Do you prefer twin or single engine?

[Galaxy]

Hello all,

I am in the process of trying to locate my first boat. We are a family of 7 and planning to liveaboard and eventually cruise, hopefully internationally. We have been mostly focusing on Trawler type boats and looking in the size range of 55-70'. I have heard that there are pros and cons to having either 1 or 2 engines. I was wondering if you wouldn't mind sharing your experience and why you would prefer or recommend one over the other. Thanks.

 

[madorwhat]

Hello all,

I am in the process of trying to locate my first boat. We are a family of 7 and planning to liveaboard and eventually cruise, hopefully internationally. We have been mostly focusing on Trawler type boats and looking in the size range of 55-70'. I have heard that there are pros and cons to having either 1 or 2 engines. I was wondering if you wouldn't mind sharing your experience and why you would prefer or recommend one over the other. Thanks.

def go for twin

 

[rustybarge]

Hello all,

I am in the process of trying to locate my first boat. We are a family of 7 and planning to liveaboard and eventually cruise, hopefully interŷnationally. We have been mostly focusing on Trawler type boats and looking in the size range of 55-70'. I have heard that there are pros and cons to having either 1 or 2 engines. I was wondering if you wouldn't mind sharing your experience and why you would prefer or recommend one over the other. Thanks.

The max size single engines trawler yachts seem to be in the mid 30'/400hp/8 ton range.....and return about 1.5 mpg at 15 kts. The beneteau Swift trawler 34 is a good example of a modern take on this.

Imo that's really streching the boundaries for a single engine boat, although fishing vessels have massive commercially rated single diesels, but that's another thing completely.

 

[Scubadoo]

On trawler type boats, I would consider a single engine with a wing engine as backup for that size of boat. I prefer single engine for cost reasons (fuel, maintenance etc). Is there any real point on having twin engines for displacement type boats? after all you don't see that on commericial fish boats etc.

 

[MapisM]

why you would prefer or recommend one over the other.

Definitely single, on a displacement boat.
Reason being very simply that two engines = two problems.

 

[Whitelighter]

Single engine with a wing engine for security.

As for 34 being the max size for a single engine trawler, google Nordhavn.

And the swift trawlers aren't really trawler yachts either, at best they are 'trawler style' yachts/boats on standard semi d and planing hulls

 

[rustybarge]

Single engine with a wing engine for security.

As for 34 being the max size for a single engine trawler, google Nordhavn.

And the swift trawlers aren't really trawler yachts either, at best they are 'trawler style' yachts/boats on standard semi d and planing hulls

Sorry, I persumed he meant a semi-D trawler types, maybe like the Grand banks which don't have any singles in the range...

 

[rosssavage]

+1 for the single and wing on a Trawler.

Having had a breakdown at sea on one of my two propulsion systems, was I glad that I had options.

Engine was fine, hit an object that cost me my prop, shaft, rudder, gearbox couplings and engine mounts on one side (and no, I didn't hit the bottom!!).

Single engine = wait for the RNLI, twin = get to my destination rather slower than anticipated.

 

[longjohnsilver]

Definitely single, on a displacement boat.
Reason being very simply that two engines = two problems.

Yes very much agree with that. Until now all my boats have been single engined, and even now although I have twin engines still my preference for our current boat would be a single.

 

[Nautibusiness]

Assuming we are actually talking of a passage making motor yacht, trawler style, expedition style, whatever style... but defo passage making with liveaboard comfort and facilities then a single engine and wing would also be the only sensible way to go forward.

Could the OP suggest a budget he will be considering as their is a world of choice out there depending on what he wishes to spend?

Edit to add:
The only time I would consider changing that view would be if I was looking at a expedition / trawler style catamaran. And for a family of seven and International cruising in mind I think it would be a massively worthy consideration as they are incredibly spacious for their length offering, good (not incredible, but certainly good) cabin accomodation, but amazing living space which tends to be more important if actually living onboard.
The ride of a well built cat is surreal too. Very flat and easy going.

Take it to the next step and look at SWATH style liveaboards and the ride in incredibly rough seas remains almost totally flat.

Like I said before my edit... The budget would be helpful.

 

[Firefly625]

def go for twin

def go for single

In a Trawler Yacht for your purpose you want simplicity & economy. Keep your engine serviced and fuel in good condition and do your daily checks religiously and reap the benefits.

