Mercury Diesel Sterndrive test ride
 

I got a ride today on a 2012 Chaparral 19' deck boat/bow rider powered by a 150 hp 2.0L turbo diesel sterndrive. This boat was just repowered after having "sunk" on the trailer last year. (plug in, lots of rain, dead battery).

Old power was a 3.0L 135hp EFI. I can't speak directly to the performance with the old motor, but the brief ride today was interesting. New power was a reported $23K installed including a new fuel tank. (This was almost $6K more than was quoted prior to install)

Old 135hp gas motor (as reported by owner):
Top Speed - 42 mph
Cruise speed - 25 mph
Fuel consumption at cruise - 5.5 gph
Fuel consumption at 80% power - 8.5 gph (about 35 mph)
Time to plane - "about" 4 seconds

New 150hp diesel motor (observed with Smart Gauges):
Top Speed - 48 mph
Cruise speed - 24 mph
Fuel consumption at cruise - 2.9 gph
Fuel consumption at 75% power - 6.7 gph (about 35-36 mph)
Fuel consumption at WOT (3950 rpm) - 7.9 gph
Time to plane - 4.5 seconds.

It falls off plane at about 17 mph now, He never noticed what if did before. New power plant is about 115-120 lbs heavier than the old, according to the owner.

That's 8.3 mpg at cruise, a 65% increase in economy, and still better than 6 mpg at WOT! New motor has power steering (not ordered, but installed and charged by the dealer in P'cola anyway, an extra $900)

Because of the Diamond 4 Prop, I think with changing the prop he can get better planing performance with the right SS prop.

I noticed it is VERY quiet, even at 75% power. We were able to talk without trying to shout over the engine noise. WOT is still noisy, though.

One thing: Even with the diesel, it still didn't ride like a SeaCraft. It still rode like a Chaparral. :\
And Choctawhatchee Bay was really rough today. :(

How much does the diesel package weigh? (Total of engine & Outdrive) Would two of them fit in a 23' I/O set up?

Don't know about 2 of the 150HP but one of these will fit nicely:https://mercurymarine-gsdesign1.netd..._370_tier3.pdf
It is a twin turbo 4.2L 370 HP VWMarine engine with a Merc label. Brake Specific Fuel Consumption is about 40% of what it is for a small block chevy and it weighs about the same. I'm pretty sure it costs a good bit more though...

Cost is the big factor considering diesel power when compared to any gas set up OB or IO. On commercial boats that put 1k+ hours a year on the power it can make financial sense to go with diesel as the amount of fuel used over time will offset the increase in cost. That said, most recreational users will never use the amount of fuel over time to offset the overall cost difference between the two.

Overall fuel cost is a lot less of a factor for us here in the US than for motors in the Med where a lot of boats come with these small automotive diesels. Regular gas for a car on the motorway is still between $4.50 and $6.50 a gallon in Spain, France, the Netherlands and Italy. As of this spring, low sulphur road diesels was about 78% of the cost of gas on the street in France. That little VW, even with the suprise price increase still went for about two times what a new Yamaha F150 would go for with its controls I suspect. if you were paying those kinds of prices, how long would it take you to make up money if you were burning less than 60% of the fuel at cruise fuel that cost 80% as much?

Each is about 115 lbs more than the 140/3.0L with the alpha one drive. As for size, it's a bit bigger, especially in height, 3" longer, 4" wider, and 9" taller than current the current 3.0, and just 4" taller than the pre-1992 carb'd 3.0L

32"L x 30"W x 30"H, compared to 29 x 26 x 21".

Oh, yeah, it's about 2.5x the price, not counting the changes necessary to your on-board fuel system. Complete package; motor, transmission, transom group and drive is over $20K USD installed.

But if you use the boat a lot, and plan on keeping it for 20+ years....

Interesting. That is less than I thought it would be if the price includes the outdrive. I thought that low $20K price was just for the "bobtail" engine. If the 230/260hp 3 liter V6 with the Bravo setup if priced proportionally to the 150/170 2 liter package, then maybe it becomes a bit more attractive option in situations where folks are converting slightly larger I/0 boats to bracketed 6 cylinder 4stroke outboards.

the 370hp V8 with a Bravo XR drive is about 45k. Same width as the v6 just a little longer.

