Yanmar Diesel Outboard
- Thread starter Barry Rietz
- Start date
This 50 hp engine by Yamaha and "Cox" 300 hp 8 cyl. 3.7 to be distributed by Mercury both hit the magazines/web sites a little over a year ago. The 50 hp is estimated to cost about $25,000 (Buy a lot of gas for that!)
The issue on any of these is EPA emissions. That is what killed the earlier 30 and 40 hp diesels which have been available for a number of years--in many. parts of the world--and a few smuggled into the USA...
The Yamaha 50 was expected to pass EPA muster sometime next year--then it will be on the US market. Not a lot about them--most super yachts want more than 50 hp on their tenders--and 300 hp may be fine for the larger RIBS--but when they get up in size, many have inboard diesel boats. (having a single fuel for the main engines and tenders is a real advantage.).
The issue on any of these is EPA emissions. That is what killed the earlier 30 and 40 hp diesels which have been available for a number of years--in many. parts of the world--and a few smuggled into the USA...
The Yamaha 50 was expected to pass EPA muster sometime next year--then it will be on the US market. Not a lot about them--most super yachts want more than 50 hp on their tenders--and 300 hp may be fine for the larger RIBS--but when they get up in size, many have inboard diesel boats. (having a single fuel for the main engines and tenders is a real advantage.).
Just curious, but asking anyway:
So what does a 300 hp 3.7 "Cox" or a 50 hp Diesel ob weigh?
More weight on the stern is a direct enemy of a planing boat.
Seems like a heavy diesel ob would be best suited to a small cruiser/tug like the Cutwater 25 with owners that would be happier at displacement speeds most of the time.
The dual counter-rotating crankshafts with their dual con rods on each piston is an interesting anti-vibration solution. Whodathunkit? German engineering, again! Ha! :lol:
Joe. :teeth :thup
So what does a 300 hp 3.7 "Cox" or a 50 hp Diesel ob weigh?
More weight on the stern is a direct enemy of a planing boat.
Seems like a heavy diesel ob would be best suited to a small cruiser/tug like the Cutwater 25 with owners that would be happier at displacement speeds most of the time.
The dual counter-rotating crankshafts with their dual con rods on each piston is an interesting anti-vibration solution. Whodathunkit? German engineering, again! Ha! :lol:
Joe. :teeth :thup
I looked into the 50 hp diesel last winter. The 25 Grand price tag & not meeting EPA specs was the main turn off. The combination of the 50 hp diesel & a 6 hp Suzuki kicker would weigh 437 lbs, which is only 11 lbs more than my twin Honda 40’s, so weight was not a deal breaker. The 50 hp on this diesel could give 12 mpg at displacement making a possible operating range of 592 miles without carrying additional to the regular tank fuel. Even with 30% of the time at planing speed it would still equal my range now carrying an extra 50 gallons & 300+lbs. With the diesel torque & correct pitched prop it should plane a CD22, but that would be the $25,000 gamble.
Jay
Jay
Marco Flamingo
Active member
When they advertise "quiet and smooth," do they mean quiet and smooth for a 2 cyl diesel outboard or quiet and smooth compared to a 50 hp 4 cyl 4 stroke gas outboard? The could also claim that it is the quietest and smoothest 50 hp diesel outboard in the world, but that means nothing.
I'm curious and would like to take one for a spin, but not $25K curious.
Mark
I'm curious and would like to take one for a spin, but not $25K curious.
Mark
Maybe true, but if you compare HP gas vs. diesel for trucks, which is easy since some 1/2 ton, and most 3/4 and 1 ton trucks have both, you don't get the picture of utility for pulling a trailer. I don't claim that pulling a trailer is the same as putting a boat on step or that this OB will put a 22 CDory on step until I see it, but torque is what will pull a trailer up a hill, and diesels generally have far more torque per HP then gasoline motors.
I'm very intrigued and thinking about replacing my 02 Honda 90 outboard at some point, but I'm not ready to put $25K into an unproven outboard, and even then maybe not.
Torque is a very misunderstood concept. Take two engines, one diesel and one gas both making the same hp. Yes the diesel makes more torque and at a lower rpm, maybe 400 ft lbs at 2,500 rpm vs 300 ft lbs at 3,500 rpm for the gasser. But transmissions can easily solve this.
Gear down the gasser by 25-30% vs the diesel, ie pull up the hill in 3rd rather than fourth gear and it will produce the same torque and get up the hill at the same rate, a depending on both engines having the same hp.
