Power Cat or Sailing Cat?

[MartinR]

Originally Posted by Chotu

After all these years living and traveling that way, I'm now ready to spend all those weeks in the actual destination, not trying to get there. You know?

Airplanes might be the best and cheapest option

[Simi 60]

Originally Posted by MartinR

Airplanes might be the best and cheapest option

To get there yes, but when you are there how much does a decent water view hotel room cost?

[bluenomads]

CatNewBee, that's exactly why we're planning (eventually!) a hybrid electric conversion. Two electric motors running (relatively) quietly in the hulls, while the diesel DC genset runs on the other side of the bulkhead in the front of a hull. Noise is separated as the genset can be anywhere you want, not limited to being the motor connected to the propshaft any more!
Yes, limited to about 7-8knots continuous (see recent mesg about a 46' Leopard running like this) but not running around at 20; pretty quiet!
If you need more speed, leave one larger diesel in one hull and use it in a serial hybrid mode for electric (ie. turned off), but turn it on at a more efficient high-rpm for the speed to get somewhere.
Expensive? yep, depending on how, what and who does it. But relative to the entire rig and sail wardrobe of a 45-50' boat? Not too bad I reckon!

[CatNewBee]

There are cats out there with generators in the front compartment in the nacelle next to the anchor chain. I wonder how loud they are and if you still hear and feel the vibrations in the owners cabin when they run. Boats are good sound transmitter, I can hear the compressor of the freezer in the guest hull from the owners berth.

Also very annoying in our Lagoon are the splashes in the fuel tanks under the berth when not totally full or not sufficient empty when under way and even on anchor with some swell. I guess, you'll need some big tanks somewhere distributed across the hulls for weight and balance considerations.

Also having combustion things upfront brings up the question of cooling intake and exhaust somewhere nearby that may bring up some unwanted fumes to your nose. Having this aft is less of a problem.

I know how smelly cruise ships and ferries can be on deck, so I would not want this on my boat.

But probably solvable.

[FlyingScot]

Did budget come up? If not this is usually the first question.

I heard the idea of still needing to work but also later in life so being in a hurry.

Many seem to choose a cheaper boat and use the time saved by not working for cruising more slowly.

Go too far in the first direction and you might be better off flying everywhere and chartering. Too far in the second and your boat may not fit your image/lifestyle expectations.

[Simi 60]

Originally Posted by bluenomads

CatNewBee, that's exactly why we're planning (eventually!) a hybrid electric conversion. Two electric motors running (relatively) quietly in the hulls, while the diesel DC genset runs on the other side of the bulkhead in the front of a hull. Noise is separated as the genset can be anywhere you want, not limited to being the motor connected to the propshaft any more!
Yes, limited to about 7-8knots continuous (see recent mesg about a 46' Leopard running like this) but not running around at 20; pretty quiet!
If you need more speed, leave one larger diesel in one hull and use it in a serial hybrid mode for electric (ie. turned off), but turn it on at a more efficient high-rpm for the speed to get somewhere.
Expensive? yep, depending on how, what and who does it. But relative to the entire rig and sail wardrobe of a 45-50' boat? Not too bad I reckon!

Why not simply run your existing engines in the 7 to 8 knot range and use less fuel?
Your proposed conversion will buy a lot , perhaps a lifetimes worth of diesel for what you already have.
Added bonus is no effort to do it.

[bluenomads]

You're totally right Simi. I'm expecting the existing diesels to last some time.

But when they do snuff it, I'll be ready for the 2cm cube fusion-based fuel cell/reactor. I saw it in an old movie in some fancy car, so I'm sure it won't be long before I can buy one in the green shed...but I bet it won't fit my Ryobi whipper snipper

[NPCampbell]

This may shed some light on fuel economy for power cats. These are the numbers for a Leopard 43 PC delivery from Cape Town to Brazil:

4315 miles traveled
7.1 mph avg speed (using 1 engine at a time)
27 days of travel time
898 gallons consumed
4.8 mpg avg
264 gal fuel tank
528 gals of fuel in drums on the deck
303 hours on each engine

https://blog.leopardcatamarans.com/c...-leopard-43-pc

[SteveSadler]

Those are some well documented specs. I wonder what the mpg would be if the passage was 1 kt slower and 1kt faster?

[NPCampbell]

Originally Posted by SteveSadler

Those are some well documented specs. I wonder what the mpg would be if the passage was 1 kt slower and 1kt faster?

This appears to be using both engines. These look like pretty lofty numbers. I am guessing this was in pretty favorable conditions:

@6.9mph = 6.0 mpg
@8.1mph = 4.5 mpg
@9.5 mph = 3.5 mpg

https://www.boattest.com/review/leopard/3795_43-pc

[valhalla360]

Originally Posted by SteveSadler

Those are some well documented specs. I wonder what the mpg would be if the passage was 1 kt slower and 1kt faster?

On our 34' Gemini with a 25hp EFI Mercury Outboard. We figured around:

- 4kts 10-12 mpg
- 5kts 7-8 mpg
- 6kts 6 mpg
- 7kt 3 mpg

That's a sailboat, so maybe a nudge better if we stripped the mast of but probably not huge. Hull speed is around 7.5kt and we never ran long enough at that speed to get a feel for fuel consumption.

We found at faster speeds minor variations in wind/waves had less impact...of course with bad conditions, all bets are off.

[Chotu]

And then there is the other idea I completely forgot about when making this post...

Probably would increase mileage to better than a Prius. Approaching Tesla fuel economy.

And STILL gets under all the bridges under power when inshore.

Kitecontroller for sailing boats

[blazing928]

I remember reading about a power cruiser that uses exhaust gas temp and a variable pitch prop to get the best economy.