Houseboat Outboard Engine - which motors, top speed, and gas mileage?

by Gene Abbott
(Columbia, SC)

Considering houseboat outboard engines, and wonder which motors, top speed, and the gas mileage results we'll see if we change outboard motors?

We own a 12 x 48' Aqua Cruiser houseboat, and it currently has a 115 Mercury outboard motor that needs to be replaced.

We're looking at a 75 hp Honda 4 stroke, but are wondering if this motor will push this houseboat.

Any advise would be appreciated. Gene




Reply - Answer
Well Gene, welcome to the houseboat forums, and sorry to hear about having to replace your Mercury outboard :(

You are curious if a 75 hp four stroke outboard engine will push your houseboat, and the answer is yes, however you may notice a slightly lower top speed.

Now let's look at some of the difference between the two motors. The 115 hp Mercury had a slightly bigger diameter propeller than the 75 hp. And the 115 hp outboard will have a slightly more pitch on its prop compared to the 75 hp.

In reality, to push a houseboat hull through the water, it requires a lot less horsepower than people think. But to get the last 10% increase in top speed, really requires a big jump in engine displacement (or HP).

Now if I remember rightly, the Aqua Cruiser hull is a catamaran hull, that has a certain amount of lift when reaching top speed, you may end up realizing a 10% drop in cruising speed.

Will you get better gas mileage, yes, as I am guessing your Mercury was likely a 2 stroke, and the newer 75 hp Honda is a 4 stroke (better efficiency) and there is claims of up to 40% better fuel consumption.

There are some houseboat owners that have already done some outboard engine re-powers, and they may be able to post some of their numbers, testing, or real life performance results to help you in the decision.


Lastly, hopefully some of our readers will share and post comments about their houseboat outboard engine performance experiences. Feel free to use the "Click here to post comments." link found near the bottom of this page.


Thanks again for sharing, IAN - from www.all-about-houseboats.com

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