Twin Diesels versus single

[Dnnsmrgn]

How many out here in Trawler Land ,have used single engines ? I know everyone is going to say two for redundancy in the middle of the ocean. However I would like to know if there are any brave and adventurous souls that have done it. I will be going from South Carolina to Bahamas and further parts south. Please feel free to unload on me .

 

[RT Firefly]

Greetings,
Welcome aboard. MY opinion only! Never worried about the redundancy with twins. I don't recall ever having to run on one engine. I was more concerned about maneuvering. 1 or 2 is a recurring question and I'm sure there is more than one thread on this topic.

 

[mvweebles]

Our Willard 36 displacement trawler is powered by a single Perkins 75hp diesel. We left Ensenada MX (just south of San Diego) last October 30th and spent the next 5-1/2 months or so heading south. Weebles is currently taking a breather on the hard in Chiapas MX, near the border with Guatemala - over 2200 nms. For much of the trip, we were in the company of Muirgen, a 50-foot trawler with a single engine. Muirgen decided to sprint ahead and continued to Florida in March. She started in PNW so has close to 6000 nms under her keel on this adventure. We'll resume our journey this October with stops in El Salvador, Nicuragua and Panama before transiting the canal and eventually to Florida

Do I worry about having but one engine? I worry about a lot of things, and do worry mildy about a single engine. But in the end, it's been one of the most reliable systems on Weebles. Just keeps ticking over.

I'd prefer some sort of redundancy but she's the boat I want to own in Florida, the new home of Weebles when we complete our trip in a year or so.

Best success in your deliberations. Best piece of advice I can give is it's not about the boat, it's about the adventure. Don't over think the boat.

Peter

 

[Flatswing]

Check with your insurance company. Some severely limit your cruising range with a single.

 

[Choices]

I have had both, but currently one. Sure makes working in the engine room easier with one. Traveling at trawler speeds there in no reason for two.

It is easier to dock with two, unless you have thrusters. That's the real ticket.

 

[AlaskaProf]

While I support the idea of enroute redundancy, I have never required it. But there is something supremely satisfying about maneuvering through confined spaces with both engines at idle and jockeying the shifters while watching the bow swing within inches of docks, pilings, etc. Even better in a crowded marina with spectators.

 

[Comodave]

Welcome aboard. I wouldn’t be that concerned about either. If you have a single then be even more religious about maintenance. I would be more concerned about overall condition of the boat. Then pick the one you like the best.

 

[tiltrider1]

Crossing oceans is about range not about how many engines you have. Nordhavn’s come with twins and singles. Both work when the appropriate engine is matched to the appropriate boat.

I would rather be on a well maintained single then poorly maintained twins.

 

[SteveK]

My sig line has the answer

 

[Lepke]

Before electronically controlled diesels, most commercial fishing boats were single screw. Now they're mostly twin screw.

 

[BruceK]

I`ve owned both and never had an engine failure, single or twin. But there is comfort in twins, and they are better for maneuvering, better even than single plus thrusters both ends, imo.
My understanding of single engine ocean crossers is they usually have a get home wing engine, often run for tight quarters and docking work etc (and for exercise), and which serves as backup for the main.
Single outboard powered offshore fishing boats here usually carry a smaller outboard, mounted ready, as a get home safety measure.
Twins or single + wing is my view.

 

[O C Diver]

Before electronically controlled diesels, most commercial fishing boats were single screw. Now they're mostly twin screw.

I traveled 39,000 miles 6,000 hours in 8 years with my single engine boat. Only engine issue that stopped me was a ECM (Electronic Control Module). Unfortunately the manufacturer (John Deere) requires the ECM to be programmed to the specific engine, after the old ECM has failed. Simply, you can't have a spare onboard as a replacement.

Because my cruising was coastal and inland USA and Canada, I would likely use the same engine again, but mount the ECM off the engine with a cooling fan. That option (wiring harness) is available now, but may not have been available for my engine.

