Date: 6/24/2009
Name: Dave Doan
email: daved@rapidnet.net
subject:6 hp. vs. 8 hp.
I'll second Andrey's comments. I've got a Nissan 6 hp. short shaft on my 21. (Same as the 6 hp. Tohatsu, different paint.) In calm conditions it propels the boat 2.5 knots at idle, 4+ knots at just off idle, and 6 knots at full throttle. Most articulated mounts seem to be rated for 5 hp. with a 4 stroke motor so the weight and power of the 8/9.8 might be a little much.I've never wanted for more power but I'd definitely recommend going for a long shaft (20 inch vs. 15 inch length.) In really rough conditions the short shaft can cavitate causing momentary loss of drive.
I should mention that a spring loaded mount to counter balance that motor weight is highly desirable. The original mount on my 21 had no springs and it was a back breaker to get that 55 lbs. up and secure. The extra weight of the 8/9.8 might overpower the springs of the mount and make it very hard to lift. For the record, I chose a Fulton 1710 mount and it has worked very well.
In closing, I think you will be as amazed as I was at the fuel efficiency and quiet, clean operation of these Tohatsus. My only criticism is the single cylinder vibration which you will soon learn to minimize with minor throttle adjustments. Bottom line: if I were choosing I'd go with the 6 hp. 20 inch shaft.
Dave
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