O/B vs. I/O experience

TomB985

Petty Officer 1st Class
Joined
Apr 4, 2011
Messages
213
Hi everyone,

I recently purchased my first boat last month after months of looking. I grew up with boats, my parents had a 1989 18' Starcraft SS180 with a 115 HP Merc O/B for most of my childhood, and a 16' Whaler with 50 HP Merc before that. I spent lots of time operating the Starcraft throughout my teenage years and really learned to love boating.

I'm 25 now, and when looking for a boat I was heavily biased towards outboard engines due to the simplicity and weight. I think a 2-stroke outboard has much less that can go wrong with it than an I/O, and acceleration always seemed to be better, but unfortunately they are a rare breed among bowriders. I did lots of research and looking and found my best value to be a new 2011 Larson LX850 with the 190 HP Merc I/O. I was(and still am) leery of I/Os, but outboards are expensive and seem to depreciate faster than I/Os do, as it seems like nobody wants an outboard on a bowrider! Several manufacturers make them, but they are hard to find and salesmen have told me that they are hard to sell.

So I've had it for about a month and a half now and probably have around 20 hours on it. Much of the driving experience has to do with weight, as the chunk of iron in my bilge is around 600 lbs heavier than the outboard I grew up with. Because of this getting on plane takes much more effort and takes a lot of power if there is weight in the stern. I have more power on tap, but it certainly takes more power to get this heavy thing on plane with 4-5 adults in it unless we have some weight in the bow. Once on plane its a much nicer experience as my V6 I/O is a quieter running engine and operates at lower RPMs, so I can understand why people like their I/Os.

One thing that's driving me absolutely crazy is the bow wander this thing has. I've been told this is normal and a typical characteristic of an I/O. I'm not certain this can't happen with an outboard, but I have never seen it in anything I've driven yet. This adds a whole new dimension to low speed handling, and this thing is an absolute chore to dock compared to the boat I grew up with. No big deal, I like to consider myself pretty good with a boat and I've always been able to make it work.

One thing that's concerning for me is the noise my boat is making when turning under throttle. It's gotten worse since it started and I think I have a bad U-joint. The noise started only when turning past 1/4 turn, but it's consistently gotten worse over the last few weeks to the point where I can hear it if I trim in or out after getting on plane. It's under warranty, but a great reminder for me of one of the reasons I still think I like outboards better. Like anything else mechanical, new boats can also break. I know these are mostly pretty reliable units so I don't let it get to me, and I expect that once fixed I'll have no trouble for many years.

So in conclusion, I do like my new boat and am confident I made the right choice. For around the same price as a 125 HP outboard Bayliner with wood floors and a mediocre warranty I got a 190 HP Larson I/O with composite transom, fiberglass floors, and a lifetime structural warranty. Had the same boat and deal existed with an outboard we would probably have liked it better, but understanding the different things that can go wrong as well as how to properly maintain it should negate most downsides. My family and I are happy with the new boat and expect that with regular maintenance it'll serve us well for years to come.
 

BF

Lieutenant
Joined
Apr 8, 2003
Messages
1,489
Re: O/B vs. I/O experience

I think your experience is pretty much the same as mine... FYI, one of the boats I have now is a 17' bowrider with 3.0 Mercruiser. FYI, the low speed bow wander thing is not due to being an I/O, it due to the deadrise of the hull. Deep V's with lots of deadrise at the stern do it worse. Both my I/O and my outboard boat with 150 hp do it.

Bummer about the U-joint... warranty is good. By the way, you do know that you should never start or run the engine in your I/O when the drive is tilted up beyond the max "trim" point, right? Being in Neutral doesn't matter, the U-joints are still turning. That means shallow water operations with an I/O can be a PITA. Treating an I/O like you would an outboard, (trimming way up and idling into shallow water) will lead to a premature death for U-joints. My dad had an I/O and regularly had to trim way up to get out of shallow launch area. He replaced U joints on his mercruiser almost every season. That was the main reason he went back to an outboard (that and weight).
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: O/B vs. I/O experience

Can you post your speed at WOT and RPM's? It could be propped a little off for how you are using it.

Are you eperienced in the fine art of drive trimming?

As for the rest of your experience, I agree withg BF on all points, it is typical of the differences between I/O and O/B. 2 cycle O/B's did get a little more complicated along the way, and a 4 cycle O/B is not much lighter than a comparable I/O of similar output.

