Does fouling occur in the raw water pipes?

[wipe_out]

It never fails to amaze me just how fast things grow on the parts that have no anti-foul.. It also amazes me just how strong the growth is.. Even a 20kn ride doesn't get it off the trim tabs and it holds on after brushing too.. Probably going to have to scrape it off..

Anyway this got me thinking..

Does the growth occur in all the raw water pipes, channels through the sterndrive and engine cooling system?

 

[kashurst]

you get a build up of lime scale - inside the heat exchangers I have found tiny sea shells growing. I have never seen plant life though I think that needs sunlight

 

[Heat Exchanger Guy]

This is one of the main challenges when designing a Marine Heat Exchanger. Sediments such as shells and sand will build up inside the tubes and pipework if you allow them to, the best way to prevent this from ocurring (other than filtering the water) is by using a high flow rate to constantly flush sediments through and out of the system. The trick is to get a flow rate that is fast enough to prevent sediments from building up but also not so fast that it erodes the tubes and tube sheet.

The heat exchangers you find in narrow boats on the likes of Kubota engines are only small, so a good rule of thumb is a pump that provides around 64 L/min flow per 100hp. If there have been regular problems with blocked tubes then a faster pump can be fitted but remember that too fast will reduce the life span of the heat exchanger.

Hope this helps!