Twin engines

[Palmtree]

Hi,

With a twin engined boat, for river speeds, will it run on a single engine or will the off center thrust of the prop cause a problem?

Ian

[wayneakp]

Hi there

I can only comment on shaft drive boats but yes it will run on one engine but you will have to apply a little rudder to compensate for the off centre leverage. Be aware though that the prop on the non running engine will cause the shaft and hence gearbox to rotate as you move thru the water. Some gearboxes apparently do not like that.

hope that helps

Wayne

[Guest]

Also, possibly, ( I have no experience of this myself ), the props should be of the correct pitch for the pair to be running.

If only one is running, then it's running with half the normal torque available for the same mass of boat to move at any give engine revs/speed.

Exactly the same as "over-propping" a single engine, which can be quite damaging.

( IMHO )

I'm envious really, my boat is only a single....

[Antares_9]

You will get a bit of offset thrust Ian, but run alternatively to keep the hours ballanced and you should be OK short term, as Strowie says some do not like freewheeling. All in all I would suggest smaller props for long term river use would be a more appropriate solution, unless you have turbos to load up that is.

[Palmtree]

Hi,

Thanks for the feedback, plenty of food for thought....

Ian

[diesel falcon]

Another factor is (as with my boat) some power streering systems depend on one engine only,meaning the steering is very heavy if that engine is off and it,s very difficult to get the the boat to go where you want at slow speeds ,putting the gearbox in gear will stop it auto rotating

[senator]

Clanny is happier running one engine on the rivers. Goes straighter, possibly due to a few more revs giving better directional thrust as she is on duo prop outdrives.

Doesn't like to turn in the direction of the running engine though so starting the other one up for moorings.is a good idea.

Does save about 1 1/2 pints of beer an hour in monetary terms.

[Palmtree]

With the single engine low speed steering issue, by dropping one of the trim tabs on the running engine side will the drag act as a secondary rudder?

Ian

[Jim]

Twin tabs and twin engines Ian? Not going salty are you?

[MY littleboat]

With the single engine low speed steering issue, by dropping one of the trim tabs on the running engine side will the drag act as a secondary rudder?

Ian

Dont forget what a trim tab does as opposed to a rudder (or outdrive)

Rudder (or outdrive) primary effect is to yaw the boat, the secondary effect will be roll

trim tab - Primary effect roll, secondary effect is yaw

Although running a single tab down it is more likely to make the boat list but secondary effect will be to to correct the yaw so you will just crap along. However, physics aside, at river speed all this is fairly negligable and you probably wont have to use a tab.. just accespt that the boat will travel at a slight angle through the water!

[Guest]

so you will just crap along.

"Best Freudian slip of the year award"

One prop stopped, one tab down, boat listing, extra drag and fuel consumption, = "crapping along"....

[Jim]

It might catch on as a new "nautical expression"

I think Gavs IPhone smells as badly as mine does, or is it a case of fat finger syndrome?

[senator]

Hi Ian, don't think the tab would make any difference at all to the steering issue, for one thing they have virtually no effect at rivet speeds and for another the poor turning in one direction is because the thrust is being applied out of centre. A twin engine boat turns more easily than a single even without using opposing engines as long as you are turning in the opposite direction to the running prop, try to turn in the same direction and it is working against you.

It is only moorings where it will cause you a problem though and running just the one engine equates to a saving of £4 an hour on the rivers with Clanny.

[MY littleboat]

I'm not sure if that was a freudian slip or a fat finger... anyway gotta shoot, dying for a crab!

[Palmtree]

Twin tabs and twin engines Ian? Not going salty are you?

No plans for the salty bits.

It might be easy to go out there, and this type of boat looks able to handle some limited conditions, but with no training or experience it is not fair to expect others to come to your rescue and pick up the pieces. Many years ago I used to work with some volunteers on the Lowestoft Lifeboat and appreciate what they do and encounter.

