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30' Sport Fisherman   Boat building project

design and build of a center console offshore sportfishing boat 


Merc Prop testing
Suzuki  and prop testing





  Power and Props

The original motors were a pair of 2000 year model Mercury Optimax's and as of 2009 I have re-powered with a pair of 2007 (new in box) Suzuki DF300, 300 hp four strokes. 

The optimax's were running good but I was ready for a change and I hoped the 300hp Suzuki's would add some cruise speed as well as more top speed. I was surprised to find the DF300's did not have much for more speed as top speed has only increased a couple of miles per hour and no real increase to cruise speed. The only benefits so far are the increased torque which allows the boat to hold a plane are speeds down to 20-25 range where the Optimax's would not hold the boat on a plane below 27-28 mph and of course the four strokes are a lot quieter. The electronic engine controls, throttle and shift, are very nice and the gage network that provides a lot of information including pretty good fuel consumption inforamtion.

The Suzuki lower unit design (I guess hydrodynamics) are nowhere as good as the Mercury's and I still don't have these engines sorted out completely. In a nutshell, the Mercury and for that matter Yamaha's and E-tec's have lower unit housings that look like the shape of a nuclear submarine while the Suzuki's are shaped like a supersonic jet's. The really high performance units that Mercury makes for racing engine and go fast outdrives are needle nosed as well but these also are on racing type boats. I think there is a reason Merc only fits these to high performance applications rather than the fishing boats.





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Last modified: November 09, 2015