As most of our regular readers know, we just completed a 10,000 mile, eight month voyage to the Arctic and back on Morgan’s Cloud, our 56-f00t McCurdy and Rhodes aluminum cutter. A voyage that constituted a gruelling test of all the gear on the boat. Here is our report on how the engine and drive-train did:
Perkins M92B Engine
In the Arctic, where it tends either to blow like hell or not at all, a reliable engine is vital. We repowered with a Perkins M92B a year before leaving on our Arctic voyage.
The Good
- The M92B has run reliably and smoothly for over 1000 hours.
- We had a small fuel leak from a return line fitting, and when I completely miss-diagnosed this trivial problem as something much more serious, the engineers at the Perkins factory in the UK were immediately responsive, knowledgeable and patient in supporting me.
- Our decision to change from a six cylinder 120 HP Cummins to the four cylinder, 86 HP, low revving (2400 RPM top end), high torque, industrial engine, has delivered even better fuel savings than we had hoped for: economical cruise in smooth water is an astounding 7 knots at 1.5 US gal (5.3 l)/hour and if we are in a hurry, 2.4 US gal (9 l)/hour yields a tad under 8 knots.
- The very high torque of this engine means that we don’t miss the extra 34 HP of the Cummins. In fact I can’t really detect a difference, even when manoeuvring in tight quarters in a strong wind, which is when we use the most power.
- The Perkins burns far cleaner than the old Cummins.
- The Perkins is very well laid out and easy to work on, with one exception.
- The shop, parts and operators manuals are very good, but see below.
- Parts are readily available from the US distributor, fairly priced, although not cheap, and can be sourced in a hurry, for a price, via FedEx.
- Carl, the parts manager at Perkins Power Northeast, is a great communicator and goes the extra mile.
- The power and torque of this engine match the boat perfectly. We cruise at 1500 to 2000 RPM, which is right in the sweet spot on the power curve, properly loading the engine, and still have plenty of grunt in reserve.
- The electric fuel lift pump, which we initially had reservations about, makes the engine a breeze to prime and incredibly tolerant of air in the fuel, as we found when our primary fuel filter started to suck air.
- Then engine just feels and sounds robust and commercial.
The Not So Good
- The engineer that decided to put the on-engine fuel filter behind the cooling piping should be condemned to change said filter once a day for the rest of his or her life. On the bright side, because we have a fuel polish system that in turn lets us use a very fine off-engine primary filter, we only need to change the on-engine filter once a year.
- The shop manual is for an industrial engine with an electronic injection pump, which is a very different engine, although based on the same block, as the M92B. There is an excellent user’s manual that does accurately match the marine engine, but even so, there is an information gap between the two that can be frustrating. Having said that, the great factory support from Perkins goes a long way to ameliorate this problem.
- We still don’t like the fact that the energise-to-run solenoid requires 24 volts on an otherwise 12 volt engine and therefore requires a 12 to 24 volt converter (supplied)—just an unnecessary complication.
- The heat exchanger is a bit small for the engine so that if it becomes even slightly dirty, on either the fresh or salt water side, the engine will run hot when being pushed over 2200 RPM. On the bright side, it is easy to clean.
- We have had to replace three formed hoses on the salt water side of the cooling system due to pin hole leaks. We suspect that this problem was caused by our engine being stored for two years before it was sold to us.
Verdict
The Perkins M92B is a great engine that we highly recommend without reservation.
ZF 45A Transmission
This is a commercial grade gear that is heavier and more robust than those found in most sailboats. We think it worth the extra expense and weight, particularly with the number of transmission horror stories we hear from other cruisers.
The Good
- The vertical offset allowed us to move the engine up higher than the old one which has improved access to both the engine and the bilge under it.
- Unlike many smaller and lighter transmissions, the ZF is fitted with an oil filter, which must be a good thing.
- We got the reduction ratio at 2.03:1 pretty much exactly right to optimise our fuel burn and still give us plenty of grunt in a tight spot.