Yes the gasser will be running at a higher rpm up the hill, but that is what it is designed to do.
But most people feel more comfortable running at a lower rpm up the hill and that more than anything supports the diesel's high torque image.
David
Gear down the gasser by 25-30% vs the diesel, ie pull up the hill in 3rd rather than fourth gear and it will produce the same torque and get up the hill at the same rate, a depending on both engines having the same hp.
Yes the gasser will be running at a higher rpm up the hill, but that is what it is designed to do.
But most people feel more comfortable running at a lower rpm up the hill and that more than anything supports the diesel's high torque image.
David
Interesting that virtually none of the outboard manufactures put out HP vs Torque curves. There is an old saying
Gas outboards are propped to take advantage of the speed and HP--Diesels are propped to take advantage of the torque. In the high speed diesel, the highest torque is about at the "hump" required to get the boat on a plane. I assume that this 50 hp diesel could be similarly propped.
Part of the other side of the equation is the fuel consumption--the Diesel is about 1/3 more efficient than the gas engine for the same fuel burn. (14 hp per gallon an hour vs 20 HP per gallon per hour for the diesel)--add in that the diesel at the same HP generally does have more torque.
As to David M's comments--that is why the modern cars are now coming with transmissions up to 9 gears forward--Most are at the top end and are there just to try and eek out more fuel economy. I recently purchased an RV with a Mercedes V 6 3.0 liter turbo charged diesel: 188 hp at 3600 RPM--and max torque of 325 ft lbs at 1400 to 2400 RPM in a plateau. The HP at 1400 RPM is about 85 and at 2400 RPM is about 145, The engine is virtually never run at 3600 RPM--and most driving is in the 1400 to 2200 RPM range. (In my book this is a "high speed" diesel.). This same diesel block in a car application gives 245 HP and 428 ft lbs of torque, at about the same RPMs. On the other hand, my wife's car also has a German engineered supercharged V 6 3 liter gas engine with 310 HP (at 5500 to 6500 RPM) and 325 ft lbs torque at 2900 to 4500). So the 310 HP car has the same torque as the 188 hp diesel--and the 245 HP diesel (on the same block--souped up has 245 HP and almost 100 ft lbs of torque. Why the higher HP and torque in the car?--speed/gearing--and longevity. The truck diesel is pushing up to over 15,000 lbs. The car is only about 3900 lbs! Durability would not be good with the hopped up diesel or gas engine in the truck.
. A lot of torque is required to get a boat on a plane--not as much to push the speed further at the high end.
Gas outboards are propped to take advantage of the speed and HP--Diesels are propped to take advantage of the torque. In the high speed diesel, the highest torque is about at the "hump" required to get the boat on a plane. I assume that this 50 hp diesel could be similarly propped.
Part of the other side of the equation is the fuel consumption--the Diesel is about 1/3 more efficient than the gas engine for the same fuel burn. (14 hp per gallon an hour vs 20 HP per gallon per hour for the diesel)--add in that the diesel at the same HP generally does have more torque.
As to David M's comments--that is why the modern cars are now coming with transmissions up to 9 gears forward--Most are at the top end and are there just to try and eek out more fuel economy. I recently purchased an RV with a Mercedes V 6 3.0 liter turbo charged diesel: 188 hp at 3600 RPM--and max torque of 325 ft lbs at 1400 to 2400 RPM in a plateau. The HP at 1400 RPM is about 85 and at 2400 RPM is about 145, The engine is virtually never run at 3600 RPM--and most driving is in the 1400 to 2200 RPM range. (In my book this is a "high speed" diesel.). This same diesel block in a car application gives 245 HP and 428 ft lbs of torque, at about the same RPMs. On the other hand, my wife's car also has a German engineered supercharged V 6 3 liter gas engine with 310 HP (at 5500 to 6500 RPM) and 325 ft lbs torque at 2900 to 4500). So the 310 HP car has the same torque as the 188 hp diesel--and the 245 HP diesel (on the same block--souped up has 245 HP and almost 100 ft lbs of torque. Why the higher HP and torque in the car?--speed/gearing--and longevity. The truck diesel is pushing up to over 15,000 lbs. The car is only about 3900 lbs! Durability would not be good with the hopped up diesel or gas engine in the truck.
On the other hand an outboard motor only has a single gear transmission, if the 50 hp diesel develops max torque at only 2500 rpms & that allows a CD22 to get on plane it may be possible slightly over 1000 rpm could maintain displacement speed of 6 to 7 mph. If so, as I said before, the milage would be incredible compared to my total 80 hp twin Honda gas four strokes. For those like me, that would be completely satisfied with a cruising speed of 12 to 15 mph & almost doubling the present mpg it just might be worth the upfront cost.
