I’ve had my eyes on these bow prop propellers for a while now. I had an accident with my three blade and decided to give it a try.
There are multiple brands and props out there they are all made to be used in a duct. I managed to find one that’s 140mm in dia.
The prop uses a shear pin to keep it in place and normally a bolt/nut to keep it from falling of the shaft.
The one I choose came with a 11,5-ish mm bore so I decided to adapt it to my 10mm shaft.
First I drilled the bore in the prop to 12mm and the got a 12mm stainless pipe with 1mm walls. I cut the pipe to the right length and used an hydraulic press to fix the pipe in the prop.
I then drilled a hole in the shaft for the shear pin and also made a cut for the clip that hold the prop in place.
Hopefully I will get it in the water for a trial soon.
The hub on the prop is a bit bigger than the hiorth original and I might do a 3D print add on to the torpedo to get a smooth overlap between torpedo and prop.
This is the prop I got: