Outboard Motor Installation

Question

I am wondering why some boats have say 1- 90 HP engine and some have 2 -45 HP engines. What is the benefit of the 2 engines? Or, maybe I should say the benefit of one 90 HP engine over the 2 engines.

Answer 1

All else being equal, a single larger engine is more efficient than 2 smaller engines (I assume capt bill means you'd be single-engine trolling).  Only real reason for twins is redundancy, for safety.  

Every boat should have an alternative means of propulsion;  for a small boat on a small lake, a paddle will do.

Answer 2

Nice to have a backup.  A single engine is probably cheaper.

But:

Two 150 hp for example have more get up than one 300hp.

Two propellers are more effiecient than one by a small margin. Not sure about top end but they will definately get you going faster.

Answer 3

Weight and force distribution on the transom.

As mentioned, sometimes using one engine is putting all your eggs in one basket. If you drop the basket...........

Answer 4

I've often thought that "twin outboards" are over sold. A single large engine is much more efficent. And a small 15 hp outboard for trolling might be desirable. I think Jtexas has it right!  

Answer 5

when your in the middle of the ocean and you start to think??

you'll find your answer

Answer 6

Besides the security of having two motors here are other benefits.  Maneuvering can be easier, fuel consumption while trolling is lower and less strain on the each motor for cruising.  

Boat Safe!!

edit:

Another great reason , duals not needed on smaller boats, but on larger boat the added HP is.  Such as the a Grady White Sailfish 28' - there is no single 450 HP outboard - but you can hang 2 - 225 hp on it.  There is a trend to use outboards on larger boats, some using not 2 but 3 and 4 outboards.

Answer 7

There is one critical reason for having two motors that is being overlooked. While redundancy is great, and cost may be a factor, if you do it right, the motors will be set up to have props that rotate in opposite directions and have reversed pitch. This eliminates something known as "prop walk" which is the tendency of a boat to slip sideways due to the action of a rotating prop. If the props have opposite pitch and direction, the tendency of each to move the boat sideways will be cancelled out making the boat more accurate when tracking a particular course, or moving into or out of a slip.