Back to the topic.

When we took our new boat on the river trial we tried both engines on single running and yes a bit of rudder was required to compensate for the thrust. This was not a problem. What did surprise me was how well you could handle the boat on the two throttles for slow speeds and not use the rudder.

Ian

[pks1702]

Twins give you the ability to steer with the engines Ian, at low speed this will come into its own for you.

[Palmtree]

Hi,

It looks like when the boat was re-engined both shafts rotate the same way. The river trial or the low speed work on tickover did not show up any problem, however we have not had to moor it yet.

Ian

[diesel falcon]

Best way to get the hang of it(don,t think i,ve mastered it all yet...i havn,t!!)is to go to the middle of a broad and practice ,best on a windless day :that way your not under the gaze of the expert skippers on the bank!!

[MY littleboat]

Ian

Having thought about this for some while, I can guarantee a number of things. Having two engines will have at least the following effect: It will double your oil expenditure, your spark plug and lead expenditure, it will increase the swearability modulus in that the reduced space in the engine compartment will invariably mean that you have less room for your elbows and more importanatly your head to fit into. You will then have two engines to listen to when you suddenly get an attack of 'Skippers Super-Hearing' whereby even the smallest whine will have to be verified. Invariably the time will come when one engine for whatever reason refuses to start and this will mean that you will call off your journey a few hundred metres up river whilst you completely ignore the fact that 90% of the other boats on the river only have one engine anyway. You will invariably put the wrong engine for'ad as the boat neetly pirouettes away from the mooring you were aiming for, and likewise whilst stern mooring, the same effect will inevitably turn your stern moor into a side-on! As well as your oil and possiblt fuel costs doubling, so will your alchol intake as I cannot explain, but in recent years the amount of Fosters/Carlsberg and wine we get through has increased umteenfold (We do however have a crate of Carling knocking around somewhere at a very reasonable cost - (which I keep next to the remnants of a very expensive set of champagne glasses... well expensive to me). With the added edition of engines, your cruising buddies will also change. Whereas guys who used to wave at you majestically as you sailed past in your half-decker thingy will still wave, only now use less fingers! Your new friends, having got to the 'pub' in the time that takes to get there instead of the previous few days 'hell and high seas' journey, will ensure that you have sufficient alcholic intake that will ensure you will be 'checking your fenders' far more frequently than before and you will no longer be able to decipher why the other people in the pub, when you were a saily and thought they were all drunkards, suddenly seem quite normal! And lastly, don't forget, your new Broads toll will include the unwritten rule that you can now run a several hundred metre extention cord to an electric point in order to keep the sound system pumping out the tunes to any hours of the morning!

Welcome to the real world of boating

Oh and I nearly forgot.... (for those that remember..)

Bachman Turner Overdrive....Let's Rock!

[MY littleboat]

So Ian. What's the latest?

[Palmtree]

Hi,

Not much going on as we are waiting for the boat handover at the end of next month. One thing that has been sorted is the new name of the boat.

Peccatrix

Ian

[Antares_9]

One thing that has been sorted is the new name of the boat.

Peccatrix

Ian

I just hope people don't see that as some kind of invitation Ian

[Palmtree]

I just hope people don't see that as some kind of invitation Ian

Twin Diesel, American built, sea going, unable to get under potter, owned by an ex sailing boat owner and on the Broads!

If that is not a sin I don't know what is.

Ian

[Guest]

Twin Diesel, American built, sea going, unable to get under potter, owned by an ex sailing boat owner and on the Broads!

If that is not a sin I don't know what is.

Ian

you want some ballast ill get you under

[Brian]

Twin Diesel, American built, sea going, unable to get under potter, owned by an ex sailing boat owner and on the Broads!

If that is not a sin I don't know what is.

Ian

Ian i cant believe im reading this !! You were a Saily man, everytime i saw you on the Broads you were Tacking

Whats with the change ?