Motor shaft length

Hello I have a 2004 getaway with the Cheata motor mount. I'm looking to get a Honda 2.3hp gas motor was just curious on what shaft length I should get? they offer short (15) or long (20). Thanks in advance for any help on the issue.

I haven't installed a motor on my Getaway (yet) but have exchanged DMs with two Getaway owners who have. One is a former owner who had the short shaft Honda 2.3 on a cheata mount. The other is a current owner who is "pretty sure" his Torqeedo is the short shaft. I think the long shafts drag and catch waves too much.

BTW both of them greatly preferred the homemade mount described in a long thread by KeithB on this forum that you should be able to find by searching. One of them switched from the cheata to the homemade mount (~$100 in parts) and the other wishes he had before he sold the boat.