Do the big ships care about bottom cleaning?

[Gudgeon]

Originally Posted by fstbttms

Except that the brush carts are hydraulic, you are correct.

The brushes they were using a few years ago in Pearl Harbor were air powered.
Could have changed as I am no longer there.

[fstbttms]

Originally Posted by AKA-None

I guess what we need are remoras...

https://www.youtube.com/watch?v=MeZkcUhFtx0

[Leggy]

Originally Posted by fstbttms

For the most part, this is 100% untrue.

Not quite. The majority will use bottom paint with biocides and slippery properties. This is applied on a maximum five year period where all ships must have a SPS - a special periodic survey for insurance purposes. Since the hull needs to be dry to check sea chest inlets etc then this is a perfect time to clean and re-apply anti foul (not a legal requirement but a good idea). However there are some ships that have no paint at all, instead they use the clean metal hull to transmit an impressed current system to ward off growth - it works pretty well also.

[AKA-None]

Originally Posted by Leggy

Not quite. The majority will use bottom paint with biocides and slippery properties. This is applied on a maximum five year period where all ships must have a SPS - a special periodic survey for insurance purposes. Since the hull needs to be dry to check sea chest inlets etc then this is a perfect time to clean and re-apply anti foul (not a legal requirement but a good idea). However there are some ships that have no paint at all, instead they use the clean metal hull to transmit an impressed current system to ward off growth - it works pretty well also.

It’s been decades but I’ve personally never seen a shop come into dry dock with a bare hull
All have been painted

[fstbttms]

Originally Posted by Leggy

However there are some ships that have no paint at all, instead they use the clean metal hull to transmit an impressed current system to ward off growth - it works pretty well also.

Impressed current anti fouling systems to protect sea chests and other piping systems? Yes. The entire hull? Not so much.

[Leggy]

Originally Posted by AKA-None

It’s been decades but I’ve personally never seen a shop come into dry dock with a bare hull
All have been painted

Yes it’s true that most are painted, hence the use of the word “Majority”. Personally I have been on three with such a system. They are oil rigs that spend most of their life in the same place on DP and need good protection for when we do move.

[Leggy]

Yes the entire hull. I’ve been on three drilling units with such a system- for the entire hull.

[fstbttms]

Originally Posted by Leggy

Yes the entire hull. I’ve been on three drilling units with such a system- for the entire hull.

"Drilling units" are not ships.

[Sailmonkey]

Originally Posted by Leggy

Yes the entire hull. I’ve been on three drilling units with such a system- for the entire hull.

I’ve been googling my heart out and can find no manufacturer of whole hull impressed current anti fouling.

Catholic protection yes, seawater cooling loops yes. Entire hull no.

Got a link to a manufacturer of a whole hull (ship or modu) impressed current anti fouling system?

[S/V Illusion]

Originally Posted by fstbttms

While I appreciate the support, this statement is also untrue. Yes, the Navy is exempt from American laws governing anti fouling paint that the rest of us have to follow. This does not mean that the Navy uses TBT anti fouling paints. They do not, and here’s why: The Navy has to do business in ports of call all around the world. And in those places, the Navy is not exempt from the laws governing anti fouling paint.

Actually, the American Navy, as well as every other branch of our military must comply with all standards, rules and requirements. The Navy isn’t exempt from anything including enforcement of environmental compliance rules.

[fstbttms]

Originally Posted by S/V Illusion

Actually, the American Navy, as well as every other branch of our military must comply with all standards, rules and requirements. The Navy isn’t exempt from anything including enforcement of environmental compliance rules.

I may be mistaken about an exemption for anti fouling coatings, but a quick Google shows many examples of environmental law exemptions for the DoD and Navy in particular.

[spaman]

Originally Posted by redneckrob

It's serious money for them, they definitely care. However on the plus size when you spend the majority of the year sailing at 20+ knots it definitely helps minimize the fouling. Drydock and bottom paint takes care of the rest.

Very few commercial ships can or will run at 20knots (wsnp).
Container ships run to a schedule (in theory) and will work on a fast turnaround.
Bulk carriers will more likely run at economic speed which will average 12-13 knots, but can up to 15 knots. Due to more extended stays in port and often waiting for extended periods at anchorage, growth quickly forms and after 23-28 days the bottom is likely need cleaning with divers. Drydocking can be extended up to 3 years, but generally every 2.
Tankers can get away with up to 5 years between drydocks depending on the trade, but will still have bottoms cleaned intermittently, especially if this starts to affect the performance. They are more likely to trade at 14-16 knots depending on size, cost of bunkers and the state of the market.

[rmesfo]

Originally Posted by ItDepends

Mat is right, as usual. Commercial shipping use pretty much similar paint to recreational boats. There are differences, but they are more related to specifics of use patterns than anything else.

When he says "for the most part" what he is NOT saying is the exception is the Navy. They still get to use TBT paints. Why? Because the government makes the rules. They are quite happy to force a commercial operator of a super panamax to haul every 2 years for new paint, but we just CAN'T do that for an aircraft carrier, of course. It's obvious.

Your point is?

[Scorpius]

Originally Posted by GreenWave

Which is why the limiting rules applied to recreational boats is just dumb. By far the commercial quantity is much higher and likely has a bigger impact on the environment.

I don't agree. Most recreational boats in the water spend over 90% of their time tied to a dock in a marina with hundreds or thousands (Marina del Ray?) of other recreational boats. The impact on the local environment of all that concentrated, immobile, bottom paint is massive. Commercial vessels spend FAR more time moving and at sea where there is far more water and far less bottom paint per square mile than in your local marina.

[fstbttms]

Originally Posted by Scorpius

I don't agree. Most recreational boats in the water spend over 90% of their time tied to a dock in a marina with hundreds or thousands (Marina del Ray?) of other recreational boats. The impact on the local environment of all that concentrated, immobile, bottom paint is massive. Commercial vessels spend FAR more time moving and at sea where there is far more water and far less bottom paint per square mile than in your local marina.

This guy gets it