Caterpillar D343 - Economy and Specs?

Just wondering what kind of fuel economy should one expect to get from a Caterpillar D343 in a 75ft trawler?

Whats the best can hope for



Also does anyone know what oil pressure should read and the water temp range?


Thanks

@mahal, if I remember right you bought that boat a couple of years ago. What have you been up to since then that you don't know your boat yet? BTW would like to see some photos of it.

Sitting on a mooring working on it waiting for covid to go away

That’s really nice. Looks like you have a lot of potential there. Since the covered aft deck is huge, but the deckhouse is rather short, it shouldn’t be too difficult to extend the house, leaving say only 10ft of covered aft deck outdoors.

You haven’t posted anything about your running parameters, boat dimensions, gear ratio, prop size and type, but an old Cat like that (depending on what your rpm is) likely isn’t generating more than 16.3 to 18.3 hp/gal-hr.

Thanks, unfortunately a lot of the wood that was used to cover the aft deck is damaged so will have to replace it but will enclose it all and leave about 10ft of the aft like you suggested.



The boat is an old Desco Marine 75ft, I think the its 75ft long 23ft beam. I am not sure the depth or the prop size yet.



I am hoping to do whatever speed I need to get the best fuel economy, right now, trying to determine how much fuel I should take on for a 300nm trip.

This is a guess. At 8kts I am guessing 1.25 gallons per nm. I would suggest 450 gallons for the trip with a 75 gallon reserve.

Others might guess differently.

tiltrider1 said:

This is a guess. At 8kts I am guessing 1.25 gallons per nm. I would suggest 450 gallons for the trip with a 75 gallon reserve.

Others might guess differently.

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good guess on 1.25 per mile.

I would load another 100 gal fuel reserve since there are many unknowns

Being that it's not a sale trip, it won't hurt to load some extra fuel. It's just that much less you'll need to buy later.

Any idea what your displacement is?

What HP rating do your engines have?
D343 being a Pre-Combustion engine don’t like being run slow.
Trying to run them slow to conserve fuel will only oil them up.
Here are the fuel curves.

Wow, 240 hp on 14 liters, that’s great! However at 17.5 hp/gal-hr the fuel consumption is as horrible as my WW2 Jimmies. CAT parts are expensive so I hope your engine doesn’t need any major repairs.

Mako said:

Wow, 240 hp on 14 liters, that’s great! However at 17.5 hp/gal-hr the fuel consumption is as horrible as my WW2 Jimmies. CAT parts are expensive so I hope your engine doesn’t need any major repairs.

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Efficiency calculates a little better for the higher output version (18.6 hp-hr/gal). But still not great. That said, it may still be better than the old Detroits in the real world depending on how the efficiency scales as you reduce RPM / load.

rslifkin said:

Being that it's not a sale trip, it won't hurt to load some extra fuel. It's just that much less you'll need to buy later.

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Actually, the fuel is pretty expensive here, so if I can make it the 300nm, then I can get it for half the price.

Mako said:

Any idea what your displacement is?

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I cannot find a spec sheet, and I think Desco went out of business a while back and not sure how would get anything from them. I read online from 60-150tons. I am thinking I am on the lighter side as there is hardly anything onboard now.

Arun52 said:

What HP rating do your engines have?

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No, the boat had zero paperwork that came with it other than a bill of sale
I was told it is 365 Hp. I actually didn't find the serial number on the engine until just a few days ago because it was covered in paint. But I think it is the turbo intercooler model.

It's a big commercial boat, not built for economy. But older Caterpillars ran on #3 diesel if you can find it. You probably have fairly rectangular fuel tanks. Measure the tank, run in a circle for an hour at your cruising speed, and remeasure the tank. Do the math. I think you'll find 15 to 20gph depending on how it's loaded.

With twin 460hp in a 52’ boat at 33,500Kg running at 2000rpm and 18Knts using an average of 190L per hour.
Engine temp around 185 to 190.
Oil Pressure 80psi
MG514 Gears 200psi