I’ve been wondering: where should engines, and thus the saildrives/props, be positioned?
It seems that there are 3 schools of thought:
- Propeller shafts (advantages: low maintenance / disadvantages: loss of space - comfort due to engines being set further forward, maintenance access).
- Engines installed fully aft (advantages: gain in space - comfort because engines are set aft / disadvantages: propellers are very exposed (will catch everything dangling overboard when going astern, risk of contact with docks, rocks, etc.), less efficient propulsion in heavy seas because propellers close to the surface and weight very far aft, having an effect on centering (causing pitching) and flow of water that can send the rudders violently to their stops when going astern.
- Engines set further forward (eg. on the Nautitech 46): (advantages: better weight centering, propulsion efficiency because the propellers are deeper, protected, water flow has less impact on the rudders when shifting to astern / disadvantages: “lost” space, comfort - noise - vibration in the aft cabins, heat?).