Bollard pull is probably not quite the right thing anyway, as the thrust may vary a lot at zero hull speed.
You could make a rough estimate from the pounds/feet per second number, then make a reduction for propellor effieciency. (50 to 70 per cent efficient?)
In non-redneck units
1hp = 748Watts= 748Nm/s
1m/s =3.6 km/h, 1nm=1.842km so 1knot=1.95m/s
so 1hp@1knot=748/1.95=383N x efficiency
383N=39.1kgf=~86LbF
Doesn't sound much does it? suggests horse pulling canal boat at 4kts with force of 21Lb? ???
Any gsce stoodents on here?