21' Diesel Nordic in Feb. Powerboat mag
 

Just been reading the other thread about diesels and picked up the Feb issue. They're using the Duramax engine that Habana Joe mentioned in the other thread. They're using it as a test engine for IMCO's new SCX drive and this boat, on its rev limiter, hit 77 mph. They claim they're getting 7-8 mpg!!! (I'm assuming that's cruise speeds and guessing mid to high 50's for speed but they didn't specify since the article was more about the outdrive.) The boat will be at the LA boat show and they're working on a deck boat next.

So.........would you????? I think I would. With my cut down windshield, all I hear is wind noise anyways, so wouldn't miss the roar of a 525. Can't wait until they strap this into a bigger boat!

My BS meter just went off the scale. If they are getting that kind of mileage, it is at an idle. They are not going to get 2 times the mileage of a gasoline engine. I think we need an independent test. A 20' Baja only gets 3.75 mpg at 39 mph with its little 350 (boattest.com), and the heavier Nordic 21' with a heavier diesel engine that may be 30% more fuel efficient is somehow getting a 100% increase in mileage. Uh-huh.

I think this pretty much shows you can't trust the manufacturers for any diesel fuel economy claims.

Michael

I won't speculate about MPG, if the mag says it, it might be true, but here are some questions.

The diesel with that drive much cost double (I'm guessing at OEM level) what a Merc package does to attain the same speed?

If the ecomony is 4 MPG more than gas at cruise and both fuels are the same price $4/gal and let's say the package cost $15,000 more than a Merc you would have to travel roughly 15,000 miles additional miles at a 50 mph cruise to equal the price difference of the diesel - that's 300 hours at cruise speed - is that right?

If so, why ever bother with a diesel in a small boat?

I think that's point I keep trying to make - that's why all the diesel projects get canned for smaller boats - it makes no sense.

Don't get me wrong...Diesels are great but nothing like the sound of a healthy big block in a boat.

I agree 100%

OH i don't know, I like they way an unrestricted v8 diesel such as the durmax or 6.0 sound. Not the same as a nice BB..but it does sound good.

The story was about the Drive ,, and I call BS on the whole test!! an Alpha would hold up on a 21 ft boat that is light weight ,,, put those engines in a 10000lb boat and run it wide open ,, then tell us how good the drives are and what kind of fuel your burning !
It was a waste of good paper space ! :evilb::D

RHC

[QUOTE=HabanaJoe;2434606]If the ecomony is 4 MPG more than gas at cruise and both fuels are the same price $4/gal and let's say the package cost $15,000 more than a Merc you would have to travel roughly 15,000 miles additional miles at a 50 mph cruise to equal the price difference of the diesel - that's 300 hours at cruise speed - is that right?

If so, why ever bother with a diesel in a small boat?


A perfomance diesel in a small boat makes perfect sense when you consider they are getting similar performance as a 500efi or 525 in that size boat and you take into account that the performance diesel's durability will take you through a minimum of one complete rebuild of the big block at cost of $8000-$15000.

Your total return on investment in reduced maintenance, rebuild costs, down time (ie. boat at the shop and not on the water) and decreased fuel consumption make the initial added cost of a performance diesel package a very attractive option to consider once it is fully tested and dialed in. IMO

EXACTLY...especially with the turbo making 30+ lbs of boost!

In the March issue of Powerboat that I got yesterday they have 39 nor tech that they tested with a pair of 480hp yanmars hooked through the ASD-8 drives.

Where the options are listed it lists the yanmar upgrade @ $50,000 from the base power package (merc 525efi's). It doesn't mention anything about the price on the Arnesons. If 50k is really the charge to go to yanmars and asd-8's that doesn't seem bad at all to me.

In the fuel economy section they list: 40mph=2.6mpg 50mph=2.5mpg 60mph=1.9mpg 70mph=2mpg 80mph=1.9mpg
Top speed was 80mph @ 3,475rpms

This is a good example of what I would be looking for in a diesel application. I don't need to go 100mph but I would love to get 2mpg @ 70 mph and 2.5gph @50mph. Most of my running is done between 45-65mph and anything I could do to improve reliability, maintenance intervals and fuel economy I would be all for.

My boat is an old apache 36' v bottom and I would guess it to be much less efficient than the 11,000lbs nor tech stepped bottom boat, but with seeing the numbers I do think that eventually it will be worth while for me to go the diesel route.