I had heard that low to mid 40's number for the 4.2 liter engine, but once again was not aware it included the beefed up Bravo drive which is a pretty big ticket item on its own. That is somewhat encouraging. The test numbers that I have seen for the 370hp have been in the 10-10.5 gph range at the economy cruise speed of 3000 rpm and around 20-21 at WOT of 4200. That's about 2/3 the fuel burn of a 300 Verado. If the 265 hp 3 liter in in the low $30K range, how much more is that than the MSRP for a new 4.2 liter Yamaha Outboard with the fly by wire setup?

Even if the cost was a wash, which I am doubtful, the extra weight and reduced performance at cruise and top end would be a deal breaker for me. The slowest I cruise is 24 knots and on a good day 28-30.

Personally I love diesel power but not on small boats. I've seen them on 23' boats and other than fuel economy they just are not very impressive.

"cruise is 24kts and on a good day 28-30" ?

people often make a few mistakes - first one: over estimate their abilities

second: over estimate the speed of their ship


I believe you've made claims concerning speed before - I would have to see this cruise speed claim

Call me doubting Thomas...48 mph...I just don't see this happening...I can just barely get 50 on a good day and on ruff water also.:confused:

While there is no need to defend my cruise speed spec here as many on this board know what speed and cruise capabilities of my full dressed Tsunami are...... Here is a pic of my plotter at WOT with 2 people and a 60 gal of fuel. Also note that my power is a tired ol 2004 Suzuki 4 stroke 250 swinging a 16x21x3.

Off my new plotter at low cruise.....

I have chased after Moose and I know his sled flies...its to bad my wife was screaming slow down after I jumped his wake and wanted to pass him...:D:D

ok - this piqued my curiosity and I ran some numbers...
Merc says at 4200 it puts out 370HP and at 3000 it puts out 330HP/572ft-lbs and uses 7.8gph.

If my prop slip numbers are ok and the performance numbers posted here for various Sceptres are somewhat close then WOT would be low 50's, cruise in the low 40s (mph) and fuel economy should be near 6mpg at cruise. One challenge might be that, having so much power even at the low end, idle & trolling speeds might be faster than most want. A 40mph (or even 35mph) cruise would be pretty tough for me on a lot of days - I dont bounce back from that kind of beating as well as I used to.

I have a Bravo 1X Diesel drive going in my Sceptre so all I would need is the motor - I would love to be a guinea pig if someone else would fund it! All that said, the parts would scare me. That motor is built by VW for only Marine apps, Touareg, Audi A8&Q7 and the Porsche Cayenne. I'm thinking an ECM or a turbo would pretty be hard to get (and harder to get properly installed) in most places even with a healthy checkbook.

Seeing is believing but feeling is real....

30 knot cruise day.....

24 knot day......

The Mercury numbers for the 3 liter 260 hp V6 which is realistically a more apples to apples comparison with a 250 4S outboard, is that same 24-25 knots at 8.6 mph in a Sea Ray 250 SLX with an manufacturers claimed empty weight of 5900 pounds and a Mercury claimed "as tested" weight of almost 7700 pounds.Althou the prices seem to be coming down a little, cost is still an issue with the diesels and weight is an issue in boats not originally set up for I/O propulsion,but that would also be the case with a gas I/O setup. The one "problem" with the VW/Mercury engines is that it is almost like the old days where you had to go with a big block gasser with you wanted 300+ hp. That is obvious not the case with the modern outboards and small block Chevy MPI inboards today. With that said, the V6 VW and inline 6 BMW's which are realistically designed to replace small block V8's in lower state of tune much like the current 4.5 liter V6's gassers are, weigh about 200 pounds less in bobtail form than a 300 hp 5.7 liter V8 and 90 pounds less than the comparable 250 hp 4.5 liter V6. The 330/370hp 4.2 V8 weighs almost 200lbs less than the 380 hp 8.2 big block and maybe 60 pounds more than the 350 hp 6.2 liter small block, all with closed cooling systems. The 2 liter I4 which you can get in flavors from 115 to 170 hp weighs about 60 pounds more than the 3 liter gasser 135 hp and about 200 less than the older 180/220 hp 4.3 liter V6. These engines are inboards and the slot right into the spots of the engines that they are designed to replace. If you need crazy HP and gasser weight at the attendant high price, you would probably want to look at one of the Duramax conversions from the Swedes or Banks Engineering. You bobtail block weigh would still be about 100 lbs less than a 502.