- The transmission has worked flawlessly to date.
The Not So Good
- None of the fluids recommended in the manual are readily available in North America. I spent a good half day on a search to determine what the correct locally available ATF was.
Verdict
Highly recommended.
Aquadrive
The change to a four cylinder engine from the old six gave us room to install an Aquadrive system. Here again, we went up a size from that normally recommended for an 86 HP engine to a B10 21:210 axel with an upsized B20 CV 21 thrust bearing.
The Good
- The system transfers the thrust load from the propeller, normally absorbed by the engine mounts and transmission, to a thrust bearing that is bolted to a custom built heavily reinforced support plate that we welded into the hull.
- The transfer of thrust loads to the hull allowed us to use very soft mounts, also provided by Aquadrive, which significantly cut down on the noise and vibration from the hull.
- The axel allows the engine to be out of direct alignment with the shaft and this feature, together with the great job that Chris (welder) and Dave (machinist) at Billings Diesel and Marine, did modifying the beds, means that if we have to get the engine or transmission off the mounts for any reason, they can simply be bolted back into place without any alignment—how cool is that!
The Not So Good
- Although we have had no problems, the Aquadrive adds a whole lot more gear to the drive train that could fail.
- The unit must be sent back to the manufacturer for service every 3000 hours.
- I know of at least two Aquadrives that have come apart in service (very exciting) due to the bolts holding them together backing out. We have drilled and wired ours to ameliorate this risk.
The Verdict
Highly recommended.
Halyard Exhaust System
A disadvantage of center cockpit boats with engine rooms under the cockpit is that it is difficult to design a wet exhaust system exiting at the stern without causing too much back pressure, a sure engine killer.
When installing the Perkins we took the opportunity to take out our old metal dry exhaust system with wet jacket and install a Halyard water drop system consisting of a HFS-o40 separator and HTT120 silencer-water lift, customized for a 3-inch inlet and a 4-inch outlet. We also installed a water flow alarm and no return valve in the water drop exit.
The Good
- The exhaust back pressure measured at the engine is well within specification.
- Standing on the stern right next to the exhaust with the engine running, the loudest sound we hear is the engine room blower!
- There is a much lower risk of getting water back into the engine than with the old system.
- The system has worked flawlessly to date.
- The new system takes up less room in the lazeret and bilge than the old.
The Not So Good
- The system requires its own 2-inch through hull fitting and we hate adding additional holes in the hull.
- The new system takes up more room in the engine room than the old.
The Verdict
Highly Recommended
Coming Soon
This is the first of what will be an ongoing series of reports on how the gear on Morgan’s Cloud performed. We will tell all: the good, the not so good, and the bad. Thankfully, there was very little of the latter.
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{ 22 comments… read them below or add one }
John, What do you see as the advantages/disadvantages of a high torque/low revving engine? It sounds as if one of your reasons was for fuel savings which you are pleased to have accomplished. To what degree do you attribute the fuel savings to the low rev/hi torque engine vs the new engine just being 25% smaller? I am also interested by what you mean when you describe the Perkins as an “industrial” engine? Thanks, Dick Stevenson, s/v Alchemy
Hi Dick,
The key to the fuel savings is, as I understand it (I’m not an engineer) the torque curve of these engines which matches the drag characteristics of displacement hulls better than that of higher revving lighter engines. More on that here and here. In addition a lower revving engine will generally, all other things being equal, be more efficient than a screamer. Here is a comment from Conny Harlin, who is head of the power-train division of a large engine maker (not Perkins) that explains more about this.
When I say “industrial engine” I referring the fact that the Perkins engines are based on engines designed for industrial use where they will be required to run at or near full load for their entire working lives driving something like a generator or big pump. Marine use, on a displacement boat with a properly sized gear and prop, is much more like industrial use than the intermittent use that many lighter high revving engines are designed for.