Just out of curiousity, what do you guys with experience think a 10,000 (dry) 36' apache with a couple 480 yanmars and asd-8's do speed wise? I am guessing cruise @ 50 and top end of 74mph. Am I dreaming, or is that possible?

Liquid Liability,

The exaggerated point I was trying to make was based on fuel economy alone.

I was being scarastic about diesel ecomony vs $'s saved. Yes, maintainence should be less money, it will last longer, how much? I say last longer with a qualifier, when you run your diesels hard and throttle them they don't last like steady state running in a cruiser would.

On fuel consumption alone, you can't put enough hours on a performance boat to ever make it worth it, that was what I was trying to say.

Another note, I think, not sure when most people on here re-build a gas engine it is because they are experiencing a problem and not rebuilding for scheduled overhauls like a race engine. If that is correct than expect the price of your diesel rebuilds to be very high which will hurt your assumptions.

You don't know me from anywhere, search my posts, I am the biggest fan of diesel power. I have patents, my shops did research work for the major engine & component manufacturers yada, yada, yada.

I want it to work, but even in say a 31 Bertram when you pull out the gas power and replace with diesels to give equal speeds it is very hard in the time you own it to make the investment worth while unless you run a charter operation with near dialy useage.

Baywatch - how many hours a year do you put on your boat running at 45-65 mph, not total but at those speeds?

Habana Joe,

Thanks for the clarification on your point. I was not trying to stir anything up and you can probably tell by my membership time and number of posts that I do not poke my nose into a lot stuff on here, especially like some of our northern brethren (i.e. MarylandMark, Masher44). The point I was trying to make was simply that if I had an option of spending an extra $10-$15 grand to get a marine conversion Duramax/outdrive set up that will give me 50% or more longevity between rebuilds and have the same performance it makes sense to me. The reduced fuel consumption would be the icing on the cake and not the reason for the exercise.

The big issue as I see it now with a marine version of the Duramax, Cummings or Powerchoke is trying to developing a transmission or gearbox that will increase the prop speed to those comparable to a gas motor, which would let the diesel operate at RPM levels that will allow it to be throttled and live for a long time. Anyone who has had one of these diesel motors knows they will not live for long at 5000+ RPM regardless of what you have done to the internals.

Hopefully someone will figure it all out and there will in turn be enough demand to make it a cost effective option.

I didn't think you were stirring the pot, no problem. If you go to the other diesel thread in general here you will see I posted 5 pages from 1990 about a project of ours.

We own the gear box, patents, prototypes etc. They are still sitting in our factory in IND. collecting dust, they never went into production so they are machines housings (very expensive), hand cut gears, etc

I think I know where you are going with this. Last season I put right at 100hrs on the boat total so I would guesstimate that actuall hours running between those numbers was more like 55-60hrs. In my part of the world you spend a lot of time idling in and out of no wakes. On the fuel savings alone it would probably take me something like 100yrs of use to make it worth the expense.

I eventually want to create a performance vessel for doing journey's like the great loop and trips through the caribbean. It is many years out but I dream of having a diesel powered sport boat that I can actually travel on not just runs to lunch or the beach on the weekend. With my current set up my cruising range is 250miles @ best.

Thanks

baywatch - what kind of drives are on your boat? Also, about how much room in the front of your engines to the bulkhead?

You have no problem running the diesels in that Apache and getting 70 mph with a 50-55 mph cruise.

Let me see if we can play on paper with using your Apache.

Before, anyone says anything, I'm partial to the Cummins product for many reasons - some of them are:
- more Cummins dealers worldwide than any other engine,
- more marine dealers (diesel) than anyone else
- common engine that is used globally in trucks, buses, equipment & boats
- coupled with Mercruiser their reach is even now greater
- greatest amount of over the counter hot rod parts

No, I'm not a dealer and you all know I don't work for Cummins either - I base my opions on years of experience with diesels and the marine markets for little hi-po diesel engines.

Gotta ask this question.

Exactly how many miles, this is a truck engine after all, do people get on their GM truck with a Duramax before it needs a rebuild? Street driving, towing, personal use or commercial?

With this we can start to paint a picture of the life expectancy of this engine in a boat as it is not a stock Duramax when it goes into the boat and it is not seeing the same load conditions as it does in a truck.

It is not uncommon to get 250-300K miles on a gas engine in a truck now days with no major problems so I am curious as to what more we can expect from an automotive diesel.

