Ultrasonic Hull Shield

[mvweebles]

Originally Posted by fstbttms

I would be satisfied with a much simple and less expensive comparison test. Two similar boats in similar locations in a moderate or high fouling saltwater marina (Northern Europe, the UK, PNW and US Northeast need not apply.) One boat has new high quality copper bottom paint and the other boat has the same but with the addition of an ultrasonic system running 24/7. Neither boat is moved. Bi-weekly or monthly video inspection. This would tell the tale of the tape within a few months, IMHO.

Agree 100%. Also agree it's suspicious the manufacturers don't do it. Or perhaps they have and the results were less than persuasive so they don't broadcast the results.

[rwestmont]

Newbie on this site, but here is my experience for the 4 Transducer Hull Shield system. I installed it here in Va Beach, VA 18 months ago on our 2000 330 Express Cruiser, but the boat wasn't hauled and cleaned as recommended by the manufacturer until 11 months ago in June '23. Then it was sanded and painted blue as the photos show. In summary, both I and the boatmaster that lifted the boat yesterday were extremely impressed with the hull. Yes there was slime as I only run it a few times since Feb '24, but the growth on the hull was very sporadic at best. The few barnacles that were present brushed off at ease.

The metallic drive-train, trimtabs, lights and strainers were fouled to a point the boat could not get on a plane. I was told by Hull Shield folks that I needed 5 transducers for this setup (one fwd, one in the Lazarette, one on each transmission), but decided to give it a go with only four. Clearly, those transducers on the transmissions were ineffective, but I was told by local mechanic when the boat was hanging that he installed the transducers on each shaft strut and that was effective. So that's my plan and I'll update here this Oct when I'm scheduled to get pulled again. Bottom line, it works, Navy's been using ultra-sonic repelling devices for years.

Sorry, didn't realize I could not post photos, only a link. If interested, send me an email and I will forward.

[rwestmont]

Figured it out, here are the images from yesterday before cleaning growth on drivetrain and trimtabs. She runs 28kts now, very happy.

[mvweebles]

Originally Posted by rwestmont

Newbie on this site, but here is my experience for the 4 Transducer Hull Shield system. I installed it here in Va Beach, VA 18 months ago on our 2000 330 Express Cruiser, but the boat wasn't hauled and cleaned as recommended by the manufacturer until 11 months ago in June '23. Then it was sanded and painted blue as the photos show. In summary, both I and the boatyard that lifted the boat were extremely impressed with the hull. Yes there was slime as I haven't run it a few times since Feb '24, but the growth on the hull was very sporadic at best. The few barnacles that were present brushed off at ease.

The metallic drive-train, trimtabs, lights and strainers were fouled to a point the boat could not get on a plane. I was told by Hull Shield folks that I needed 5 transducers for this setup (one fwd, one in the Lazarette, one on each transmission).

Certainly glad you're happy with the results. But with all due respect, another anectdotal story isn't compelling. Question for you: when you talked to Hull Shield, did you happen to ask them why they don't provide testing from an unbiased outside testing lab who can design an objective protocol? Compelling for me would be catamarans - one hull protected, the other unprotected.

Originally Posted by rwestmont

Bottom line, it works, Navy's been using ultra-sonic repelling devices for years.

I hate to sound cynical, but the US Navy does a lot of crazy stuff that either has no practical application or has a very narrow use-case. Recall, it was at the Navy's lead in the 1970s that led boat builders to use reformulated mil-spec resin that blistered badly. Uniflite, then one of the largest builders in the world, went out of business as a result......

[rwestmont]

Thanks for the response, I will ask Hull Shield when I inquire what happened with the mounts on the transmission (as recommended in the installation) and send photos. It's possible there is some sort of barrier between the transmissions and shafts on my setup that is blocking the sound waves, just speculating. Regardless, most likely adding two more transducers and mounting on the struts, then running grounds to each trimtab.


As a commercial diver back in the 80s, and working in all the local shipyards including Norfolk Navy yard and NN Shipbuilding, we did not observe Navy hull cleaning operations over many years. So I surmised whatever they were employing, worked to some degree.

[mvweebles]

Originally Posted by rwestmont

As a commercial diver back in the 80s, and working in all the local shipyards including Norfolk Navy yard and NN Shipbuilding, we did not observe Navy hull cleaning operations over many years. So I surmised whatever they were employing, worked to some degree.

It's been a while since I researched ultrasonic hull anti-fouling, but I seem to recall the use case in large commercial vessels is extremely narrow and does not translate to broad scale protection.

Some things don't scale well. If they did, I'd only fly on airplanes made entirely of whatever they make Black Boxes from that survive any crash.

[Ed-White]

I have recently sold my old boat that had been moored on the river, hence virtually zero growth albeit some grass at the water line. The new owner installed two hull shields at $500 per. After being delivered to his salt water mooring buoy I visited after two months, and see considerable growth. About 1/2 inch of barnacles on the rudder, which is the control, because it is not in the field. The other parts of the hull have growth especially alone the waterline of barnacles and various sea anemone. There appears to be some clear areas close to the transducers. Other issues are that the product shuts down when the battery voltage slips below 12.6 volts. There are 200 watts of solar and an air breeze wind Genny on the boat. The units draw 25 amps in bursts, then drop down to 3-4 amps or less. So x 2 that can be quite a draw on the battery bank. There was a glitche with the solar not putting out but that is now fixed. It will be interesting to see how the system holds out over the summer, swinging on a mooring buoy in the Salish Sea.

[SailingHarmonie]

Originally Posted by rwestmont

As a commercial diver back in the 80s, and working in all the local shipyards including Norfolk Navy yard and NN Shipbuilding, we did not observe Navy hull cleaning operations over many years. So I surmised whatever they were employing, worked to some degree.

Yes, what the Navy does works exceptionally well. However, it has nothing to do with ultrasonics.

The Navy has a specific exception to the rules that outlaw tributyl tin antifouling. TBT is an order of magnitude more effective, and more toxic and more persistently polluting than copper based paints.

[fstbttms]

Originally Posted by SailingHarmonie

Yes, what the Navy does works exceptionally well. However, it has nothing to do with ultrasonics.

The Navy has a specific exception to the rules that outlaw tributyl tin antifouling. TBT is an order of magnitude more effective, and more toxic and more persistently polluting than copper based paints.

You are correct in that the US Navy can use whatever they want on the bottom of their vessels. You are incorrect in your inference that they use TbT anti fouling paint. They don't. And the reason is that the US Navy has business to do in countries all over the world. Countries that almost without exception do not allow vessels with TbT paints on their hulls to enter. Not to mention the public relations nightmare it would cause in THIS country.

For the most part they use the same off-the-shelf paints that you and I have access to.

[CaptTom]

Originally Posted by KingTide

Totally agree on comparison testing results. I have a unit on a power cat, only on one side. Will see in a couple of months when it comes back.

Any results? It's been a couple of months.