Ted

 

[JoeCanuck]

My boat has two engines. However, I don't overestimate the redundancy provided by twin engines since, in my case, both engines share the same fuel tank. A meaningful proportion of engine problems while underway are generated by fuel/tank issues.

Twin engines with separate fuel tanks are obviously more redundant than twin engines sharing the same fuel tank.

My two cents.

 

[rslifkin]

My boat has two engines. However, I don't overestimate the redundancy provided by twin engines since, in my case, both engines share the same fuel tank. A meaningful proportion of engine problems while underway are generated by fuel/tank issues.

Twin engines with separate fuel tanks are obviously more redundant than twin engines sharing the same fuel tank.

My two cents.

And even with separate tanks, there are still failures where you won't be able to continue (such as fouling all of the running gear in a fishing net). Or if you do something that takes out running gear on one side and your steering. You'll have a usable engine remaining, but you won't be able to actually go anywhere.

 

[mvweebles]

Crossing oceans is about range not about how many engines you have. Nordhavn’s come with twins and singles. Both work when the appropriate engine is matched to the appropriate boat.

I would rather be on a well maintained single then poorly maintained twins.

Nordhavns and their brethren come with wing engines - arguably, a subset of a twin engine boat. When PAE/Nordhavn sponsored the rally to cross the Atlantic, it was open to all boats though one of the criteria was the boat had to be either a twin or have a wing engine. Although not explicitly stated, the OP seems to suggest he either has or is considering a single-engine trawler and wants to know if others have undertaken significant passages with single engine boats. His itinerary: South Caroline to Bahamas and beyond.

As a guy with a ton of miles on a single engine trawler, I can tell you there is a sizeable gap between the intellectual single-vs-twin debate - why an engine might fail, why it would be both instead of one, blah-blah-blah. Sort of a theoretical discussion with facts and numbers. As a cruiser with one engine, there is another side to the coin - an emotional reality of heading to somewhere where little assistance is available. Anyone who tells you there is no difference in the vulnerability between a single or a twin is either lying to you or to themself. You either wrap your head around it or you don't. The fault conditions that creep into the back of my mind are a high pressure fuel line cracking. Or a transmission failure. Or a pump shaft breaking causing engine overheat. The sorts of failures that rarely get discussed in single-vs-twin.

@Lepke - fishing boats have operators with a broad skill set and usually a comprehesive set of tools, including welders, bench vices, and other stuff to fabricate repairs.

I'm fine with cruising my single engine. But I'm not blind to the risks. Some are just the nature of cruising beyond boundaries of modern civilization, and I like having a single engine. But make no mistake - you do have to make peace with the single-point-of-failure.

Peter

 

[psneeld]

Have had both single and twin as liveaboard/cruisers.

Both had engine failures such as split high pressure fuel lines, fuel issue (both quality and supply issues), alternator bracket failure/belt breakage. No major issues as I had all running again in hours or could have if I had spares (which I did) except for a carbide drill to modify fix the bracket.

Each of my 3 liveaboards/cruisers were different enough that each was a huge learning curve about systems and handling. Looking back over those 45 years, I would say that many of the failures were preventable or fixable with a pretty small, but specific set of tools.

Commercially, had but just a few engine problems that were the accessory variety rather than the base engine in many, MANY thousands of hours.

Botom line.... I don't know what my next one would be.... the biggest difference is with the internal concern about engine failure (even by attached systems) at the wrong time. That problem came from many years of excellent training.

Any pilots here probably have heard the old jokes about helo pilots being paranoid compared to fixed wing pilots. I thought my fears would subside when the USCG went to a 2 engine helo and was a more modern aircraft. In reality, for several reasons, that engine was kind enough to just barely able to fly you to the scene of the crash.

All in all, I get to use my favorite expression..... single/versus twin? It depends. And when I say it depends...to me it depends on almost EVEY aspect of each boat, each skipper, the skill set aboard, the equipment/tools onboard, etc, etc.

