Twin over Single

[BarryD]

Sorry to re-hash an old argument have I got all the information here...

Twin - Pros
Redundancy, Low speed manouvering, Relaxed higher speed cruise - lower stressed engines

Twin - Con
Initial cost, Weight, double the fuel burn, servicing complexity

Much obliged.

Barry D.

"No, No, no - come off the plane before entering the lock..."

 

[byron]

Single screw one engine stops "gissa tow mate"
Twin screw one engine stops no "gissa tow mate"


ô¿ô

 

[paulineb]

Another pro

If one breaks down you always have the other one to come home on.

With one engine you have to come back on a wing and a prayer and get the oars out.

Pxx

 

[Geoffs]

Don't think you'll double the fuel burn. If you need 300hp to push the boat along, broadly, you'll burn the same with one or two engines. You will burn a bit more with two engines, extra engine internals/gearbox to drag round, extra under water drag with leg, shaft, props etc.

 

[KevB]

A nice sound when they are running in unison and double the wash to pi$$ of our raggie friends. ;¬)

 

[Deleted User YDKXO]

Not necessarily lower stressed. Two small engines may be more stressed and certainly more noisy than one large one. Larger engines tend to work at lower rpm
Sounds like that bet is going to be lost

 

[BarryD]

Ahh Appealing.

Ahh now thats appealing, vroom vroom - too many V8s in my life anyway.

Barry D.

"No, No, no - come off the plane before entering the lock..."

 

[ccscott49]

If you have isolated twin fule tanks, and seperate batteries for each engine, you really do havre belt, braces and a piece of string!

 

[petem]

don't forget resale.

IMHO:
Below 28ft one engine
Above 28ft two engines

Argument for getting home not always that clear as many smaller boats can take an auxillary outboard e.g. Cranchi Turchese 24.

Argumant for low speed handling also not that black and white. Is a single with bow thruster inferioir to twin without?

 

[hlb]

Well beside s it being better with two, it's just a load more fun. Just like having two wagley thingy's. Pauline would not know which way to look!

Haydn

 

[toobaz]

Re: Twin over Single.....more power!

At the end of the day, you have more of the fluffy feeling factor with two, as everyone says, if you loose one you still have the other to fall back on and the chances of getting home safe and sound.

Barry

 

[lanason]

AH but

Well how come all raggies seem to agree on a SINGLE engine - ever seen a raggie with twins. Well twin kids maybe but not engines.
If the boat is trailerable and inboard then only choice is single -maybe twin outboards but ..........
So its Single for me and an aux Just In Case

Adrian )

 

[ToMo]

Wots a wagley thing? nm

.

 

[boatone]

Re: Oh dear..................

..turning 40 must have addled your marbles Adrian(?).....on a raggie boat the raggies ARE one of the means of propulsion so they only need small stinkyrevrevbrrmbrrm as back up..............gerrit?

TonyR
boatone@boatsontheweb.com
www.boatsonthethames.co.uk

 

[ccscott49]

Re: AH but

Not all raggies, depends on how big the boat is and what its used for! Mine has twins, so does my brother and quite a few other peeps I know. I also have two sticks and lots of rags, which of course are the other "main engines"

 

[mtb]

Well lets look at all the evidence ,
Most mfv and working boats that dont require high speed go for a bigger and longer lasting engine, because of lower revs they tend also to have a bigger gearbox with a lower gear ratio gear box, my tug has a 3 to 1 ratio.
Fuel economy well that speaks for its self
I think that its actually quite rare that an engine that is looked after
*properly *
breaks down completely and with out any warning .
The engine space to be honest is still about the same for a single or twin ,certainly if the space is under the floor because there will be other things built in as well .
The only time it becomes an issue is when the engines are boxed in and your living space surrounds them then of course singles are better.

high speed its always twin engine .
Better handling ,
That's if the person in control knows how to use and can actually control the boat to manoeuvre .
But two times every thing twice the servicing cost two electrical systems two fuel systems two gearboxes ,two shafts / out drives , two water intakes or bigger for the pair , bigger fuel capacity needed more batteries for starting
some times it can be quite difficult to synchronise both engines which of course goes out the window when one propeller gets a knock.
If its petrol's then after the engines have run for a few years then it can be a constant battle to get them to synchronise,because chances are the carburetters will be worn differently .
None of us go out to sea with an engine that needs work or has a fault that could develop into a complete break down , so all this twin get you home stuff !!!
I firmly believe most problems only occur after servicing !! bet that get a response but I say that after most of my working life dealing in mechanical engineering and have read just that on here quite regularly.
Bet you expect me to say I'd vote for single engine but nope I think it depends on what your own requirements are.
MIck




http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v/cheep or swap for tug

 

[ccscott49]

Mick,
A lot of people go to sea with a defective engine (even if they dont know it), the RNLI figures show this, most of their call outs are to defective engines. I don't go to sea with a defective engine, obviously neither do you, but we have to consider others without our technical knowhow and anything mechanical, will breakdown! even if its due to crap fuel. Anything electrical has a duty to screw up!!! There are also a lot of cowboy mechanics out there, you have your engine serviced, you are a mechanical nitwit and it breaksdown, whos fault is that? you hired the guy in good faith! Twin engines for me, completly separate fule systems, with cross overs and return crossovers, seperate batteries and an emrgency tank of known clean fuel. Twin separ filters with crossovers on each engine. I dont need the RNLI for an engine breakdown, I hope!!!!! Plus of course two masts and sails!

 

[DepSol]

Have a single and no probs about asking for a tow if it goes pop.

It is well maintained annual service, plus half yearly checks. So anything normal can be picked up quite easily and oil changes done twice yearly except for outdrive only annualy.

Fuel contamination is never going to be a problem cos the Soltron is always added to the fuel.

Therefore down to bad luck however, if it goes tits up I will drift and radio for help. If I am drifting towards rock I'll drop the anchor and radio for help or worse case drop anchor stick the 3.3 on the dinghy and motor to safety to then get a tow.

Usually someone around in the CI even if it is a fisherman.

So quite happy with a single.

Dom

 

[lanason]

Re: AH but

Yours must be a Stinkpot with rags then !!!!!!

Adrian )

 

[lanason]

Re: Oh dear..................

I am an Engineer, got a BSc in it, to prove it and I know what an engine looks like - it has metal bits and bits that go round and round and bits that go upy and downy. Rags are things that wifes spend all our money on and they wear them.
So dont be a silly billy.

Sandra Dee


Adrian )