ITTC Dictionary of Ship Hydrodynamics

[Ad Hoc]

Originally Posted by Leo Lazauskas

Maybe I'd be more correct if we included something along the lines of "at high Froude numbers", if we could just agree on how high high is.

You mean say higher than Fn 1.0..?

Like these : http://www.turbojet.com.hk/eng/vessel/vessel_layout.asp

Typical fast ferries over Fn 1.0, these aren't planing! Bummer!!

Me, pedantic...nah

[Leo Lazauskas]

Originally Posted by Ad Hoc

You mean say higher than Fn 1.0..?

Like these : http://www.turbojet.com.hk/eng/vessel/vessel_layout.asp

Typical fast ferries over Fn 1.0, these aren't planing! Bummer!!

Is the draft much smaller than the (demihull) beam at Fn=1 for those vessels?

My personal definition of planing is that it begins when at least half of the
weight is being supported by hydrodynamic forces. Someone had a criticism
of that, but I can't remember why. )

[Ad Hoc]

Originally Posted by Leo Lazauskas

Is the draft much smaller than the (demihull) beam at Fn=1 for those vessels?

Not on the Cat's...but on the larger car/passenger ferries like these typ. monohulls it is:
http://en.wikipedia.org/wiki/Super_SeaCat

There are a bunch of them made in France and Italy at varies companies such as: Fincantieri/Rodriquez etc.

Gets tricky doesn't it....!!

[Leo Lazauskas]

Originally Posted by Ad Hoc

Not on the Cat's...but on the larger car/passenger ferries like these typ. monohulls it is:
http://en.wikipedia.org/wiki/Super_SeaCat

There are a bunch of them made in France and Italy at varies companies such as: Fincantieri/Rodriquez etc.

Gets tricky doesn't it....!!

There's no doubt it's tricky if the definition is based on the principal hull
dimensions.

There might be less doubt if we based it on hydrodynamic features, such as
the Froude number based on the distance from the centre of pressure to
the stern, or lift/weight. But that would also make the definition very
technical and opaque to most people.

Apologies for that earlier crack about NA pedantry.
As of today I'm now a fellow traveller!
Leo (AssocRINA).

[Ad Hoc]

Originally Posted by Leo Lazauskas

Apologies for that earlier crack about NA pedantry.
As of today I'm now a fellow traveller!
Leo (AssocRINA).

Apologise for what??....it was a fair comment

Words have clearly defined and universally (well to most) meaning, if we don't say what we mean we don't mean what we say

Originally Posted by Leo Lazauskas

There's no doubt it's tricky if the definition is based on the principal hull
dimensions.

This was the same difficulty when the HSC code about in 1994. The debate in the early 90s, prior to being published was very similar indeed. It is one of those "definitions" that is visual, rather than maths based.

Such as, if we were to look at a hull, which has chines, hard chines, and saw the flow of water was all below the chines and being "over turned" with no cross flow back down to the free surface as such and not creeping up around the sides etc....and looked at the transom and saw it was ventilated...we would all say...hey "we" are planing!

Trying to make some kind of "measure" of this condition for a definition becomes tricky. Perhaps a different approach is required. Like the related to the virtual change in VCG..but that gets more tricky.

I don't think there is a simple answer, despite it being obvious visually. Other than more than half the weight being supported by forces other than hydrostatic.

[medaca]

Originally Posted by daiquiri

Because general culture is important, as is speaking the same language when discussing about boats and ships:

http://ittc.sname.org/CD%202011/Dict...ary%202011.pdf



Cheers!

Thanks for the link... Helpful!