Fortunately I will probably not buy another long distance cruiser, if I did, knowing enough makes the decision a very difficult one. The other common saying in boating besides "it depends" is" every boat is a compromise".

 

[SteveK]

The only difference between single and twins is operator personal preference.

 

[SailorGreg]

I flew single engine helicopters for twenty years. I have a twin engine boat by choice. Contrary to some of the anecdotes here, engines do quit. If you revel in the challenge of what to do when your single quits offshore, get a single. But if you loose sleep while obsessing over that same event, get a twin.

 

[psneeld]

I flew single engine helicopters for twenty years. I have a twin engine boat by choice. Contrary to some of the anecdotes here, engines do quit. If you revel in the challenge of what to do when your single quits offshore, get a single. But if you loose sleep while obsessing over that same event, get a twin.

 

[High Wire]

If you’re anxious about a single then just buy a boat with twins. I’ve owned both and prefer a single.

 

[dannc]

I have had both, but currently one. Sure makes working in the engine room easier with one. ...

Engine room access is important. Having an engine room large enough to easily work on two engines can be a problem. The same engine room with one engine can be workable but add a second engine and it can be difficult to access the engine and engine room.

 

[sean9c]

Check with your insurance company. Some severely limit your cruising range with a single.

Never heard of that one.

 

[Mac2]

Depends. I've had both. I like the protection of the single (protected prop and rudder) in the PNW. I did everything possible to protect my single. Installed fuel polishing system, oil polishing system, alarm on every part of the engine (raw water alarm, oil, exhaust temp alarm, etc.). If you're looking for a single with a get-home, I would get twins. Get-homes don't get used enough (folding props get fouled with growth etc), and often are under powered to actually move the boat in adverse conditions and twin engines are a built in extra parts shop.
I have twins now. Love the redundancy and maneuverability. For me it is much less stressful with twins (both running gear is protected)-that probably has more to do with my personality. The only thing I don't like is the fuel burn of twins.
So I would say it depends where you cruise, how mechanical you are, how close is help, etc.

 

[dannc]

This is not going to be helpful for must used boats but the new build we are considering can have twin, single, or a hybrid single engine. I supposed one could have a twin hybrid but that seems a bit too much. The single engine would be around 160 HP and the twins would be 85 HP. The boat can have almost 7 KW of solar panels but more can be added.

The engine room is tight but workable with one engine but twin engines would be difficult. I think one would have to have additional access from the cockpit to maintain engines. That access then has other issues.

In our case, using the boat in speed restricted waterways will happen, and running a "larger" single engine to go 4-6 knots is not going to load the engine. With twins, one would run only one engine when in a speed restricted waterway but even the "smaller" engine is just going to be loafing along at that the speed limit.

The solar panel power production and short 30-50 NM "passages" going around 5 knots make a hybrid an interesting solution. The hybrid is also a get home engine, though with reduced range and power, especially on a sea way. The other pro and con of the hybrid is it uses the same prop and prop shaft as the diesel. Flip a coin if that is good or bad.

It is a boat and full of compromises....

 

[Mako]

Unfortunately the manufacturer (John Deere) requires the ECM to be programmed to the specific engine, after the old ECM has failed. Simply, you can't have a spare onboard as a replacement.

Shame that Deere acts that way. When I was shopping I had this specific conversation with Agco Sisu who confirmed they would supply an entire electronics spare inventory, from sensors to pre-programmed ECM to the diagnostic computer.

It gets expensive though. Better to stick with a mechanical engine if possible.

 

[Captain_Michael]

When searching for a trawler to purchase, I read a good bit on the single vs. twin question. I do not plan to cross oceans, but I do plan on open water cruising which I define as up to 100-150 miles off shore and occasional overnighters. For that style, one can make an argument either way, and the comments submitted so far provide a good summary of the pro and con. At the time I was looking, there were not a lot of boats on the market, so insisting on either a single or twin was going to slow the process. After reading a good bit in greater detail, I decided to focus on the boat and its condition, and as long as the engine(s) had received good care and surveyed well, singe or twin would not matter.

