Single engine vs twin in your experience?

[Discoverer]

I’m sure this topic has been discussed before, but since the information is scattered across different channels, it’s difficult to gather it all in one place. I’m currently searching for my first trawler and would love to hear from those of you with firsthand experience:

1. Which configuration do you have, and why did you choose it?

2. What are the biggest pros and cons you’ve experienced?

3. Have you ever regretted your choice, or would you switch if you could?

4. Any specific advice for someone trying to decide between the two?

I’m particularly interested in how these setups perform in real-world scenarios, such as engine failure or docking in tight marinas.

Do you think the fuel efficiency of a single screw outweighs the redundancy, maintenance costs, and complexity of a twin engines? Or is the added safety and maneuverability of twins worth the trade-offs?

Thanks in advance for sharing your insights.

 

[SteveK]

It depends. Let me think about this.

 

[Ken E.]

As you mentioned, lots has been written on this already and it is highly subject.
1. I have twin engines. I like the redundancy and close-quarters handling.

2. Pros: redundancy, close-quarters handling.
Cons: space, access, weight, fuel consumption, cost of maintenance.

3. If you don't cruise far from home (we do), and your area has a reliable towing service, a single makes a lot of sense. Based on the Alaska trips we make, I would only have twin engines. Some would argue this point but I sleep well.

4. This is a Ford vs Chev question. No particular other advise other than do your homework, like you're doing. There are tradeoffs either way.

 

[psneeld]

Safety and maneuverability are way down on my list for single or twin. Both are easily resolved for me.... but not necessarily everyone and some boat models need extra effort in these categories.

High on my list is if and when I have an inevitable reason to shut down an engine.... how critical is it to keep moving and/or would I prefer to.

With a twin and I need assistance with the repair, I may prefer to continue on because I am a twin to a location more suitable/affordable for the repair. As a single, how easy/expensive for a tow to that further location?

I used to snowbird from Jersey to Florida for nearly a decade. I also delivered mosty twins from Jersey to Fl and vice versa. Sometimes I had major engine issues (even with brand new engines from the factory), but fortunately could limp to where they needed to go.

On my own boat, I thought this highly traveled and populated route up/down the ACIW was a safe bet that it would be very rare to run into a situation that I couldn't handle and there was plenty of assistance along the way. I did sweat breaking down in a few spots where the cost of repairs and staying on land if the boat had to be hauled might have hurt the wallet more than I would have liked.

So for me, the decision for another boat whether single or twin would depend more on where I cruised and how often would I encounter stretches where keeping moving after an engine failure was important to me. One factor is always how many spares and tools can you carry and what onboard manufacturing of random auxiliary pieces and parts to assist in those repairs is possible.

 

[READY]

Let's discuss favorite anchor.

 

[Discoverer]

Let's discuss favorite anchor.

Let’s not drop the anchor on this engine debate just yet. Single or twin—what’s your pick and why?

 

[Jeff F]

Single or Twin Screw!!

Hello all. We have been looking at a trawler in the 36 to 40' range for some time now. I have had a bias toward a twin screw vs a boat with a single. A single must have a bow thruster to be considered. May I ask from personal experience your preference and why? Thanks in advance John

www.trawlerforum.com

 

[Discoverer]

Single or Twin Screw!!

Hello all. We have been looking at a trawler in the 36 to 40' range for some time now. I have had a bias toward a twin screw vs a boat with a single. A single must have a bow thruster to be considered. May I ask from personal experience your preference and why? Thanks in advance John

www.trawlerforum.com

That’s exactly what I am looking for! If you have a link to the previous discussion, just pop it here. Thanks!

 

[Jklotz]

D, as previously stated, there have been many threads about this already. Hell, I probably started one of them Not trying to get on to you, just suggesting you do a search and look at some of them and post again if you don't get your questions answered. It's a bit of a hot topic round here, no point in stirring the hornet's nest if you don't have to.

 

[Discoverer]

D, as previously stated, there have been many threads about this already. Hell, I probably started one of them Not trying to get on to you, just suggesting you do a search and look at some of them and post again if you don't get your questions answered. It's a bit of a hot topic round here, no point in stirring the hornet's nest if you don't have to.

If this topic has been deeply discussed, is there any consensus at all, or the answer still 'it depends'?