These industrial engines are designed to run at high load for at least 10,000 hours before replacement or rebuild, whereas many recreational high revving marine engines will be at the end of their lives in 2000 to 3000 hours.
Dear John, I would like to comment on your statement that parts are readily available by couriers like FedEx. Some parts of the world that may work well, but in many of the countries I have spent time, Customs waylays the delivery and puts complications/expenses in the mix that effectively undermines delivery. Many countries, even 1st world, the best advice, (as absurd as it sounds) for important items, is often to fly out yourself, get the part and return with it in luggage. “Yacht in Transit” usually makes no difference to officials as well. So couriers can and do get the part to the country with speed only to have actual delivery become infuriatingly elusive behind a web of rules, fees, forms and protocols, always in a different language, and usually in a different location from where you are. Dick Stevenson, s/v Alchemy
Hi Dick,
A really good point. What I was saying, not very clearly I might add, was that Perkins seem to be able to provide pretty much any part quickly via courier if the local distributor does not have it in stock. But, as you say, that does not solve the problem of uncooperative and even corrupt local customs officials in some countries. That is one of the reasons we carry a huge inventory of spare parts. But, when all else fails, going to get the part, as you suggest, may be the best option.
Nice to hear that you guys are happy with your “Perkins” with low rpm /high torque layout. You see what a change in fuel-consumption that makes….I would also like to add that a low rpm engine last longer before it’s time for overhaul due to wear of bearing,bushings,seals.
And the best is “No worries about Turbo”failures!!!
ZF is a German quality brand and have been around in the industry like Perkins.
I do like your engine room,,clean, organized,and a NO bilge “Crap” floating around.
I’m glad that you guys are happy with your investment of power ,,,,Conny, S/Y Crusader
Hi Conny,
Thanks very much for the kind words and good information of low revving engines and ZF.
(Conny knows what he is talking about because he is the head of the power-train division of a large manufacturing company–not Perkins/Cat, as well as a boat owner)
Hi John,
Your mention that your Perkins has a 24v energize-to-run solenoid switch certainly caught my attention! Let me describe the events of a delivery from hell, or more specifically from San Diego to Costa Rica. The boat was a 54′ sport fisherman powered two brand new MAN V-10′s. Upon arriving at the fuel dock in Cabo for our first 1200 gallon refill, we were unable to get the engines to restart. One engine would start, but as soon as you tried to restart the second the starter draw killed the first. The “yacht’s” tool kit consisted of a couple of rusty Craftsmen socket wrenches, and as it turned out the owner had run out on an outstanding bill in Cabo so no mechanic would touch it. Next morning everything was back to normal, so after scratching our heads we toddled on south. When we shut the engines down at our next stop we were again dead in the water. The background cause probably stemmed from needing to run the engines at too low a RPM for the regulator settings as we were trying to save fuel and make long runs. (the difference between 8 GPH and 80 GPH on a boat of this type is a mere twitch of the wrist!)
Here is the sequence of the problem: The engines will not run unless they are receiving the full 24 volts required to hold the fuel supply solenoids open. The boat had a generator that runs continuously producing 120v. This in turn was set up to charge the house 12 v battery bank through a charger unit and charge the 24v engine bank through a separate charger. Engine mounted alternators also charged the engine battery bank. There was no crossover switch between the house and the engine batteries, as this would have involved a voltage conversion.
In this set up either a deteriorated battery bank or regulator or 24 v charger failure creates a power boat with zero horsepower rather than 2400 hp! We finally ended up disconnecting the house bank, re-jumping it to produce 24 volts, jump starting the engines from it, and getting enough output from the alternators to bring the engine bank up to 24v.
The take away lesson:
If you have an energize to run propulsion engine system, you MUST have a back up energy source capable of independently producing the juice necessary to keep your engine running. If you depend upon an inverter I’d want two installed in parallel ready to switch on immediately, powered from two separate battery banks. If you are sailing to remote and challenging locations either install a generator as the independent energy source or choose an older engine design that can run independently of electricity.
