T&T: Hull Speed 20% faster and more economical, by new

[Arild Jensen]

Faure, Marin wrote:
> If the "Flexi-fins" are not hydrofoils (which do work) or Dolefins (which also work), that leads me to conclude
> that they are some sort of trim tabs mounted on the transom.  Or under
> the rear portion of the hull.  Or perhaps attached to the chines of the
> hull near the stern.  As such they could certainly push the back of the
> boat higher which, particularly for planing boats, could reduce drag.
> But this would make them simply a variation on products that are already
> available and well proven, specifically trim tabs.  There are also
> add-on devices for converting the soft-chine of a semi-planing boat like
> certain Bayliner models to a hard-chine, which also increases the lift
> at the rear of the hull and reduces drag.
REPLY
 From what I gathered  by looking at the website, the innovation 
involves  reducing hull friction.

While delving into the more arcane aspects of viking ship navigation I 
read that th replica hulls  were able to move faster than the 
theoretical hull speed.
The description  was they "surfed" down the forward slopes of some 
bigger swells.  Sort of like the ULDH  in the Transpac races..
(Marin I think you once said you crewed on one of them.)
After much research it was discovered the flexible hull frames created a 
shallow convex tunnel along the keel timber. This tunnel trapped  sea 
foam and air bubbles under the hull and effectively reduced hull skin 
friction. 
At least that was the explanation  developed to explain the observed 
fact  of  faster than  predicted hull  speeds. 
I wonder  if  these "flexi fins"  might do something similar. One of the 
photos shows a frigate class naval ship.  No way that hull is up to 
planing speed. 
Evidently   the invention  is something other than  simply a planing 
hull  adaptation.

Perhaps the original poster can  expand  on the scientific details.  Can 
this  device or design  actually make a difference to trawler hull fuel 
economy?

cheer
Arild