Single or Twin Engines: Which is faster?

[ebry710]

I found out the my Marlin can be fitted with two engines. A good reason is to allow for one engine to be used as a kicker. But, after thinking about it, would two engines effect the performance on the boat? So the question for any "salty dog" is. ....... with all conditions the same, do you think two counter rotating, 30 hp engines are slower, same or faster then one 60 hp?

I have heard that the turning radius increases, but the utility of using a single engine as a kicker sound cool.

ebry710

 

[tmcalavy]

Re: Single or Twin Engines: Which is faster?

Depends on many variables, including the knowledge of the person rigging each boat. You'll get several opinions for each option. The best argument for twins is a back up engine when you need it, if you are going out on big water.

 

[tashasdaddy]

Re: Single or Twin Engines: Which is faster?

as said different views on this. you have twice the maintenance. if you are running on the same fuel source (tank), fuel gets contaminated (#1 cause) both motors are effected, you have to consider weight of 2 vs the 1, also the drag of 2 lower units vs 1 with the same HP.

until you get to the bigger off shore boats, i see no reason to run twins. i would rather run one motor with an auxillary trolling motor, 6hp or so, on a separate 3 gallon tank. this way if the main craps out, you have the aux, so you can maintain control, and possible get home, or till help arrives.

this last weekend i had the bolt in the steering linkage comes loose. i trolled back to the boat ramp with my electric trolling motor.

to answer the question all things equal, the single is going to be faster. because things are not equal, you have the drag of 2 lower unit.

 

[Laddies]

Re: Single or Twin Engines: Which is faster?

A single engine when rigged properly is always fastest as twins have double the hydrodynamic drag

 

[kenmyfam]

Re: Single or Twin Engines: Which is faster?

Single wins out because of the drag factor. Small troller would be a good back up.

 

[steelespike]

Re: Single or Twin Engines: Which is faster?

I think in 07 most 30 hp were 4 stroke about 160 lbs. The evinrude Etec 2 stroke 60 is 240 lbs.obvious weight advantage.plus the single is cleaner through the water.Older setups say 88 weights are a trade off.because the 30 hp is lighter.

 

[lmannyr]

Re: Single or Twin Engines: Which is faster?

Everyone is right on. Nothing to add. Good luck on your choice.

 

[ebry710]

Re: Single or Twin Engines: Which is faster?

In summary, weight and drag seem to be the answer to the question. Turning radius, maintenance cost, common fuel contamination problems and extra set-up cost add to the my selection of a single higher horsepower outboard with a 6 hp kicker.

Thank you all
eBry710

 

[kenmyfam]

Re: Single or Twin Engines: Which is faster?

Wise choice

 

[Frank Acampora]

Re: Single or Twin Engines: Which is faster?

Well, Not So Fast! Think about this: If you are going long distances or say offshore (although I wouldn't expect that with twin 30s) You just might want to consider two equal sized engines for the reliability and power factor.

While it is unlikely that ANY engine will quit on you, if you get into situations where you absolutely must have power to maneuver or a decent turn of speed, then the insurance of a twin installation may be adviseable. And, properly set up twins are not 10-15 mph slower. Yes, you have more weight and drag, but the speed loss is not so objectionable over a single installation.

It is unlikely that both engines of a twin installation will quit at the same time. A single larger engine of a pair will get you home a LOT faster than your itty-bitty kicker.

And then there is aesthetics: Some of us just LOVE the sound of twins singing. I have a single 140 on the back of my 21 foot cuddy. If I had the room for them, there would be twin 75s

 

[kenmyfam]

Re: Single or Twin Engines: Which is faster?

Well, Not So Fast! Think about this: If you are going long distances or say offshore (although I wouldn't expect that with twin 30s) You just might want to consider two equal sized engines for the reliability and power factor.

While it is unlikely that ANY engine will quit on you, if you get into situations where you absolutely must have power to maneuver or a decent turn of speed, then the insurance of a twin installation may be adviseable. And, properly set up twins are not 10-15 mph slower. Yes, you have more weight and drag, but the speed loss is not so objectionable over a single installation.

It is unlikely that both engines of a twin installation will quit at the same time. A single larger engine of a pair will get you home a LOT faster than your itty-bitty kicker.

And then there is aesthetics: Some of us just LOVE the sound of twins singing. I have a single 140 on the back of my 21 foot cuddy. If I had the room for them, there would be twin 75s

Remember, the original question was "single or twin motors, which is faster"

 

[red85k100rs]

Re: Single or Twin Engines: Which is faster?

I don't know the answer. But i thought i would pipe in because I am about to start my twin project.
I have a 14' alumacraft row boat. I have had a 1968 johnson 20 on it for 2 years.
Well I picked up an exact same motor. so I am going to try to put em both on. They are light enough that I think I can make it easy on/off so the twin setup would only be for fun and the single for fishing.

any thoughts. someone must have done this before. I can't be the only crazy one out here

 

[dingbat]

Re: Single or Twin Engines: Which is faster?

Remember, the original question was "single or twin motors, which is faster"

Well...twin 250s would certainly be faster than a single 300

 

[noelm]

Re: Single or Twin Engines: Which is faster?

OK here goes, I have fitted heaps of twins and singles, so, if HP is equal, as in (say) 2 X 100HP compared to a single 200 then the 200 single WILL be faster, no question about it, BUT if the two were to be allowed to compete in a "tug of war" then the twin 100HP will win easily, the twins will also be able to push a much heavier load at a more constant speed because of the added torque availble, but the answer to the original question is YES!

 

[ebry710]

Re: Single or Twin Engines: Which is faster?

Thank you. That does answer my original question. Use a single outboard for speed and duel outboards for power. Thank you all for a great forum.
ebry710

 

[JustJason]

Re: Single or Twin Engines: Which is faster?

what do you mean use dual for power????????????
A single double the HP will always be faster than twins.....
Twins+ are for bigger boats....
or for smaller boaters wanting more peace of mind.

 

[kenmyfam]

Re: Single or Twin Engines: Which is faster?

Well...twin 250s would certainly be faster than a single 300

Back to the original question again. Twin 30hp outboards or a single 60hp outboard.

 

[noelm]

Re: Single or Twin Engines: Which is faster?

I guess when it is all said and done, I don't think two small Engines (30HP) is really worth all the trouble, just fit a single 60HP and be done with it.

 

[Solittle]

Re: Single or Twin Engines: Which is faster?

Well lets see noel if we have like boats and you are runnin with a 60 and I am runnin with twin 30s and one engine quits on both boats - - who is gettin home faster?

 

[ebry710]

Re: Single or Twin Engines: Which is faster?

Noel:
We had decided that a single outboard is more practical in this situation.

"In summary, weight and drag seem to be the answer to the question. Turning radius, maintenance cost, common fuel contamination problems and extra set-up cost add to the my selection of a single higher horsepower outboard with a 6 hp kicker".

I was originally interested in the speed issue and the single engine was decided to be faster. The dualie seems to promote more power.