Congrats!!
First trailer to dock trip is always enlightening..

WOW!!!! Un-believable custom build!

I meant to ask and didn't see it anywhere. Can the drives/props be spun independently? Can you put one in forward, one in reverse? (That would make a massive difference in docking maneuverability).

No they can't. splitbox turn them always same speed. It wasn't bad to dock, big turning radius but in reverse it spin over it own center axis. I drive it at first attempt two times to dock. Crew just step on land, no hassle.

I want to see some Roost video- Man it has be Huge!!

I suspect quite a bit less than 3x BBC for the same mph.

A good diesel can punp out very respectable BSFCs. A well setup turbine can as well. Low 0.4s.
The big trick for a diesel is to minimize the air restrictions flowing through. The Cummins 5.9 is an example of what not to do, despite being an amazing engine.

I agree this boat will burn LESS than the 3X gas motors it came with. I own a Formula 400ss. This boat came with either twin BBC (gas) or twin diesels. Independent tests results show the gas version gets a best or 0.8 mpg while the diesel gets a best of 1.65 mpg. I usually see about 1.4 mpg while a buddy with a gas version claims he seeing about 0.5 mpg. In the states at least diesel is nearly a dollar a gallon LESS than gas on the water and the savings is tremendous.

Yet more expensive on the road WTH?

Fuel consumption should be near half of triple 525 at same speed. Engine analyzer show under 0.3 BSFC, hydrodynamic drag and drive losses are way down. It doesn't need to turn six anglular gear in 140 heavy oil at 5500rpm.... My transmission spin like straight shaft in 4th gear, splitbox are not full of oil and it have straight cut gears, drives are just straight shafts and surface piercing props should get 10-20% more efficiency. Time will tell us when I managet to get old lady on plane.



Here you can see calculation, AFR is lean, no smoke. It's calculated with air to water intercooler, 75% cooling efficiency.

First problem is fixed, raw water pipe leak water before shut valve. Flange fitting was assembled without O-ring, I have had to test fit pipe and then it was forget to seal. Pipe is inside extension box, behind raw water pump, but I managed to fix it.
Next problem is too much hydraulic pressure on engine hydraulics. Series connected raw water pump hydraulic motor and accessory drive motor, didn't work. I have now all parts to split system for own flows. Adjustable pressure compensated valve can split one pump flow for two motors, one motor spin regulated speed and other variable if pump flow change when engine speed change.
Crankcase vacuum pump have signs that rotor had seized axially, that can make hydraulic drive pressure acting weird. I take rotor out from pump and put just straight shaft in so pump is now like belt free pulley. This way I can test engine with conventional breather soon. Some puke tank from used oil can could be good if it puke again at some reason. My home city gas station dock got bilge water suction hose for this summer! I can wash and clean bilge there soon.
Camera backlight have to fix too, I can't close hatches before there is some light for dash camera.
Next weekend is Saaristo Poker run in Nauvo, Finland, I will go there to spend some time but if I get engine running tomorrow, test run may be in sunday.

https://en.wikipedia.org/wiki/Brake-...el_consumption

End of that link is good list of engine BSFC, sad that there is no BBC. With roots blower they may be worse than 2 stroke rotax.

Years ago I dreamed to build gas turbine boat but it's only good if you run whole time WOT, BSFC is very bad at part load, not good for cruiser boat.

Road tax