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Old 19 May 2013, 12:33   #1
Country: USA
Town: Pacific Beach
Boat name: Dash II
Make: Willard
Length: 7m +
Engine: Cummins
Join Date: Aug 2007
Posts: 564
What made you decide on 1 or 2 engines?

I am still researching and looking for my next rib.
It will be between 7-8.5m in length.
I have seen configurations of twin 115, twin 150, single 225, and single 300. The twin 150 seemed to be the most popular. I currently have a Yamaha on my 4m, and am very happy with that engine.
I like the idea of twins for a few different reasons.
If one engine breaks while out on the water, you have another to get you home.
With two engines you have fantastic maneuverability in tight places at low speeds.
Although i have never owned a twin screwed boat, i believe you can probably level the boat out without trim tabs, by just adjusting tilt and trim on each individual engine.
Not sure, but kind of wondering if engines are not run as high of rpm to achieve same cruising speed when you have twins? If this is true, probably less wear and tear when run at lower rpms?
The last reason i like twins, is because it looks sexy as hell!

I would appreciate any and all constructive opinions.

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Old 19 May 2013, 14:33   #2
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,077
From what I understand a twin 150 will not give you the same speed as a 300. More like the same as the 225.

Will cost you more than a 225, possibly more than a 300.

Redundancy of engine is good, provided the engine failure is not electrical or fuel unless they are fully independant too..

Twin 150 weighs more than 300

Twice the maintainance

Twice the chance something will fail makign you believe it was 'just as well' you had the spare engine.

ShinyShoe is offline   Reply With Quote
Old 19 May 2013, 14:52   #3
Country: UK - Scotland
Town: Glasgow
Boat name: Thunder
Make: Halmatic Arctic 22
Length: 6m +
Engine: 2 x 150 Etec
Join Date: Oct 2008
Posts: 494
I went with twins for the redundancy as we tend to do some fair distances offshore, also for the drive from twin props for the weight we tend to have on board.

They also sound really rather good!

All the other comments on the downside are valid, double the maintenance costs, not as fast as a single 300, heavier etc.
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Old 19 May 2013, 15:00   #4
Country: UK - England
Town: Sussex
Boat name: Aintree
Make: Redbay Stormforce
Length: 7m +
Engine: Twin 150's
Join Date: Jun 2009
Posts: 251
Just went from a 250 opti to twin 150 merc four strokes on the same boat. Acceleration is better with the twins and top speed the same. Although almost twice the weight on the back. Prob eats same amount of fuel. Went for it as has a break down last year mid channel. Twins would have got me home. The price for two Mercury new 150 four strokes is probably quite close on price to a 300 Suzuki or Yamaha.

Depends on how far out to sea you go also

They also sound epic as they seem to sing to each other!
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Old 19 May 2013, 16:36   #5
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willk's Avatar
Country: Ireland
Make: Redbay Boats
Length: 9m +
Engine: 370hp
Join Date: Feb 2008
Posts: 12,147
Originally Posted by redthunder View Post
They also sound epic as they seem to sing to each other!
When you sync a pair of engines by ear, it's a special moment.

OP - in my experience, as boat length increases, the ease with which you can perform twin engine manoeuvres decreases.
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Old 20 May 2013, 06:47   #6
Country: Ireland
Town: Castlebar
Boat name: Clewless
Make: Valiant DR 490
Length: 4m +
Engine: 60 hp ETEC
MMSI: Awaitng one
Join Date: Oct 2007
Posts: 1,118
I have limited experance with a twin engined rib but on a tornado 6.5 with twin 100 it was very stern heavy and not nice to drive. the balance was sh*te

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