RIK,

I understand where you going, this is my input.

Case in point, in my 2006 Ford diesel p/u (stock) I can cruise down the road at 70 mph and the boost gauge is reading maybe 12-14. I hit a good hill and maybe make 22 and still run 70 mph. When I trailer my boat which is 14-15,000lbs loaded at 70 mph the gauge reads over 20, hit a hill and try to keep going 70 and the gauge is pinned and I can't make 70.

The engine will go over 200,000 miles without taking the valve covers off and that is with 20,000 mile oil changes.

If you look at % of time where the engine is at 80% load is probaly less than 5% of overall engine hours.

Now put that same engine is an Navistar straight truck where it is working at 50% load for 50% of the time (this engine is also much less HP than a Ford) and you won't go 150,000 without some problems.

To go further with that, when you try to figure hours to miles a regional use truck is usally at 33 miles to 1 operating hour.

That means the Navisar truck engine went 4,500 hours at reduced HP and at only 50% hp for 50% of the time.

Now take take engine to 3 times the HP, turn it faster, have irregular cooling (if seawater cooled) and run at 80% load or greater at 80% of the time and you see why things BLOW UP!

I have bravos for drives and without gettin in the boat I would guess that I have about 6-8" to the bulk head. I'll attach a pic but it doesn' really do a good job at showing the space in the front between the pully's and and the bulkhead. Boat weighs right about 10,000 with the bravos and very light fuel.

I'm interested to hear your thoughts.

I was hoping you had #3's, that would be easy and the engine bay might have been longer? I can tell from the picture it is tight.

When the weather warms up can you check if you have 55"-60" from where the bellhousing attaches to the drive to the front bulkhead?

Also, what are the drives centered on - 34"?

I'll have to look when it warms up. I should have 55" not sure about a full 60."
I was thinking mabye B-max drives as an alternative to the ASD's? I have seen a few sonics with b-max's hooked to yanmars, but not sure how trouble free they were.

I will take better pics and measure once it warms up.

What about the Arneson/Bravo conversion kit? The rear of your engine would stay in the same spot.

baywatch & Payton,

The reason I ask is simple, baywatch is you are serious about converting to diesel in the future I made want to help you. If you read my notes (5 pages) on the other diesel thread here you see I make refernce to a gear box. I might be willing to dust that off and make you a set of those so you can run your same bravo drives.

This is not a tomorrow thing, I need to rework the design a little, build a proto and slap it on a genset for 1,500 hrs.

Now Konrads or Arnesons??? Depends on what you want to do.

I don't know what ratios Konrads come in but here is where RIK and myself disagree. I will give him credit that his turn a big wheel slower advise is good for 99% of the boats out there. It's the little 1% of the world that I have spent years playing in.

In my experience running the diesels in open water where you had to actually throttle a boat (not just cut the engines back) when we tried big wheels, the second you move that throttle back and props loose a little bite the diesels loose boost. With the big wheels you just can't accelerate the engines quick enough to get that back and boat just flops rather than fly like a gas boat.

The bigger reduction gear also works in reverse now because of the prop drag and further holds the engine back. Here's an example when you push start a car do you use first gear or high gear? You use high gear which is less reduction, the same with a prop, the water grabs it like push starting a car in 1st gear.

Again, if you are just crusing, high speed running on the smaller lakes, bays, etc. That big prop provides good top speed, great cruise speed and great economy - RIK is right.

Run the boat from Sandy Hook to AC with a 20 knot South and wind and you'll suck wind!!

Again, my opinion alone.

Propeller RPM is dependant upon application. Displacement and application determine rpm.

Slower is more efficient is an argument the cruisers all rave about, but at the same time a fat boat will not get on plane or stay on plane with a shallow ratio.

There are trade offs to each.

RIK,

If you were to do his 36 Apache and convert it to Arneson's and let's say I gave you 425 Hp (crank) at 3,000 rpm's - how would you set-up the boat? You have many more applications to draw from than me and you never know I just be a customer again sometime soon?

The boxes I talk about were a means to an end, can't sell engines if people needed to rework the whole boat and I assume your bravo conversions were designed for that same reason to sell more drives.

FYI - I will more than likely challenge what you post as a response to this simply because I want to debate this application and see where it goes. On a personal level I would love to see more people with diesels and maybe your drives (LOL), I think a good airing could help that?