Hi RDE,
Sounds like a horror story on a way too complicated boat!
While I wish that the Perkins had a energize to stop solenoid running on 12 volts, I don’t really feel that the way the Perkins is set up is that big a threat to reliability. We have a bunch of different ways to make or get 12 volts including the house bank, an independent engine battery, three separate chargers running off the generator and the generator start battery itself. Also if we did not have 12 volts the solenoid would be the least of our problems since we would not be able to turn the starter motor and start the engine–a limitation that applies to most engines out there since the demise of hand cranks. We do carry a spare 12 to 24 volt converter (and a spare solenoid), but I would not wire it in parallel since both the service unit and the spare could be damaged in, say, a lightning strike, and changing the unit is a matter of five minutes (two screws, one plug).
In summary, while I think Perkins made a design error in this area, few things are perfect and I don’t feel that it is a problem that disqualifies the engine.
Hi John,
Sounds like you have adequately thought thru the redundancy problem. Why am I not surprised!
One thing I did find surprising on the MAN installation was how little voltage drop from full charge was required to shut the solenoid.
Cheers,
Richard
ps; If you think the sport fisherman was overly complicated you’d love the 112′ Sparkman & Stephens twin engined, active stabilized, triple gen set sailboat I once managed the build for! In fact all boats that try to become floating houses are too complicated, with the possible exception of Steve Davis ‘s designs.
Dear John,
Thanks for the clarifications which, for me, inexorably leads to more questions. Beta and Nanni engines are based on Kubota blocks, some Westerbeke on Mitsubishi blocks. Would you consider them “industrial” engines? The only “built for marine use from scratch” engine that I am aware of is Yanmar (unsure about Volvo, Vetus etc.).
I could see a high revving engine only getting 2-3000 hrs on a boat where there is only 50-150 hrs a year on the clock. Many (or most) sailboats likely fall into this category and they would likely figure they got their money’s worth at 20 to 30 years of use. Those of us who live aboard and go significant distances often clock up 500 and more in hrs. per year. Many (again likely most) have higher revving engines and I do not know any of my cruising friends who believe they will get so few hours out of their engines.
As for fuel economy, I would be very curious as to the actual figures comparing a well set up high revving engine and well set up low revving engine. I suspect it is not all that great for the average displacement sailboat. A conundrum is the fact that basically, lower speeds save fuel dramatically (as measured miles per gal.), but the engine “likes” higher speeds. (My Westerbeke 42B uses approx 0.55 gph to push me 5.0 knots and 0.95 gph gets me 6.0 knots—4500 hrs on eng). I almost never go optimal speed/rpm for the engine (70-80 % of power available if memory serves which would push me approx 6.6 knots) as the fuel usage just shoots up off the charts (mpg drops comenserately). I am not sure how to get around this we all want “reserve” power for emergencies and those times when it is important to pound our way up-current, up-wind and up-swell/wave.
Thanks as always for your thoughts, Dick
I’m really not enough of an expert to get into this level of detail with any authority. But I think the key issue here is just the one you identify: With a high revving engine it is very difficult to load it properly in a sailboat and still have enough power for all conditions. The result is the insanity we often see with say a 75 HP 3600 RPM engine in a 45 foot boat where no more than 40 HP at about 2400 RPM will every be used and the same boat would do a lot better with a 40 HP low revving high torque engine, assuming you could find such a thing these days. (My first draft suggested a Beta, but then I found that their 38 HP revved at 3600 RPM–woops.)
I guess the real bottom line for me is how many commercial vessels or industrial generators do you see driven by high revving screamers? Precious few. In fact Yanmar themselves will not even sell an engine to a commercial lobster boat in Maine. So, yes the weekend sailor that does 150 hours a year will be fine with a screamer, but those of us that put commercial equivalent numbers of hours on our engines might be better served to consider the engines that the pros use.
