Pontoon Boat & Deck Boat Forum

first post here and plenty of good info. Wife wants a pontoon. she is insisting on an inboard motor which I don't want. She is under the impression that it will be so quiet that we will be able to chat at full throttle. We have neither one ever been on a pontoon. So what is the noise differcence between inboard and outboard, thanks, Vic

I have a 40 hp 2 stroke and I have to go to the back of the boat and lift my sundeck to hear it. I mean I hear a little bit of a humming noise, but the way most toons today are built, the sundeck/changing room is like a big, padded wall between you and the outboard.

I have a 96 Johnson 115 2 stroke not loud at all, use my toon for diving. I don't need a race car but I do need lots of buoyancy for all of are gear, I thought that a I/O would subtracted from that.

At full speed water noise is louder than engine. At cruise we can have a normal conversation with anyone on boat

I can tell by your post you have not test driven or been on a Pontoon lately. Test drive both I\O and O\B and see for yourself. We have a Suzuki 250SS 4 Stroke and it is So quite .I have to look at the tach to see if the motor is running.

D.James
2008 Premier 235 Grand Majestic LTD
36"PTX Suzuki 250SS
Greers Ferry Lake AR

I've been on boats with outboards and of course mine's an I/O. Both are comparable in noise level, the water and wind noise cause more problems for me than the engine does.

Todays outboards are super quiet and I/Os have water cooled exhaust coupled with them being under the deck, both which make them about as quiet as outboards.

my I/O is louder than i expected, though i've read other places that mine is a "noisy" motor. i've heard the honda outboard owners comment in several places about how quiet their motors are.

i/o or outboard--the noise level is a function of soundproofing.
new outboards have modern soundproofing materials in their
cowling that help a lot. (and of course 2 stroke vs 4 stroke
makes a difference.) i have an i/o in my 28 foot pontoon.
it used to be pretty loud at full throttle. when i replaced
the furniture i added a sundeck and was careful to provide
a tight enclosure around the engine compartment. i used
3/4" pressure treated plywood wrapped in marine vinyl and
padded on the tops. it is very quiet now. most of the engine
noise i hear now is from the exhaust coming up through
the wake.

That would be why the PC is so quiet, lots of insulation and seating back there.

I agree with the previous posters. However, the main reasons I've never considered an I/O in my previous 4 pontoons were:

1. They are more difficult to service than outboards.
2. They take up lots of valuable deck space.
3. They are heavy.

1) True, however I/Os are simpler to work on, (i.e less complex) than most outboards. Access to maintenance items is cramped. Mercruiser's improved that alot by using remote oil, engine block, and manifold drains.

2) Not on any pontoon I've seen, I/Os are under the deck. Outboard pontoons have less deck space if the outboard is not set further back.

3) Yeah, but not by a whole lot when comparing similar horespower motors.

I/O used in cold climates need to be winterized, unlike outboards....

i think i/o's are much easier to work on than outboards. access is tighter
but as bmr said, the systems are simpler. i've worked on every system
my i/o has. i doubt i could do that with a late model outboard. i agree
they are heavier, like maybe 300 lb heavier, and i believe the i/o hp rating
is at the flywheel (before sterndrive losses) whereas the outboard hp rating
is at the prop shaft, so a 140hp i/o doesn't really give you 140hp at the prop.
but i love my old i/o, mainly because i can do all the work. winterization is
a pain, but it's not so bad. she gets lots of tlc at that time.

The weight comes from everything being iron, heads, manifold, riser and block. No aluminum heads to warp. I've seen Mercruiser 4 cylinder motors from the 70s still going with just with a valve job and manifold replacement.

In fact, the original 2.5 4 cylinder Merc. motor in my '68 Cheiftain would still be running if the former owner winterized it correctly.

thanks for the info guys, I can see where wind and water will be louder than the motor. Vic

a commercial fisherman on the east coast told me that they all run
i/o's out on the ocean. not sure if that's true or if it is, why.
probably because they do a lot of their own maintenance?
and maybe they last forever compared to outboards?