Hull with the least wake

Something anyway...

SOR states displacement speed. Any locale that has no wake rules probably also precludes enough speed for hydrofoils, and almost everywhere is unsuited to WIG craft.

 

You would be going too fast to follow a crew rowing.

 

It matters little.

Just because you think you can't see much of a wash/wake behind a vessel, does not = no wake.
The key element is the energy in the wave.... and as such any vessel will produce wash... the key deep longitudinal waves and soliton (Solitary wave) wave can carry significant energy, but their wave period is very long, so you don't actually notice it. Because most people focus on the traverse waves, which are "easily" visible.
It is the energy of the wave that is the issue...which is a function of the wave period.

 

At a given displacement and speed, a SWATH can show less wave drag and much more friction drag, it is the "cost" of the concept. But less wave drag means less energy in the form of gravity waves at the free surface, whatever the period of these waves.

 

And so can a catamaran.
Your point being?

 

... being that the displacement is let say at ~ 90% in the submerged hulls and ~ 10% in the streamline struts crossing the free surface. A SWATH is not a catamaran from that point of view.

 

And that's all.

You seem to be misrepresenting or misunderstanding residuary and frictional RESISTANCE, as the effect on wash/wake.
That's incorrect... it is the displacement, the total displacement along its length, thus the length - displacement ratio that is the governing factor.... the displacement of said shape moving through the water.
How this displacement is arranged is mute.

 

May be I misinterpret the OP question, my answers are about "least waves" at the free surface, not "least wake" in the meaning of dissipated energy in the wake of the body.

 

Same thing.
The waves, or in this context wake/wash is the effect of a shape, in this case having a displacement over a certain length, creates waves on the free surface as it moves.

This is totally different to the residuary (wave making) resistance.

 

Do you mean waves at free surface not dependent of the waterdepth of the submerged hull ?

 

That depends whether the submerged body is totally submerged or not.
In the case of a SWATH - it is not.

 

Thank you for elaborating. I was thinking plane turbine type ducted prop at the opening and cylindrical tubular hulls in cat config. My uneducated reasoning was with parallel outer lines the flaring out of the hull would be missing so no ploughing action of the water and that the inside will be high speed froth shooting through the tunnels which might reduce friction..... which would make it appear as a tube without wall thickness to the medium its travelling through. Oh well, another scatterbrain idea of mine

 

Some examples of SWATH and even SWASH (... Single Hull, with an active stability through small foils) developed by students within the Hydrocontest competition, for the category heavy payload (200kg) :
PowerPoint Presentation (epfl.ch)
Teams (hydrocontest.org)
SWASH on the right side (~ 280 kg inc. 200 kg of payload) and Foiler on the left side (20 kg payload category) :

 

Ok guys, let's try this a different way cause I'm not building an experimental or limited use design.

What currently available production designs (available and typically sold to recreational boaters) produce the least amount of wake at displacement speeds?

 

Nigel Irens' designs have a good reputation -
Power - Nigel Irens Design https://nigelirens.com/boat-category/power/