With all that said, it is still really great time to be looking for a new outboard.

just about anything flies,in flat water


24kts in a short chop ? big short chop - BS ! never gonna happen !

pictures prove nothing !

i'm not easy to impress - not my first rodeo

I know how my 23 cc runs in a big short chop - I know it will NEVER run 24kts in a tight chop

talk is cheap-we've had this discussion before http://www.classicseacraft.com/commu...t=26748&page=4

The BOAT in theory might ride at 24 knots in tight chop, just not with you on board, right? ;-)

You're questioning my cruise speeds and now you are backpedaling and splitting hairs with sea conditions..... Note to Pelican..... Moose doesn't go out on shitty days.

Again, I stated my cruise speeds and you are calling me out. No problem, I have every trip I ever made with this engine logged with all gps tracking points including speed, time and location. If you would like to examine them all then you better bring a box lunch cause you will be a while as I have logged over 1800 hours.

You come off as quite a "know it all" and that is fine if you can back it up. I can and here is what I know for fact. My Tsunami as it sits has a WOT speed of 42 knots. On flat days I cruise at 28-30 knots. On 1-2' days I cruise at 24 knots avg offshore. On shittier days it's down to 18 with the tabs down. (Those days are rare as if it is crappy offshore I play golf) I don't know or care how the seas work up Nawth but I know the Gulf as well as anybody and what my sled will do in it on any given day. If you want to continue to run your yammer why don't you put your money where your mouth is and come take a ride at the next gathering instead of running your gums behind a keyboard. Don't forget your wallet.

Now that you are retired...get over your NJ attitude :D ..Why don't you make the next outing and have a discussion with everyone that makes sense...

All the he says I says is strictly a matter of opinion. If you can't take the beating in short chop...and Moose can so what?

Besides this thread was on a Merc/diesel.

JMHO!:cool:

not retired - not old enough


nj attitude ?

listen - if you're gonna make a claim,back it up, last time this guy started typing about speeds and seas he back peddled a whole lot

"know it all" - well - NEVER claimed to know everything,nor will I ever...but,i've got a whole lot of experience,and i'm pretty sure you've figured that out - you've asked me for advice privately a few times - concerning your stern drive set up,recall that ?


cruise speed,max speed,ride quality - all of these are often exaggerated by owners -

kind of like ol "kmoose" claiming his speeds "Originally Posted by kmoose View Post
Here is a short video running offshore in some snotty 5 foot slop during the last fall gathering. Your CC should ride a little better driving from midship. Set your speed at a comfortable pace and keep you eyes open"



listen,a sea craft is a good hull - I have one,remember ? I know what the hull can handle and what it can't - typing,"stretching" isn't the best thing to do - but again,most owners exaggerate;exaggerate the speeds,the sea conditions and the ride quality...

that's what I've pointed out

Ol' Pely must have a special kind of anti SeaCraft chop up Nawth but then again I think they measure wave height up there from the center of the sine. Down here a "tight" chop is easier to run as the gap can be bridged at speed. I do think the express models do better bridging chop than the CCs due to their lighter bow weights but that of course is just speculation.

nj attitude ?=New Jersey...Duh!

No where did I ever say that "know it all"...and what does me asking you about stern drives in a "private" message have to do with any thing going on in this rant and rave session. Of course I remember...does that make you feel any better?

All I said is come and join us and leave the Jersey attitude in Jersey.

