The boat I am planning is to be mid-engined, probably a JP3 with a PRM 260 gearbox.
The thing is, I want to make proper use of what would normally be the boatman's cabin and use the space as a galley. I need the space to have similar headroom to the rest of the boat, but of course there is the matter of the prop shaft. I have briefly considered and have pretty well rejected, hydraulic drive on the grounds of cost, complexity and increased fuel consumption.
The next option I'm considering is to build an offset prop shaft, i.e. an independent lay shaft, supported by plummer blocks and driven either by triplex chain and sprocket or HDT belt and pulleys at either end. This would allow the shaft to be dropped down to the level of the bearers. This arrangement would also give the opprtunity to finely tune the engine:prop ratio. The prop shaft itself would be quite short and I assume, would need a thrust bearing to resist the force of the prop. The short shaft from the gearbox would be supported by a plummer block.
I'm sure I remember seeing photos or a video of a similar arrangement some time ago, but I think the objective in that instance was to allow the engine to be offset one side.
My questions are: has anyone else done this? What issues were encountered? Any thoughts re chain/sprocket vs. belt/pulley?
Help/input appreciated.