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Racers and anglers have you heard about Hydrodynamic friction of the gearcase? Too low or not too low?

December 25, 2017

It’s a proven fact that a boat goes faster when you trim an outboard higher. Less gear case in the water equals less drag, and since drag is inversely proportional to speed, the faster you go, the more drag the lower unit creates.

Trimming out also raises the bow, cutting drag even more by reducing surface area touching the water.

 

One of the most controversial, least understood areas of marine high performance is that of the Nosecone and Gearcase. Yet the hydrodynamic friction of the Gearcase is the number one determinant of ultimate speed, go figure!

 

Gearcases have changed dramatically through the years as manufacturers and racing enthusiasts come to the realization Gearcase design = Speed and efficiency. Now it has reached a point where whole model changes are dictated by the design of the Gearcase.  Whether we talk about factory design, Bob's Machine Shop, Mazco Propellers, Land 'n Sea, or HydroMotive design low water pickup Gearcases, performance boaters reaching the 70MPH or better range know Low water pickup is the way to go for added performance.

 

Basically, the Gearcase should function in two ways: 1: To provide a water intake for cooling the motor and 2: To provide proper leverage to carry the bow of the boat.  If your Gearcase design is limiting either of these functions, you're not going to reach your boat's design speed capabilities.

 

Brings brings us to  the fact that a nosecone's main goal it to reduce hydrodynamic friction while providing proper - if not improved - water intake capabilities.  They also can serve an additional purpose in higher speed boats - reducing "blow out". 

 

When you go too fast with a stock Gearcase, the water hits the front of the blunt bullet and actually "bounces" around the prop.  Solution:  Add a nosecone to improve the hydrodynamics of the Gearcase.  Blow out occurs when the water hitting the Gearcase travels at such a speed that it actually deflects off the front of the Gearcase and bypasses the propeller, causing the propeller to lose its bite causing the motor to rev up, the boat to fall and sometimes turn out of control.

 

Certain brands of boats are more prone to blowout than others based on their hull designs and will dictate more care be taken in the setup stage.  Before you decide to see how fast you can go do your homework and ask the web for help, its not worth the risk of getting yourself and possibly others hurt or damaging your prized possession.

Solution:  Be sure to have a competent, knowledgeable, experienced person rig your boat.

3#AlwaysFlushIt with Marine Engine Flushers. #riverracer #offshore

 

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