BOATS: Whats the benefit of twin outboard motors rather than a single?

Question

I currently have twin Mariner 50 hp 4 strokes, but im looking for more power and better fuel economy. Would it be best to change to a bigger single engine 4stroke??

Answer 1

two motors gives you 2 propellers so you will have more pulling power down low to get you going and on to the plane.

Ih high speed applications twin motors with counter rotating propellors reduce chine walking (60mph +)

Once up and going twin motors present twice the underwater drag ie 2 outboard legs to resist the water. hence increasing fuel usage and lowering speed for the same total horespower compaired to a single motor. A single motor also weighs less than 2 smaller ones another benifit of single ie less weight more speed less fuel used.

For off shore use twin motors are a safety advantage providing each has its own separate fuel tank.

Before adding more horsepower check the hull is rated to handle the power.

Before changing motors you could speak to your boat shop about raising the height of the motors you presently have. Raising the motors provides less drag hence high speed and reduced fuel usage.

There are also foil attachemnts for outboards, I can recomend one called a permatrim, i use it on  my 200 hp merc on a 17' boat it is out of the water due to the height of my motor but helps the boat get on the plane and hold it at low speeds, also reduces rooster tail at high speeds.

Also if your present motors are old any of the present generation of motors will provide better economy.

2 stroke V's 4 stroke 2 are lighter and faster but use a bit more fuel (current motors) old 2 strokes use lots more.

4 stroke you have extra maintenance (engine oil to change) timming belts valve clearances etc but use less fuel and quieter, better for trawling (continued low speed use)

Answer 2

I would certainly add to the safety aspect of having two rather than one engine.  There is also some added benefit to manouverability in certain situations.  If you are looking for economy try looking at Suzuki engines, my sailing club have switched to them for the safety boats and they have proved to be good performers, reliable and economical.

Answer 3

the only benifit is that if one breaks down then you always have one to fall back on.

i actually prefere 2 strke as in my opinion theyre faster but not as reliable but better in rough seas

Answer 4

from a safety point of view stay with 2

Answer 5

One beedling obvious one... what if one breaks when you are bllody far out? spare always helps