Monday, April 23, 2018

Propeller Polishing

                                                    Propeller polishing.

Although a lot of stories from individuals can be found on the internet is not touch the propellers
and especially do not clean or polish them.
One of the explanations is that the propeller can get in unbalance and that it will create damage
to the bearings.
Well in case of the Storebro there are no bearings involved in the propeller shaft except the outer bearing which is lubricated by the surrounding water further it is a free shaft which is connected
by a semi flexible coupling to the engine.
Important is of course that the propeller shaft is in line with the outgoing engine shaft.
A smooth and polished propeller can reduce your fuel cost with 3 to 5 %, and with the
old engines I have every liter/gallon is one.
Further a propeller with oxidation creates a rough surface, which not only can create cavitation
 but also extra noise.
Therefore the decision was taken to clean and polish the propellers.

Although difficult to see from attached picture the surface of the propeller is very rough.

The tools I used for cleaning and polishing the blades is not a metal wire brush or sand paper since I do not want to remove any of the metal of the propeller just the oxidation.

I used for this cleaning nylon brushes which do remove very slowly the oxidation, this is a slow process and takes time but it does remove what needs to be removed in my opinion..

As can be seen from the below picture the propeller is cleaned but still a discoloring can be seen which indicates that I have not polished till the bear metal but just removed the oxidation.

The below picture shows in better detail that the blades are clean and smooth but still some surface roughness can be seen, to remove this one needs to use sand paper or another mechanical means to remove this , which will result in removing metal, what I do not want to do.

At the same time I cleaned the rudders from oxidation no specific reason 
but it looks nice for the picture.

Finished product of two cleaned propellers and rudders.

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