 

[SteveK]

If this topic has been deeply discussed, is there any consensus at all, or the answer still 'it depends'?

yes "it depends" is the answer as there are pros and cons of equal value. One post I remember is someone wanted a single but bought the right boat and it had twins. I am sure there was someone who wanted a single but bought the right one with twins. There is no right or wrong.
It depends.

 

[BruceK]

A well plowed field, you should find several threads.
I`ve owned both. Going from single to twins was like night to day, a whole new world of control and maneuvering. My present boat has a bowthruster I activate leaving/entering the marina but rarely use. Thrusters both ends on a single would help but still inferior to twins imo.
Fortunately both my twin boats had good ER space even with twins. Some you cannot pass between the engines and work on them from either end. Current Integrity models only have singles, I was glad to find an earlier one with twins.
In nearly 2 years at my current marina we have twice assisted twin engine boats docking on one, sfter engine failure. They did fairly well docking but needed help.
It`s one factor choosing a boat, other features could outweigh twins, keep an open mind, but as you see, I have a preference.

 

[boomerang]

I probably prefer a single ,if for nothing else but from a maintenance point of view. The last fluid change I did to our twin engine boat was $500, including filters. Coming from single engine boats, $500 was a big change.
Honestly though, I've gotten older and have kind of lost my mojo. Back in the day, I didn't care about currents or wind or tight quarters. I rather enjoyed the challenge of doing stuff with a single engine boat that others would never attempt. But that were when I was younger, more arrogant and more cocky. The last few cruises we had on our last boat with it's single engine, we found ourselves in a couple of dicey situations leaving our slips. I got us out fine and impressed the folks holding fenders on their boats half expecting me to bump into them. While I got us out with some crafty boat handling , I didn't experience the adrenaline rush that I would've in the past. I was just glad it was over.
Now I'm happy to not have to think as much about boat handling due to the advantage of twins. Our next boat, if it's a single, will have a thruster.

 

[DWJensen]

Inshore/nearshore, I'm all for a single and that's what I have now. We are looking for a bluewater boat and would still prefer a single as that's what I'm comfortable with, but I do want some sort of get home option in our next boat (wing or take off) for offshore passages.

Lots of arguments for each, but I'm on the single side. Less maintenance, generally better fuel economy and I'm comfortable using prop wash and walk to dock.

If I found two boats that were exactly the same except one was a single/wing and the other had twins, I'd go with the single BUT I wouldn't let twins keep me from buying a boat that I liked otherwise.

 

[Delta Riverat]

For me it was easy, I bought a boat I liked and it has twins.

 

[C lectric]

We have a single engine boat. We have had it since May 1985.
I have finally run out of room ?? to store spares, service items, tools, although even that may be pushed. I just have to use a lot more ingenuity.
It is a single engine, 32' boat.
No THRUSTERS EITHER so far .

If I have a twin engine version of this boat I would NOT be able to get into the E.R. without major contortions.
Yes , a few times I have wished for a twin but over the last 7000+ hours and 39 years I am NOT sorry it is a single.
I have never had serious problems with steerage out in the Strait or at the dock.
Of course I avoid rough seas as much as possible but that is not always possible entirely.
For many years I have pulled into tight spots, in the wind or current. Not always without some apprehension but no banging other boats either.

Unlike some of them hitting us.

 

[mvweebles]

Topic has been discussed many times but I like the way it's phrased.

I have a single engine boat and I cruise moderately long distances.

Pros of a single (my opinion). Protected running gear. Access in engine room. Huge benefits for me. Allows me to tuck up into anchorages.

Cons of a single for me: lack of redundancy. I carry spares but still, nothing like a spare engine. I've never needed one (yet) and it hasn't kept me from exploring (boat is currently in South Mexico near Guatemala). But still, it's a fact.

Non-issues for me: maneuverability of a twin. Speed of a twin. Fuel efficiency of a single (nice bragging rights but meaningless in the big scheme).

I like singles. But if I were looking from scratch, I wouldn't exclude twins. Just not that high up on the priority list. .

Peter

 

[klee wyck]

I currently own one of each. I am not sure I have a preference.

 

[O C Diver]

I prefer a single, but wouldn't cross an ocean with only one.

