Check and consider replacing the Sun Odyssey 41 DS sail drive control cables as well as changing the gearbox mechanism orientation.
Several 41DS owners have reported breakage of their gearbox control cables: http://jeanneau.proboards.com/thread/6701/engine-control-cable-breakage-on
In summary there can be failure of the engine control cable at the first bend at the rear of the saildrive, where the control cable makes a 90 degree turn. The tight turn may be even more acute when the wooden enclosure at the rear of the engine is closed as the wooden lip can push the cable forward another inch or so.
The breakage of this control cable may result in the engine becoming stuck in either reverse or ahead, typically when manoeuvring. This has resulted in significant damage on at least one occasion.
The cable manufacturers typically recommend a minimum cable bend (radius) of 8 inches. The cable should be replaced with a multiflex type which can tolerate tighter bends – for example Multiflex Edge
The optimum solution is to also relocate the gear selector lever and bracket to the starboard side of the gearbox by rotating the control arm on the engine 90 degrees. This will allow a much better sweep in for the cable.
You will need to add extra washer/s below the split pin at the gearbox end. This is to ensure it does not foul on the cover studs. This Yanmar technical bulletin provides more detailed guidance.
The connection of the lever at the helm also needs to be changed from the bottom to the top as the lever action need to be swapped, IE to push instead of pull. This will be rather time consuming, removing the old cable due to all the cable ties.
It has also been found on some 41DS installations that the fuel pipe in plastic trunking may also be poorly routed, crossing the Webasto heater exhaust pipe, allowing the plastic trucking to melt and potentially creating a fire risk.
More information on this issue may be found on the Jeanneau Owners Forum