makes sense Mark, I thought we might be getting off the path with the prop calculators....I used prop calculators before to determine speed after we had baseline

There is a coincedence here, someone mentioned Jerry Gilbreath a few posts ago. Jerry is one of the rare people who can look at a boat, learn the horsepower, look at the set up, and judge the speed very accurately. Thats another of his attriblutes and is better than all the calculations that will be shown here...

If you know your current horsepower and speed, then use this formula...

New Speed = Old Speed times [ the square root of ( New Horsepower / Old Horsepower ) ]

also

New Horsepower = Old Horsepower times [ ( New Speed / Old Speed ) squared ]

Good luck!

This is the way I do it as a broker:

### in MPH quoted by seller
Subtract 10MPH for every six months the liar has had it on the market.
then
Add 2 MPH if the boat has clear title
Add 2 MPH if his wife is within earshot
Add 2 MPH if he honestly does not want to sell the boat

On the other hand
Subtract 2 MPH if the owner owes more than the asking price
Subtract 2 MPH if the Wife is not around
Subtract 5 MPH if the owner has been drinking
Subtract 5 MPH if a hot 22 year old blonde is within earshot
Subtract 10 MPH if Stinsen quoted the speed!

IDRPSTF,

iI bought a boat using that formula once and it was pretty accurate, now if only I can remember where I put it

The boat or the formula?