ORC VPP limits

Will the OCR VPP predict resistance curves for hulls with ratios as high as

L/Disp = 9
lwl/bwl = 6
bwl/Tc = 14

And thus produce accurate VPP results for these hulls, tks.

 

What is L? and what is "Disp" (displacement?)? because the normal "displacement-length ratio" (DLR) is given as shown below and your number makes no sense (i.e. Length divided by ????....lbs, tonnes, m^3?) even with "bwl/Tc = 14" which basically says you have nothing in the water (i.e. the maximum draft of the canoe hull is 1.2% the length of the hull <rolleyes> What is this?...an inflatable paddle board with no one on it?).

DLR = displacement in LTons/(lwl in feet/100)^3

VPP is designed around a nominal sized, well proportioned, sailing vessel hull. Too big or too small and it falls apart. The ratios show that you really don't have that.

 

DLR = Displacement/(Lwl/100)^3 Where Displacement is in long tons and Lwl is in feet. A long ton is 2,240 pounds.

Larsson/Eliasson’s Principles of Yacht Design, uses the inverse of this concept in Length/Displacement ratio, LDR. This is Length in meters divided by the cube root of volume of displacement in cubic meters, a true dimensionless ratio. LDR = Lwl/Vol^0.333 (The Design Ratios - Eric Sponberg)

 

Can we at least stop using pounds and feet. NASA, Aviation and Medicine all use IS units... Just the important stuff, were lives matter like boats?

 

The limits of the Keuning regression method of the Delft Systematical Yacht Hull Series are as below. Has the ORC extended this, ie the guys at the Wolfson Unit helped?

 

You can find some info there : https://orc.org/uploads/files/ORCsy/2024/ORC-VPP-Documentation-2024.pdf

BTW, ORC no longer uses DSYHS since 2012.

 

No, because it works better in the ocean (i.e. 1m^3 is 1.02 tonnes but 35 cf is i long ton). You are never going to get rid of navigational measurements (hours, minutes, seconds, degrees, minutes, seconds, nautical miles, knots, etc) and traditional measurements work better with those, especially without resorting to a calculator. You want to redo all navigation in radians?

That's just bottle washing and button sorting, why not just use the Volumetric Froude Number; a much more useful piece of information (though you could use the LDR for parametrics off known VFN, but without other geosim ratios it would quickly drift into uselessness).
Anyway, your ratios make no sense. A LDR of 9 implies a 9m lwl hull with a displacement of 1 m^3. However a beam of 1.5m and a tc of 10.7 cm gives a block of 1.44 m^3 so a block coefficient of 0.69...which means you either have a lot of hollow or a lot of rocker.

 

Got a response from the ORC.

"we introduced a completely new model based on CFD simulations of a large fleet (several hundred) of hulls. This model was further updated in 2022 with the introduction of a neural network-based model. Currently, we use a 50-50 average of the two."

Think I can assume my hull is represented.