A massive tip that for some reason makes your boat go so much faster is the fact that of how you place your rudders. And propellers. I have tried so many different combos and found that the propellor right behind the rudder with a block back inside the boat makes your boat go up to even 3 times fast. No joke!!!
Like this.
See it's speed?
83.2 knots. Now look at it without the propellers behind the rudders and one block in the boat.
Dosnt look much different correct? Well now I would like you to look at the stat change in speed.
25.1 knots!!!! That's horrible compared to before!!!! I removed nothing else or changed nothing but how I had the propellor. So just follow the diagram of my ship above and make your ship have 3x the speed!! Literally... Hope this helps!!!! ^-^