Glen-L.com

have a casale 12deg toploader with 1.14:1 over drive (want to put in riviera ) can I change the gears from in shaft to out shaft to gear it down . or should I get 1:1 gears . or leave it the way it is ,and choose suitable prop.

I'd leave it the way it is and choose a suitable prop. You can always change the gearing after real-world testing !

To help you with prop selection, here's a screenshot of our latest propeller calculator.

The following image is a side-by-side comparison of two engines (375HP 8.2L and a 300HP 5.7L) with .86:1 VS 1:1 gearing for each engine.
Recommended WOT range is 4200-4600 RPM for the 8.2 and 4600-5000 RPM for the 5.7 .

Theoretically, 207 shaft HP will be required to attain 50 MPH. Overpowering a hull is never a good idea.

Disclaimer : Our original spreadsheet required an extensive rewrite and is still in the validation phase. It won't be released until its been thoroughly checked out !

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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.kanecustomboats.com

thanks for that info . this forum is fantastic with the prompt replies and vast experience and the effort that goes into most replies