The Offshore Voyaging Reference Site

New Engine, The Proof is in The Voyage

JHH5_102200As most of our regular readers know, we completed a 10,000 mile, eight month voyage to the Arctic and back on Morgan’s Cloud, our 56-foot McCurdy and Rhodes aluminum cutter in 2011. 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:


Login to continue reading (scroll down)

46 Comments
Oldest
Newest
Inline Feedbacks
View all comments
Dick Stevenson

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

Dick Stevenson

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

conny Harlin

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

RDE

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.

RDE

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.

Dick Stevenson

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

RDE

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.