Bolard Pull

[Rakar]

Can someone explain how to calculate Bollard Pull.

[jehardiman]

Bollard pull is just Kt evaluated at J=0 for any n. You get the number either from propeller test or you (rarely, because of the risk involved) measure it directly. For most "large" standard series props it will be between 30 to 35 lbs per hp delivered. Some props in thruster/nozzle configurations will get ~40 up to ~60 with tight tolerancing. Specalized wheels can get up to 200 lbs thrust per hp delivered, but these are very quirky in their behaviour.

[FAST FRED]

For tugs and other comercial boats Bolard Pull MUST be demonstrated, and documented.

Many big ports will have a service (great one in Norfolk VA) that performes the measurements, for a fee.

FAST FRED

[SailDesign]

Rakar,
I don't usually do this, but here is an Excel spreadsheet to estimate bollard pull for you.
PLEASE remember, this is an old spreadsheet, prop technology may have changed, and as usual you get what you pay for (in other words, use this at your own risk and preferably check with known data)
Steve

[Rakar]

We carried out direct test on a vessel, recently an AHTS ( Caterpillar 3606DITA @2722HP x 2 ) with Kort nozzles and the average BP we managed to get is 67.72 Tns.
I realized it really doesn't match with theoratical calculation.
To my understanding ,few other factors govern the effectiveness of BP namely water depth, wind etc. but they can effect that much?
Can some one do a theoratical calculation and let me know as when I did it came to be aroung 85 tns.

[StianM]

When you where doing the bollard pull test did you use bowthrusters to keep the boat steady?

Use off bowthrusters can reduce the bolard pull.

[PNACS]

Can You post more dteails of your Propeller (dia, pitch, rpm etc) & engine .?