Raw Water Cooling Question

[Meck]

Hi, our boat is in a marina that gets an incredible amount of growth from barnacles and other types of critters, and a mechanic her recommend putting bromine or chlorine tablets in the Raw Water strainers to eliminate the restrictions from the marina growth.

Does this sound like a good idea?? Will chlorine cause corrosion or damage to the heat exchangers?

Any comments would be appreciated

Meck

Meck

[Don Lucas]

I'm in the chemical water treatment business, so for a change I really am an expert on this one.

It's a BAD idea. Chlorine and bromine attack copper and if you place directly in the strainer you are going to get a high concentration that is going to go after your tube bundle as well as the strainer.

[GordMay]

Bronze strainer bodies should have good corrosion resistance to sodium hypochlorite (chlorine); but the S/S strainer basket may have poor resistance.
➥ Metals and Corrosion Resistance

But, I defer to Don's specific expertise.

[Meck]

Thanks for the replies.

Don, by tube bundle do you mean the heat exchanger? I have Yanmar 40hp engines and everything in and around the strainer is plastic.

Meck

[Don Lucas]

Gord's answer made me look at the chart. Bronze is a 3 "not useable" for the sodium hypochlorite (sodium bromine would also be about the same thing). Except for high end stainless metals (beyound the 304/316 boaters normally talk about) the only material that really is OK for "bleach" type halogens is plastic type materials.

[Don Lucas]

Meck

Even if the strainer etc is plastic the chlorine is going to go up the lines into your engine and heat exchanger etc. If you really are at the point you need to add a biocide you need to look at a non-oxidzing biocide (dangerous stuff don't get any on you). This isn't all that available, but I don't see any reason you couldn't use a fuel additive biocide as these are all non-oxidzing. In the long term I would think changing your thur valve fittings etc to a copper based material may be the best answer.

[GordMay]

Originally Posted by Don Lucas

Gord's answer made me look at the chart. Bronze is a 3 "not useable" for the sodium hypochlorite (sodium bromine would also be about the same thing)...

dam ... i MUST HAVE CHECKED SODIUM CHLORIDE (SALT), NOT SODIUM HYPOCHLORIDE.

THANKS, DON !!!

[David M]

Vinegar perhaps. Lowering the pH make it impossible for shell (calcium carbonate) growth to occur.

[Pete7]

Can you not just close the engine seacocks ? perhaps flushing with fresh water first.

Pete

[barnakiel]

Originally Posted by Meck

a mechanic her recommend putting bromine or chlorine tablets in the Raw Water strainers

Well, this mechanic is not a biologist, are they. Clean, antifoul. If you are sure your raw water system parts will take it, you can try an acidic solution (but nothing too strong) to kill the critters overnight and dissolve their calcium shells. Then flush immediately.

b.

[Chief Engineer]

Be careful some one may call P.E.T.S. on you
People for the Ethical Treatment of Shellfish
Funny...there are no chapters in Maine, Alaska, Lewsieanna or Mirlin.

[David M]

Originally Posted by Pete7

Can you not just close the engine seacocks ? perhaps flushing with fresh water first.

Pete

I think you nailed it Pete. Life inside the lines needs water circulation to survive. By closing the seacock you eventually create an anaerobic environment, without light or oxygen where neither plant life nor animal life can survive. That's why stagnant seawater smells so bad, that is dead phytoplankton and and zooplankton decomposing. Add to that you have copper in the solution from the bronze fittings...a biocide to growth. You get a double whammy to growth simply by closing the seacock.

[chala]

During an infestation of black striped mussel, quarantined boats where required to fill their cooling system with common dishwashing detergent, the marina was treated with copper sulfate and the infestation over come. I still use detergent in my stern tube, it prevents growth on the duramax.

[barnakiel]

The s.c. black stripped mussel infestation was a PR ploy back in OZ some time ago. Later it turned out there was nothing in the water just the govt had a bad need to lower unemployment rates by creating more public sector employment.

But god did I have a swell conversation with the inspector that came to fill my seacocks with his washing liquid. And he had a swell time, I guess, trying to get to all 33 seacocks that I have very well hidden in my little shooter ;-))

;-)))

b.