The Shipyard ( Dry Dock ): Builds & Questions > Working Vessels
Coastal range ex-Smit-tug
Hande:
I'm sure, the direction of the spins wouldn't matter in my model.
On the other hand, I like to think of it as a miniature of a real thing.
I leave the propellers according to your first configuration (left clockwise, right anticlockwise).
Thank you!
derekwarner:
Hande......one point you may wish to review is the outside diameter and profile of the propeller blades compared to the inner diameter of the nozzle
The design concept here of improved thrust is relative to the velocity of water through the mouth of the nozzle and the redirected turbulence that is created by the close diametrical clearance between the propeller & the nozzle
You will also find that propeller blade geometry is vastly different when used with nozzles.......in that the tip of each blade is flattened out to blend in with the profile of the nozzle ID or bore
To call a spade a spade ...the propeller's you show here [image 4633] with the nozzles you depict would have near ZERO thrust benefit over the propeller's alone >>:-(
Apart from that, your build and detail as shown to date is of first class construction :-))
Keep us posted with many more images ......Derek
Brian60:
While what Derek says is true for hydro dyamics and waterflow through the nozzles, it is not always followed in real life. The first photo here shows simply what Derek means, the tips of the blads are flattened so as to follow the nozzles closely so enhancing thrust.
The second one shows also that a lot ships 'followed fashion' in that they put Kort nozzles on but were quite happy with the thrust of ordinary propellors inside of them..
Hande:
It would be interesting to see a picture of Smit Nederland's or sister ship's propellors.
I would like to bet that Billing boats had no concern about thrust efficiency when selecting the propellers for the kit.
The ones that came with the kit are 3-blade and generally are just regular propellers.
I suppose changing the propellers at a later stage is merely a question of buying them. No technical obstacles?
xm607:
Looking at the photo of the props I did not realise how poxy the Billing ones are, might change for some modified plastic four blades.
Steve.
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