Outboards, 2x140 or a single 250, which is best?

[damon]

I'm looking at two almost identical boats, one has a single 250 suzuki, the other has two Suzuki 140s. Does anyone have an opinion on which might be better and why?

Things like Servicing costs vs safety of failover power vs weight vs performance vs handling.....

Advice please!

 

[Kawasaki]

Damon, be interesting to know what the boats are.
Plus what use You intend to put the eventual purchase to.
You never know on here, someone might have a similar set up/ make etc.

 

[No Regrets]

You know the answer already by the sound of it.

The Twin engine setup is going to offer a failsafe in the ocean (And it's obviously not a River boat is it?) at twice the servicing cost and a probable 25% increase in fuel consumption.

The good points should be less torque effect under power assuming you have the LH/RH prop setup, a slight performance gain and the priceless safety thing.

If you can afford the twin engine boat and its associated costs, go for it.

However, I am a novice, so somebody will come and trample all over this theory soon..... /forums/images/graemlins/frown.gif

 

[damon]

Interestingly, the twin engined boat is cheaper.

 

[ccscott49]

I'd go single, single everything, you can always have a wee get you home motor. Twins, double the servicing, higher fuel consumption, more weight, double everything to go wrong. A good single would do me.

 

[Steveu]

I'm no expert but opinion on outboards for RIBs is firmly for the single engine. They say that 2x140 won't push you through the water nearly as fast as 1x250 and the shortfall is said to be as much as 30%. Inquire on rib.net forum for people who have actual experience of this. Basically it seems to split into people who fit a single engine 'cos that pushes the boat along best and a much smaller number who go for a twin in case one motor fails at sea. If this happens though, don't assume you'll be planing home on the second engine as it most likely won't be able to get you over the hump on its own. I'd go for the single. My own outboard hasn't missed a beat in 8 years.

 

[Solitaire]

OK, so where do we start? The 140 engine is very good on the right boat, but it is a 4 cylinder, the 250 is a V6 - our school boat has the 200hp version (same basic engine) and has done over 300 hours and runs as sweet as a nut. The 250 will have far more grunt and the torque is infinitely better than the 4 cylinder.

A major consideration though is that 2 140's will weigh in at 372 kilos, the 250 weighs in at 263 kgs! That's a lot of extra weight - 109 kilos - to carry and fuel and speed will suffer as a result. Further more your servicing costs will be higher on 2 engines. A basic service on the 250 will be around £175 plus VAT and spares - fuel filter, spark plugs etc plus the oil. You can nearly double that with 2 140's.

Don't get me wrong, the 140 is a great little engine, but I'd go for the 250 if it were me.Take a look at the specs on Suzuki's web site

You could always consider a V8 350 outboard of course - but that really is heavy - 373 kilos, 90 kilos more that Suzuki's 300 hp.

 

[duncan]

[ QUOTE ]
a slight performance gain

[/ QUOTE ]

increased weight and increased drag will deliver a performance reduction from the twin set up here - quite a big one.

 

[Dave_Snelson]

If the safety angle is a must (long distances off-shore) then go for the twin engine. The fact that the RNLI do gives you a clue.

If you were to get a small aux as Colin suggests, then go for the single. It will be much, much cheaper to own. And maybe quicker.

 

[ccscott49]

I wonder if that V8 would fit my 3.45 meter Zodiac RIB????? Hmmmmmm be fun!

 

[MapisM]

Single forever.
I'd go for the Yam F250, rather than the Suzuki, but that's another story.

 

[Solitaire]

[ QUOTE ]
I wonder if that V8 would fit my 3.45 meter Zodiac RIB????? Hmmmmmm be fun!

[/ QUOTE ]

Now I reckon you'd get on the plane with that! But there again, with your new resolution maybe an old seagull will do /forums/images/graemlins/laugh.gif /forums/images/graemlins/laugh.gif

 

[ccscott49]

Twin seagulls!!! Now you're talking!!

 

[Solitaire]

Or a single albatross /forums/images/graemlins/wink.gif

 

[ontheplane]

I'd agree with everyone who's said Single is best - and I'd argue forever with the guy who said the twins are safer.....

Here's my logic.

Assuming that a modern outboard properly serviced is (by itself) probably around 99.9% reliable then you have a 0.1% chance of a component failure - have two engines and you have a 0.2% chance that you will have a component failure on one engine...

The main reason you might lose your main engine are:-

a) Contaminated Fuel:- assuming two big engines will share the fuel tank then both engines will fail - if you have one big and a small aux then only the big will fail as the Aux will probably have it's own tank. Similarly if you make sure you fill the Aux tank from a different place (easy to do if you don't fill it often) then you cover yourself.

b) Striking an underwater object:- both large engines down and you rip off the gearcase of one you'll probably take out the other as well - as long as you leave the aux trimmed up then you'll cover yourself against this

c) Electric Failure - With a total battery loss you'll be doing well to pull start a 140hp but with a small aux you can pull start it - and if you get one with a charging circuit on it, you could then charge up the battery.

No the small Aux won't get you on the plane, but as long as you aren't too far out you can just come home slowly. If you are a long way out, call the Coastguard if you can't make headway.


Anyone got any more to add?

 

[damon]

Thanks for all the advice, it makes interesting reading. I've made a cheeky offer on the single engined boat and been turned down, early days yet and I don't think it's going anywhere. Not in this weather anyway, unless it floats off the hard of it's own accord.