There will be times and situations where the failure of a single engine will be life threatening. What you need to decide is the percentage of cruising that fits into that category. Then decide if the percentage is low enough for your comfort level.

Ted

 

[Jklotz]

FWIW, we are searching for our boat and I'd prefer a single with bow and stern thrusters. Our intended cruising grounds are the AICW and Bahamas. If the right boat comes up but it has twins, we'd probably jump on it.

Having been through a couple of these twin vs single threads, I can tell you the outcome is always the same. Summing it up, "it depends". I'm no expert, but one thing I've summarized is crossing oceans and serious blue water passage making requires a very different boat than a coastal cruising one would. And every boat is a collection of compromises. Maybe a better way of approaching it would be to determine what your goals are for the boat and what you plan to do with it. In our case, it has helped narrow down our search.

Hope this helps.

 

[READY]

I own one of each. Different use cases but it would be hard to defend either as the "right" choice. If this were a general aviation pilot forum it would be a thread on low wing vs. high wing. If RVs it would be trailer vs Motor home.

 

[Portage_Bay]

I’m sure this topic has been discussed before, but since the information is scattered across different channels, it’s difficult to gather it all in one place. I’m currently searching for my first trawler and would love to hear from those of you with firsthand experience:

1. Which configuration do you have, and why did you choose it?

Current boat is twins. Chosen for the comfort and layout, it came with twins.

2. What are the biggest pros and cons you’ve experienced?

Because you asked "experienced" not theoretical.

Pros:A twin well handled can spin in place. Improves close quarters handling.
Cons:Maintenance and repairs are higher. Access to the engines is more difficult.

3. Have you ever regretted your choice, or would you switch if you could?

As I said, the choice was the boat not the engines. No, I would not change for a single just because. Nor would I reject a single if the rest of the boat was what I wanted.

4. Any specific advice for someone trying to decide between the two?

Carefully consider your cruising goals, boat handling experience, tolerance for performing routine maintenance in a crowded engine room. There is no one right answer. Singles are easier to maintain, cheaper to maintain and the running gear is usually better protected. Twins for most people will handle better, not always but mostly. Twins running gear is usually less protected. A small strike with a log or a touch of the bottom in a single is usually no big deal. With a twin it can be a serious problem. Bent props, shafts and rudder stocks.

I’m particularly interested in how these setups perform in real-world scenarios, such as engine failure or docking in tight marinas.

Do you think the fuel efficiency of a single screw outweighs the redundancy, maintenance costs, and complexity of a twin engines? Or is the added safety and maneuverability of twins worth the trade-offs?

You won't find the fuel efficiency difference between twins and single to be meaningful. It takes a given amount of power to move a boat at a given speed. That power comes from the fuel. If a boat requires 100 HP to run at hull speed a single will need to produce 100 HP. A twin will need the same 100 HP, 50 HP from each engine. The only fuel penalty for a twin is a very slight difference in the parasitic overhead.

Safety comes from the management and maintenance of your power plant and fuel. Diesels if reasonably well maintained rarely fail.

Maintenance with twins is double. No way around it. I had to replace the risers on my last twin. V8s no less. That's four where a single inline six would be one.

Thanks in advance for sharing your insights.

 

[magna 6882]

I think it may be more about the boat then just the power options. I have seen some twins when they popped that hatch it was just an OMG moment. Some components just a nightmare to get to. Those boats needed a twin because so many repairs could never be done on a trip.I like the twin concept if in a boat big enough to get around both engines. I went with a single for the maintenance reason. I can just sit on either side on the engine. I also have oversized variable speed thruster that help with maneuvering . The pros and cons i think are fairly obvious and would depend on the boat and cruising grounds.

 

[psneeld]

Hopefully one sees the generalized comparison for what it is.

Some posters describe their own experience/boat and give pro and cons.... they sorta loose meaning if comparing to a completely different boat.

For example, there are larger twins with walk in engine rooms and walk around engines, then there are singles with very tucked in engines with almost no room to enter at all.

A twin can spin in place, but so can singles with 2 thrusters.

True singles often have protected running gear, but some twins do too.

And on and on and on. That's why this topics usually fizzles into "yeah, but". That's because it is "yeah, but".

