1 vs 2 diesels, insights please..

First post and thanks in advance to community.
Attending boat shows with wife as we prepare for cruising life in next 2-4 years. Identified trawlers as our preferred platform (liveability, no rushing around, shallow draft, etc) with East Coast, Bahamas and perhaps into Caribbean (USVI, BVI) as cruising grounds. Great loop an interest too. Looking at a range of brands (Kadey Krogen, Krogen Express, Norhavn, Helmsman, etc).

QUESTION: I'm leaning towards twin diesels for redundancy, safety - all the talking points from the twin engine crowd - that is comforting to me. That said, i really lean in and listen to the single engine trawlers group that say it's no necessary due to sea tows, cell /satellite services and so on. "The only thing that stops these diesels is bad fuel."

Am i wrong in thinking twin diesels is the way to go and the liklihood of failures across two engines is near impossible? I know this is a common question, thanks in advance.
Thanks!!

My sig line explains it. I prefer redundancy, easier to maneuver in close quarters, except I hear you can get thrusters for that.
It really is a personal choice. You already heard the pros and cons. Either way can be made to work. Good luck

My rule of thumb, singles for well populated cruising, twins fo areas that are remote from help and service.

May not be critical, but I love convenience.

Welcome aboard. It all depends on your preference. There is no right or wrong. I would guess that the individual boat will determine which way you will go. Either one is great, but the real difference is the particular boat, condition would weigh heavily with me unless you absolutely love working on boats, which I do. I would figure out what your must haves are and nice to haves and must not haves. Then buy the best condition boat that meets most of them and is in your budget. Then if it has one or two engines so what…

I'm a single guy. I like the accessibility of a single engine (though some twins have decent outboard access, but not many - if you won't be doing most of your own maintenance not a big deal i suppse). Singles usually have better protected props .

All my cars and trucks have one engine. I've been towed twice in the past 30 years and 300k miles: once when I hit a massive pothole that took out two tires. Once when a fan belt shredded.

I won't deny that having a twin provides redundancy. Personal decision on how much risk a single exposes you too given your cruising plans, and how comfortable you are.

Good luck with your decision.

Peter

Greetings,
Welcome aboard.

Single vs twins is almost as contentious as which anchor is best…

mvweebles said:

I'm a single guy. I like the accessibility of a single engine (though some twins have decent outboard access, but not many - if you won't be doing most of your own maintenance not a big deal i suppse). Singles usually have better protected props .

All my cars and trucks have one engine. I've been towed twice in the past 30 years and 300k miles: once when I hit a massive pothole that took out two tires. Once when a fan belt shredded.

I won't deny that having a twin provides redundancy. Personal decision on how much risk a single exposes you too given your cruising plans, and how comfortable you are.

Good luck with your decision.

Peter

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I am on this camp and this is as simple as an explanation You'll get.

add Trusters and or get home option would contribute to redundancy.

Greetings,
Mr. TG. Post #7 says it all. For me, ease of maintenance is foremost.

Two always. There are two choices:



Two main diesels

One diesel and some kind of "get home" rig

Access to outboard side of twins is difficult unless beam is >15'. Replaced a starter in 1 engine. Shredded a fan belt once. Recently wrapped a line around a prop several miles offshore in not very comfortable conditions. Came back on single engine. Seatow dock is 10 miles away, if they are available at the time. Could be a long wait if they are all busy towing other boats in.

I am solidly in the twin corner. Maintenance is not a significant factor for me. Getting back is.

As a good friend with a single engine KK 48 said when getting towed for 70 miles, "I sure wish I had twins".

RT Firefly said:

Greetings,
Mr. TG. Post #7 says it all. For me, ease of maintenance is foremost.

Click to expand...

You can have your cake and eat it too....
I prefer twins, each in a stand-up engine room of their own....

I can stand on either end and either side of the JDs on DOMINO.

TrawlerGreg said:

First post and thanks in advance to community.

