Mark and Georg,
the idea is to use the Volga for fuel efficiency. And not to forget for comfortable flying over the waves.
The hydrofoil boats/ships were designet to reach 30-40Knts with half the needed power/fuel consumption required for gliders, we can not compare it with ships in displacement mode, than the ship would be quite long - see the ratio between LOW and speed in displacement mode.
The gliders leave the bow wave behind the transom and can be faster using less power than displacement ships,
the hydrofoil does it even better and as a bonus the ride is comfortable, not to campare withe the ride in a glider.
If you take a RIB with 250 HP and ride at 70 Knots after half an hour or less you will need a break or a spine surgeon for your back...
In a Hydrofoil you just forget about the waves...and enjoy the ride.
The Volga is not so comfortable as a Kometa or Voshod, but for a private person it is OK. For commercial operations it is another question.
The Volga was constructed for 70-100HP, if you put a more powerful engine you would have reserves.
But the engine should be lighter than the original- we are living in the 21 century and and when modernizing an antique boat from the 1960 we should use engines that are state of the art, or at least not too old, fuel efficient and affordable in operation and maintenance.
What the use of a super-duper common rail diesel that costs Euro 15-20K for just 200-500H of sailing per year?
Well I am not a Scottsman, nor frugal, but even a motorboat must be efficient in a way.
At the moment I am marinizing a GAZ 53 engine with a higher compression - 1:9 / instead of 1:6,7/ and it will be Bifuel - petrol + LPG. According to my calculations it should burn ca. 22-25 litres of LPG imstead of 22-29 Lt.of Benzin.
I would recommend the book : "Tragfuegel Boote des Schertel-Sachsenberg Systems eine Deutsche Entwicklung" im Elbe -Spree-Verlag.
There are a lot of interesting topics not just history of the hydrofoils. Technical stuff too and a lot of picturees, some of which look very familiar.
A 4 cylinder Diesel is ok on the power and torque side, but it is unballanced and causes a lot of vibrations.
Take a L6 cylinder turbo- Diesel, they are always ballanced and do not cause so much vibrations. That is good for the Aluminumstructure of the boat.
Georg has is right with the original gear ratio and ca. 3000 Rpm you can still use the original propeller. if you change the gear box ratio another propeller is due, thanks to the greater torque awailable. It is allways a combination of gerbox, propeller and engine, a question of tryal and error or good calculations.
General hydrofoil related questions, comments, tips, etc