Info on Fins added to the lower unit

[yamaha chris]

Looking for info on Fins added to the lower units. I have a 9.8 mercury 60's or 70's model and need more top end speed. Thinking about adding a fin to the lower unit. Does anyone have any experence with them and do you think this might get me some more top end speed.

Thanks
Chris

 

[ddennis]

Re: Info on Fins added to the lower unit

You won't get any more speed, and may very well lose some if you install one. They are intended to aid getting on plane and staying on plane at a lower speed. Its a mixed bag around here, some love them and some hate them. Most will reccomend using Smart Tabs....however on a small engine like that you wont see any benefit with them either. Best bet may be a different prop. What are you running this engine on?

 

[yamaha chris]

Re: Info on Fins added to the lower unit

I'm running it on a 15' ozark runabout. I'd like to put a little bigger motor on it but we have a 10 hp limit on the lake. Would a prop make that much difference.

 

[ddennis]

Re: Info on Fins added to the lower unit

Pushing a 15 foot runabout with a 10 horse...you arent going to break any speed records. Best thing would be to put a tiny tach on it to see what your rpm's are at WOT to make sure you arent lugging it too bad...then post the results here along with what prop you have on it now..

 

[yamaha chris]

Re: Info on Fins added to the lower unit

Thanks for the info Ddennis. I'll try to get the info posted this weekend.