 

[MapisM]

Having had a breakdown at sea on one of my two propulsion systems, was I glad that I had options.
Engine was fine, hit an object that cost me my prop, shaft, rudder, gearbox couplings and engine mounts on one side (and no, I didn't hit the bottom!!).
Single engine = wait for the RNLI, twin = get to my destination rather slower than anticipated.

Not necessarily.
Chances are that with a single screw you wouldn't have had any of those damages.
In any proper trawler, the prop and rudder are EXTREMELY better protected than with any twin installation.
Not to mention the shaft, none of which is even exposed, in a single engine full D hull.
If you hit anything afloat big and heavy enough to damage the u/w gear of a single engine trawler, it's more than likely that it would have made a mess also of both props in a twin boat.

 

[rosssavage]

Yes, in that scenario. Any other reason for engine failure and that's that - and there are PLENTY of single point failures on any marine engine.

You don't need two big engines - a wing engine is fine, but I'm not getting stuck because of a simple mechanical failure.

 

[rustybarge]

Trawler type boats and looking in the size range of 55-70

.......once you get up to the 70' range miracles suddenly happen.....you've got twin decks and twice the space!!

....and 2.3 mpg at 8 kts.

WALLY//ACE

OVERVIEW // IMAGES
TECHNICAL SPECIFICATIONS // LAYOUT
COLOUR SELECTOR
WALLY//ACE CONSTRUCTION FILM
Length overall // 26.23 m – 86’0"
Length hull (measured) // 23.95 m – 78’7”
Length waterline // 25.50 m – 83’8”
Beam max // 7.75 m – 25’4"
Draught drives down // (half load) 1.75 m – 5’7"
Displacement (half load) // 94 tons – 207,234 lbs
Fuel tanks // 14,000 ltr
Fresh water tanks // 3,000 ltr
Engines // 2 x CAT C12 287 bkW @ 1800 rpm
Max speed // 12 kn
Accommodation // 6-8 guests + 4 crew
Naval architecture // Wally / Allseas
Styling // Wally
Interior design // Wally
Range (cruising speed) // 5,000 nm @ 9 kn

 

[MapisM]

You don't need two big engines - a wing engine is fine, but I'm not getting stuck because of a simple mechanical failure.

Fairenuff, but doesn't that count as "single", when answering the OP question?

 

[MapisM]

.......once you get up to the 70' range miracles suddenly happen.....you've got twin decks and twice the space!!

That's actually a 86', looking at her specs...
That aside, it seems that at Wally they are running out of innovative design ideas lately!

 

[rustybarge]

That's actually a 86', looking at her specs...
That aside, it seems that at Wally they are running out of innovative design ideas lately!

They quote hull length at 78', does that include the massive swim platform?

 

[MapisM]

They quote hull length at 78', does that include the massive swim platform?

Dunno for the Wally (it's still just a drawing btw, innit?), but if you're asking about the Arcadia I think it doesn't.
In fact, without it she fits (just) in the 24m limit, which has its advantages.

 

[rustybarge]

Dunno for the Wally (it's still just a drawing btw, innit?), but if you're asking about the Arcadia I think it doesn't.
In fact, without it she fits (just) in the 24m limit, which has its advantages.

The Wally has a low drag hull.....hence the amazingly low fuel consumption.
Even if you could afford the €5m price tag, you'd need a fortune of hundreds of millions to pay a planing version that does only 0.3 mpg., that's over €20/ mile.

Low drag displacement hulls has to be the way to go.

 

[Deleted User YDKXO]

There is no right or wrong answer to this. Even the well known displacement trawler boat builders can't agree. Nordhavn tend to offer singles even upto 70ft or so and although they do offer twins, they try to encourage buyers not to specify them by reducing fuel capacity and fitting only a wet exhaust. On the other hand, Kadey Krogen seem to offer mostly twins, certainly in 50ft+ boats and Selene seem to hedge their bets, offering both on most models.
For me personally, there is no argument, it has to be twins. I've had too many instances of one engine going down and not just because a prop gets fouled and I would need a lot of persuading before I bought a boat with a single engine. Neither do I think that a wing engine is the answer. If you're going to pay for the installation and maintenance of a wing engine ie a second engine, why not just fit a twin engine installation in the first place? Not only that but wing engines tend to be ignored and not used which means they might fail when they're really needed. Neither do I accept that a single engine has to be more economical on fuel by definition. I once had a chat to Tony Fleming (of Fleming Yachts) at a boat show and he was adamant that a single engine is not always more economical than a twin as it depends on the choice of engines and the design of the hull
So, twins for me and if it costs me a bit more fuel and maintenance cost, I'm happy to pay that for the extra insurance