Cross Channel, Single Engine

[Stoshak]

Advancing in years, we are thinking of moving from sailing cruiser to mobo. We are Solent based, but usually cruise to CI and France at least once a year for a month or so.

When crossing the Channel, or transitting Cherbourg to StPP, we use the engine, motor sailing as a rule. So if the engine fails we can sail.

Twin diesel cruisers seem to be very much more expensive than singles. So my question is, what are forumites opinions on the suitability of single engines for cross channel cruising.
Not in rough conditions, of course.

Thank you.

 

[Geoffs]

Did my first crossing to StPP the weekend before last. Single engine Volvo D4/260 in 25ft boat.

No problems. Always make sure engine well looked after and prepared, serviced etc. Thoroughly check over engine before departure, don't go if anything amiss or worrying.

I ran mine up at boatyard and checked it over, anything obvious, oil leaks, water leaks etc. Then ran it under load and re checked.

I went with someone else (Duncan from hereabouts) and would always try and go with another boat, just in case. But modern diesels are pretty reliable (I might regret saying that /forums/images/graemlins/frown.gif ) , I'd think twice about going with a petrol engine. In fact I did, as I used to have a petrol boat.

 

[Whitelighter]

With any boat, you should be prepared to do some on the spot repairs if required, and it would be worth aquiring the basic know how to do so.

The main things that stop an engine are blocked strainers, belts coming off etc etc. All *can* be changed at sea.

The biggest cause for problems is contaminated fuel though. Quite a few twin engine boats only have one tank, so if fuel is your problem having a second engine isn't going to help as your fuel comes from the same source.

I don't see a single engine cross channel as a major problem, go prepared, take spares but learn how to make basic repairs/change filters competantly before you go. After all, you are never more than about 30 miles from land.

 

[nedmin]

The benefit of a single engine is that as its more accessible it is easier to maintain.Whats more dangerous losing your engine in the outside lane of a motorway or 1/2 way across the channel? Assuming youve picked good weather.

 

[thefatlady]

If you can run to twin engines, do.

If not, and assuming your boat is not too big, take a spare outboard just in case. You can't row the boat. If you never need it, that's great. If you need it just once, you will be sooooo pleased you got it.

Even 5 miles off shore is a long way if you have no engine.

 

[Nick_H]

I think the problem is not so much single engine as single prop. There's so much crap floating in the channel that its only a matter of time till some of it winds round your prop. If going single engine on a shaft I would have a rope cutter fitted, not such a problem with outdrive cos you can lift it to clean it.

That said you can't argue with the maths, if there's a 1 in 100 chance of one engine letting you down, there's a 1 in 10,000 chance of two doing so (fuel problems aside). I know which odds i'd prefer.

 

[TigaWave]

Most fishing boats seem to only have one engine...

 

[landlockedpirate]

Done lots of open sea stuff with a single engined, petrol boat including Alderney and Guernsey. Longest trip was 150NM from Barcelona to Menorca.

As long as the boat is well maintained, you have ample safety equipment onboard and you have sufficient experience I cant see a problem. However I have always done these trips in company and as mentioned above the only problem we had was picking up some rubbish round the prop coming out of Cherbourg. Having another boat alongside for moral support and assistance was a great help (But not as much help as the superb divers knife Wifey had bought me for Christmas /forums/images/graemlins/smile.gif )

People think petrol boats are less reliable, but I'm sure its down to maintenance, rather than design, when engines fail. Having said all that I would prefer a diesel boat if one was available.

Mark

 

[oceanfroggie]

This has been an interesting question and there are many ways of looking at it.

One well maintained engine is likely to be more reliable than two badly maintained engines. On the one hand there are half as many things to go wrong if you only have one engine (told that by a 747 skipper when he switched to A330 on the transatlantic run, ie from 4 to 2 engines), and on the other you have backup if you need it. As has been suggested rope cutters on shafts for single or twin are essential. The entire commercial fishing fleet that fish the UK waters in winter storms are only single engined boats and they seem to manage quite well. Generally twins give speed and manouverability, but a single with a bowthruster is just as manageable. Singles are likely to be displacement speeds so longer passage but fantastic range and fuel economy, which is not a problem in settled conditions.

We switched from single to twin shafts some years back, and I have to say I do like the perceived 'comfort factor' in my head at times.

Noel

 

[rickp]

[ QUOTE ]
That said you can't argue with the maths, if there's a 1 in 100 chance of one engine letting you down, there's a 1 in 10,000 chance of two doing so (fuel problems aside). I know which odds i'd prefer.

[/ QUOTE ]

I don't think you can make any such a claim. You'd need to analyse failures on twin boats vs failures on single - you can't just multiply the odds as they're two different systems.

Rick

 

[MapisM]

[ QUOTE ]
you can't just multiply the odds as they're two different systems.

[/ QUOTE ]
Why? If you strictly look at the chances of a major engine fault (and not at other things like fuel, electronics, etc.), then I'd rather agree with such calculation.

 

[andyball]

Ha, I wouldn't

if 1/100 of one engine failing, the odds are still 1/100 for the second.... otherwise 5 reds in a row'd be a sure-fire bet for black at roulette wouldn't it?

 

[Whitelighter]

Yes, but the odds for both to change are different.