Attending boat shows with wife as we prepare for cruising life in next 2-4 years. Identified trawlers as our preferred platform (liveability, no rushing around, shallow draft, etc) with East Coast, Bahamas and perhaps into Caribbean (USVI, BVI) as cruising grounds. Great loop an interest too. Looking at a range of brands (Kadey Krogen, Krogen Express, Norhavn, Helmsman, etc).



QUESTION: I'm leaning towards twin diesels for redundancy, safety - all the talking points from the twin engine crowd - that is comforting to me. That said, i really lean in and listen to the single engine trawlers group that say it's no necessary due to sea tows, cell /satellite services and so on. "The only thing that stops these diesels is bad fuel."



Am i wrong in thinking twin diesels is the way to go and the liklihood of failures across two engines is near impossible? I know this is a common question, thanks in advance.

Thanks!!

Click to expand...

We have twin Lehman 120s. We have had propulsion stoppages twice, NEITHER from an engine failure. There are plenty of failures that can stop any diesel, not just bad fuel or a plugged fuel filter.

catalinajack said:

We have twin Lehman 120s. We have had propulsion stoppages twice, NEITHER from an engine failure. There are plenty of failures that can stop any diesel, not just bad fuel or a plugged fuel filter.

Click to expand...

I seem to recall that at least one of those failures was a blown drive saver, which you removed as it was essentially a self inflicted vulnerability, though it worked as advertised. Not sure if I have that right.

Twin engines is one way to solve a vulnerability. I have had exactly two engines stop or alarm. One was I forgot to turn on a fuel valve. The other was on a client's older trawler with twin Lehmans. The impellor was shredded due to lack of maintenance.

If redundancy is the concern, solve that. Get-home engine or hydraulic motor off generator PTO, even a sail plan might get you somewhere (mid ocean). I wouldn't cross an ocean with a single, but there are many ways to reduce what is already a low risk. Including closing the engine wisely, carrying spares, and maintenance.

Thoughts?

Peter

Greg,
Welcome aboard the TF!!!!
And thanks for restarting this potentially "contentious" issue
Olthers here have it right. It is a personal preference. No right or wrong (although in the future, under certain circumstances you may think you should have gone the other way)
I prefer singles, especially in "smaller" boats (below 45 feet but can vary). Engine access for repairs and maintenance can be difficult in what can be a very cramped engine room. Not so bad if you hire out all the work (slight cost increase due to access maybe), but can be very frustrating for a DIYer in some boats. Also, costs are higher with twins for maintenance (double the labour, parts etc.). As previously stated by another, generally the running gear is better protected when there is a single engine reducing some of the other reasons for problems besides fuel.
If you do decide on a single, make sure you do the recommended maintenance and don't let it lapse. This will help with reliability. Many boaters (meaning quite a few) tend to take some short cuts on their recommended or best practises maintenance. EG. on their raw water cooling system or impeller changes. With a single, (for best results ), keep up on all engine maintenance. In my opinion, a well maintained single diesel, operated by a "prudent" boater is pretty darn reliable. Having at least a bow thruster will make close quarters movement very safe and easy (with practise).
Twins offer redundancy (get home if both engines are not affected by the issue and fouling and fuel might affect both), and they offer increased maneuverability over a single without a thruster. Pros and cons to both.

Good luck on your choice!

psneeld said:

My rule of thumb, singles for well populated cruising, twins fo areas that are remote from help and service.

May not be critical, but I love convenience.

Click to expand...

Good advise. A strong case can be made for a single if you're within the range of a towing service. If not available, you're on your own.

