Fuel Consumption of 40ft Cat, or Why Buy Sails?

[Cotemar]

Originally Posted by Factor

He needs to get a tune up

I use a litre an hour per engine, and I only run the engines to get in and out of the marina. So even though we use the boat a lot, we still only have 350 hrs on the engines, partly because it sails well and it sails well partly because you can get the props and the associated drag out of the water.

OK, thats good at 2 litre (1/2 gal) per hour for both engines. But the OP has no mast, so will just be motoring all the time just like a power cat with smaller engines. The OP would be putting a lot of hours at higher RPM's on those gas engines.

[nimblemotors]

Originally Posted by tamicatana

Since running your engines more frequently, you'll need to factor in not only fuel, but more frequent changes: oil/lubricants, strainers, belts, impellers, coolant, other fluids. Wear and tear on parts and seals. Things like that. It may be a wash...

Also, there is absolutely no reason that the price of fuel will not rise, and likely will rise significantly.

Yes the engine wear and maintenance needs to be taken into account for the long term. I do plan to use electric power quite a bit, which has a small fraction of the costs of the gasoline engine. The price of oil is frankly unpredictable, it could just as easily collapse as skyrocket.
but fuel can come from other sources, I'm particular fond of this recent development, making ethanol from seaweed:

Unlocking Seaweed's Next-Gen Crude: Sugar - NYTimes.com

[Cotemar]

Originally Posted by nimblemotors

I find a lot of inspiration from the PlanetSolar Boat, circumnavigated from ONLY solar power. Of course, THAT many solar panels will cost more than sails!

I got a lot of inspiration from watching PlanetSolar set that solar powered record also. The reality is that we do not have million dollar sponsors to help set up our cats.

I use a shot glass of fuel on most of my trips and fuel is the last thing we ever have to worry about since we use so little of it.

We never run an engine at anchor because we have and oversized solar panel setup

[Factor]

Originally Posted by Cotemar

OK, thats good at 2 litre (1/2 gal) per hour for both engines. But the OP has no mast, so will just be motoring all the time just like a power cat with smaller engines. The OP would be putting a lot of hours at higher RPM's on those gas engines.

Yep - dont disagree with that at all, if you want a power only boat, then a very very slow revving diesel is the answer, but equally the answer is in hulls not designed for sail. I just wanted to point out that petrol outboards can be reasonably efficient.

[ArtM]

Double Exposure has a sailing catamaran of the same name that has planing hulls, and can get up over 10kts I think - maybe more - on a pair of outboard motors.

https://www.facebook.com/pages/Doubl...s/102088833014

[Cheechako]

No real reason to add sails, but there is nothing like making 9 knots under sail, no motor noise etc. Also, nice to have both options. On a mono you need the mainsail to keep the boat from rolling. But not so much with the cat. You will wear out the diesels alot faster with no sails. In the plus side for engines,is if you are running the engines all the time you dont need to spend money on SOlar and wind charging etc. Another cost savings. My guess is if you add it up, engines only is cheaper.... for a limited cruise anyway....
Lets see, maybe this is a rough estimate of rigging a cat:
Spar and boom etc: $20k?
Two sails, full batten main etc: $18k
standing Rigging: $10k?
Primary and halyard winches: $8k
Soft rigging: $1k
Furling:$2500
Main Cover: $350
Total about $60k
Divide by about $4 per gal = 15000 gallons of diesel. at one gal an hour and 8 knots that's about 120,000 miles of cruising. to break even and I didnt add in the solar and or wind gen cost. If the new diesels last 6000 hours that leaves you with a boat you can sell in 6-10 years and walk away before having to replace the diesels again....

[nimblemotors]

Originally Posted by ArtM

Double Exposure has a sailing catamaran of the same name that has planing hulls, and can get up over 10kts I think - maybe more - on a pair of outboard motors.

https://www.facebook.com/pages/Doubl...s/102088833014

I don't do facebook, is that why that link doesn't work?

My hulls are hmm, must be some nautical term,
but bottom is flat, sort of rounded but using three flat surfaces.
Another reason not to sail is I would need to figure out how to put in boards/foils, the previous dagger board setup was a "hack".

I think it would be really cool to put a big motor in it so it will go really fast if I want to, of couse, 1mpg at those speeds, but can outrun a storm (I can tell the wife that is why I need it to go really fast
I can do 400hp pretty easy without a lot of weight.

[Cheechako]

Originally Posted by ArtM

Double Exposure has a sailing catamaran of the same name that has planing hulls, and can get up over 10kts I think - maybe more - on a pair of outboard motors.

https://www.facebook.com/pages/Doubl...s/102088833014

Did anyone notice the really cool steering wheel on that boat? also, scroll down, there is a photo showing 21 knots speed...?

[Cotemar]

Originally Posted by nimblemotors

I don't do facebook, is that why that link doesn't work?

My hulls are hmm, must be some nautical term,
but bottom is flat, sort of rounded but using three flat surfaces.
Another reason not to sail is I would need to figure out how to put in boards/foils, the previous dagger board setup was a "hack".

I think it would be really cool to put a big motor in it so it will go really fast if I want to, of couse, 1mpg at those speeds, but can outrun a storm (I can tell the wife that is why I need it to go really fast
I can do 400hp pretty easy without a lot of weight.

Your ideas are all over the map. What kind of cat do your own?

[ty.gregory]

Originally Posted by Cheechako

Did anyone notice the really cool steering wheel on that boat? also, scroll down, there is a photo showing 21 knots speed...?

No I did not.

[ArtM]

Originally Posted by ArtM

Double Exposure has a sailing catamaran of the same name that has planing hulls, and can get up over 10kts I think - maybe more - on a pair of outboard motors.

https://www.facebook.com/pages/Doubl...s/102088833014

I think he might have told me 26 knts or something like that - I don't recall. It was fast enough to waterski. I think he has a YouTube video showing the boat hitting speed from a slow start.

[nimblemotors]

Originally Posted by Cotemar

Your ideas are all over the map. What kind of cat do your own?

It was a custom build by Gary Lepak. Here is what it used to look like, I have dismantled it into just the hulls and am building another boat with them,
so at this point the new plan/design is still under consideration.

[nimblemotors]

Originally Posted by Cheechako

Did anyone notice the really cool steering wheel on that boat? also, scroll down, there is a photo showing 21 knots speed...?

Don't think the focus would be on the steering wheel..

Didn't see anything about its ability to plane.

[Cheechako]

cool looking boat

[Cotemar]

Originally Posted by nimblemotors

It was a custom build by Gary Lepak. Here is what it used to look like, I have dismantled it into just the hulls and am building another boat with them,
so at this point the new plan/design is still under consideration.

Forget everything that I said. Put two outboards on it and call it a day.
Happy motoring.