Planing hulls that are Semi-displ.

It is very hot and humid in FNQ this time of year, perhaps groper's aircon is down ?

 

Well heaven forbid that i had to define the lift direction - it should have been assumed that it was positive lift i was referring to. Again, therein lies the difference between a displacement and planing hull - the displacement hull will typically generate negative lift whilst the planing hull uilizes positive lift.

So in order to please your semantics, let me rephrase what you quoted me on, with the addition of 1 extra word;

" asking about hulls that are displacement AND planing is absurd, they are mutually exclusive in their physical form, i.e. they CAN generate positive hydrodynamic lift or they can NOT. It's that simple."

So you feel all warm and fuzzy now?

How about contributing something worthwhile in addition to what i have? Got anything?

 

This thread would be boring some people semi-rigid, I suspect.

 

One more pissing contest for the forum. Gentlemen please.

Yes. I have taken up sides here. My little flattie sailing/rowboat will plane like a demon in 12 to 15 knots and it will hold its own very admirably in displacement mode. We can have both kinds of performance but not ultimate performance in either regime. In other words, you can not have your cake and eat it too. In displacement mode it does, indeed sink, but not to a measureable extent. I suspect that buttock run angles and buttock fore angles are a big part of the deal. We develope some positive or negative hydrodynamic pressures by virtue of velocity and angles of attack and/or regressions

Carry on.

 

Certainly, the impression of dynamic lift applying to heavy displacement hulls as well, is supported by the greater resistance to roll once underway, I have more than once seen people who turned green with mal de mer on a drifting vessel improve markedly under power, diesel fumes and all !