Blackout

I hope to build an O/B rigger from scratch this winter and was looking for some tech.

I know the rear sponsons are moved back to help support the o/b engine in corners. I have also read that the turn fin is usually placed farther to the rear. Any other differences between i/b and o/b riggers?

Also, I found a 1991 magazine article on Mark Grim's Predator. The article makes mention of a "side mount rudder". What is that? I don't think they were talking about the turn fin? I assumed o/b riggers steered with the engine, not a rudder.

Thanks.

Got RPM

The rear sponsons have to be large enough to keep the boat afloat when the engine dies. Because the CG is farther to the rear on an OB, the turn fin (which has to be mounted near the CG) is farther aft. With few exceptions (OPC), fast boats don't turn well with a steerable outboard - it causes hooking when turning. The faster OB rigger guys were locking the OB straight ahead and using a rudder on the right (like an IB rigger does) to steer. Some racing rules allwed this, some did not.




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ryan_t888

What size rigger with what motor/engine?

Ryan

Blackout

3.5 size rigger. Probably use a stock o.s. first, then upgrade to something faster if all goes well with the hull.