40 Pipe Stinger Size?

[jaxracer]

Carl,

I do not run this boat in rough water because it is a very light weight layup. The bottom running surfaces have been coated with West System #423 graphite powder mixed in #105 West System epoxy resin with #206 slow hardener. One thin layer is applied with a foam roller. After cure the surface is lightly block sanded with 800 grit wet or dry paper. The final surface should be "very flat, but not very smooth". On calm water I see a 2 to 3 MPH increase in speed over a slick smooth epoxy painted waxed surface. I do not see any improvement in handling.

JA

No! This is the same ramp used in the Nelson .45 long stroke Pylon racing engine & the Nelson Fai speed engine. The ramp not only increases high end RPM (29,000 to 32,000) it helps the engine to pipe up.

JA

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Hey Jim, what proportions are you using for the graphite powder and the epoxy resin?

Thanks!

 

[Jim Allen]

Hey Jim, what proportions are you using for the graphite powder and the epoxy resin?

Thanks!

Mitch,

I use 5 resin (1/2 teaspoon size) & 1 hardener (1/2 teaspoon size) with 4 "SLIGHTLY" rounded teaspoons of graphite. This amount will cover the bottom running surfaces of a large size hydro including rear running surfaces. Mix the graphite thoroughly in the resin. Add the hardener & mix thoroughly. Apply with a "FOAM ROLLER". Keep rolling until you have a thin even layer. You can continue rolling even when the resin begins to set. Wet sand with 800 then 1500 grit wet or dry  paper. DO NOT wet sand the surface until it is completely smooth. What the surface should look like is similar to a flattened orange peel but also flat. One thing you will notice about the surface is, that it CANNOT be scratched the way an epoxy surface can be easily scratched. In fact the finished surface will become metal-like! I use masking tape along vertical edges which leaves a very sharp, extremely durable edge. Sometimes I will do the non- trip surfaces on hydroplane sponsons.

JA

 

[Carl Van Houten]

Some of my customers have been doing that for years but I just haven't tried it. If it actually produces 2-3 mph I would certainly say it would be well worth the trouble. I have always prepared my sponson bottoms with a dry (no wax or Rain-X etc.) gelcoat surface and a 600 grit crosshatch. I may try your method this summer. I'll let you know how it works for me.

 

[Jim Allen]

Some of my customers have been doing that for years but I just haven't tried it. If it actually produces 2-3 mph I would certainly say it would be well worth the trouble. I have always prepared my sponson bottoms with a dry (no wax or Rain-X etc.) gelcoat surface and a 600 grit crosshatch. I may try your method this summer. I'll let you know how it works for me.

Carl,

I block sand the epoxy painted surface with 220 grit dry paper. Clean any dust residue  with a tack cloth.

JA