 

[Max1]

How many out here in Trawler Land ,have used single engines ? I know everyone is going to say two for redundancy in the middle of the ocean. However I would like to know if there are any brave and adventurous souls that have done it. I will be going from South Carolina to Bahamas and further parts south. Please feel free to unload on me .

I suppose it depends on the size of your boat. I noticed that many boats over 35 ft are twin engines only. Single engines for smaller although occasionally I've seen twins that are smaller. In my case I have a 36 ft trawler with a single Ford diesel engine in it.
I specifically wanted a single engine trawler. I'm quite happy with it although in my first year I was concerned about reliability. But here's the trick. You have to know your engine backwards and forwards. The more comfortable you are with your engine, the more you're confident that it will continue to run. One thing I have learned now in 3 years of summer-liveabard boating, is that you must carry spares. Were on the water, roaming all over and on the hook for weeks at a time. I've had several incidents that I was not prepared for and others that we were. In all cases I've dealt with the situation on the fly. Today I have spares to deal with any situation. For example one year I I had one injector line crack due to fatigue failure. The solution for me was to run it on five cylinders instead of six, with the broken injector being piped into a plastic bottle. Ran like that for a month and a half until New injectors arrived. Not a problem.
This summer I had a bolt let go on my alternator which backed out and cut my alternator belt. Fortunately I had spare belts and replaced it in open water. So my advice on a single is make sure you have spares for every item on your engine (realistically speaking).
-Spare fuel line,
-spare fuel filters
-spare alternator
-spare alternator belts
-spare raw-water impeller.
Having a couple of jugs of engine oil, Cooling oil, and transmission fluid is also good to have. And finally and above all, inspect and service your engine frequently.
My 2c

 

[slowgoesit]

We're the single engine Muirgen Peter referenced in the third post on this thread. We left Seattle Area 2 September of last year. We arrived here at our new home in Florida on 26 April.

• 6 months and 24 day later. 6,400 nm
• a little less than 1000 engine hours
• three oil changes
• speed varies between 6.5 and 7.5 kts
• Average fuel burn of 2.4 gph
• in the neighborhood of 2,400 gallons of diesel consumed
• longest non-stop "sprint" was across the Caribbean, 8 days, 1,250 miles
• groundings: two . . . no I don't want to talk about that
• Anchors dragged, 1
• chased by pirates, once
• macerator pumps replaced, 4
• electrical issues, 1 with generator, 1 with a nav light
• refrigeration issues, 2
• fish caught, lots, more than we could eat on the trip
• long lines snagged, 7

Engine failures . . . . nope, none, nada, zero, zilch. Like Peter said, we're aware of the probability of an engine failure, but it wasn't high on our list of concerns.

Add in the 2,200 nm trip to Glacier Bay, AK and back to PNW, and in and around trips in PNW. Over our 40 months and 10,000 nm during our ownership we've had zero engine problems that weren't caused by our selecting a fuel tank totally filled with air, . . . no, I don't want to talk about those either.

We love the access our single engine gives us in our stand up engine room.

Singles aren't for everyone, but we've never regretted having only one engine. YMMV

 

[Dnnsmrgn]

I wish to thank everyone for their input. My only thought is that if storage is permitted on what ever I buy, I will have spares for everything except the block and heads. LOL My main reason in looking at single screw is fuel burn. I saw one that was single , with 400 gallon fuel tank ,stating it had 2000knm range. I don't know if this is common or BS . But, that got my attention.

 

[slowgoesit]

2000nm on 400 gallons is 5nm/gal with no reserve . . . . Not too likely IMHO . . .
Anything over about 3nm/gal is pretty darn suspect.