Do you prefer twin or single engine?

Neither do I accept that a single engine has to be more economical on fuel by definition.
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The aquanaut 15mtr range have bulbs on the bow.....how much better Mpg?
Looks like a single screw.

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Most large fishing trawlers have a single engine and have no problems. The key with single engine installations is the robustness and redundancy of the fuel systems. On board fuel polishing system, separate fuel tanks, multiple parallel filters that can be changed while the engine is in use, etc. I remember a pal of mine years ago who was a long haul airline pilot commenting on the merits of flying twin engine wide body aircraft over oceans instead of four engine jets. His view was half as many things to go wrong, and two modern engines statistically more reliable than the previous generation of engines then in use on 747s. He had training over to A330 after his airline had a long internal debate about using four engine A340s, but they opted for the efficiency and economics of twins. As I once commented to a highly obnoxious and intoxicated pax, the aircraft had four fire lighters strapped on to our wings which in fact were aerodynamically shaped petrol bombs strapped to the tinfoil tooth paste tube we were sat in.
 
I won 't mention the elephant in the room........stabilisers.
At displ. Speeds stab. are a necessity, not an option.
Cost?......£100k.

So getting back to the OP question: I'd say single or twin semi- displ. Hull is the only option worth considering.
Calm day.....pottle along at displ. Speed,.... no rolling.
Lumpy......speed up to 15 kts......no rolling.
The extra fuel consumtion Is still going to be a lot cheaper than stabilisers.
 
Going on the basis of reliabilty and cost there are only two choices.
The answer to all boaty questions:

Shaft drive or outboards?
Semi-displacement or Catarmarans?
then diesel or petrol (yamaha 350hp outboards available)?

And not forgetting the cauldwell outboard/inboard hybrid @ 450 hp

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....so what size boat can you afford to cruise extensively?
 
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Given free choice on this one mine would be a Nordhaven with one main engine with a swing to get me back to port in the rare event if an engine stopping problem.

Good article in MBM a couple of months ago, but a new one will cost around £750 k, so reckon on £500k for something decent secondhand. Plenty of space for 7, and a good number for the watch keeping rota. Set them going 1 in 3 West Country with yourself floating as Skipper.
 
oceanfroggie said:
Most large fishing trawlers have a single engine and have no problems. The key with single engine installations is the robustness and redundancy of the fuel systems. On board fuel polishing system, separate fuel tanks, multiple parallel filters that can be changed while the engine is in use, etc. I remember a pal of mine years ago who was a long haul airline pilot commenting on the merits of flying twin engine wide body aircraft over oceans instead of four engine jets. His view was half as many things to go wrong, and two modern engines statistically more reliable than the previous generation of engines then in use on 747s. He had training over to A330 after his airline had a long internal debate about using four engine A340s, but they opted for the efficiency and economics of twins. As I once commented to a highly obnoxious and intoxicated pax, the aircraft had four fire lighters strapped on to our wings which in fact were aerodynamically shaped petrol bombs strapped to the tinfoil tooth paste tube we were sat in.
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Still got at least two engines though :)
 
Deleted User said:
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
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Yup.

With a commercial aviation background and more than one occasion under my belt when I've had propulsion issues with one side and continued on the other, twin for me every time.

Except my RIB..:)
 
Deleted User said:
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
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Yeah, and that had absolutely nothing to see with the fact that he only builds twin engined boats, of course. :D
With all due respect for TF, needless to say.
You would hear the same BS from any other twin engine - only builder, in fact.

PS: coming to think of it, he might well have been right if he was talking of catamaran hulls, actually.
But I have a funny feeling that he didn't... :)
 
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If only I had a couple of million quid:p, The 23mtr range gives you twin decks. I think that makes about 75' in old money.
...get a load of all that space.....'Van de Valk 23 mtr in build.' :) Has to be worth going up 5' from the single deck 60'-70' range to get double the internal volume.

Saloon
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Lower deck.
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rustybarge said:
I won 't mention the elephant in the room........stabilisers.
At displ. Speeds stab. are a necessity, not an option.
Cost?......£100k.

So getting back to the OP question: I'd say single or twin semi- displ. Hull is the only option worth considering.
Calm day.....pottle along at displ. Speed,.... no rolling.
Lumpy......speed up to 15 kts......no rolling.
The extra fuel consumtion Is still going to be a lot cheaper than stabilisers.
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Certainly no need for them in a cat.
And use a SWATH cat and you could all but play snooker in a force 8
 
MapisM said:
Yeah, and that had absolutely nothing to see with the fact that he only builds twin engined boats, of course. :D
With all due respect for TF, needless to say.
You would hear the same BS from any other twin engine - only builder, in fact.
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Similarly you wouldn't expect anything other than the same BS from boat owners with singles:p Just remember; God gave you two of everything important, not one:D
 
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