As for fuel efficiency comparison of two well set up engines, one a screamer the other high torque, I guess I would just defer to Conny Harlin on that one (see the link on my last post).
The bottom line for us is that the Perkins has given us really good fuel consumption at low revs (we can go down to less than a gallon a hour at 6 knots if we must) but will still push MC into a 25 knot breeze with a big chop, it just works for us, and way better than the higher revving Cummins ever did.
Hi John,
I’ve often seen identical block marine engines (including Yanmars) with two different power ratings and service recommendations available from the factory. Often the only difference is the governor settings for RPM, and perhaps the injector pump delivery mapping. So I’m not sure how much difference there really is between a “low speed” and a “high speed” engine in these smaller sizes.
That “yacht rated” 3600 rpm 75 hp engine you mention will in fact produce about 40hp at 2400 rpm. If it were coupled to a controllable pitch propeller like we sometimes use in large sailing vessels it might well run quite comfortably loaded up to work at 2400 rpm and last as long as the same engine rated at 40hp, assuming it has electronic sensor controlled fuel mapping. In order to use the available 75 hp. you need a way to change the propeller loading on the fly.
Choosing a broad torque curve and a simple, non-turbo design like the Perkins gives a long engine life and the widest usable power band that can be absorbed by a fixed pitch prop, even though it might theoretically be outperformed by the set-up I just described.
Hi RDE,
Great comment, as you say that’s the bottom line. Sure there are other ways to deal with the intrinsic inefficiency of many sailboat power trains–variable pitch props, diesel electric (in theory)–but a low revving engine with a flat torque curve like the Perkins is the simplest and least expensive. And it has the added advantage that low revving engines, all other things being equal, last longer too.
John,
I seem to recall that you changed your prop pitch with the new engine installation. Couldn’t some of the fuel economy and performance be attributed to that change?
Keith
S/V Pearl
Hi Keith,
As it happens, we did not change the pitch at all. But that is simply coincidence because the new engine was smaller, but the transmission has a slightly higher reduction. See this post for more on how prop pitch affects fuel economy.
I’ve done a couple of AquaDrive installations but have no long term experience with them. What is your bottom line conclusion? Is the cost justified?
Hi Richard,
I think it depends on the number of hours you do a year. For us, it is well worth it since it enables us to get less vibration and noise with a four cylinder, that is intrinsically unbalanced, than we did with our old six, which is intrinsically balanced and therefore smoother.
Also, I believe it will make the mounts and transmission last longer without service, which will help to offset the cost.
I guess if pressed for a rule of thumb, I would say more than 500 hours a year, its worth it, less than that, not.
Hi John, have had a Perkins like yours in a sail boat. The engine crashed after 12 000 hours by accident. I think they last about 22 000 h i fishingboats before main service. Clean dieseloil without water is important to make them run long and fuel polishing is good.
I put in a Yanmar with a ZF and Aqua drive. The Yanmar is still ok and I hope it will last til 22 ooo hours. The ZF broke down in The Arctric with no wind. A friendly fisherman told me that I used the wrong oil and gave me 5 gallons of SAE 30 single grade oil. ZF told me not to use it but I tried and has now made 8 000 hours on the wrong oil.
Aqua drive needs good alignment! The two shafts can be on different levels, but they must be paralell. It is a common mistake to beleave that they can absorbe everything. I make the alignment at normal speed with warm engine, ca 2000 rpm, off shore. Alingnment can not be done in harbour or ashore. To do this you need laser tools. Fixtur laser has the best tools, but there are many options. My aquadrive has lifetime of 100 000 hours. I was first offered the 3000 h, but denied, got 30 000 h offer, but choose 100 000h. It has now made 20 000 hour without service. It is bigger than yours, but the price is almost the same.