On the Yukon River with a moderately loaded CD22, I was able to run on plane at 12 mph on a single 40 hp Honda at 5200 rpm with a 10 pitch x 12 inch prop. That’s the same pitch prop, I use for heavy boat cruising in SE Alaska & high altitude cruising on Yellowstone Lake. To me it’s very possible the 50 hp diesel could be a good set up for those that are wanting an extended cruising range while retaining the ability to get on plane even if only at 12 to 15 mph cruising speed.
Jay
On the Yukon River with a moderately loaded CD22, I was able to run on plane at 12 mph on a single 40 hp Honda at 5200 rpm with a 10 pitch x 12 inch prop. That’s the same pitch prop, I use for heavy boat cruising in SE Alaska & high altitude cruising on Yellowstone Lake. To me it’s very possible the 50 hp diesel could be a good set up for those that are wanting an extended cruising range while retaining the ability to get on plane even if only at 12 to 15 mph cruising speed.
Jay
robhwa wrote:
of course I meant "far more torque per RPM"...
For me, getting the boat planing and moving at a moderate speed still on step EFFICIENTLY is what I am looking for. With logs, deadheads, sandbars, waves, etc. I don't want to go fast very often. As a younger man, I have hit things at speed. Not fun any more. If I wanted to go 40+ mph all of the time I certainly wouldn't have a CDory.
Chester said
Well, not really for a boat with a single gear and a nonadjustable prop. Getting the boat planing and moving it forward is what most people are looking for, not the HP that the motor itself can develop. My propping is to put my boat on step and move it at moderate speed at middle RPM, not maximum speed at max RPM.
For me, all other things equal, diesels would have major advantages. Safety (fire on a boat!!!), efficiency, economy are key. I watched a gasoline boat burn in a Seattle boatyard, set off by fireworks near Gasworks park on July 4. Once the gasoline tank was breached and gasoline spilled into the cockpit, it took a couple of minutes to completely destroy the boat. If the fire dept hadn't already been there many other adjacent boats stacked into the lifts would also probably have had the same fate.
Safety would say diesel. However, I trailer, launch in difficult places, maneuver in shallow water, beach, and sometimes leave the boat in the water over extended periods. The simple act of raising the outboard cuts corrosion substantially. That would say outboard.
I am always a skeptic, but a diesel outboard, if it will put my boat on step, and doesn't put too much weight on the transom, seems a great option for people like me. I realize that I might not be able to load the boat up and still get it to plane, but I could still move it efficiently at hull speed. However, $25K? We'd probably need to see more competition. That is what I paid for my whole setup, boat, 90 and 9.9 motors, trailer, canopy, nice Avon tender and electronics.
of course I meant "far more torque per RPM"...
For me, getting the boat planing and moving at a moderate speed still on step EFFICIENTLY is what I am looking for. With logs, deadheads, sandbars, waves, etc. I don't want to go fast very often. As a younger man, I have hit things at speed. Not fun any more. If I wanted to go 40+ mph all of the time I certainly wouldn't have a CDory.
Chester said
Well, not really for a boat with a single gear and a nonadjustable prop. Getting the boat planing and moving it forward is what most people are looking for, not the HP that the motor itself can develop. My propping is to put my boat on step and move it at moderate speed at middle RPM, not maximum speed at max RPM.
For me, all other things equal, diesels would have major advantages. Safety (fire on a boat!!!), efficiency, economy are key. I watched a gasoline boat burn in a Seattle boatyard, set off by fireworks near Gasworks park on July 4. Once the gasoline tank was breached and gasoline spilled into the cockpit, it took a couple of minutes to completely destroy the boat. If the fire dept hadn't already been there many other adjacent boats stacked into the lifts would also probably have had the same fate.
Safety would say diesel. However, I trailer, launch in difficult places, maneuver in shallow water, beach, and sometimes leave the boat in the water over extended periods. The simple act of raising the outboard cuts corrosion substantially. That would say outboard.
I am always a skeptic, but a diesel outboard, if it will put my boat on step, and doesn't put too much weight on the transom, seems a great option for people like me. I realize that I might not be able to load the boat up and still get it to plane, but I could still move it efficiently at hull speed. However, $25K? We'd probably need to see more competition. That is what I paid for my whole setup, boat, 90 and 9.9 motors, trailer, canopy, nice Avon tender and electronics.