20 inch is fine 25 would drag. GO In a message dated 9/6/2015 8:25:04 P.M. US Mountain Standard Time, Bill_Ruth@whidbey.com writes: Plan on buying Tahatsu 5hp or 6hp long shaft (20") to use on the cut out transom of my newly acquired M17. Would a 25" shaft work better (Tahatsu 6hp SailPro)? Bill Ruth M17 1977 #277