Besides I still don't believe a that merc/diesel pushed that boat to 48 mph.

I`ll take open season for 500 Alex.

The best thing coming outta So Fl?

What is 95 N?

Padre, seems some could use a compass. Morally and spiritually.

Mr. Whackers Seafari touches 50 light with his 150 E TEC.
I see 39 with my old smoker 150.
Folks didn`t think I`d live that long. R R R

The 48 mph number we achieved in the Chaparral was was statute mph, NOT nautical mph. So translate that to 41-42 kts. That was the speed showing on the GPS, trimmed out WOT in a moderate chop to choppy conditions in Choctawhatchee Bay. We reached 45 mph easily, and then played with the drive trim, and she gradually eased up to a max speed of 48 statute miles per hour.

It makes no difference whether you believe it or not. Not my boat, not my motor: I have no dog in this hunt. It was just an interesting day on the water, which is generally better than an interesting day on the shore.

:) On the other hand, MY 1987 Chaparral 198F with its 1988 Johnson 140 Looper can reach a WOT speed of 39 mph at 5400 rpms, cruises at 25 mph inshore, burning about 7.5-8.0 gph at cruise.
My '71 Seafari with original Mercruiser 140 ran about 24 mph at cruise for 5 minutes before blowing the headgasket. No idea how much fuel I used.
THOSE are My claims.

I'm with ya Terry!! Very light fuel load, perfect water, slight wind at my back, light load of beer I can see 50 on the Raymarine, however the fuel flow is showing numbers like yours that do not compute in my financial world. :)

I'm installing nitrous next week as soon as I get back from New Jersey to watch Mel's team lose to the Saints.

Yuck!!! Back from New Jersey?!?! Dang Ken, what did you do wrong to deserve such a fate? You will be OK, a few days in beautiful Marion County and things will be back to normal! :)

I was referring to the derail, not your numbers.

Diesel RPMs
 

The diesels engine needs about 22 to 1 compression ratio to detonate the fuel. To do that you need a long stroke engine or you will put an awfull lot of load on the top end. My "rule of thumb" research is that 3400 RPM Volvos, Yanmars and Vws last 6 to 10 years. 2400 RPM 3208 Cats last 15 to 25 years and 1800 rpm in-line Detroits last 20 - 30 years. If you spool 'em up you'll burn 'em down.
The old 170 Yanmar put out the same torque as a 454 at 3200 rpm's. the problem is the Yanmar was "against the wood" and the 454 was a half throttle. I run them all easy - an engine only has so many "frams" in - no use in using them all up today. Equipment is expensive to replace and It's tough to figure out how to depreciate "toys" with the IRS!!!

Terry's right, "high speed" diesels often don't last any longer than gas engines, per yacht surveyor Dave Pascoe, who has lots of experience with them and has written several articles on the subject. He's also addressed the "Gas vs. Diesel" subject at length.

Although slow speed diesels like the old Ford/Lehman are noted for lasting 6,000-10,000+ hours cruising at 1400 rpm in an 8 kt trawler, that engine only develops 135 HP from 360 Cu. in., or .375 hp/cu in.! The Mercruiser diesel is developing over 1.2 hp/cu in., so if you figure engine life is inversely proportional to hp/cu in., I'd be surprised if it lived for more than a few hundred hrs in a marine application! Although it's performance is indeed impressive, the big question is, for how long?!

I would expect a bit more than a couple of hundred hours out of the VW's. The one thing that they have gong for them is a graphitic iron block like the Duramax engines. The base 2 liter VW only puts out like 57 hp per liter.

