Ultrasonic antifoul - long term test

[Ex-SolentBoy]

We have had this installed for several years now (the one from Blue and Green Marine).

I will be writing a full report, but thought you may be interested in a couple of pictures.

The boat has been in the water now continuously since March 2011 when she was launched with a new painted hull in Awlgrip.

Stupidly, we left the ultrasonics off untill July that year by accident. They have been on since until we hauled out this week and took the pictures.

During the 2 seasons we have logged about 1000nm, so actually very few miles per day on average.

The guys at Falmouth Boat Yard doing the pressure washing were very impressed. Bear in mind that they haul boats in and out viryually every day. One of them said to me that they have seen boats with more fouling after 6 months in.

A few points:

1. The hull and rudder really only had slime on them. According to Blue and Green this is dead organic matter and they are still hoping to be able to prevent this, but do not yet do so. It was easy to wipe/wash off.
2. You can see extensive growth on the cooling plates for the fridge and freezer. Being metal these are not protected by the ultrasound. For next season I am going to consider putting Propspeed on them but I need to check first if it will hinder the cooling.
3. Loads of growth under the keel. We failed to antifoul this when the boat was lifted for launch and the bottom foot or so of the keel is solid lead, so little protection there anyway.

 

[Saguday]

Interesting.

Any evidence whether the ultrasound bothers marine life, like dolphins and such like?

 

[Ex-SolentBoy]

Interesting.

Any evidence whether the ultrasound bothers marine life, like dolphins and such like?

I did ask that question. I was told it is nowhere near the frequencies that they are sensitive to, and anyway, it is such a low power signal they would need to be almost touching the hull to hear it.

 

[dt4134]

You can see extensive growth on the cooling plates for the fridge and freezer. Being metal these are not protected by the ultrasound. For next season I am going to consider putting Propspeed on them but I need to check first if it will hinder the cooling.

I don't understand that. Can you explain what makes you think ultrasound won't protect metal?

I'd have thought that the main reason would be reflection at the boundary between the fibre glass hull and the metal fitting, but surely that could be overcome quite easily.

 

[prv]

To be clear, are those pictures straight out of the water, or after washing?

And was the hull painted with conventional antifoul, or just plain paint?

If that's plain paint and before washing, then I'm impressed.

Pete

 

[Ex-SolentBoy]

I don't understand that. Can you explain what makes you think ultrasound won't protect metal?

I'd have thought that the main reason would be reflection at the boundary between the fibre glass hull and the metal fitting, but surely that could be overcome quite easily.

You need to talk to Blue Green about this. The explained it to me, but I would screw up the explanation. Call Mike Arnold and ask him. Something to do with sound propogation I believe.

 

[Ex-SolentBoy]

To be clear, are those pictures straight out of the water, or after washing?

And was the hull painted with conventional antifoul, or just plain paint?

If that's plain paint and before washing, then I'm impressed.

Pete

The pictures were taken within a couple of minutes of hauling out, before washing.

The paint was Awlgrip anti foul of course. Does anyone paint boats with plain paint?

Next spring we are launching two Rustlers. One with the ultrasonic and new anti foul. One with last years anti foul and the ultrasonic. It will be interesting to see the result.

In advance of any scientific proof, I am confident to say it makes a significant difference to anti foul period requirements.

Perhaps as the configuration improves it may well do away with it entirely, but for now whether it is justifiable from a cost or convenience standpoint depends on your particular situation.

 

[Vara]

As good as Coppercoat but with power penalty.

 

[prv]

The paint was Awlgrip anti foul of course. Does anyone paint boats with plain paint?

Not usually, but I thought they might if they were testing ultrasonic fouling protection. Otherwise how do you distinguish between the effects of the paint and the ultrasound?

I'm sure I had read (not from you) that the ultrasound was intended to replace antifoul, avoiding the effort of painting and, for the tree-huggers, not putting nasty stuff in the water. If so, somebody needs to be trying it without paint.

Pete