# proximate diameter of a single screw 92 meter container

Discussion in 'Propulsion' started by martuk, Dec 19, 2008.

1. Joined: Dec 2008
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### martukNew Member

hi
as a project a have to design a propeller (b series ) for a single screw 92 meter container ship.
i have required formulas acoording to formulas i need a starting diameter and rotaional speed N
i assumed some values but i think they are totaly wrong i have no idea about how to find proximate values

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### Olavnaval architect

Martuk,

this is quite easy: Just take the distance between the lower surface of the afterbody and the baseline (i.e. the largest diameter possible) at the propeller position and subtract 0.10 m from this to ensure proper tip clearance.

Rules of thumb:

Dprop, max ≈ 0.68 * T and
Dprop, min ≈ √(Pinst / 500kW)

Rotational speed should then be determined from thrust coefficient KT = T / (ρ * n² * D^4) at maximum efficiency from the propeller diagram.

Hope this helps...

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Location: istanbul

thanks

4. ### apex1Guest

Hello Martuk.
I am actually in Istanbul and have some time to assist you if needed
Just send PM to make appointment.
Regards
Richard

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### quyetvtt46Junior Member

you can determine diameter D according to fomular : (n)^(1/2)*D=11,8(T)^(1/4) or (n)^(1/2)*D=13*(Ps/vs)^(1/4)
n: revolution of propeller
D: diameter of propeller
T: thrust of propeller
vs: velocity of vessel
Ps : bracket power of main machine

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