Page 35Propeller Protection

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This doesn’t really have much to do with Stirling engines.

But I repeatedly see propeller shafts being fitted to hulls for Stirling boats without any
propeller protection.

Boats and propellers have been around a long time.
Boat building practice is to protect the propeller and rudder with something strong.
It’s called a skeg.

It’s to protect against accident and poor helmsmanship.

Running aground is to be avoided.
I repeatedly see boats “cut the corner” around the downstream end of an island.

All river islands have a sandbank at the downstream end.
Grinding the propeller into the sand and bending the prop shaft (and rudder) is to be avoided!

Likewise “bank crawling”. I know the rules say “keep to the right”. But do not hug the bank.
Shallow water is full of water weeds. The propeller will get clogged.
Stay out from the bank in the main channel. Water that is 8 or 9 feet deep has no weeds.

When out walking – life is much better when you stay to the paths.
Don’t walk through the brambles.
It’s the same with small boats. Stay away from weeds and shallows

”But weed shedding propellers are the answer”. No. Helmsmanship is the answer.

Priority 1 for a Stirling boat propeller is that it is large and slow – for efficiency.
Scimitar profiling may help with weeds – but reduces efficiency.

Interestingly, Kort nozzle users report that the nozzle prevents debris from fouling the propeller