Single or Twin engines

D3B

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This is likely to upset a few people.

many of you know i have new SC29 due mid April.

now i am starting to think single or twin engines.

i am not interested in the extra speed from the twins but ask fellow forumites for their humble opinion.
single D4 260hp with bow thruster
or twin D3 160hp no bow thruster

Doug
 
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Deleted User YDKXO

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Advantages of twins
- Safety if one engine goes down
- Slow speed manouevreability
- Resale
Advantages of single
- Cheaper
- Easier and cheaper to maintain
- Possibly less noisy

If your budget stretches, I would go for twins but I dont think a single would be a problem on a boat of this size. Just make sure the bowthruster is as powerful as you can get (check with the manufacturer) and you've got a bracket on the transom for a get-you-home outboard
I would also check with Sealine what proportion of SC29's are being sold with singles. You dont want to be the only one buying the boat with a single otherwise it will be difficult to sell the boat on when you want rid
 

jimh

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I too had the same dimema 2 years ago - in the end opted for the single. I chose the single in the end (KAD 300) because i liked the 'feel' of the EDC and the boat was obviously cheaper. My primary concern at the time was the reliability of just one engine - especially on extended voyages (cross channel etc).
Having had the boat now for 2 years, I am absolutely delighted with my decision - coupled with the bowthruster ( a MUST with a single) manoevarability (is there a spell checker tool anywhere??) is fantastic, maintenance costs are lower but the most important thing is engine access - with one engine and the concern of engine failure, I am confident of being able to change fuel filters and belts at sea with masses of space available all round the engine.
I have read many reports of twin inst boats being disabled picking up rope and fowling both props that I personally feel the obvious perceived advantage of twins is probably actually significantly less than reality - It would be interesting to read into the stats.
I personally would not recommend bolting an outboard bracket onto your boat for several reasons - you would probably need at least a 15hp to make any sort of headway - none probably into a tide - and they are not light - then you need to store it and its petrol and that's not to mention the asthetics !!! - better to radio for a tow........all INMHO

By the way - if your boats being delivered in April - surely its spec'd out by now ???
 

D3B

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Thanks Jim
yes she is spec'd but build time is supposed to be 5 weeks so i may have asked the question in time.
think i might get an engine course under me belt!
Poor girl at Burton Waters didnt seem too happy that i was asking for change /forums/images/graemlins/blush.gif

SWMBO doesnt know yet, so i might not get permission to add the cost.
im sure i can persuade her with safety issues /forums/images/graemlins/smile.gif
 

Nat

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Hi there
having had the pleasure of breaking down twice, once about 8 miles out & having to limp back (night) on aux outboard at about 2 knts. Second time in heavy swell. about 300 metres off rocks, outboard useless, so dropped hook & waited for tow. My advice would be twins. Safety is paramount & I think if you are going to do any serious distance on your own a single engine is out of the question, I,ve just changed boats mainly for this reason
Singles ok if you are just going for short trips in company & there is always someone on hand to help. Its not funny when you break down at sea with nothing in sight especially at night.................Nat
 

DavidJ

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Just to add to your cost. Seriously include the bow thruster if you go for twins. Maybe if you had the opportunity of shafts it would be far less an issue but with stern drives and duo-prop you don't get the control (unless you are really experienced!) especially with a side wind.
Come the day your sell on value will be better as well.
David
 

LittleShip

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One of the largest fleets around the British Isles is the fishing fleet and to the best of my limited knowledge they have single engines. There is noting wrong with one engine if you look after it. Most diesel engine problems are fuel related so it wouldnt matter if you had three engines, most petrol engine problems are ignition.
Thats the way it looks from here !
 

