Hallo Matthias,
Here in the Netherlands I was advies to buy a 18 inch folding propeller by the local Volvo dealer. Not a 17 inch.
I found out in the manual that if you have a S- sail drive and reversing gear MS2/MS25 you can put your gas handle on neutral.
So the propeller is turning while you’re sailing. Every 10 hours you need to switch the engine on for 5 min to cool down the reverse gear.
This knowledge saved me lots of money 😉
“When sailing, the control lever must be in the neutral position if the boat is equipped with the HS25 reverse gear. If the boat is equipped with an S-drive or reverse gear MS2/MS25, the control lever must be in reverse when using the folding propeller and in neutral when using the fixed propeller.
Important! S-drive and reversing gear MS2 with fixed propeller: When sailing long distances, start the engine every 10 hours for five minutes to cool down the drive/reversing gear. If this is not possible, a propeller shaft brake should be fitted.”
Translated with http://www.DeepL.com/Translator (free version)
Good luck!