Joe Gere

[QUOTE=HabanaJoe;2437536]In my experience running the diesels in open water where you had to actually throttle a boat (not just cut the engines back) when we tried big wheels, the second you move that throttle back and props loose a little bite the diesels loose boost. With the big wheels you just can't accelerate the engines quick enough to get that back and boat just flops rather than fly like a gas boat.QUOTE]

That is an excellent point, as soon as you get off the gas under load in a diesel, you loose boost and it falls flat on its face. Seems you have to slowly load the engine to get it into high boost under load. I noticed that in my friends Ford F250 Powerstroke pulling a boat over the pass. It was perfectly happy pulling over the pass at over 70 mph. As soon as someone pulled in front of us, he had to let off on the gas. The trans downshifted and it took a while to load it up again in high gear to get back to speed.

Do the new diesels have blow off valves like the newer gas turbos? The blow off valve would allow the turbo to stay spinning when the throttle is chopped for a breif time (this keeps the turbo spinning while shifting gears). As soon as the throttle is re-opened the blowoff valve closes and it is right back to boost.

Anyone know an approximate price on a 400hp Duramax ready to drop in?

Propster,

There are two type of valves that I think are similar to your description (these are their high level functions):

Pop-off valve - This in on the intake side, when boost pressure is too high it will allow the engine to relieve some pressure as to not make to much horsepower.

Waste-gate - Exhaust side, when using a small turbo you can actually have exhaust pressure that exceeds intake pressure, when that happens engine can't breath anymore and power goes flat. It lets the engine loose some of that pressure.

Neither of these devices helps keep the turbo spooled up as far as I know? With a waste gate as soon as you lift off the throttle the exhaust pressure and temp drop and the waste gate closes. In theory I guess with a small enough turbo you could keep enough flow to keep it spooled up?

Key things:

36' OAL

10K Displacement

Non Step Bottom

Goal top speed

Use a 1.13:1 reduction ratio. Use a Hering 18.25 X 31 5 blade propeller.

Should reach 66-67 ish.

His goal of twin 480's would reach 72-74

RIK,

You my friend are good, yes you are, you have a gift!

Name the the movie and I'll send you a shirt!

I think it will go a little faster, a little under proped, I think you could 72-75 from it, with 425's.

Why such big dia. and not OD?

Would have to know more details about its current performance in order to get an accurate synopsis.

Don't think 10K lb will want to stay on plane well with od and small diameter with only what, 33' bottom??. It would want to fall off real fast below 30 mph and not make a happy boater.

Would need a 7 blade propeller and we are starting to reach for special things in order to make things work on that path and then who can afford the special things?

Vicarious learning:

388 Slingshot has let's say a 34' lwl? Beam 8.5' and with a pair of 440's with a displacement of 9,000 lbs will reach 84-85ish.

Stepped bottom and for the most part an pretty efficient bottom.

Example #2

37' OL with twin 420's cat's with a displacement of 10,000 lbs and a beam of 8.5' will reach 74-75 max.

Once again a somewhat efficient bottom.

Now, take a non stepped, and somewhat not known as an efficient bottom, add weight and the results will be lesser.

Ok, but first what movie is the line from?????

7 blades - extreme!

I agree with the fall of plane theroy but why is he able with the Bravo drives to stay on plane? I'm guessing the props are small and with the hubs the blade area is not much and they are probably 4 blades?

baywatch - tell us about what the boat does now, how much HP, what size props, at what rpm can you stay on plane down to?

The blow off valve would be on the intake side between the compressor side of the turbo and the throttle plates.

On a gas engine, the throttle plates are downstream of the turbo compressor. When the turbo is spooled up and the throttle is suddenly closed (like when you shift the gears), the compressor hits a wall at the same time the hot side is not getting a lot of pressure, effectively slowing the turbo quickly.

The blowoff valve opens when you let off on the gas and vents the pressure to the upstream side of the compressor or to the atmosphere. It would keep the turbo spooled up between shifts.

Not sure if diesels use a blow off valve, but it would work real good on a performance boat that would see airtime or in a truck with a manual trans. It would not be a big benefit in a truck with an auto shift (turbo stays in boost between shifts) or in a boat that never needs to be throttled quickly.

You two definately know your stuff. You have pretty much pegged perfomance numbers and props without me giving you the info.

