I/O vs OUTBOARD

[ggundersen3]

Looking at buying my 4th bowrider since 1999. Considering going back to an outboard (135HP Mercrury)after 2 I/O's. I had an Evinrude 90HP outboard on the 1st one (16' bowrider)with no problems at all and plenty of power out of the hole for tubing/skiing. I've had 2 I/O's since then, A Mercruiser 3.0L Alpha One 17' sea ray)that ran great but struggled pulling up skiers even with a ski prop. Then I had an OMC 5.0L (19' bayliner)that for sure got the job done. I know I/O's are just more sluggish out of the hole for various reasons. Is there any ratio to compare the 2? Like it takes a 190HP I/O to equal the power of a 135HP outboard. Is there any ratio like that?

 

[coolbri70]

Re: I/O vs OUTBOARD

outboards where designed to be boat motors and are lighter, I/O are car motors adapted to boat use and are heavy, they need more horses to get all that cast iron out of the waterop2:

 

[Texasmark]

Re: I/O vs OUTBOARD

It's several things, some mentioned.

First is 2 cycle vs 4 cycle and available torque to turn the prop for a given rated HP.

Second is the weight vs HP race.

Third the ability to see your engines position with an OB sticking up in your rear vs an I/O you can't see. BTDT

Then comes the upgrades to the 2 cycle community evening the score on fuel economy.

Had both. Have the OB. Will always have the OB. My money. My equipment. My choice.

Mark

 

[oldjeep]

Re: I/O vs OUTBOARD

Looking at buying my 4th bowrider since 1999. Considering going back to an outboard (135HP Mercrury)after 2 I/O's. I had an Evinrude 90HP outboard on the 1st one (16' bowrider)with no problems at all and plenty of power out of the hole for tubing/skiing. I've had 2 I/O's since then, A Mercruiser 3.0L Alpha One 17' sea ray)that ran great but struggled pulling up skiers even with a ski prop. Then I had an OMC 5.0L (19' bayliner)that for sure got the job done. I know I/O's are just more sluggish out of the hole for various reasons. Is there any ratio to compare the 2? Like it takes a 190HP I/O to equal the power of a 135HP outboard. Is there any ratio like that?

17ft with a 3.0L, it was the skier struggling not the boat If you truly want to ski then I/O or inboard, if you want it to be easier to get up then 4.3L minimum. As for the general OB vs I/O - its a personal choice, I think that outboards suck to work on, others think they are easy to work on.

 

[ggundersen3]

Re: I/O vs OUTBOARD

Ok thanks for all your help. One more thing.. I haven't inspected this boat yet but lots of photos show it to be in good condition. One thing though....the merc motor looks small to be 135hp even though it says "135hp". I've seen other merv 135's in this same era (1988-89) and they look the same. Is that a 4 cylinder motor?????

 

[spoilsofwar]

Re: I/O vs OUTBOARD

If you have the option between I/O and outboard on the same boat, you get the outboard... If the hull comes only in I/O, you get that.

 

[bear_69cuda]

Re: I/O vs OUTBOARD

Not sure on (88-89) 135 Mercury being 4 or 6 cylinder? I currently own two boats with outboards, my 115 Yamaha 2 stroke has a awesome hole-shot on my 1720 Key West with a 4 blade prop... I had a Bayliner with 3.0 and was a bit sluggish out of the hole.. I also owned a Cobalt 226 with Injected 454 Volvo with duo-prop and I can affirm it was not sluggish with hole-shot... More like a rocket ship launching, and torque enough to pull a skiers arms from their sockets! :bolt:

Good luck!

 

[bear_69cuda]

Re: I/O vs OUTBOARD

This link says that year range 135 Mercury outboard is a 6 cylinder http://www.iboats.com/basics/mercury.html

 

[coolbri70]

Re: I/O vs OUTBOARD

try this with a 15 hp I/O

 

[Chris1956]

Re: I/O vs OUTBOARD

That's pretty cool pulling a skier with that small motor. I presume it is mounted on a canoe?

I skied behind a 4HP Merc on a aluminum rowboat. Of course, my ski was a picnic table top....

For the record..I/O usually make far larger wakes than outboards. Any experienced skier prefers skiing behind an OB for that reason.

 

[Scott Danforth]

Re: I/O vs OUTBOARD

I/O vs OB thread.....opcorn:

 

[coolbri70]

Re: I/O vs OUTBOARD

That's pretty cool pulling a skier with that small motor. I presume it is mounted on a canoe?

I skied behind a 4HP Merc on a aluminum rowboat. Of course, my ski was a picnic table top....

For the record..I/O usually make far larger wakes than outboards. Any experienced skier prefers skiing behind an OB for that reason.

I found this on youtube, looks like an aluminum rowboat, and theres at least 2 on the boat, 1 at the tiller and 1 spotter/ camera operator, I know theyre not very heavy, but still impressive

 

[thumpar]

Re: I/O vs OUTBOARD

If you like watersports go I/O or inboard. If you are only fishing go outboard.

 

[Chris1956]

Re: I/O vs OUTBOARD

Thumpar, Would you care to explain your rationale for your statement? I would like to know the "why".

 

[Georgesalmon]

Re: I/O vs OUTBOARD

I'll tell you why Outboard for fishing. Simply because there is more room in the boat. In the same size boat the I/O will take up all the room at the transom.

 

[Chris1956]

Re: I/O vs OUTBOARD

George, So it is OK to be crowded for water sports? Did you really mean to imply that?

 

[southkogs]

Re: I/O vs OUTBOARD

I/O vs OB thread.....opcorn:

:couch2: … pulls up a chair next to Scott.

 

[Maclin]

Re: I/O vs OUTBOARD

An outboard configuration with splashwell soaks up interior space also, what with the splashwell and all, the motor when tilted intrudes some. A smaller fishing boat with just transom and no well does seem to have more room until you see the gas tank and batteries, etc back there and start to think about stepping in or over all that. With splashwell about 15-18 inches, maybe 24, is taken up at the rear for battery, tanks, pumps and the like, and this same area with an I/O is used up as well, so both have that small area in the rear unavailable for people room anyway. The I/O engine house pokes in an additional 3 feet or so but usually has seating on either side of the house to gain back some utility. I/O's almost always have a built-in fuel tank where with Outboards that is not as much the case. Built-in tanks free up more space for either type.

I like the swim platform and so does the family right now as this crew has only seen I/O with platform on our 22 foot Cuddy. They have mentioned they would feel intimidated by an outboard. We shall see as I just picked up a smaller runabout with Outboard for "me".

The I/O has a big keyhole in the transom that takes maintenance to keep from sinking. Outboards have a dip in the transom height in the middle that allows smaller waves to slop in where an I/O would have an advantage, but with the splashwell draining design the Outboard gains back some "height" to keep backwash at bay though at the expense of room at the rear of the interior.

I like the ease of preparing an Outboard for colder weather when compared to the I/O.

 

[further]

Re: I/O vs OUTBOARD

Here's a pretty good write up on the subject I found:

Drivetrain Comparisons

 

[thumpar]

Re: I/O vs OUTBOARD

My reasoning for I/O or inboard for watersports is that you don't have the motor in the way. With an OB you need to use a bridle to pull. It is not ideal. We had one growing up. You also can't have a platform on an OB. For fishing the OB is nice because you can tilt it up to get into shallow spots and not worry about damaging things.