The odds for red on one spin of the roulette table are 1:2
The odds for red on the second spin are still 1:2
But the odds for both spins to be red are 1:4 (called before the fist spin takes place)

 

[oceanfroggie]

What are the risks?<ul type="square">[*]Fouling shaft or shafts - more likely both if net or rope
[*]Mechanical failure of one engine
[*]Broken hose on engine flooding boat (two engines twice the risk)
[*]Engine fire (two engines twice the risk)
[*]Fuel contamination - will take out both engines if from same source or supplier
[*]Steering failure - two engines can be good to get home
[*]Aground - single engines with skeg no damage
[*]Touch bottom - single engine escapes - twin screws - ouch!
[*]Caught in bad weather limited to displacement speed
[/list]

 

[rickp]

Yes, but you're talking about discrete probability there and I don't believe that you can make a similar claim for engine failure on a single vs a twin.

Take the Angela Cannings case - probability of cot death in a family was 1 in x. Prof Meadows made the same logical step as is being made here - if the probabilty of 1 death is 1 in x, probability of two deaths is 1 in x*x - ie. much more unlikely. He was wrong because that assumes there are no other factors at play (such as genetics), but getting your head around this stuff is tricky.

My view is that its the same in the twin v single debate. Theres too many other factors which influence things. You could make that claim if the three engines where on the same testbed, same fuel, same power, same loads etc - then fine. But once installed, experiencing different loads, cooling, maintenance, air flow, etc. etc. - all bets are off.

Rick

 

[Stoshak]

There is much in the way of self - help to be done. So cooling system failures, fouled props and so on may be amenable to en-route fixing.
The worrying thing is primary engine failures - mechanical valves, crankshafts etc turbos and engine computers.
As a matter of interest, is it possible to fit an emergency outboard or do the bathing platforms etc prevent it.

 

[Whitelighter]

I agree with you. My point was specific to the roulette example highlighted by Andy - that probability changes depending on what stage you choose to calculate it.

 

[Stoshak]

When I was still waged, before becoming old and frail and contemplating powerboats, I was much involved with safety of systems with lots of statistical input.
The Numbers Game. Ah yes - the last stronghold of the snakeoil salesman's smoke and mirrors. Just try a quick spin round the track with a Boeing, Airbus or GE representative and you'll see what I mean.
Anyway, enough of all this, we need to proceed further with my problem.
I have been sufficiently encouraged by the kind and helpful responses so far to start another thread entitled 'Suitable cruiser / sortsboats for Channel crossing on a limited budget'. So further inputs will be gratefully received.

 

[duncan]

[ QUOTE ]
If you can run to twin engines, do.

If not, and assuming your boat is not too big, take a spare outboard just in case. You can't row the boat. If you never need it, that's great. If you need it just once, you will be sooooo pleased you got it.

Even 5 miles off shore is a long way if you have no engine.

[/ QUOTE ]

I love these questions and answers........

Generally speaking you are talking smaller boats with one engine. When they are down at 21ft or less a small OB doubles for the tender, the fuel is more likely to be petrol in the main engine so you can realistically make progress and have enough fuel onboard to actually get somewhere (eventually)
At 25ft or so (which is a common single diesel size that people 'cruise') the natural tender OB size of 4/5hp is great on a tender but pretty crap on the transom - any breeze and tide and you are only going one way! Equally the OB will be petrol and the main engine probably diesel (all the boats I have cruised in company with have been anyway but I accept it's a generalisation) - so unless you are carrying a large amount of petrol you simply aren't going to complete your journey under your own power - even given the above considerations.

Increasing electronic engine controls and components is a worry and was the main driver behind my choice of a Yanmar - no electronics. If I loose the turbo I am still going to outperform my back up. With a drive I stand a chance of clearing any netting etc that could create a much bigger problem with a shaft.

I am more worried about being out alone (single handed) than being out with one engine in the channel waters - although I have made a number of crossings without seeng another small boat I, or crew, can reach Portland CG from St PP on the vhf.

I don't set out with the intention relying on anyone else for support but if I really need it it's there. I carry an extensive spares and tool kit (weighing about the same os the tender OB!).

I carry enough anchor gear to anchor anywhere but the hurd deep , enough food and water for months so if I loose the engine and the radio I can eventually make landfall using the tides and handbrake- well close enough that I can use flares!

I agree Rick's underlying point about 'odds' - the reason for the first falure may well have a significant bearing on a possible second; maintenance and checks are pretty key to marine gear.

Last year Phaeton did 3 unaccompanied channel trips - 6 crossings - around Poole / Alderney/ Guernsey / Cherbourg. Are my odds of a gear failure, incident, next time higher or lower than for the first time?!?

Finally, and to emphasise the OB thing, my first crossing last year (a Tuesday in early May) was in a S6 taking just under 7 hours Poole to Braye - OB would have been about as much use as an egg beater.

 

[Nick_H]

I agree the maths in my previous post doesn't quite hold true as some problems would affect both engines, but the principle still does

Take a look at the post "engine died!!", just been posted. They had two engines so carried on with the other one and got home fine. I've lost an engine that couldn't be fixed on the spot twice (nylon sack round prop in choppy sea once, other time engine blew up due to raw water blockage). We got to a marina on the other one then called the engineer. If we'd been on one engine it would have been coastguard rescue both times, and one was mid channel with associated delay, traffic, rolling, sea sickness etc.

Like the example about the jumbo, notice he moved to a plane with TWO engines /forums/images/graemlins/grin.gif