Your shaft seems to small, the bedding to light and the gearbox must be fixed. The bedding should be stiff also sideways, bed weight the same as the engine, but better two times the engine. Then it is quiet. If you have rubber moutings, get them as stiff as possible, but better is to leave the engine direct on the bedding.
In my motorboat the engine runs at 300 rpm and use 150 grams diesel oil pr. hour pr. HP. That is 40% less than your Perkins. It has has no gearbox, the ZF takes about 20% of your energi production. It has now passed 120 000 hours and is expected to do 200 000h before next service. I always heat the engine before start and start the lubrication oil pump before start. So when I start the engine is warm with 3 bar oil pressure. That makes the engine last.
Hi Svein,
All very interesting. I guess we have different goals: To us the whole point of going with the Aquadrive, which was installed in strict accordance with their instructions using a custom made alignment tool, was to use soft mounts so that we could cut down on noise and vibration.
Yours, sounds like a full on commercial installation, which while great for your needs, may not be practical or cost effective in a sailboat. For example, although a 100,000hr life is impressive, we have only run our engine for 12,000 hr in 26 years (including previous owner). Therefor 100,000hr would take…a couple of hundred years–you get the point. And we probably use more engine time than most sailboats. So, like in all things, our engine is a compromise. We have designed and sized the engine installation for our intended mission and acceptable maintainability at a cost level we can live with.
Hi John, i do not expect to do the 100 000 h, I want the safety of it. The cost is almost the same. If you go to Svalbard, there is no boatyard.
The modern theories of rotating shafts are not well known. But all Nato-ships are very quiet, mostly the subs. When Kongsberg Weapon and Thoshiba published how to make a quiet propeller, all the Nato gouvernmets were angry. Norway had to send the spyship Marjata to the Murmansk fiord to observe the new russian quiet subs. This is why theories of rotation shafts are not known to you and your boatyard. But they are simple and not costly to follow and you can improve your boat a lot. It is the theory of the stright line. Easy physics for an old sailor used to the same maths with his sextant. If you know sinus and tangens, you can do the theoretical part of it.
Sweden is outside Nato and the swedish company Fixturlaser has published how to get a quiet engine and shaft. Some of those principels I have mentioned above. I understand that you do not want to take out your Perkins and do your istallation proper. We call that a comprimis. What risks do you take sailing your way: water leaks in the through hull fittings, oil leak in the gearbox, oil leaks between gearbox and engine, and bearings in the aqua drive break down. But with a good sailboat that is not important to many.
I have with a friend adjusted many sailboat engines like yours without doing any rebuilding. We use laser tools offshore. We try to find the best possible solution of the problem within the ecsisting frames. Often we just do small adjustments like lifting the front end of the engine something like 2mm. The normal result is: 30% noice and vibration reduction, 10 -20% reduction in oil consumption. Lifetime of the bearings increased almost to the normal 30 years. If you say you dont like the cost of this, I will do it for free to you in Norway.
Aquadrive is an offspinn from the car industry. Car parts are much cheaper than marine parts. I buy aquadrive parts by Kardang aksel in Oslo to a fair price. You do not have to pay much for that stuff.
Hi John, Morgan’s Cloud and crew are very much welcome back to Norway. You just have to cross the fiord. We will fix some laser sensors to your shaft, gearbox and Perkins and then sail off until the engineroom has the normal temperature. Then we do the alignment. We work mostly on The West Coast. The oil industry (drilling platforms, work boats) has lots of rotating shafts with lots of power and speed. They need perfect alignment. Here it is not a question of noise, but to prevent brake downs. Stops are costly.
Last week I was sailing in the Skagerak and reading 3 different pilot books of Norway. I have now ordered yours and will bring it with me on a two week trip in The Barensts Sea, starting next week. I look forward to that.
Best regards and fair winds to you.
Hi Svein,
All interesting stuff, particularly aligning an engine with a laser. I have always felt that there had to be a better way that feeler gauges.
Maybe we will take you up on it when next in Oslo. We love free!