How many engines is ideal?

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Think Steve’s contribution covers it.
My thinking about boating divides any transit into the following.
Inside range of a tow service.
Inside helicopter SAR range (roughly 200nm from CG point of origin).
Outside both.
Think these three divisions determines engine number and need for get home system.
Inside range of a tow service think as long as you’ve kept up with maintenance risks of failure is so low as expense and additional maintenance of a get home is unnecessary.
Think outside range of tow service either twins or a get home may be wise but open running gear acceptable.
Think outside range of both you’d better have a full blown “belt and suspenders “ set up. Separate props and running gear. Separate fuel supply. Primary (or both) prop protected by keel. Spurs or other line cutter. Emergency steering.
We have always carried spare pumps for all key systems, many spare filters, redundant nav sources with independent electrical supply, spare belts, injectors, hoses, alternator, fluids and other mission critical spares. Do this as listen to fellow cruisers. Often the engine(s) are fine as is the running gear. Rather it’s the accessories that fail. The old saying “if you didn’t bring it with you-you don’t have it” is all too true.
 
Wifey B: We're going to see more engines/motors and not just for speed. Think ahead to hybrid or go to Greenline today. For business, we're buying Honda Accord Hybrids so now even cars have more than one. It's got two electric and one gas.:)
 
Hippocampus said:
Think outside range of both you’d better have a full blown “belt and suspenders “ set up. Separate props and running gear. Separate fuel supply. Primary (or both) prop protected by keel. Spurs or other line cutter.
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Not sure I agree completely about the get-home engine idea.

True redundancy would mean you’re emergency propulsion would NOT rely on diesel. So that leaves sail. For the majority of trawlers, which don’t have huge masts of motorsailer proportions, there have got to be ways of rigging a sail or parachute of sorts. A system that yields 2 knots downwind is better than sitting idly bye bye.
 
Our single engine trawler has a utility ketch rig designed for stabilization and as an independent get home option. Still, I’ve been curious about some of the AC or DC sail drives driven off the generator or generator/batteries as a get home option giving us a belt, suspenders and coveralls.

That said I’ll never forget Richard Bost telling me, if you lose your engine but you have enough food and can make or catch water you can wait until the prevailing currents and winds get you “home”...it just won’t be your home. [emoji4]
 
Most passagemaking single screws with a get home have a separate fuel tank for the get home Mako. From the nordhavn 40 on up until you get to the the huge ones with twins the fuel for the get home is a separate gravity fed tank. You do need to replenish that tank if going a long way via a transfer pump but before entering the get home tank it’s polished. Bad fuel even if all tanks are contaminated isn’t an issue. Down side of this set up is periodically you need to polish that get home fuel tank. Usually people drain that tank into the main tank(s) and just refill it. That way fuel in that tank is always fresh and clean. Like with everything on a boat if not used gremlins set in. So people will run the get home before leaving and before entering a harbor.
People forget most blue water vessel have SSB and/or satphones. As long as you’ve

Kept the water out
Kept the crew in

You can yell for help.


Fortitude looks real sweet. Did you add the rig?
 
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For a new build redundancy can be obtained ,although a proper sump in the fuel tank can solve almost problems , short of running dry.

For an existing boat dirty fuel would still be the mot common failure, the simplest solution might be two fuel centrifuges in the supply system..One is spare.

Yes, gravity feed is your friend , and still not taxed.
 
I guess that all depends on how good a mechanic and boat handler you are?
 
The Lugger on my Nordhavn46 was really basic, natural aspirated, dry stack/keel cooler, nothing on the engine or controls were electronic. Ran WOT for days, only shut down to check the oil.
Soooo, all you really need is one reliable engine.
 
OldDan1943 said:
The Lugger on my Nordhavn46 was really basic, natural aspirated, dry stack/keel cooler, nothing on the engine or controls were electronic. Ran WOT for days, only shut down to check the oil.
Soooo, all you really need is one reliable engine.
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Until!
 
Art said:
Until!
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Was still running perfectly when the boat yard's ape pull a stand out before putting in another stand allowing the boat to fall over, generating a rather large hole in the port side.
 
OldDan1943 said:
Was still running perfectly when the boat yard's ape pull a stand out before putting in another stand allowing the boat to fall over, generating a rather large hole in the port side.
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Bummer... Hope ins panned out!
 
Well I am sticking with my single engine Nordic Tug.... I do have a respectable sized tender AND a good sea anchor. My cruising grounds are the Inside Passage - Seattle to Alaska.

However, I was curious about “emergency steering:” how do you rig that up? I am not sure how that would work on my Nordic....
 