Nat

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Hi Jim
The 8 mile out one, The risers & manifolds started leaking water internaly causing the engine to hydraulic, fortunatly did not wreck the engine, only the starter when I tried to restart.
Second one was the drive shaft in the leg sheared. just 50 hrs after new gear set fitted, no warning sounded like I picked a rope up lifted leg to have a look but everything fine dropped it back down put it in gear & crunch nothing.
Decided then enoughs enough. Two engines required.......Nat
 

jimh

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OK - not sure if the first one could have been attributable to poor maintenance - the second one definitely a good case for twins and I am sure that there a many similar examples too. The point I am making is - with a good (new in my case), and well maintained engine it maybe more of a 'perception' that you have greater reliability at sea.
 

rickp

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Indeed. Our next boat is a single engined 45'-er. Got very very good engine access and dual racors with water alarm etc. Prop is well protected behind a keel. They've made 140+ of these boats, and have fitted 2 with a 'wing' engine (with saildrive). So far, we've not opted for that (although there is still time).

I think if you go single engine, you want to carry more spares, know what you're doing with them, be slightly more circumspect in your choice of routes and carry more anchor chain. I plan on kidnapping Col too /forums/images/graemlins/wink.gif

Rick
 

wakeup

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Although with two engines you are twice as likely to have a break down and twice as likely to get a fouled prop?? So you are more like;y to need the second one ;-)

So you had better practice driving on one, most twin engines perform attrociously on one engine...
 
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Deleted User YDKXO

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The recent Nordhavn rally got 18 boats across the Atlantic without engine failure and most if not all of them were single engined. I think, though, it's worth mentioning that there's a big difference between the low revving, non turbocharged diesels fitted to long distance displacement boats and the high revving, turbocharged diesels fitted to the average planing boat. IMHO the latter are bound not to be as reliable as the former so the choice between singles or twins is more difficult on a planing boat
 

wakeup

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False Sense of Redundancy

Most people buy twin engines under the false belief that they have some resundnacy built in to their boat in the event that one engine fails.

Most engines failures on not usually mechanical, most are fuel related, electrical or sterring related.

So unless you also fit completely independent wiring systems, fuel systems, steering systems and throttle systems then you are kidding yourself.

Statistically the most reliable configuration is a well maintained single diesel engine.
 

rickp

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To be fair to the NAR fleet, I think only one boat was singled engined, and every other boat had a wing engine. If you're heading 1k miles offshore, I think a wing engine makes a lot of sense. From the DVD, the only times a wing engine was used was a fuel problem and a rope-around-prop on the non-Nordhavn (though I could be misremembering).

Point taken on the turbo v non-turbo engines. A similar point about legs v shafts I think (with the more vulnerable & complex gearbox arrangements on legs). Its all a complicated trade off.

Rick
 
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Deleted User YDKXO

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Re: False Sense of Redundancy

Again another bit of received wisdom. From memory, I've had 5 instances of having to limp back to port on one of two engines, twice for fouled prop on one side and once each for running out of fuel on one tank (self inflicted), failed engine mountings and failed drive belt. None of these were fuel related engine probs. I dont agree that there is no redundancy in having 2 engines. Generally there are separate fuel tanks with separate feed/return lines and filters with a shuttable cross over pipe. Throttles, especially mechanical ones have a high degree of separation, charging and battery systems are also largely separated. Steering is about the one system where a failure probably affects both sides. So, whilst there is not complete redundancy or independence, there is a substantial degree certainly enough for people like me to favour 2 engines over 1
There is another point as well. Statistically, a single engine may be more reliable than either one of a twin engine configuration but that is not a valid comparison. The correct comparison is to compare the statistics for single engine failure against double engine failure in a twin configuration because both mean complete disablement and I bet the latter is less common
 

milltech

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I think cruising range has something to do with it too. Although none of us wants to call out the RNLI or bleat for help on the radio, if you're summer crusing on the south coast an engine failure is going to mean little more than a minor inconvenience and a chance to experiment with the anchor.

Then again, most modern boats don't have marine engines in them, so they are as susceptable to electrical failures as the trucks they're borrowed from.

If you plan to be a frequent crosser of the channel, and if like me you're hopeless mechanically, then I'd go for two. When I had a single, only a snapped throttle cable gave me minor heart failure of Cap de la Hague. However I was always very aware of my own limitations, especially after nightfall in mid channel, then I listened to every beat.
 
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