On Mon, 18 Jan 2010 09:55:14 -0500, " Tuuk" wrote:

Is it possible that there is too much electrolisis loss? And these barnicals
are attracted to that? Using anodes or disconnecting battery or another form
of cathodic protection. Have a look at some other boats in the slips to see
if theirs has the same problems. If they don't then you may have a
electrolisis issue as the prop is the most obvious spot of focus for this as
it is the thinest/best part under the water for transfer of electrons.

Cathodic protection is exactly the same as it has been for the past 15
years or so. The propeller and shaft are insulated from the rest of
the boat and an anode is placed between the prop and the stern
bearing.



"mmc" wrote in message
ng.com...

"Vic Smith" wrote in message
news
On Mon, 18 Jan 2010 18:38:26 +0700, Bruce In Bangkok
wrote:


Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Haven't tried it because I don't have a boat.
But you made me think that if you knew your boat would be idle a long
time, wrapping the prop it in a old piece of poly tarp might work.
Maybe even a thick black garbage bag.
Should be easier to put that on and crack/cut it away than spend 2
days scraping.
Barnacles need some light to grow, right?
We sometimes want a patch of lawn for garden and the easiest way
to kill the grass is to lay something on it that blocks the light.

--Vic
You're right, that does work Vic. The owner just has to remember to take
it off before getting underway!
Hope you're well and staying warm.


Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Mon, 18 Jan 2010 09:48:00 -0500, "mmc" wrote:


"Bruce In Bangkok" wrote in message
.. .

Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Any paints I've tried get burned off. A friend has gotten his prop plated
with copper and swears by it.


Interesting. There is a plating shop near here that might be able to
do that. I shall ask.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Mon, 18 Jan 2010 09:51:00 -0500, "mmc" wrote:


"Bruce In Bangkok" wrote in message
.. .

Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

I'd go with Vic's suggestion for extended periods or areas with warm water
like Thailand ;-)
Might hang a tag on the engine intake seacock to remind you to remove the
covering before getting, or attemping to get, underway.

Been there, done that and it works a treat if you are going to leave
the boat for some time. In this case I was living on the boat and
working on a second boat. The enthusiasm for finishing the second boat
precluded sailing the first boat.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Mon, 18 Jan 2010 10:39:05 -0500, " Tuuk" wrote:

Check the ingredients of that antifoul paint. If its ingredients include
somethings like zinc or cadnium or nickle or magnesium or something with a
negative potential, then they are simply trying to solve their anodic
galvanic reaction which might be attracting the animals. Easier to solve
with a rectifiar or battery issues.

No exotic additives. From all I can find out the paint is basically a
very hard anti-fouling applied over some sort of (perhaps) epoxy based
primer. The one magazine article I read stated that the paint lasted
an entire season on a trawler yacht but I'd really like to see it in
action before spending the money.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Mon, 18 Jan 2010 16:28:05 +0100, "Edgar"
wrote:


"Bruce In Bangkok" wrote in message
..

Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Ordinary ablative antifouling might be better than nothing if you hardly use
the boat but it washes off in no time at all if you run the engine. I use
some expensive stuff in a spray can that Volvo produce for their underwater
units. This seems basically to be the same sort of antifouling but harder,
so it does not wash off so quickly. Also it makes a somewhat slick surface
so that barnacles find it harder to stay on while the prop is running.
I have a theory, not yet put to the test, that the very slick paint that has
been produced to make a wall graffiti-proof would be the way to go because
barnacles could not stick to it at all once the prop started to rotate.. The
reason I have not yet tested this idea is because the smallest quantity that
I have found for sale is about 10 gallons.


You are correct that normal anti-fouling paint doesn't stay on the
prop however several paint companies are making a paint specifically
for propellers. The recommended procedure is to (1) sandblast or grind
the propeller to a specific surface finish; (2) clean the propeller
chemically clean; (3) apply a specific primer and finally (4) apply a
specific anti-fouling paint. The whole procedure is involved and the
paint is expensive and apparently deviating from the specified
procedure results in failure. Thus my questions.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

This works well:

http://www.sgnis.org/publicat/ab97_43.htm


Connect a bi-phasic livestock fence shocker to your propeller shaft and you
will experience no electrolysis.

Noj

On Tue, 19 Jan 2010 07:32:32 +0700, Bruce In Bangkok
wrote:

On Mon, 18 Jan 2010 16:28:05 +0100, "Edgar"
wrote:


"Bruce In Bangkok" wrote in message
. .

Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Ordinary ablative antifouling might be better than nothing if you hardly use
the boat but it washes off in no time at all if you run the engine. I use
some expensive stuff in a spray can that Volvo produce for their underwater
units. This seems basically to be the same sort of antifouling but harder,
so it does not wash off so quickly. Also it makes a somewhat slick surface
so that barnacles find it harder to stay on while the prop is running.
I have a theory, not yet put to the test, that the very slick paint that has
been produced to make a wall graffiti-proof would be the way to go because
barnacles could not stick to it at all once the prop started to rotate.. The
reason I have not yet tested this idea is because the smallest quantity that
I have found for sale is about 10 gallons.