I have a single Cat on my Mainship 35/39. The previous owner installed a series of two oil filters. If one got clogged with some goop he turned it off and turned the other one on. Saved him from two bad loads of fuel. The gunked up one can be replaced. I have never had a problem and with the bow thruster and prop walk to starboard, it is easy to dock. My twin Bertram was a cinch to dock but .7 mpg wasn’t that easy on the wallet! On a cruise yesterday upstream in the St. Lawrence we did 8.5 mph sog at 1900 RPM and going downstream 12 mph sog at 1900. We got 7.1 mpg. A tad better than the Bertram at 30 mph at 3,000 rpm. Unfortunately our diesel is $5.99/gal. Too bad they won’t sell #3 fuel oil with no road tax for less than $3.00!

Lots more boat choices if looking for two engines. Still, one is enough for me.

Greetings,
Mr. mp. You loosing weight?

I’ve had singles and I’ve had twins. I can make a great case for either. When you find the boat you love the choice will be made for you. You will rule out a lot of good boats if you let single vs. twin be your major criteria.

I wanted an ER with headroom and working space so the engine would actually get worked on as we are not attached to a marina with a mechanic a phone call away to farm it out to.

Thinking back to vehicles I have owned, the only one that I worked on was the 1980's F100 with an engine bay I could almost sit in.

Wanted the same with the boat
So a big reliable no electronics single it is.

mvweebles said:

I seem to recall that at least one of those failures was a blown drive saver, which you removed as it was essentially a self inflicted vulnerability, though it worked as advertised. Not sure if I have that right.

Twin engines is one way to solve a vulnerability. I have had exactly two engines stop or alarm. One was I forgot to turn on a fuel valve. The other was on a client's older trawler with twin Lehmans. The impellor was shredded due to lack of maintenance.

If redundancy is the concern, solve that. Get-home engine or hydraulic motor off generator PTO, even a sail plan might get you somewhere (mid ocean). I wouldn't cross an ocean with a single, but there are many ways to reduce what is already a low risk. Including closing the engine wisely, carrying spares, and maintenance.

Thoughts?

Peter

Click to expand...

Yes, it was a blown Drivesaver which illustrates my point exactly in that there are other causes of loss of propulsion. As for the Drivesaver working as advertised, in my case, that was not true. I did not hit anything. I had gone aground in Cayo Costa, FL. I attempted to back off the shoal. As the boat began to slowly slide off the sand bar, I applied more power. Drivesavers are torque-rated. Yup, I ripped it apart. Having a second engine, I was able to slowly drive the 45 miles to Ft. Myers arriving on Christmas Eve in the dark.

I did call Towboat US to pull us off that shoal. At 56,000 pounds the boat that did so was not capable of towing us anywhere other than off the shoal. We would have had to anchor in Cayo Costa for another night waiting for a more powerful boat and the next day was Christmas. So, yes, on that day having a second engine came in more than handy.

I carry all manner of spare parts, even a full set of hard pipes that go from the injector pump to the injectors. Who does that? But a spare Drivesaver? Besides, even if I did have one aboard, that would be a very difficult job at anchor and, in my case, as it turned out for reasons I won't get into (another long, sad story), impossible. And I do keep aboard most any tool you can think of, including a sawsall.

By the way, having those hardpipes aboard saved us on our third day of ownership when one cracked and we had to shut down one engine. We attempted to anchor but, in heavy winds, we could not get the anchor to set. In the waning light I could see someone's facedock. We tied up there in total darkness. Yes, saved from disaster by having twin engines.

As far as crossing oceans with a single, Richard on Dauntless (Wxx3 on this forum) did it on a single-screw Krogen 42, across to Europe, back to the States, then thru the Panama Canal, and up to the Pacific Northwest.

So, what it comes down to, first and always, is risk assessment which is personal to each of us. When we determined to purchase a trawler, we narrowed our choices to either a DeFever 44 with twins, or a KK42. We were glad we chose the DeFever. Ours even has two generators!

You may recall that I eliminated those Drivesavers, spacers in their place. They are, the Drivesavers, of suspect utility anyway despite what the manufacturer touts. They also make it impossible to be sure of an accurate engine alignment.

