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have you noticed how boats both large and small tend to be painted a different0:04
color under the water most often it is red but actually nowadays you can get0:09
almost any color you like the reason for it goes back to the0:13
earliest days of sailing ships back in those days wooden sailing ships would0:18
slowly plot around the world a combination of their slow speed and0:21
rough hull made them an ideal breeding ground for underwater growth just take a0:26
look under a pier you will see the sort of growth these ships used to suffer0:30
we're talking barnacles worms seaweed and things like that so what's the issue0:35
well all of these things have negative impacts on ships over time you get the0:39
obvious of things like damage to the hull itself due to worms and the actual0:44
growth then you get issues like the additional weight that they have to0:47
carry around and reduction in maximum speed due to the extra drag of course on0:52
sailing vessels that dragon weight would impact their ability to sail upwind0:56
which would yet further reduce their efficiency what you need is a way to1:02
stop marine life from growing on the bottom of the hull and this is where1:06
antifouling comes in antifouling fairly obviously is just a system designed toAntifowling
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reduce fouling by animal and plant life on the underwater sections of a boat or1:15
a ship early solutions were to place copper sheets on the hulls of ships the1:20
Cutty Sark is a great example of this and I'll link to the greenwich maritime1:23
museum below if you want to see more about that the primary purpose of the1:28
copper sheets was actually to stop worms eating their way through old wooden1:31
hulls a secondary benefit though is that the copper would reduce the growth of1:36
plant life of course as wooden hulls were a place by iron worm issues did1:40
reduce but they've never been eliminated just look at the leisure industry today1:45
and you'll still see plenty of wooden hulls around and of course regardless of1:49
its construction material we still have the same old issue of drag caused by the1:53
growth of plant life is probably more important now to keep that under control1:58
what were the cost of fuel and efficiency savings on long passagePaint
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we still need antifouling to stop a combination of worms barnacles and weed2:07
from growing on the underside of hulls but instead of using the old technique2:10
of copper sheets we now use a form of paint instead that antifouling paint2:16
works on the same principle and actually still uses copper as a biocide though is2:21
mostly cuprous oxide is now mixed in with the paint rather than copper sheets2:25
it's the natural red color of those copper oxides that's led to the2:30
traditional red color of antifouling modern antifouling systems can be broken2:34
down into two broad categories hard and soft soft coatings are designed to wear2:39
off over time continuously exposing fresh biocides as the outer layer of the2:44
paint wears off hard coatings on the other hand are designed to be a lot more2:47
durable they're meant to last a lot longer as the biocides are released the2:52
durable layer of paint remains but of course the biocides contained in the2:56
outermost layer do get used up both systems work on the same principle they3:01
gradually release biocides commonly based on the chemical element copper the3:05
difference is that soft coatings slowly allow the paint to flake off as well3:10
as you can imagine there are environmental considerations to think of3:13
no matter what way you look at it antifouling releases via cites and3:18
possibly paint into the environment that is one reason a lot of ports don't allow3:23
cleaning of hulls they don't want the extra dose of biocides and paint3:27
released by the scrubbing process so what are your other options the cleanersAlternatives
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one is to simply use normal hardware and paint on the other side of the hull but3:35
that will result in a lot of aquatic growth that's fine on a small boat that3:39
you can pull out the water and clean quite often but is not so great on a3:43
container ship running around the world what would happen if for example a3:47
container ship picked up some seaweed in Asia and carried it into the Baltic Sea3:51
where it takes hold and overtakes some of the native species similar things3:55
have happened and do actually continue to happen though it's not so much from4:00
hull growth because of antifouling is more of an issue for a ballast water but4:04
that's a topic for another video so aside from just using no antifouling4:08
what could you do there is talk of systems that slowly use some sort of4:13
jelly from the hull the theory is that as4:15
the growth attaches to the hull the using jelly seeps off and takes the4:19
growth away with it I've never seen it in use but if anyone4:23
has let me know in the comments below cuz it'd be fascinating to look into4:26
otherwise there are some silicon based paints that make it hard for barnacles4:30
and things to stick to the hull itself unfortunately these don't actually stop4:35
the growth but it makes it easier to clean off send that most ports don't4:39
allow cleaning anyway not only because of the historical antifouling issues both so4:43
they don't want to clean off species that are not native to the harbor itself4:47
the last thing they want is to be overcome by some sort of invasive weed4:51
from the other side of the world anyway hopefully you've enjoyed today's video4:55
and have liked learning about the paint on the bottom of the hull for more4:58
content like this every other Friday be sure to subscribe5:01
right here on the channel until next time thank you for watching and good bye
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