First let me state that I truely don't plan to do anything along these lines for several years (realistically I would say 4-5 years out). The curreny power only has 250 hrs and that is after I put 100hrs on last season. I plan to use it and enjoy until the current power gets tired and I am hoping technology continues to gravitate towards the diesel option. I do appreciate your input as far as determining if what I want to do is attainable and what sort of a price tag the project would have on it. I certainly don't want anyone to put too much time into the numbers expecting me to do something in the next 12 months. Joe, regardless of where this thread goes, I will definately contact you personally when I am ready to pull the trigger on the project.

As far as numbers are concerned minimum planing speed without tab input is right about 2400rpms depending on air temperature (rpms run about 100 higher if it is cool and dry). Speed at that RPM is right about 31 mph on a hand held gps. I am running stock 502 mag mpi's that currently have 250hrs. They are supposed to be 415 hp at the prop and I am currently spinning non labbed 4 blade 24 pitch bravo 1's. Regular bravo 1's with 1:5 ratio.

The best I have seen for top end was 67.1mph on a handheld gps at 4980 Rpms. That was light on fuel (200 gallon tank) with me, my wife and our two year old. Temp was in the mid 60's with slight wind chop. It will do 65mph any day but I rarely run it above 60mph. With a small child it is sort of like having a caddy that will cruise beautifully through the snottiest water at 45-55mph all day long.

Most of our running is between 3,000 and 4,000 rpms which at 3,000 rpms is about 38 mph and 4,000 is closer to 55mph if neutral on tabs with slight trim.

Hopefully this helps and I appreciate the info on what is possible with the old resin bucket.

Thanks,

Josh

So, after we look at what your boat does speed wise, it all comes right back to same thing. RIK blindly came up with a speed based on diesel Hp and helped to support the theory - Hp is Hp whether it is diesel or gas, it takes X Hp to go Y mph and it doesn't matter what drives it - I've said that before.

RIK, here is where I always have a problem. Take Josh's boat and at 2,400 rpm he has a 1,600 rpm prop speed to give him 31mph. My thinking and testing (years ago and engines & props have changed since), says to me if I over-drive 15% (.85) and run the engine at 1360 rpm with that small prop, I should be able to duplicate his same speeds and be on plane(providing weight doesn't play a big factor)? I think then when I get running faster I have a larger power band on my engines compared to prop rpm because of the OD.

When I would run reduction every little change in engine rpm is magnified at prop speed.

So, I would want to vary more prop speed with less engine rpm's because I have an engine with less rpm's to work with???

6, 1/2 dozen or the other as they say I guess.

propster - I hear what your saying but, diesels don't have a throttle plate in them. Blowoff, popoff etc, all the same thing, I think you'll find they are more to prevent compressor stall which is the turbo is still making boost and there is no where for it to go. The compressor starts to shutter and make fluttering sounds which will damage it over time. They vent the pressure to prevent damage but that actually has no bearing on spooling back up. Most all gas engines run very small diameter turbo's so they spool up with very little exhaust pressure. The waste-gate let's that excess pressure escape so even when you lift off the throttle for that split second you still have ample heat and pressure left to keep it turning. Your absolutly right the throttle closing will back up boost and they relieve it for damage control.

Also consider when your boat is flying in the air your off the throttle for many more times the duration than you are during the quick shift of a gear.

Hey, I wasn't that blind when I pulled the numbers. I even got the plainning speed.:D

The od will put less torque to the water than the ud and this is where things will not start to go bad.

The boat is heavy, narrow with a high deadrise and the hp is low, reducing torque compounds the problem.

RIK, I meant that as a compliment meaning you didn't know what he had and when he said what he had it just worked out to be close to the same diesel hp and speed.

I gave you a BRAVO (not the drive)LOL

agreed:D

Habana Joe,

The movie was "Analyze This." Too easy.

Beyond that, I have nothing that could be mistaken for intelligent to add to this excellent conversation.

100 plus

Go to my site pick out a tee shirt send me a pm witn style, size & address Happy Valentines Day!

Saw the diesel Nordic in the lobby of the L.A. Boat Show. This engine has a ways to go before it is "commercial". The exhaust manifolds and crossover pipe looked like the truck parts, with just a loose heat shield over them. There was an aftermarket engine controller, water to air intercooler, but otherwise the engine looked pretty much like the truck engine. Before they could put it on the market, they would also have to pass EPA emission tests.

Michael