Gas turbine?

[Bruce K]

I understand there must be a reason that gas turbines are not use in recreational powerboats in the medium size ranges 12 to 20 m, but ther are used in smaller aircraft, helicopters etc. The fuel used is as safe as diesel. They are verl light for the power produced, and have very long service intervals, as there are no reciprocating parts. Any ideas why they are not in common usage, perhaps the noise generated is not able to be controlled? Any ideas?

[Panope]

Fuel inefficient.

[CalmSeasQuest]

Not to mention; very pricey.

[saghost]

Fuel efficiency is horrible at anything except full throttle, and not great there. Throttle response is slow for most turbine designs - chopping power immediately will cause a flameout, so the computers generally won't let you, and the turbine takes time to speed up, too. Large amounts of high temperature exhaust present a much bigger fire risk than the traditional marine wet exhaust.

But I think price is the main driving factor here. Folks aren't ready to pay for the turbines, and the lower weight and lack of vibration and improved reliability/reduced maintenance cycles aren't valuable enough in this market to offset the downsides.

There are folks trying to make microturbines affordable using new manufacturing techniques, and that might change things. If the MiTRE project hits their goals and is making a 40kW turbine range extender that's 35% efficient to electricity and costs less than a thousand to make in a few years (intended for electric cars,) I could easily see someone attaching that to a small battery pack for buffering and a big 40-50 kW electric motor and making lots of fun little boats and stealing market share. But they have to solve the manufacturing challenges that create the cheap reliable microturbine first.

(Capstone microturbines of conventional construction and similar size and slightly lower efficiency today are more like $30k.)

[GrowleyMonster]

What they said. Not efficient, not economical, not practical. Where turbines shine is in weight and space penalty. You get a lot of horsepower per pound of gas turbine, and they are very small for what they output.


If money is no object, I could see a rich boy's water toy powered by a pair of gas turbines, and it would be crazy fast. It would make "fuel guzzler" sound like kind words, though. And I think you would pretty nearly have to go to school to learn to operate, let alone maintain, them. They are probably in use somewhere in fast hydrofoil ferries due to light weight vs power.

[kmacdonald]

Originally Posted by Bruce K

I understand there must be a reason that gas turbines are not use in recreational powerboats in the medium size ranges 12 to 20 m, but ther are used in smaller aircraft, helicopters etc. The fuel used is as safe as diesel. They are verl light for the power produced, and have very long service intervals, as there are no reciprocating parts. Any ideas why they are not in common usage, perhaps the noise generated is not able to be controlled? Any ideas?

They are being used in the small go-fasts around here. It's the latest rage with them. They burn kerosene, often called jet fuel.

[IslandHopper]

Will fit ok and the engineering shouldn't be to bad but a little NOISY, and you will be real popular on them early morning marina departures lol.............

https://www.youtube.com/watch?v=sM7PK5d2Yug

https://www.youtube.com/watch?v=WDhoYXw2IPc

[billknny]

I have seen a turbine powered boat. On San Francisco Bay, did 85 knots. You could hear it ten miles away.

As has been suggested, a rich boys toy.

[Saleen411]

Originally Posted by billknny

I have seen a turbine powered boat. On San Francisco Bay, did 85 knots. You could hear it ten miles away.

As has been suggested, a rich boys toy.

Most all of the Hong Kong to Macau ferries are powered by gas turbines.

Max speed 43-50 knots.

[Metal Boat]

As a man with a Pratt and Whitney PT6 ticket I can tell you exactly why they are not used in small boats.


1. Ludicrous Price.



A PT6 costs upward of 500,000 USD just to overhaul and that is for about 1200 HP. They have some very fancy mettalurgy in the hot section.



2. Terrible fuel economy at sea level.



Turbines work best in thin air at altitude with heaps of ram air being forced down their snot. Jets use a terrible percentage of usable fuel climbing to height.


3. Noise


They sound just great. Its sexual.



4. They prefer a constant RPM.




5. Start one wrong and you will melt the arse end and get a very big bill and its very easy to do.

[Adelie]

On top of the problems listed, serious reduction gear costs unless you go with an electric drive then you have serious conversion losses.

[Lepke]

The navies of the world went to gas turbines because it was cheaper than steam to build or maintain and a needs a much smaller engine room crew. On a steam warship, the engine room requires about a third of the crew. And turbines probably use less fuel than steam and don't produce as much exhaust heat. But they still use a huge amount of fuel.
I don't see gas turbines ever becoming common for recreational vessels unless a new very cheap fuel come around.

[sveinung]

There's some boats that come turnkey with turbines, like Nor Tech's 50'. At this price point I thinks fuel, or any other kind of, economy is low down on the priority list

Nor-Tech Hi Performance Boats | 527
https://youtu.be/76sMnz8hjjE (see 1:15 in)
https://youtu.be/_680Q_JcJzY

[jamhass]

There is a machinist in SF Bay who put a small gas-turbine into a jet-ski. One amazing machine.