Sticking with my Cummins single as well. I have an emergency tiller that mounts through a panel on the swim platform.
 
jimdavi said:
Sticking with my Cummins single as well. I have an emergency tiller that mounts through a panel on the swim platform.
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SMILE
We spend a lot of time worrying about and planning for things that will happen.
 
" Ran WOT for days, only shut down to check the oil."

WOT for days ??? , sounds like the designer screwed up !

Sure an industrial rated engine run at its 24/7 rating can take the use but its rare that WOT is cruise speed.
 
FF said:
" Ran WOT for days, only shut down to check the oil."

WOT for days ??? , sounds like the designer screwed up !

Sure an industrial rated engine run at its 24/7 rating can take the use but its rare that WOT is cruise speed.
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LOL was a Nordhavn 46. The engine size was perfect. Lugger.
 
The ideal number is ONE!!

Plus one on the genny

pete
 
The MOST common failure requiring outside assistance on blue water recreational craft is steering. Causes are myriad. Hit a wave and fallback. Debris. Failure due to poor engineering. Failure due to being over stressed from continuous use. For most set ups be they balanced spade or transom hung, or skeg hung or hung on trailing edge of keel they will fail if the boat slides backward fast enough. Nearly all ocean races require some form of ancillary steering. Cruising sailboats commonly use their Hydrovane or Monitor wind vanes to totally bypass all components of the main steering. Faster boats have a gudgeon and pinion system pre fabricated they can deploy if need arises. Solid direct rod linkages are preferred for main steering rather than wire or hydraulics. We had four ways to steer. Direct rod linkage for main. AP on separate arm, emergency tiller direct to rudder post, and Hydrovane.
We will outfit next boat (trawler) with two independent APs and it will of course come with hydraulic steering and a emergency tiller. Most people have modified their survival weather techniques to use Jordan Series drogues rather than sea anchors to decrease risk of steering failure.

Would note my friend Mike Keyworth proved you can steer most any craft using drogue(s). Either a single one on a bridle or two if you have a way to vary the amount of pull between your two stern cleats.
 
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What I’m getting out of ‘this thread, past teaching and experience is:
Ideally you should have two totally independent propulsion systems. Choices are:
Sail assist.
Twin engines with mechanism for independent clean fuel.
Main and get home.
Any engine system that doesn’t have independent running gear involves spending a lot of money and only addresses part of the risk. Given the reliability of a well maintained diesel not even the most likely risk.
 
Now that you mention the steering issue, twins are definitely better than a single + wing. With twins, you can maintain steerage at somewhat reduced speed, at least in decent conditions, as long as both engines are running, provided the steering has failed in something resembling a straight ahead position.
 
You also can with two long lines even if you don’t have a drogue. Tie in a bunch of knots and voila!! Warps. Vary the length of each and off you go without the weight, expense and complexity of two big engines. Will note the first few Artnautica 58 made in NZ were single screw. But the more recent ones made in the Netherlands are twins. However the twins are of very low HP. Little Yanmars , Betas and the like that you would see in a sailboat
 
Any thoughts on what’s the best prop to use for a wing? What’s the coating to prevent growth?

Back about 100 years ago commercial sail boats were being powered with engines as an afterthought.
These boats were heavy and the engine and prop were never on center line so had to be efficient at pushing.

The Paul Luke units have the blade area to do the job as wing propulsion.

The normal gen set would do a lousy job of powering as a get home since it would need to be too big for efficiency during most of its operational life.

By simply stealing the concept from the advanced gen sets like Honda this could be overcome.

Forget the 120/240v electric gen head and install a DC alt and an 4000w inverter , a pair if needed.

A std reduction gear could power the emergency propulsion , belts the front of the engine would power the DC alt, and perhaps hyd if needed.

This would allow the gen to operate at various RPM , when operating slowly the engine would be properly loaded to not begin to slobber, or destroy itself with low loading.

Remember proper loading is a RPM variant , so operating at 1200 and loaded to 80% of the proper HP load for 1200 will insure long life.

All the parts to build your own DC gen set are OTS, and some like a 300A 24V alt are available rebuilt , which would lower cost.

A similar DC alt powered from the main engine would give 120 or 240 while cruising.

Since the Luke prop is feathering, little would be lost in normal steaming .

Prop speed is a good anti fouling for a year or so.
 
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Hippocampus said:
You also can with two long lines even if you don’t have a drogue. Tie in a bunch of knots and voila!! Warps. Vary the length of each and off you go without the weight, expense and complexity of two big engines. Will note the first few Artnautica 58 made in NZ were single screw. But the more recent ones made in the Netherlands are twins. However the twins are of very low HP. Little Yanmars , Betas and the like that you would see in a sailboat
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First Artnautica 78 built in Antalya (Naval Yards) is a single, second is twin engine hybrid. Clients all want what they want I guess. :flowers:
 
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