Check out these.....
From Riviera Facebook page:-
As you may have noticed, we have gone Door Crazy. Check out the DOOR Raceboard prototypes. 14' and 12'6".
Yeah...curious. French mob Nah Skwell have something similar - the SCOW
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www.supracer.com/nah-skwell-scow-12-6-stand-up-paddle-race-board/
www.nahskwell-sup.com/en/race/
Second the like ,would love to try the short board in the background of the Riviera pic.
Select to expand quoteGoochi said..
Ok, I'll ask....what's the design reason behind it?
IMO there are a few design features that make sense to me about this design.
Mostly about stability.. and stability is a big part of sup board design.. Particular with flat water race boards because they don't need to turn much or deal with the dropping down the face of a wave and turning like a more convenenal boards shape does.. It's the parallel parts of the boards rails that offer the most with stability.. The front and back parts don't help except for a wide'ish square tail board.. Add a square nose to a square tail board and you get double the benefit.. and so because of the hugely increased stability from this shape the board can be made much narrower than a normal shape board.. and narrow usually means less drag and more speed.
I think the shape under the nose would be very important because you don't ever want the nose to push water and too much nose rocker to prevent the nose going under would result in a reduced water line and reduced glide.. I'm not sure this design would work for a downwind board because of the frequent pearling.. Pearling with a board this shape at high speed wound be very interesting.. 
The Fanatic guys found that widening the nose helps heaps with stability and when you see the plane shape of their new boards a lot of people will be amazed and just how wide they are in the nose.. But a wide nose can increase the 'boof' when you pearl.. The new Naish Glide seems to have gone the other way and made it very piercing therefore reducing the 'boof'..
I'd be interested to hear what others think about this new design.
DJ
Select to expand quotewaxer said..
Second the like ,would love to try the short board in the background of the Riviera pic.
This is a really interesting direction for the designers to take. Its very reminiscent of a wakeboard design which kind of makes sense because like a sup a wakeboard is ridden much harder on its rails
They look like the old bondwood paddle board my dad made for us kids in the 60's. I think I',m gunna cry. All they need is a pin tail, a big brass drain plug and some garden hose foot straps.
Looks interesting...
I have previously sketched a design for a similar "door" race board.
My concept was influenced from a Catamaran, but as a board, with a moderate single concave up the front, and chine rails, and single concave under the feet, to assist with channeling water under the board. (Catamaran influence on the underside)...
Design intent - reduce the overall width, by adding "stability shoulders" up the front, and added up lift, from the concave...
This just reminds me of George Greenough's thoughts... he hates "pointy nosed surfboards", because those last few pointy inches serve very little purpose... The final inch is like a dagger!
Most of us have seen a grom on a board with a non-critical nose snap... Last few inches of nose snapped off some how, and he's happy to surf it with a bit of grey duct tape stuck over it! 
Plus at the other end... the tail/bum... wide square tail twin fins from the very early 70's, before Mark Richards hooked up with Dick Brewer to take the Twin Fin to a new level...
I find these race designs (and potentials) even more invigorating than the surfing design concept... The surf design concept has sort of been done... Simmons, etc.
I agree that the idea of a square nose goes way way back and shapers have said for years that a rounded or square nose is a better design outcome. So the question would be why had it never taken off? Aesthetics perhaps or is there a practical reason for it? To me the surf shapes just look like a scaled up wakeboard. Me ill be sticking with the semi pointed round nose myself but to each their own.
The Doors , my alltime Favourite bandDont think those boards will be breakin on through anytime soon.
We saw and tried them in Cali a few months ago and you would be surprised just how much more stable they are and they appeared to be very fast and incredibly light.
Phill
wide noses help reduce the "front rudder" effect, where a pointed nose would begin to pull you violently on the side.
They are less efficient if you are able to perfectly control your boards, but in real life have some advantages and drawbacks, from what Nah Skwell says after som years producing the "Scow".
This said, I think the Nah Skwell model is a bit weird, as it is patterned along a scow sailboat that is designed to work tilted a lot on the side. I would expect a SUP design to have a rounder / elliptical front "bulge" rather than a flat one. But I am definitely not an expert on this, my longest board is 8'3"...