I/O's are quieter and are less menacing in the swim platform area and most do not hamper interior space that much when you consider the large splashwell area for an outboard. But, outboard boats do not have that big hole in the back of the boat either!
 

kahuna123

Senior Chief Petty Officer
Joined
Jun 2, 2011
Messages
703
Re: O/B vs. I/O experience

There OK in fresh water on a trailer. Not good in salt for extended use.
 

ufm82

Master Chief Petty Officer
Joined
Jul 29, 2003
Messages
827
Re: O/B vs. I/O experience

For the bow wander you may want to consider a set of tabs, whether they be Smart Tabs or Bennets or whatever you like. The extra drag they cause at idle speed can greatly reduce or even eliminate that maddening wandering. My 20' cuddy was all over the place in no wake zones and it was unnerving at first when putzing through a marina. That ran an I/O and my family liked it because it was quiet. I sold that boat and bought a 19' center console with a 150 O/B. I like this boat much better but it is louder and is not as family friendly. (Seating) However, it also wandered at idle speed. I put Smart Tabs on it for other reasons but it took out all the wander. Made the boat a pleasure to drive in the no-wakes. For less than $150 and and hour or two of your time you'll see some improvement in the overall experience.
From my perspective I think O/Bs tend to be more fragile than the typical I/O engine but each come with their own set of problems. Winterizing, access, maintenance requirements, driveline maintenance, etc. You take the bad with the good. I'm glad you feel you made the right choice. That attitude will help you solve issues as they arise and that will make for a better experience as well. Congrats on the boat and I hope you enjoy it for a long time.

UFM82
 

southkogs

Moderator
Staff member
Joined
Jul 7, 2010
Messages
14,792
Re: O/B vs. I/O experience

My past experiences are much like yours - OBs on fresh water lakes. I now have an I/O that is pretty much a slightly larger version of my last OB.

It's a completely different beast. Pros and cons, but mostly just different. You'll get used to it soon enough, and wind up liking it just 'cause it's what you have.

Listen to the advise on these boards though, there are plenty of differences that you'll need advice on. I did/do/will ...
 

cr2k

Captain
Joined
Mar 19, 2009
Messages
3,730
Re: O/B vs. I/O experience

RE: low speed wonder. Just flow with it and don't steer to correct, it will come back the other way.

Are you tucking the drive all the way in when you take off? That is the key to quicker planning. Then like any other raise the drive until you get porporse and drop till it's smooth. You didn't say if it was a Tri-Hull but I am guessing not due to your mention of wonder.

Maintenance is key to the life of an I/O more so then an O/B. Keep all your fluids changed and your drive fittings greased and you will be OK.
Oil and drive oil changes are straight forward and can be done at home saving $90-$120/hr shop labor.

In time you should become used to your new boat and enjoy it even more.
 

ezmobee

Supreme Mariner
Joined
Mar 26, 2007
Messages
23,767
Re: O/B vs. I/O experience

From new, I think OBs and IOs are comparable reliability and maintenance wise. However, you couldn't give me an old I/O.
 

seaboo

Petty Officer 1st Class
Joined
Sep 8, 2008
Messages
300
Re: O/B vs. I/O experience

From new, I think OBs and IOs are comparable reliability and maintenance wise. However, you couldn't give me an old I/O.

I'm just the opposite, I can "relate" to an I/O (very much like a car engine) and I LOVE the swim platform area.

That being said, some folks like Chevy's some Fords. Either one works, has pro's and con's, and "fits" the owner well. I have only owned 1 outboard (driven lots of them) and have owned 3 different I/O's. Liked them all but liked the I/O's more.
 

TomB985

Petty Officer 1st Class
Joined
Apr 4, 2011
Messages
213
Re: O/B vs. I/O experience

I think your experience is pretty much the same as mine... FYI, one of the boats I have now is a 17' bowrider with 3.0 Mercruiser. FYI, the low speed bow wander thing is not due to being an I/O, it due to the deadrise of the hull. Deep V's with lots of deadrise at the stern do it worse. Both my I/O and my outboard boat with 150 hp do it.

Bummer about the U-joint... warranty is good. By the way, you do know that you should never start or run the engine in your I/O when the drive is tilted up beyond the max "trim" point, right? Being in Neutral doesn't matter, the U-joints are still turning.

Did not know that...Of course I knew the u-joints were still turning whenever the engine is running but I never heard that I could do damage by operating with the drive outside the normal trim range. Do you have a source for this info? I always figured that the angle with steering at full lock was as severe as the worst the trim angle could do.

Can you post your speed at WOT and RPM's? It could be propped a little off for how you are using it.

WOT I'm around 48-49 MPH(GPS) at 4,600 RPMs. Prop has 23" pitch.

Maclin said:
Are you eperienced in the fine art of drive trimming?

Yup, learned this at a young age...but it appears to be MUCH more important on this I/O than the outboard I grew up with. I learned this the hard way after having the boat thrust it's bow in the air like a dog a few times.

Maclin said:
2 cycle O/B's did get a little more complicated along the way, and a 4 cycle O/B is not much lighter than a comparable I/O of similar output.

From what I gather there's still quite a weight difference. A 200HP Verado is 510 lbs, and my Merc V6 is 848 lbs with my Alpha 1! Nearly 350 lbs seems like a lot of weight to me!


For the bow wander you may want to consider a set of tabs, whether they be Smart Tabs or Bennets or whatever you like. The extra drag they cause at idle speed can greatly reduce or even eliminate that maddening wandering. My 20' cuddy was all over the place in no wake zones and it was unnerving at first when putzing through a marina. That ran an I/O and my family liked it because it was quiet. I sold that boat and bought a 19' center console with a 150 O/B. I like this boat much better but it is louder and is not as family friendly. (Seating) However, it also wandered at idle speed. I put Smart Tabs on it for other reasons but it took out all the wander. Made the boat a pleasure to drive in the no-wakes. For less than $150 and and hour or two of your time you'll see some improvement in the overall experience.

