one engine or two?

[chris]

I am thinking of taking the plunge and buying the boat. I have two small children so safety is a particular consideration. Intuitively having two engines seems a better option as if one fails there is another to get you home. On looking into various boats however there appear to be several interesting looking boats with single engines (eg Aquador). Being new to this, but learning all the time particularly from this forum, it then occurred to me that there might be any number of problems that might cause both engines to fail. My question is therefore is two really better than one or does it just give a false sense of security and I should not be so quick to dismiss the single engine boats? Thanks

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[Guest]

Chris, I have had both and I wouldn't ever go back to a single.

When your only engine konks out while someway off land in a rough sea it is unpleasant to say the least.

I had a single Merc outdrive, two years old, properly serviced, off Littlehampton when the engine overheated big time. Nothing I could think of doing cured the problem. We were left to bob in a three foot swell for a couple of hours until the lifeboat towed us in. We never trusted it again. (The cause was the thermostat wax leaking out of a pinhole causing it to slam shut)

We then bought a twin and have no worries going out in quite rough seas. The other point is that low speed manouvering is so much easier when you can spin the bow while keeping the transom still. The obvious downside is however double servicing costs.

Geoff

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[DepSol]

Where are you planning on keeping the boat/cruising and what use do you want from it? If you ae not going far then a single can be fine, in the CI I can get picked up in no time if my single goes down just with a quick mobile call to someone who I know will be in my vicinity. If not and like last month my engine went into safety mode then I will come back at 12 knots.

<hr width=100% size=1>Dom

<A target="_blank" HREF=http://www.soltron.co.uk>the website</A>

 

[Deleted User YDKXO]

All things being equal, I would always go for 2. I had an engine failure last week and limped back on 1 engine so 2 engines are definitely safer. On the other hand, 2 engined boats are more expensive to buy and to run and maintenance can be more difficult because access around the engines is tighter
There are some interesting single engined boats out there; you've mentioned Aquador and Nimbus would be another and you would get a larger and newer boat with a single engine for the same money.
As a starter boat, i would'nt rule out a single engined boat especially when fitted with a bow thruster. You can reduce the risk by carrying a small outboard engine which can be clamped to the bathing platform in the event of engine failure. With proper maintenance, engine failure is a very rare occurence - consider that most commercial vessels are single engined.

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[jhr]

I agree with Depsol that so much depends on where you're planning to keep the boat and what you're going to do with it.

I have 2 small kids and one engine but I'm based in the Solent and wouldn't go out (with the kids, at any rate) in any conditions where there wouldn't be others around to help if things went the shape of a pear. Also, in the Solent it's possible to drop the hook and wait for Seastart (well worth the money) if your engine packs up. Also and finally, a dinghy plus outboard lashed alongside the boat can get you moving. As I say - all fine and dandy if you're in the Solent but pretty useless half way to Cherbourg or being swept sideways down the Bristol Channel.

As a general observation, two engines will always be better than one but won't help much if your shared fuel tank gets contaminated, your engine bay gets swamped, batteries go flat, etc. etc.

Aquadors: now you're talking!

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[h4nym]

Hi Chris

Welcome an' all that!

2 Engines is definately the way to go. Will not only be more reassuring when you're out at sea, but will also make life just a ton easier and more relaxed when you're back in the marina / harbour. Infinitely easier to manoevre with 2 engines than one.

Also go diesel if you can - many fewer opportunities for things to go wrong!

But yes, more servicing / fuel etc.

By the way - don't go consoling yourself that you will only use one when you're cruising - you'll need to use both when underway - only unless you've got a problem with one!

hth

H

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[martynwhiteley]

Although I've just converted to single from twin, I'd have to agree (well a bit anyway!)

Sod's law, but my last boat with twin onld 4108's never missed a beat, and the current one prior to conversion never let me down once underway.