The Tier 3 VW's run a 16.4-1 compression ratio. As for the 170 Yanmars, I see a hell of a lot of them still running after many years. There was a gringo owner in Mazatlan who ran a couple of old 29 Robalo express boots as charter boats with pairs of those very engines. 20 plus miles out to the fishing grounds every day and 20 miles back for years. Those are 3.5 liter blocks that weighed 900 pounds dry. I was a history major, but I think that works out for less than 50 hp per liter. As for torque, don't turbodiesels tend to produce much of their torque well off of WOT? The current 550 hp Cumins QSB 6.7 has a top end of 3200 rpm but produces max torque starting at 2000 rpm. Mercury doesn't have a torque curve for the diesels or the gassers on it's performance reports. I did look up the similar 150 hp BMW based By series Yanmar 2 liter TDI. It has a top end of 4000 rpm but reaches peak torque at 2500 and holds it up to around 3500 which is about 100 rpm's shy of the max continuous rating for that engine. That would lead me to believe that if the old 4LH series 3.5 liter Yanmar actually put out the same torque at 3200 as the 454, it probably put out MORE at 2500.

jdm61
I agree with you that the 4LH - 170 Yanmar is an excellent small lightweight Marine diesel. Tino and Adib Mastry sold warehouses full of them and many are still running strongly today. I think the Cat 3208-T in 320 Hp rating is a very good motor, but the 210 hp rated 3208's are still pushing around wooden Grand Banks. The Detroit Diesel 71 series in 3 and 6 cylinder in-line configurations is a very good design and has been around since WWII. The Stewart and Stevenson 671 made 450 HP but it's tough to find one that has 1500 hours on it and still runs. The 40 year old 210 HP 671's are still working every day in fishing boats tugs and crew boats. Of course their captains have gone deaf! After 15 years, Ford is still on a mission to show Internation Harvester how to make a high horsepower V-8 diesel for their trucks. The problem is they they really haven't come up with anything better that the 7.3 "Corn Binder" in about 230 hp rating.
It's had to make lots of horsepower in a small engine without creating alot of harmful heat. If you have a little more cubic inches and turn them easy they will last much longer. I just always notice the boat adds say "2002 32' Luhrs, fresh Yanmars......" and some say "1978 34 Hatteras, 265hp - 3208 Cats.....runs good".

That is the case with most engines when you jack them up. With that said, I think that there is a lot of fairytale stuff and misinformation in the marine industry, The outboard crowd will tell you how unreliable gasser inboards with outdrives are, yet they will rave about their engines that get about the same horsepower out of significantly smaller aluminum blocks , sometimes supercharged. The "commercial" diesel crowd will tell you how unreliable automotive diesels are, yet turn right around and tell you how they get 10,000 hours out of their marinized light truck (automotive) engine. Likewise, they will try to tell you that a Cummins light truck engine will last forever, but any attempt to marinize say a Duramax will end in disaster, when said Duramx engines apparently have the same level of endurance that the Cummins B series have in commercial light to medium trucks.
As a bit of anecdotal evidence, my dad had a 65 Monterey with jacked up Bivens 16V92's that allegedly put out close to 1700 hp when fresh. They would push that big boat to a top speed of 43 knots with a semi normal fuel and gear load. When he got the boat, they had just been rebuilt. Those engines are supposed to be grenades that you will be lucky to get 1500 hours out of, right? By the time he sold the boat, he had put 4000 hours in the engines and although they were a bit tired, they were still running fine. Of course, one part of that was that our captain typically cruised it at over 1800-1850 rpm and around 28-29 knots instead of the "normal fast cruise' in the mid 30 know range or so, but there you have it. My point being that these automotive diesels are replacements for the automotive engines currently used in recreational boating. I includes outboard in that category, because many of the 4 strokes have automotive roots and it is only recently that we have seen "purpose built" large 4 stock outboard blocks, albeit ones based on automotive technology, but lagging a few years behind. So really, the fair comparison would actually be who the automotive diesels compare to their gas counterparts in automotive applications and then extrapolate for the increased stresses of marine application. The trick with the diesels will be to get the PRICING more in line with that of gas vs diesel in the automotive world where the difference is a couple of thousand dollars not TENS of thousands., but that seems to be coming as more small diesels are marinated. Of course, the bad news is that the economies of scale in the recreational marine industry are such that we can perhaps only hope that the cost of the small diesel engines will eventually get to be slightly less that the cost of the base model of the entire car that they were sourced from, much like Honda and Yamaha outboards. We appear to be at that point with this 150 VW TDI engine. LOL