered this very good value.

The existing hard antifoul is a commercial variety commonly used by yards. PropSpeed was also used. Neither did very well.

Attachment 33700
Before

Here's the diver's before and after video. Sorry its so quick.

https://www.youtube.com/watch?v=pft6gdl_MEY


Attachment 33701
After


We also turned on the new ultrasonic antifoul system. Four transducers were installed and located:

- Port side Bow Compartment.
- Port & Starboard under shaft glands.
- Rear Port side Transom area

We were limited by existing cable runs and not knowing what the effect on the batteries might be. For the two systems and four transducers looks like 0.7amps average at 32 volts.

Attachment 33702
Used a 36 to 12 volt buck converter for power. Works fine.
Will paint wood and tidy up wiring when project completed.

Plan is to install a further 4 transducers ASAP located:

- Port & Starboard rear of Genset room
- Port & Starboard above props


I've had ultrasonic antifouling on other boats and the transducer placement is sometimes hit and miss. My view is these systems can extend antifoul longevity.

So we have a starting point using 2 year old antifoul and bare rudders. Its a perfect time to test & tweak this system as we move towards our warmer months.

Does it require drilling holes in the bottom of the boat?

I think it does not, although might not be the same system offered here. I think the transducers are able to project US through the hull materials. I have read about it; rthe reviews are mixed. Very interested to see how it does with Scott's boat.

The transducers are three parts...

- an aluminium disc that is JB Welded to bare fibreglass on the inside of the hull.
- a transducer that screws onto the aluminium disc using a sealing/resonating compound in between.
- wiring back to the control box.

Correct placement of the transducers on solid fibreglass is important and its best if they are not near bulkheads or the side of the boat as the signals radiate outwards from the transducer. Our old boat also had them mounted on the gearboxes. The will not work on wooden or cored hulls.

The red dots are where I have managed to run the first four of a proposed eight transducers. The red dots were chosen because there were existing cable runs that I could use. Orange is proposed locations due to access. The control box models serve either two OR four transducers each. I chose 2 x two transducer model.

Attachment 33766

Very interested to see how this pans out.

So we are in the middle of summer barnacle season and its four months since the divers last cleaned the hull, shafts, props and rudders. Antifoul is now 2.25 years old. Ultrasonics have been fully operational since the last hull clean.

I am pleased to report that there is minimal barnacle or fouling growth near where the transducers are located. No fouling on any water intakes. No barnacles at all along the waterline. There are some barnacles on the unpainted shafts, props and struts. These will take the divers less than 10 minutes to remove. There is some coral worm on the hull. No algae. I have seen the props and shafts and struts MUCH worse.

I only have four transducers. Probably better with six. It appears that the trick with ultrasonics is to turn them on when you have the hull cleaned as this will prevent/kill new algae attaching. The ultrasonics will not work effectively IF the barnacle has already attached and is feeding on the algae.

So the maths is simple....

Cost of two systems AUD$2000 or (US$1300)

Divers three times a year AUD$900 (or US$550). Slipping and Jet wash, Antifoul, Propspeed etc AUD$7500 (or US$5000 or so.)

My insurance company is making me slip the boat next year for a survey, but this is only every 5 years.