7 Advantages of Outboard Motor on a Sled vs Inboard Engine
For what it’s worth, if Good Life was a bigger and/or heavier cruising multihull (or any monohull over 26′) then I’d say an inboard engine would be essential. However, with a light 36′ trimaran, there are definite advantages to having an outboard motor on a sled vs an inboard engine…
1) SPEED UNDER POWER: Remember that instead of plowing through the water like a monohull does, a multihull is light and moves on top of the water. That means that instead of using the motor like you have to do with a monohull in light winds, you will still be sailing in a light zephyr on Good Life. Seriously, you will chug along quietly at 5 to 6 knots with no following seas and at half throttle. Add small following seas and you will easily surf at bursts of 7 to 8 knots.
2) DEEP PROP: Normally I would say an inboard has the advantage because that grunty low-end power you get from a deep prop is nice. However, Good Life’s outboard motor has an extra long extension (possibly two if I recall) and the motor is mounted on a sled that is lowered into the water while running. That means the power / prop is as low in the water as the prop would be with an inboard engine. Also, even in big choppy seas, the sleds cowling protects the outboard from swamping because the sled moves up and down with the swells.
3) MANEUVERABILITY: Normally you steer Good Life under power with the steering wheel, but in really tight spaces you can reach over and turn the outboard motors tiller at the same time.
4) EASY TO SERVICE AND REPAIR: This is a big one, I think… Good Life used to have a diesel aboard but the previous owner eventually replaced it with the Yamaha on a sled because he couldn’t find mechanics that were willing to work on the inboard engine. (The cradle for the inboard is still there.) The issue was that most mechanics don’t like working on small boat inboard engines because the space is so cramped when they can make a lot more money working on larger boats with nice roomy walk-around engine rooms. So, the advantage here is that the outboard is relatively light and can be easily removed from Good Life in a few minutes and lowered into the dinghy and then delivered to a mechanic.
5) RELIABILITY: Normally I would say diesel engines are more reliable (although newer diesels are incredibly complicated!), but these Yamaha High Thrust four cycles have a long trace record of being super dependable and lasting a very long time.
6) STANKY: The smell of fuel and exhaust from an inboard engine tends to permeate the interior – and even when not running. Running or not, you won’t smell exhaust fumes from the outboard.
7) NOISE: Interior noise isn’t too bad on a big boat with an engine room lined with sound deadening material. On small boats though, the cacophony of an inboard resonates (and vibrates) throughout the interior. You will really appreciate how quiet it is in the cabin with an already quiet motor like this 4 cycle Yamaha running outside.
When it comes to inboard motors vs outboard motors powering a light and relatively small trimaran, it is a lot more nuanced than many believe simply because most consider it from the perspective of a heavy and / or much larger monohull or multihull where an inboard engine is essential.
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