'60-63 Trunk cabin engines

[Avenger]

How are u guys figuring this math to get the speed and is it that accurate?

The formula is fairly straightforward, there are other factors for different hullforms, but for a warped hullform like a Hatteras; Max speed in kts=150/(√(displacement/HP)) and it's a decent guesstimate. To approximate cruise speed I knock off 20%. And like everything else it's only as good as the data you put in. If you don't know what your boat actually weighs G.I.G.O. takes over.

Of course it can't account for variables like excess drag or keeping your anvil collection onboard. As stated earlier:

Remember, this is all in theory. Lots of things conspire to slow boats down.

Yes lots to slow it down like people, fuel, water, & tide. My 34c when I got it had Cummins 504's 202 hp and 13 kts was a good day more like 12 kt most days.

[Daniel]

Thank You Scrod