Hi Jelly,The Delta keel is a design that I have only ever seen in Canada where these boats are used each day , they have become very sort after and it is something quite new to us over here.
It gives a rib lift, even though you have Deep V it is situated aproximatley 1/3 the way back and goes to the Transome.
It is the bit the boat rides on when it planes as with a very deep V you need more HP to push it as fast as you suffer from drag I.E wetted surface area when you dont want it,and you can get chine walk.But a deep V has the ride in rough weather so this enables the boat to have a deep V when needed and a Nice Delta surface when you dont. Its all about position to the waves a flat bottom will slam a deep V will not.
Its a design compromise that in concept gives more lift for less HP and consequently gives you a more stable attitude to the waves and increases speed and stability whilst achieving a deep V when required.
I can only go off my instinct and what has been confirmed in CAD testing but Eksrae can tell us more from the actual Sea trials point of view and what the costomers have found.
Hope this helps.