Winged paddles generally go over the shaft, mainly because you areore likely to break the blade so it is easier to remove without damage to the shaft. That and the original already is made over the shaft so figure it's less work changing it. 

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Most blades go inside the shaft rather than on the outside.  You could easily make this part of the mould to get the right diameter insert.  The ones I've seen that fit on the outside (werners) are moulded in place.

Hi Guys,