There are great points made, but the best would be made between 2 identical hulls and layouts... one a single, one a twin.

Just a general overall comment.... I have towed in plenty of twin engine boats. They aren't magic but thankfully these failures are some percentage lower than straight engine failures. Things like fuel contamination/loss from fueling all tanks at the same time, engine room fire, fouled props, lightning strike..... probably more.

 

[twistedtree]

I think the answer is "it doesn't matter", and that's why the question will be debated for all eternity. Whichever you have, you will enjoy the pros and easily work around the cons, knowing the grass isn't greener on the other side.

 

[mvweebles]

Hopefully one sees the generalized comparison for what it is.

Some posters describe their own experience/boat and give pro and cons.... they sorta loose meaning if comparing to a completely different boat.

For example, there are larger twins with walk in engine rooms and walk around engines, then there are singles with very tucked in engines with almost no room to enter at all.

A twin can spin in place, but so can singles with 2 thrusters.

True singles often have protected running gear, but some twins do too.

And on and on and on. That's why this topics usually fizzles into "yeah, but". That's because it is "yeah, but".

There are great points made, but the best would be made between 2 identical hulls and layouts... one a single, one a twin.

Just a general overall comment.... I have towed in plenty of twin engine boats. They aren't magic but thankfully these failures are some percentage lower than straight engine failures. Things like fuel contamination/loss from fueling all tanks at the same time, engine room fire, fouled props, lightning strike..... probably more.

Fair points. While I can think of a handful of boats offered as both single and twin, best general example would be the Grand Banks 36 and 42. Both have cramped engine spaces with twins, and both have passable protection as singles. I would hands down prefer the 36 in a single config. I'd personally prefer the 42 in single with hesitation due to resale. But I wouldn't hold out hoping to find a single GB42 as they are uncommon. I would hold out for a single GB36 as they were more common and the penalty for cramped space pronounced

Peter

 

[long-cours.62]

Even if since 1994 we had mainly twin; only the Amel Mango during few month and the De Alm also during few month; all our boat was twin.
But on this I tried to be "Avocat du Diable" pour mono engine, sorry in French
Mono vs Bi !? - Trawler long-cours

 

[psneeld]

Even the shallower draft twin engine argument is overcome by singles in a tunnel.

This is why the discussion goes on and on.... apples and oranges unless you make a close comparison to nearly or the same boat.

Add in outboard driven smaller trawlers and you gain a whole different set of pros and cons.

Feel free to keep them coming, there is hardly a pro or con that exists across the breadth of all boats.

 

[ranger58sb]

1. Which configuration do you have, and why did you choose it?

2. What are the biggest pros and cons you’ve experienced?

3. Have you ever regretted your choice, or would you switch if you could?

4. Any specific advice for someone trying to decide between the two?

I’m particularly interested in how these setups perform in real-world scenarios, such as engine failure or docking in tight marinas.

Do you think the fuel efficiency of a single screw outweighs the redundancy, maintenance costs, and complexity of a twin engines? Or is the added safety and maneuverability of twins worth the trade-offs?

If this topic has been deeply discussed, is there any consensus at all, or the answer still 'it depends'?

There's a bazillion threads around here on the topic, so do a search for those too. Yes, it depends. That "piece of string" thing.

1. Yes. Because I liked the boat.

2. Better engine room space with singles, and often better prop protection... redundancy for twins. (Never had a failure with single. The one time we've needed a tow, it was with twins, this current boat (shame!)... because the electronic gear control crapped out.)

3. No... sorta. I'd usually prefer a single for the maintenance access, but have seldom found a single with a suitable boat around it.

4. Find a boat with your "must have" features and other stuff you like, analyze engine offerings afterwards.

No... and maybe. Depends on the boat. Also, the single screw boat we had could have become lots more maneuverable with at least a bow thruster, maybe with stern thruster too. (Didn't understand at the time how relatively easy a bow thruster retrofit could have been.)

-Chris

 

[long-cours.62]

Even the shallower draft twin engine argument is overcome by singles in a tunnel.

It is what I wrote here :
"...-tirant d'eau plus réduit ( pour une même position du moteur et même longueur de ligne d'arbre, même carène) bien sur avec une carène adaptée au mono cette avantage peut être nul.( voir la Belle Marie)...."