However on my first proper cruise with the new single, it did cut out from 3000 rpm on a fast flowing river (5 knts), a bit scary! Never missed a beat since though, and I conluded it was all down to the fuel return line being too large!

Knowing that it could happen again, has made me lose a bit of confidence in cruising in poor conditions. However losing one's complacency can't be all bad.

On the otherhand, if I was to choose between a twin with no tender, or a single c/w 2.6m RIB and 10hp O/B for the same price, I'm not sure the twin would then be the best option.


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[sfh]

Most breakdowns are fuel related, i have two engines and one fuel tank, if poss for increased comfort look for two diesels and two tanks

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[milltech]

Two engines are easier with some provisos.

They are only easier if they have ram rudders astern of each prop, have two engines with a centrally hung rudder and you have a pig. A single with a centrally hung rudder is very manouvreable in the right hands.

A displacement boat with a single engine will be almost as good as a twin, and in most circumstances a displacement boat of any kind will be easier to handle than a planing boat, more hull in the water, less wind effect.

I have never owned one, but many people will say stern drives are also difficult.

A planing boat with shaft drives will definitely be easier as a twin.


<hr width=100% size=1>John
<A target="_blank" HREF=http://www.allgadgets.co.uk>http://www.allgadgets.co.uk</A>

 

[sfh]

we have twin engine on legs, i think that shafts are in most situations more easy to handle

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[Rob_Webb]

As a yachtie (so what am I doing here?!), I can't get my head around having a vessel with just a single engine for propulsion. It's bad enough when mtoring in a flat calm because I always feel a bit apprehensive because I feel I am already down to my last option i.e. I couldn't sail out of trouble if the donkey died. So setting out every trip like this would make me too nervous, I'm afraid. I know many people manage it well enough but I would have to have two or at least a serious auxilary/outboard ready to swing into action promptly if required.

Just to quote a rather irrelevant but amusing flying anecdote (I'm always doing this, despite it being a boating forum!), when a senior long-haul airline pilot was once asked why he insisted on only flying aircraft with 4 engines, his answer was "because they haven't invented one with 5 engines yet"! Slight paranoia, perhaps, but you get the point.....


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[BrendanS]

So all twin enginers are paranoid?

I'd better stick with the one then as it works so well



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[LiamS]

Its better to be looking at it than looking for it

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[pheran]

I'm not sure the reliability argument for two tanks has much going for it. Lets face it, if you take on a load of contaminated fuel, the likelihood is you will have topped up both tanks any way. And if a 'bug' is going to grow in one, its just as likely to affect the other too, given the proximity and identical environment conditions. As far as I can see, the main reason, in small boats, is that two smaller tanks are easier to accommodate than one large one. I have one large tank and each engine has its own filter but the system is set up so both engines can draw thro' the other filter automatically (and sound an alarm) should one of them get blocked for any reason.

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[Observer]

I think there's a lot of ill-informed prejudice about single engine boats. Two engines is not always "better" than one. Of course there is some redundancy but there's a lot of drawbacks as well - cost, ease of maintenance, durability to start with. A planing boat of a certain size really has to have two engines, but below that size, or in the case of a displacement boat, there are some very good reasons to have a bigger single engine than two smaller ones.

As pointed out, many, many commercial vessels are single engine - I don't suppose all the owners of those would necessarily agree with the "two engines is always better" argument.

As far as the analogy with aircraft goes, when comparing twin engine to single engine planes, the saying is "the only purpose of the second engine is to power the aircraft to the site of the crash".

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[boatone]

Perhaps worth pointing out that, although bigger commercial vessels usually only have one engine, they also usually have trained and qualified marine engineers on board who are well able to cope with anything other than major breakdown. In some ten years at sea on 'big' ships, we had several breakdowns but only one I remember that the engineers couldnt fix resulting in a sister ship towing us to Bombay where we stayed for a month including Christmas.....quel domage or whatever!

I would certainly say that a single engine boater should invest some effort in learning engine maintenance and repair and make sure critical spares are carried

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