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Looking for a PHRF number for a 2019 Dufour 360, local  beer can races, Or a good guess at where to start, if we cannot find one what is the best way to come up with a reasonable number?

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The formula for the original phrf  is available online it's easy to type that into Excel and produce a basic number.

R' = 610-8.36*(SA/Disp^.333)+0.0000511*(SA^2)-55*(P/(J+E)) -30.8*(LWL^.5)-602*(DR^2/SA)

where SA= .5*(I*J)+.5*(P*E)

Local alterations taking account of outboard/ inboard engine, with or without spinnaker may have to be taken into account.

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9 hours ago, The Q said:

The formula for the original phrf  is available online it's easy to type that into Excel and produce a basic number.

R' = 610-8.36*(SA/Disp^.333)+0.0000511*(SA^2)-55*(P/(J+E)) -30.8*(LWL^.5)-602*(DR^2/SA)

where SA= .5*(I*J)+.5*(P*E)

Local alterations taking account of outboard/ inboard engine, with or without spinnaker may have to be taken into account.

Thanks

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Great Lakes covers a pretty wide area. The formula provided is probably the Schell regression formula which is pretty much discredited. Send in an application to your local phrf region and they can provide you with a rating. Probably close to rating of a Dufour 350.  Base of 123-132 + adjustments for keel etc 

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Schell formula discredited? No it's still the background formula for phrf in many areas of the USA.

Misinterpreted yes, it was never meant to be the final result, is only a guide line. The figures need to be adjusted for the sailing conditions of the area, whether the boats are fitted with, spinnakers, fixed or folding props . 

For instance I've been working on the Schell formula and  the various  FAY formulas. The" instant " formula result needs to be compared against real results for boats in your area and a compensatory adjustment applied. Once that is done I get a remarkably similar result to the RYA generated results for keel boat classes and D-PN.

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we have the Dufour 350 GL at a base of 129  and a Hanse 375 at 111  I'd think (without doing and research as I would normally do)  think the Dufour 360 should rate somewhere 6 sec. less than the small brother the 350   so in the neighborhood of 123-120.....

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13 minutes ago, dacapo said:

we have the Dufour 350 GL at a base of 129  and a Hanse 375 at 111  I'd think (without doing and research as I would normally do)  think the Dufour 360 should rate somewhere 6 sec. less than the small brother the 350   so in the neighborhood of 123-120.....

How about you research the rating scale issue between boats rating 0 relative to boats rating 99 and fix that?
It is as plain on the nose on your face and no one has the gonads to address it.

 

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14 minutes ago, dacapo said:

we have the Dufour 350 GL at a base of 129  and a Hanse 375 at 111  I'd think (without doing and research as I would normally do)  think the Dufour 360 should rate somewhere 6 sec. less than the small brother the 350   so in the neighborhood of 123-120.....

Thanks, we just need some kind of starting point, these are just low key Wed. night races, more to get some newbies out.

 

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