Must say I do like the Nordhavn design of one large engine and a smaller 'reserve' engine in case of trouble. In Norhavns you do have the space to walk around the engine, which makes maintenance easier.
In my Defever 49 I have 2 x 120 HPFord Lehmans, of which the port engine is easily accessible, but the Stbd engine is a nightmare to get to if you need to work on the coolers, change filters or something simple as changing the oil in the fuel pump. Luckily my wife is much smaller, so she fits in that space.
Also, in my boat the engine room is spacious, but I cannot stand up straight, which you can actually do in smaller Defevers.

That said, I do like to have the two engines as I don't like to be on the water (nor in the air) with just one engine. There is this saying: 'one engine is no engine, two engines is one. It is not just a matter of how far from help you might lose the one engine, also where you lose the engine is important. If there is a strong wind blowing you towards a rocky coast and you are only 1 nm off..............better work fast to get that engine going again.
Another thing I like of having two engines is the complete control over the maneuverability of the boat. Having to do stern to dockings all the time in the Med it is important to be able to have full control over the boat, even with strong crosswinds. Seeing sailing vessels (one engine) often struggle to get the boat into port makes me realize how lucky I am with two engines. A Defever 49 is a high boat, catches a lot of wind, so being able to correct a moving bow or stern instantly is important. Yes, I also have a bow and stern thruster, but try to use them as little as possible. Putting a heavy drain on the batteries and then switching off the engines after docking with no battery recharging does not strike me as a good idea.

So, maintenance wise I wish I would have 1 main engine and a back up, but for operational use I prefer the two engine set up.

TrawlerGreg said:

First post and thanks in advance to community.
Attending boat shows with wife as we prepare for cruising life in next 2-4 years. Identified trawlers as our preferred platform (liveability, no rushing around, shallow draft, etc) with East Coast, Bahamas and perhaps into Caribbean (USVI, BVI) as cruising grounds. Great loop an interest too. Looking at a range of brands (Kadey Krogen, Krogen Express, Norhavn, Helmsman, etc).

QUESTION: I'm leaning towards twin diesels for redundancy, safety - all the talking points from the twin engine crowd - that is comforting to me. That said, i really lean in and listen to the single engine trawlers group that say it's no necessary due to sea tows, cell /satellite services and so on. "The only thing that stops these diesels is bad fuel."

Am i wrong in thinking twin diesels is the way to go and the liklihood of failures across two engines is near impossible? I know this is a common question, thanks in advance.
Thanks!!

Click to expand...

This post pretty much covers my opinion on the subject.

psneeld said:

My rule of thumb, singles for well populated cruising, twins fo areas that are remote from help and service.

May not be critical, but I love convenience.

Click to expand...

Too expand a little further:

I think part of your decision should be based on your level of mechanical aptitude. Simply, if changing a fan belt is beyond your mechanical ability, you're a candidate for twin engines. Engine rooms have become more complex over the last 50 years. While a single engine can be very reliable, there are peripheral items on the engine that can and will fail. You will have to decide for yourself whether changing out a raw water pump or replacing its impeller is within your skill set. If not the redundancy of twins is a logical choice.

The other consideration is how far and how often you travel off the beaten path. While I am very confident in the reliability of my single engine, have the spares onboard to fix and replace the peripherals, and the skill to do it, I also only am in either remote areas or areas of great risk a few percent of my operating time. To expand on the second quoted post, I might consider taking a round trip to Bermuda (800 miles each way) on a single engine boat once, but if I thought it would happen several times, it would be on a twin engine boat. You will like wise have to determine what percentage of the time being off the beaten path is a reasonable risk.

Ted

TrawlerGreg said:

First post and thanks in advance to community.
Attending boat shows with wife as we prepare for cruising life in next 2-4 years. Identified trawlers as our preferred platform (liveability, no rushing around, shallow draft, etc) with East Coast, Bahamas and perhaps into Caribbean (USVI, BVI) as cruising grounds. Great loop an interest too. Looking at a range of brands (Kadey Krogen, Krogen Express, Norhavn, Helmsman, etc).

