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Propeller anti-fouling?
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 ... 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) |
Propeller anti-fouling?
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) |
Propeller anti-fouling?
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) |
Propeller anti-fouling?
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) |
Propeller anti-fouling?
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) |
Propeller anti-fouling?
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 |
Propeller anti-fouling?
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. |
Propeller anti-fouling?
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Propeller anti-fouling?
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) |
Propeller anti-fouling?
"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 |
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