Catamaran resistance

check displacement/scale of your model
check Center of Gravity position
check mass/unit of mass of your model
check froud number of your model

 

That looks really weird that the boat runs with a negative trim (down by the bow).

 

I ran the analysis in my spreadsheet. True enough, as others have noted, you have a very low length to displacement ratio. So low in fact it is outside the graph. This makes your hull a brick to move as the resistance is almost vertical.

While other parameters seems to be off a little bit based on standard parameters/Froude number you want it is easy to tweak the dimensions to fit. Attached the spreadsheet for you to play around. Length is always beneficial. B/T is secondary but should be considered. The numbers are interactive and the formulas visible.

 

In my opinion, your results are realistic. Simply there is a combination of four bad hydrodynamic aspects:

• first is the big displacement
• second is the unfavourable froude number
• third is the bow shape, which shoud probably not be parabolic and blunt, but as straight and slender as possible
• fourth is that it is a catamaran with the small spacing between hulls, where hull interference just multiplies all these other factors.

In my opinion, the solution from the resistance point of view would be either to give up such high speeds with this hull, or to completely redesign the hull by reducing the prismatic coefficient (by moving the volume more to the midship, and removind the deadrise angle at midship). In this case, maybe even the monohull would be more attractive, since this hull design almost converges to that

Also, I remember attending some sea trials of the similar catamarans, the waves generated by them at full speed are extremely high and steep, almost hard to imagine that such a small boat can generate such high waves... And those were aluminum cats, this is I assume a steel one, which easily means double the displacement...