QUESTION: I'm leaning towards twin diesels for redundancy, safety - all the talking points from the twin engine crowd - that is comforting to me. That said, i really lean in and listen to the single engine trawlers group that say it's no necessary due to sea tows, cell /satellite services and so on. "The only thing that stops these diesels is bad fuel."

Am i wrong in thinking twin diesels is the way to go and the liklihood of failures across two engines is near impossible? I know this is a common question, thanks in advance.
Thanks!!

Click to expand...

It is all about redundancy, maneuverability, ER space utilization. It used to be about bad fuel, but since ULS fuel is mandated almost everywhere, that problem has been solved.

If you find your boat and it has twins, you won't need thrusters, though you may still want them to add further to the already excellent maneuverability. Some ERs are crowded with 2 diesels, but that is only the case where your hp has been doubled, rather than split between 2 diesels. Also cost and economy suffer where the hp has been doubled, but not so much where hp is split between 2. Fuel economy depends not on how many engines are burning it, but on how big a stern wave you want to make.

Engine failures still happen. I have had times where I needed that second engine: once I had a transmission hose failure that had one side down for a month, one oil cooler leak with a similar result, one water pump failure that had one side down for a season. With only one engine I would have lost precious vacation time for each of those failures. With twins I lost a little time, as my cruising speed dropped from 8 knots to 6.5 and a little maneuverability. I learned to dock using one engine, making its prop walk my friend.

I haven't had any fuel issues whatsoever. I just changed fuel filters as I checked my log and found it had been 4 years, so changed them even though the bowls were still clean and clear. Gone are the bad old days when the filter bowls were grunged up twice a year.

TrawlerGreg said:

First post and thanks in advance to community.
Attending boat shows with wife as we prepare for cruising life in next 2-4 years. Identified trawlers as our preferred platform (liveability, no rushing around, shallow draft, etc) with East Coast, Bahamas and perhaps into Caribbean (USVI, BVI) as cruising grounds. Great loop an interest too. Looking at a range of brands (Kadey Krogen, Krogen Express, Norhavn, Helmsman, etc).

QUESTION: I'm leaning towards twin diesels for redundancy, safety - all the talking points from the twin engine crowd - that is comforting to me. That said, i really lean in and listen to the single engine trawlers group that say it's no necessary due to sea tows, cell /satellite services and so on. "The only thing that stops these diesels is bad fuel."

Am i wrong in thinking twin diesels is the way to go and the liklihood of failures across two engines is near impossible? I know this is a common question, thanks in advance.
Thanks!!

Click to expand...

Sometimes better to visit this question further along in your shopping process... especially if you're buying from the secondary market.

You'll home in on boat features you want, would like to have, don't want, etc... based on how you expect to use the boat, how you normally live your lives, etc.... until you can narrow the field down to actual candidates based on those features.

Then you can debate pros and cons not only of number but model of engine is (was) actually available. For instance, you may eventually discover a preference for a single Brand X versus twin Barns Ys... or vice versa.

There's some zen involved...

But you can solve a lot by jointly making a list of agreed-upon mandatory, good, bad features... and worry about minor details later.

There are a bazillion threads on the 1-vs-2 question here on the forum, so you'd also likely get even more nuance if you review all those, too.

FWIW, I fall into the one or the other camp. Depends on the boat.

-Chris

It's mission and personal preference. I've had both and prefer my current single engine for ease of maintenance/access and the second set of parts I buy are stored as spares instead of getting bolted on the other engine.

There is no right or wrong answer. It's just what is of particular importance to any specific buyer.

I'm glad I started with 2. Made the learning process easier. With more experience I can see advantages of one. It is a lot harder accessing accessing the hull side for service, but the low speed maneuvering capability is sweet.

With a single I would want a hydraulic bow thruster for sure.