You are correct that normal anti-fouling paint doesn't stay on the
prop however several paint companies are making a paint specifically
for propellers. The recommended procedure is to (1) sandblast or grind
the propeller to a specific surface finish; (2) clean the propeller
chemically clean; (3) apply a specific primer and finally (4) apply a
specific anti-fouling paint. The whole procedure is involved and the
paint is expensive and apparently deviating from the specified
procedure results in failure. Thus my questions.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Normal anti-fouling should not be applied to a propeller. Normal
anti-fouling paint contains copper and your prop will get eaten.

On Tue, 19 Jan 2010 05:52:52 -0500, wrote:

On Tue, 19 Jan 2010 07:32:32 +0700, Bruce In Bangkok
wrote:

On Mon, 18 Jan 2010 16:28:05 +0100, "Edgar"
wrote:


"Bruce In Bangkok" wrote in message
..

Has anyone tried any of the anti-fouling schemes intended for
propellers, and if so what was your experience?

The question comes about because I just had to dive on my prop and
clean it. When I got down there I discovered a mass of "clams" as big
as a bushel basket. Took two days to scrape them all off.

True, for one reason or another, the boat hasn't moved in the better
part of a year but still I don't believe I have ever seen as much
growth. Must be either global warming or high CO2 content :-)

In any event, it does make one think "there must be a better way".

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Ordinary ablative antifouling might be better than nothing if you hardly use
the boat but it washes off in no time at all if you run the engine. I use
some expensive stuff in a spray can that Volvo produce for their underwater
units. This seems basically to be the same sort of antifouling but harder,
so it does not wash off so quickly. Also it makes a somewhat slick surface
so that barnacles find it harder to stay on while the prop is running.
I have a theory, not yet put to the test, that the very slick paint that has
been produced to make a wall graffiti-proof would be the way to go because
barnacles could not stick to it at all once the prop started to rotate.. The
reason I have not yet tested this idea is because the smallest quantity that
I have found for sale is about 10 gallons.


You are correct that normal anti-fouling paint doesn't stay on the
prop however several paint companies are making a paint specifically
for propellers. The recommended procedure is to (1) sandblast or grind
the propeller to a specific surface finish; (2) clean the propeller
chemically clean; (3) apply a specific primer and finally (4) apply a
specific anti-fouling paint. The whole procedure is involved and the
paint is expensive and apparently deviating from the specified
procedure results in failure. Thus my questions.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

Normal anti-fouling should not be applied to a propeller. Normal
anti-fouling paint contains copper and your prop will get eaten.

I have no idea what the "propeller paint" is but it is certainly
recommended for propellers so I assume that it is compatible with
bronze.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

On Mon, 18 Jan 2010 21:18:39 -0700, "Noj Zang"
wrote:

This works well:

http://www.sgnis.org/publicat/ab97_43.htm


Connect a bi-phasic livestock fence shocker to your propeller shaft and you
will experience no electrolysis.

Noj

It is not electrolysis I'm fighting, it is shellfish.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)

"Bruce In Bangkok" wrote in message
...

It is not electrolysis I'm fighting, it is shellfish.


Let's try again. The link says:

The application of pulsed electric fields to water containing micro- or
macro-organisms has been proven to be a means of controlling the population
of these organism, or to stun them over a certain electric field dependent
time interval. The fact that the efficiency of this control mechanism
increases with decreasing pulse duration opens the possibility to utilize
microsecond pulse power technology for biofouling prevention in cooling
water systems. The advantages over other techniques used for biofouling
prevention such as its independence from chemicals, the fact that it is
possible to stun, rather than kill unwanted biofouling species, that it does
not generate shock waves which could affect the structure of the cooling
system, and that it can be installed like a filter in front of an existing
cooling system, without requiring any changes in the cooling system, make
the pulsed electric field technology (PEFT) a strong contender to existing
biofouling prevention methods. A recent field study, where tidal water from
the Elizabeth River in Norfolk, VA, was treated by means of the pulsed
electric field method, demonstrated complete prevention of biofouling in
pipes when the river water at the intake of the pipes was exposed to
electric field of 6.5 kV/cm with 770 nanosecond pulse duration. The
efficiency was 1,400 gallons of treated water per kWh, an increase in
efficiency by more than a factor of three compared to results presented at
the 1996 Zebra Mussel Conference. Experiments with even lower electric
fields and correspondingly lower energy consumption are under way. modeling
results indicate that efficiencies of more than 50,00 gallons/ kWh may be
reached in fresh water cooling systems.



The livestock fence shocker delivers said pulsed electric field of required
intensity. If the electric pulse is monophasic it delivers net charge into
the water, creating electrolysis. If the electric pulse is biphasic (ie:
capacitively coupled) it will deliver no net charge into the water, avoiding
electrolysis.

I, know, I know. It's not livestock that are giving your propellor problems
and the article only mentions zebra mussels in 1996.

But then you are the guy who wrapped electrical connections in tape for
frequently flooded aircraft runways and buried them in the ground, despite
the law saying those connections should be above ground in a hermetic box.
How many died because of that?

With barnacle growth the size of a medium shopping trolley fouling your
drive train at least you have the electrolysis problem solved as there are
no exposed metals to electrolyze.

I have studied this in depth at university in Bangalore.



Noj