Diesel repower estimate

[mattinri]

I'm looking at a 2002 36' Willis Beale with an 8.1 Crusader gas engine. Does anyone have a rough estimate what it might cost to repower with diesel? It has a 2" shaft, so hopefully that would be good to go. I'd imagine I'd need the engine, transmission, controls/console and a new prop. Maybe 400 HP range to turn 14 knots?

 

[djmarchand]

A factory remanned Cummins 5.9B 370 hp diesel will cost somewhere in the low $20s. Transmission and prop will add another $5K although you might not need a new prop. Installation will be $10K or more.

Look in the classified section of boatdiesel for running take out or remanned engines. IMO the Cummins would be a great choice for that boat.

A new Cummins QSB 380 common rail engine will cost at least $10K more. Other possibilities are the Yanmar 6LP 315 hp, the Yanmar 6LY 370 hp or the Volvo D6.

David

 

[Tuna Pursuit]

Cummins yes but if you can, go for a C. The B is a light to medium duty. With the C you get wet liners and it's just a much more rugged engine.

 

[tunaorlater]

What size shaft is installed currently and is the angle right for engine clearence under the deck? That would probably be the biggest job. Also the spacing on the stringers? I would guess the current engine being a v8 that I'll be ok.

 

[petrel]

A 370 hp B series sounds like a bad plan for a 36' boat. You need more ass for a boat that size. The C series is much more appropriate. More power at lower RPM's.

 

[Nighthawk]

C series Cummins @ 450 HP reman is about 24K. 2 year warranty for non commercial, hard to beat.

Of course the nickle and diming for a project like this will end up way more than just the engine $$ in a crate. Does the fuel tank(s) for example have fuel return connections? Engine mount brackets, stinger mods maybe, mounts, gearset, bigger seawater intake, huge exhaust mods, harness, gauges it will get pricey and if you are not doing it yourself the labor will be huge.

 

[offshore31]

don't forget that on the remans they want a core engine. and the block can't be ventilated. its more expensive if you don't have a core.

 

[CEShawn]

I think I'd up that 10k especially if you weren't doing the complete repower yourself. I mean god labor rates at yards up here are basically 100/hr. So much can be going into that... I was figuring 5K in cost to just upgrade from 200HP to 260HP and doing the work myself, thats not including the engine of course...

 

[mattinri]

Thanks everyone. The more I read, the less likely I am to think repower.

 

[jojobee]

What are you doing with the boat? Any of the yanmars or cummins (including B series) will be heavier duty than the crusader.

 

[mattinri]

We'd be coastal cruising. Typically a 4 hr run each day. I'd prefer 14 kts & hull speed once we reach the destinations. We typically put on around 200 hrs a year.

 

[djmarchand]

Let's do the math. Usually when you do these calcs 100 hours per year is a no brainer to stay with the gasser. 200 hours per year may make it possible.

Assume that you cruise for 150 hours at 14 kts and another 50 at hull speed each year. Either engine will require about 160 hp to go 14 kts (well within the capability of the Cummins B, BTW) and maybe 40 to go hull speed. The Crusader will use 13.3 gph at 14 and 4 gph at hull speed. A diesel will use 8.9 gph at 14 kts and 2.7 at hull speed. All are rough guesses but probably within 10-15%.

So the Crusader will use (150*13.3 + 50* 4) * 4.00 = $8,780 in gasoline. The diesel will use (150*8.9 + 50* 2.7) * 4.00 = $5,880 in diesel. The difference is $2,900. It will take at least ten and maybe fifteen years to make up the cost of repowering in terms of fuel savings.

The diesel will go the 2-3,000 hours over this period just fine and will probably have many more years left in her. The Crusader is likely to be very worn out. You will get some of your money back when you sell the diesel powered boat, maybe half of the repowering cost. In that case your breakeven point is something like 5-7 years.

So it is a tough call to put $30K or more in repowering to save fuel and get part of it back later. But having a diesel rather than a gasser is worth something isn't it?

David

 

[mattinri]

Thanks David, Great analysis. The gas engine is quieter, smoother, and doesn't smell like a diesel. I guess I have some thinking to do.

 

[BillD]

Let's do the math. Usually when you do these calcs 100 hours per year is a no brainer to stay with the gasser. 200 hours per year may make it possible.

Assume that you cruise for 150 hours at 14 kts and another 50 at hull speed each year. Either engine will require about 160 hp to go 14 kts (well within the capability of the Cummins B, BTW) and maybe 40 to go hull speed. The Crusader will use 13.3 gph at 14 and 4 gph at hull speed. A diesel will use 8.9 gph at 14 kts and 2.7 at hull speed. All are rough guesses but probably within 10-15%.

So the Crusader will use (150*13.3 + 50* 4) * 4.00 = $8,780 in gasoline. The diesel will use (150*8.9 + 50* 2.7) * 4.00 = $5,880 in diesel. The difference is $2,900. It will take at least ten and maybe fifteen years to make up the cost of repowering in terms of fuel savings.

The diesel will go the 2-3,000 hours over this period just fine and will probably have many more years left in her. The Crusader is likely to be very worn out. You will get some of your money back when you sell the diesel powered boat, maybe half of the repowering cost. In that case your breakeven point is something like 5-7 years.

So it is a tough call to put $30K or more in repowering to save fuel and get part of it back later. But having a diesel rather than a gasser is worth something isn't it?

David

Thanks David, Great analysis. The gas engine is quieter, smoother, and doesn't smell like a diesel. I guess I have some thinking to do.

Nothing like the torque of a diesel in a 36 ft DE !!!