Inboard vs outboard

What are the major advantages

What are the major advantages and disadvantages of both inboard and outboard engines?

"Mark, you will get decent arg

"Mark, you will get decent arguements from both sides. Only you can decide what fit's your requirements and pocket book.

And I will compare "new" motors, because used opens up many cans of worms on both sides of the arguement.

Here's my 2 cents (and I'm an outboard guy).

Dollar for dollar you can get significantly more horsepower for your buck with an inboard/ouboard set-up.

If you do some looking you can get complete volvo/mercruiser engine (4.6/5.0/5.7) plus the outdrive for about 8000-10,000 bucks. That will give you 200-300 horsepower depending on configuration.

Take a Yamaha 250 horse 4 stroke outboard as an example - the list price is a few bucks shy of $24,000. The direct injected 2 stroke model sells for the same price.

However, as you will see below, you will need significantly less horsepower from an outboard (in some cases) to achieve the same performance you would get from the I/O.

Even dropping to a 150 horse 4 stroke or DFI you will still lighten your wallet by about 15K give or take.

So for price - the I/O wins that round. And that's why so many smaller cruisers/bow riders etc are mfg with I/O's - the builder can get them to market with a lower initial cost.

Overall weight. A 250 outboard will tip the scales at a little over 500 pounds (depending on mfg). A 5 liter Mercruiser with an Alpha or Bravo drive weighs about 1000 pounds. A 150 outboard will still come in the 400 pound range.

The new Yami, V8, 350 outboard weighs over 800 pounds and sells for 35 grand, but that's a whole different "class" of motor - but may be what you are after?

However, there is no general restrictions on how much I/O horsepower you can put in a given rig. With an Outboard, the transom can only take so much weight and stress, limiting what you can hang off the back.

You will get arguements about what is easier to work on. As you get older it's alot easier to get at an outboard which is hangin' "right there" compared to an I/O which may be burried or partially burried in the floor. If you are taking it in for service, then you have no concern in that regard. You will pay 100 bucks an hour plus to have them worked on.

Which is cheaper to maintain? neither, this is a marine product, you could feed 3rd world nations for the cost of servicing either

What kind of performance can you expect. Here's a couple of new, actual "on boat" tests. I picked similar hulls (23 footers) one with a 150 horse Honda 4 stroke outboard, the second with a 260 horse, 5 Liter, multi-port injected Mercruiser and the 3rd with a Mercury 150 Optimax, Direct Injected 2 stroke outboard. That will give you an idea of the speed/gas consumption between the three "main" market options.

The dry weight of the boats compared was 3700 pounds, plus the motor weight, plus gas/batteries/stuff/passengers etc etc for the 4 stroke and the I/O - the Opti results were from a model weighing 800 pounds less (dry weight).









Summary of the results - basically, they all suck the same amount of gas. The top end speed of the 4 stroke outboard sucks compared to the other two.

Both the 4 stroke and the I/O will have significantly greater maintenance requirements than the DFI, but if parts go bad they will all cost you major dollars to repair.

So the answer is - whatever suits you."

wow! i was wondering the same

wow! i was wondering the same thing but didnt want to ask because of all the different factors.

that was great and im sure mark appreciates it as well as i do.

that took some research and time.

thanks graham!

"looking at those charts somet

"looking at those charts something is off

how can 13.8gph get you 99 miles where 16.2gph gets u 118 miles"

Different tank sizes - not all

Different tank sizes - not all exactly the same rig in the tests - just picked hulls that were close in length and weight...

i c

i c

"My bad - probably should have

"My bad - probably should have added that to my post - but I already yap too much "

if u have anymore stuff like t

if u have anymore stuff like that email it to me please!

"Richard, you looking for anyt

"Richard, you looking for anything in particular? - I have scads of useless "stuff" and access to "on boat" test reports..."

im in more of the GPH stuff

im in more of the GPH stuff

"Go to [url=""]www.boattest.co

"Go to www.boattest.com and sign up for their newsletter - send it out every couple of weeks. Or you can just wander around their main site.

You can access all the tests/results for newly tested models. They have an archive section that cost's if you want access, but there's tons of info for free."

"Very Interesting, Thanks Grah

"Very Interesting, Thanks Graham.

I always wondered, if you were in a fuel pinch, what speed would get the most range.

I was curious as how the center of gravity between the two affected performance and handling.

I would have thought that the 4 strokes would have had a higher thermodynamic efficiency advantage represented in the MPG. But, I guess, the 2 stroke weight advantage and recent improvements, gives it an even status."

The I/O allows for a broad ope

The I/O allows for a broad open view transom to display the vessel name and hailing port.

"Yes, but gobbles up valuable

"Yes, but gobbles up valuable deck space at the rear of the boat unless the motor can be completely burried below the deck itself - not desired in a center console/walk-around etc where the value is in the fishing space.

A fairly neat alternative is Merc's new Vaser's which are small enough to really fit under a rear seat. They are however limited to 100 horse (current 4 cylinder model). I have not seen if they come in a counter rotating configuration which may make them viable as a twin set-up on a boat not requiring twin V6/V8 motors."