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Rawwater system
The rawwater system is the engine's external cooling system. It cools the internal cooling system in an engine
mounted or externally mounted heat exchanger. The system is protected against galvanic corrosion by zinc ano-
des located in the heat exchanger.
Keep the engine room heated or use an antifreeze coolant in the rawwater system. Otherwise the rawwater sys-
tem must be drained when there is a risk of freezing in cold weather.
WARNING! The rawwater cocks and/or the cocks of the external cooling system must be closed before
commencing work on the rawwater system. This due to the risk of sea water entering the vessel.
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Maintenance: Rawwater system
Draining the rawwater system
1. Close the rawwater in- and outlet cocks.
2. Drain the coolant from the external cooling sys-
tem.
IMPORTANT! Check that the coolant really
drains. Deposits may need to be removed from
inside the drain plugs/taps.
Checking/Changing zinc anodes
Note! Zink anodes are consumed differently, depen-
ding on the marine environment.
1. Drain the external cooling water as described in
the chapter draining the rawwater system.
2. Unscrew the zinc anodes from the heat exchan-
ger.
3. Clean the anode with emery cloth to remove the
layer of oxide. Change the anode if less than 50%
remains.
IMPORTANT! Do not use a wire brush or other
metal tool for cleaning as this may decrease the
galvanic protection.
4. Fit the zinc anodes. Make sure there is good con-
tact between the anode and the metal goods.
5. Open the rawwater cocks before starting the engi-
ne
6. Check the installation and make sure there are no
leaks.
Checking/Changing rawwater
filter
For the rawwater inlet filter we refer to the maintenan-
ce description supplied by the supplier of the filter.
NOTE! If the water wherein the vessel operates is se-
verely polluted, contains large amounts of seaweed,
etc., the filter must be checked more often than is
specified. The filter can otherwise become clogged
and the engine overheated.
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