| Ok Bruce, I'm gonna try to help here. I've had LOTS of experience
with both types of engines in fresh and salt water. (Bought new and
used up several of each till thoroughly worn out)
>> Outboards:
>> - Turn at higher RPM than I/Os, implying possibly higher
>> maintenance costs for rebuilds of upper/lower units.
I've never noticed a RPM related problem with outboards. In reality, they
only turn a little higher RPM than IOs and *they're MADE for it*. Car engines
are designed to spend almost the entire life at 2-3Krpm. Period. My summation:
No diff for the purposes of wearing out. Outboards seem to last about the
same amount of hours as IOs
>> - Are lighter than I/Os, thus boat/motor weight is less,
>> requiring.
>> - a lower HP level to push boat through the water
>> - lighter trailering and load on the tow vehicle
Definitely true. A 115 HP OB weighs about 400. A 130HP IO weighs
about 750. (No, the relationship is not double throughout)
>>
>> - Burn gas/oil mixture, so cost/gallon is higher than with
>> an I/O, but the outboard & boat are lighter, requiring
>> less mixture gallons to be consumed.
No, IOs get considerably better mileage than outboards, probably
at least 25% better for similar applications. (Notice I didn't say
for similar HP)
>> I/Os:
>> - Are made up of a large percentage of automobile engine
>> parts. Consequently you can get parts from auto supply
>> stores rather than marine dealers, implying lower
>> maintenance costs.
Many, but not all engine parts are standard automotive parts, but
IOs require a bit more maintenance than outboards, so I think any
parts price saving is a wash.
>> - Since they are car engines (roughtly) they are easier to
>> work on
The *engine* part might be, but there is almost no maintenance to do
on the engine part of an outboard. IOs have parts that OBs don't and
some require regular maintenance.
>> - Turn at lower RPM thus reduced engine wear, reduced potential
>> for required rebuilds.
No - about the same - and when it is time, there's more to rebuild on
an IO, though it tends to be a little cheaper.
>> - Are heavier than outboards, thus boat/motor weight is greater
>> with an I/O requiring:
>> - a higher HP level to push boat through the water
>> - heavier trailering and more load on the tow vehicle
Yes
>> - Burn straight gas (regular unleaded or preminum?? don't
>> know - comments) so cost/gallon is lower than an outboard,
>> but weight of boat/motor/outdrive is higher than outboards
>> more gallons to be consumed.
No, see above. Fuel consumption less on an IO.
>>Some related questions:
>> - Does the fuel consumption/fuel cost issue become a wash
>> (insignificant) in the long run?
See above.
>> - Because they are (roughly) auto engines, do I/Os have all the air
>> pollution systems found on cars?
Right now, IOs have almost no pollution control - that will change
VERY soon - as it will with OBs.
>> - (Correlary to previous question): Which is better for the lake
>> (environment) an I/O or an outboard? (This is a genuine question,
>> not a fake PC question. It occured to me while typing the previous
>> question thinking about the oil/gas mixture.)
IO for sure.
>> - Do I/Os take regular or preminum gas?
Most take regular fuel.
>> - In the overall maintenance/operating/purchase cost department,
>> which is more expensive: I/O or outboard? Would an I/O have a
>> higher entry cost but lower meintenance costs after initial purchase
>> than an otboard, which would have lower entry cost but higher
>> maintenance costs after initial purchase.
Outboards tend to cost more to buy. Have lower maintenance costs, but
higher operating costs (Fuel and oil).
>> - How do maintenance/operating/purchase costs of the outdrive of an
>> I/O compare with the lower unit of an outboard?
Should be the same, but its a package deal when you buy your IO.
>> - I assume I/O outdrives weigh more than outboard lower units.
Maybe, but you can't have one without the other anyway. There is also
a rather large thing Between an IO engine and the outdrive called
an intermediate housing - it connects the two. You need to understand
that an IO is just as integrated a package as an outboard. You just
can't see all the parts from one angle.
Hope this helps
Kenny
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Outboards have fewer moving parts, though the engine parts
they do have can be quite expensive - marina / authorised distributor
only, not generally available at auto parts outlets such as NAPA, no
price competition, etc. I/Os include a lot of complexity in the out
drive itself - again, proprietary stuff. I havn't done the math (and
plan not to) to figure if this offsets any potential savings from
using regular auto parts in the engine. My choice is an inboard,
simple, very simple. Just a truck engine with a transmission behind
it, then a shaft straight out. Once you've had one for a little while
you realize that the engine in the middle isn't really an issue and
the seating arrangement is more social than most I/O bow riders with
back to back seats. But you didn't ask about inboards.
REAL boats have rudders (-:
Wear as a function of useage ? Dunno, so much "depends".
I don't believe that use as a ski boat is particularly hard on an
engine. Sure there are a lot of starts, but not much wide open
throttle once the skier is up - and runs are typically less than 10
minutes, 5 being more typical. "Cruising", dunno, don't do it (-:
My guess is that most boats get gunned once in a while, they also
troll around from time to time, there's more variability in the
individual owners and drivers than there is between "types".
Fuel economy ? I think my "little" 4 cylinder boat could
cost me as much as $20 a day in fuel, the Nautique sometimes costs as
much as $30. On a cost per hour basis this might come out to ~$5 per
running hour, I don't know many legal ways to provide so much pleasure
for so little cost per person. I'd rather pay ~$5 an hour to use a
351 cubic inch ~230 horse V8 than pay ~$3.33 an hour to use a 3 litre
130 horse 4 cylinder. If we get to ski together next year you'll
probably see why (-: It isn't for "SPEED" its for torque.
Hey Jeff, tell him - "there's no substitute for cubes" (-:
Reg
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| You're making too much out of the whole thing ! What's it's really
going to come down to is which boat you feel has the best value based
on cosmetic & mechanical considerations, and more importantly price.
I did all the looking 3 years ago. Wanted a 150 hp I/O or O/B, didn't want
too much power ya know. When all the pre-shopping analysis, technical
mumbo jumbo, and mental gymnastics were over I found 3 boats that were
within the price range, clean & well maintained, and I thought I could
tow with my present vehicle. What I bought was the bigger of the 3,
with a 260hp V-8 I/O. I never regretted having the extra ponies.
That boat lasted 2 years until I sold it and got what I *REALLY* wanted
in the first place, an inboard ski boat.
If you can tow it, it's clean, and you find it to be an appealling
style, buy it.
~jeff
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Bill, I think the amount of noise you get from an OB or an IO is very
dependent on the boat and to a small extent, the motor. Most of the
boats I've been in, the IO is quieter at low speeds and a bit louder at
high speeds, but I know exceptions in both directions.
Kenny
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