Ooh! Very interesting to see! Love that sound
I'd love to have an idea of where your CoG was. So much of yours is different to my current ideas, but mine is based on a predecessor so I'm sort of using that experience to design the twin.
A reminder of the original, and the new concept final design for mine:
The final hull is not a flatty, it's my own variation where there is much lower lift on the bow because the wetted volume decreases moving forward, so it rested bow down. I had to add a mass of lead as ballast to the rear of the boat, I don't know the weight but I can tell you it was a 1" cube of lead, and it was sat over the very stern of the boat, quite substantial. Correct me if I'm wrong, but looking at yours it was sitting stern down too much? My engines are sitting much further forward, and I'm betting on the rear engine slightly counterbalanced by more volume forward on the hull will balance. QED
. If your issue was not fore and aft then this particular perception of mine falls to pieces lol!
Turning to vertical balance is where I have to disagree with your install being perfect. Prop clearance on mine is to be a minimum, in reality below deck level as the deck is recessed. Just enough clearance to be safe, say 10mm. Engines are side mounted, this puts the silencers below crankshsaft height making a huge difference alone, but add the cylinder/head shift to the side and the CoG drops substantially.
My fuel tanks where never going to be up with the engines, the yellow boat above had its tank in the cowling behind the motor, and with this design hull I'd have a complete shift in handling as the weight reduced during running. It went from flattish turns on a full tank to a touch of spin-out oversteer on a near empty one, because the boat's centre of drag shifted forward as the tank emptied, hence lever advantage meant less slip and more dig and turn, not acceptable changes (bear in mind we are talking water rudder here). This is another reason why my tanks are to be much lower, and as close to the desired CoG as I can get them. The closer they are to the desired Cog the less impact fuel use will have on that CoG's actual position. This has to be coupled with hydrodynamic issues as pure CoG changes alone may be pertinent to an aeroplane, but not to a boat, because the weight of the boat changes the submerged volume changes. Hence, potentially, the operation of the boat will shift in ways other than sluggishness, it may steer completely differently as the centre of drag the steering has to pivot around can move as the boat rises. With two engines, the weight of double the fuel is not a factor which can be largely ignored with many regular boats. So these variances to yours, engine attitude, height and tank position/height, mean my CoG is going to be very much lower, I wonder if yours was detectably top heavy in turns? I get the impression the boat would heel a lot.
My test boat is yet to get wet, I'll see how it sits in water this evening.
Whatever, it's great to see another one, sorry to hear it didn't work out, I hope those two lovely engines of yours are in happier homes