Fresh Water to kill Hull Fouling?

[Old Bumbulum]

Anyone have any idea how long would you'd need to keep a boat in fresh water to kill off marine growth on the hull? My boat is in a harbour that grows weed incredibly fast, even on new coppercoat and there are fresh water areas accessible nearby.

Is this an effective way of curtailing marine growth? Once it is dead will weed tendrils fall off or does it still adhere to the hull?

 

[temptress]

So here in Singapore fouling is really bad. However we can sail up the Johor River to a mice fresh water marina /resort. 3 days usually clears all the fouling from the hull.

 

[Deleted member 36384]

So here in Singapore fouling is really bad. However we can sail up the Johor River to a mice fresh water marina /resort. 3 days usually clears all the fouling from the hull.

I guess you have to anchor because the pontoons are tiny?

 

[temptress]

Typo but we often sail right into the mangrovesand anchor. Only issue are the salty Crocs that love the mangroves as well.

 

[Sandy]

Anyone have any idea how long would you'd need to keep a boat in fresh water to kill off marine growth on the hull? My boat is in a harbour that grows weed incredibly fast, even on new coppercoat and there are fresh water areas accessible nearby.

Is this an effective way of curtailing marine growth? Once it is dead will weed tendrils fall off or does it still adhere to the hull?

Friends who have spent a week, 7 days, on the Caledonian Canal reported a clean bottom.

 

[Minchsailor]

I spent 3 nights in the Cally canal last autumn and when slipped a month later there was only a light coating of slime.

Compare with this year when there is already a veritable meadow of growth (same antifoulung).

 

[bluerm166]

Small point but MG DUFF state that saltwater vessels with zinc anodes moving to freshwater will develop an irreversible white crust which needs to be removed before protection will resume in saltwater or the anode changed.
For a stay in freshwater of over two weeks they suggest another system is used.

 

[dslittle]

Small point but MG DUFF state that saltwater vessels with zinc anodes moving to freshwater will develop an irreversible white crust which needs to be removed before protection will resume in saltwater or the anode changed.
For a stay in freshwater of over two weeks they suggest another system is used.

Hmmm. That is interesting as we spent a fortnight in freshwater before being lifted and the pear anode had certainly gone white. I rubbed it off a bit but that is worth knowing as we are back in salt water for the next couple of months!!!

To answer the OP, the boat was lifted and kept on the hard for a month after that two weeks. It wasn't even pressure washed but the bottom is as clean as a whistle so I know two weeks will definitely do the job. We are Coppercoated and it has worked well in salt water in the past so I am not sure how much is attributable to each. In fact, thinking about it, the boat hasn't been pressure washed since lifting in Kip in April 2016!!!

 

[Momac]

Small point but MG DUFF state that saltwater vessels with zinc anodes moving to freshwater will develop an irreversible white crust which needs to be removed before protection will resume in saltwater or the anode changed.
For a stay in freshwater of over two weeks they suggest another system is used.

Aluminium anodes work for me . Boat lives in fresh and visits salty water.

 

[Quandary]

I avoided patination problems when aluminium sail drive anodes were not available by using a hanging anode and cleaning it regularly, with shaft and prop. anodes the rapid rotation cleaned them.
To the OP, I reckon 48 hours in fresh water kills it, whether it then drops off is a different question.

 

[TSB240]

We are based in a normally freshwater fed dock. This summer has seen virtually no rain in the river. I have had to scrub off the rudder and 1 foot below the waterline twice this year. Never had to do this before as salinity has been much higher than usual.
Not had to antifoul since 2013.!
We don't have a zinc anode as they give no protection after a couple of weeks.