The more I read about Smart-Tabs the more I think I need a set for my boat! I first got interested in the easier planing, and I figured it would make my boat drive more like the light aluminum/OB boat I grew up with.

Are you tucking the drive all the way in when you take off? That is the key to quicker planning. Then like any other raise the drive until you get porporse and drop till it's smooth. You didn't say if it was a Tri-Hull but I am guessing not due to your mention of wonder.

Yup, I am trimming all the way down. Took me a few tries to realize that it takes a LOT of power to get to plane with the drive at cruising trim! It is not a tri-hull, it's a Larson LX850. One big reason I picked this one is the 21? deadrise.

cr2k said:
Maintenance is key to the life of an I/O more so then an O/B. Keep all your fluids changed and your drive fittings greased and you will be OK.
Oil and drive oil changes are straight forward and can be done at home saving $90-$120/hr shop labor.

I do plan on doing most of the maintenance myself. I have a couple of warranty issues to get fixed, and one apparently requires the boat going back to the manufacturer for repair. Because of this the place I bought it will be winterizing it this fall. I've always done all the maintenance on my cars, this may be a bit different but still easily within my capabilities!

Here she is:

2011-07-25193733.jpg
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: O/B vs. I/O experience

For where I boat I insist on 20 degrees plus of deadrise, but it also makes planing harder. If I were you I would add trim tabs ASAP. Helps with low speed wander and planing. I prefer helm adjustable by a lot, but both styles are a very good thing.

You're a pretty smart guy comparing steering angle to trim angle. Most miss that . . . Also, in the manual, Merc allows running up to 1200 RPM while "tilted" above max trim. Is it good? Probably not, but I do it all the time with my Bravo and I have original u-joints from 2001.

Don't be afraid to hammer the throttle to plane. Works best that way, so why not?
 

JoLin

Vice Admiral
Joined
Aug 18, 2007
Messages
5,146
Re: O/B vs. I/O experience

There OK in fresh water on a trailer. Not good in salt for extended use.

My original drives and engines are 14 years old. It's been a salt water boat its entire life. It's all a matter of periodic (annual) maintenance.

My .02
 

ewenm

Petty Officer 2nd Class
Joined
Mar 30, 2005
Messages
187
Re: O/B vs. I/O experience

about to make the same comment, can we please get over the myth about i/o,s and salt water

im on my second i/o boat, its 12 years old raw water cooled, moored in warm salt water 24/7 , we never flush it, cant be bothered.

on my previous boat i religiously flushed it out, and it made no difference, manifolds and risers last 4/5 years and thats it.

get it serviced once a year, and an additional lift out at the 6 month interval for a general check over

nothing better than walking down the jetty, kicking it over and heading out then at the end of the day, come back tie it up, maybe give it a hose down, turn off the circuit breakers and head for home

no hanging around ramps waiting and all the crap getting the thing home,
 

saxrulez

Petty Officer 1st Class
Joined
Apr 10, 2010
Messages
286
Re: O/B vs. I/O experience

The big thing for me is and always will be winterizing! I like to fish even when its dropping below freezing at night. Nothing wrong with a good I/O though.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: O/B vs. I/O experience

Tom,

I should have given more details on my weight comparison, I was meaning the weight distribution evens it out some. The outboard engine weight is all off the back of the transom while the I/O weight is distributed forward a little more.
 

mnypitboat

Lieutenant Junior Grade
Joined
May 31, 2010
Messages
1,091
Re: O/B vs. I/O experience

As mentioned, some trim tabs might help with wander. Might help with getting on plane quicker too. As far as blaming that on it being an I/O, well that isnt really fair. I have driven some really slow planing outboards, and some really slow planing I/Os. My Tahoe with a carbed 5.7 lept out of the water. My Caravelle with the 4.3l was pretty slow getting up. My current Monterey is pretty fast, but takes a bit longer to get up on plane. It is a 5.0 MPI. But it is smoother getting up too.

If you live where it freezes, then that will be your biggest issue. Winterizing is about the only really big differance in maintanance. I love the rear deck and huge swim platform. I think you will too.
 

TomB985

Petty Officer 1st Class
Joined
Apr 4, 2011
Messages
213
Re: O/B vs. I/O experience

Tom,

I should have given more details on my weight comparison, I was meaning the weight distribution evens it out some. The outboard engine weight is all off the back of the transom while the I/O weight is distributed forward a little more.

That makes good sense! Interesting how my parents' 18' Starcraft 115 O/B would move just as fast as my 18.5' Larson with 190 HP I/O. I tend to think the 500-lb difference in weight plays a large part in that. Don't know...I would be curious to see how a modern Bayliner 180 with a 125 Opti would compare with mine. I'm willing to bet it would be very close...

So why would I need so much more power to reach the same speed? Heck, I've been in a position where if I had any less power I wouldn't have been able to plane! But that light, plucky outboard I grew up with never had that problem...with 75 less horsepower! After driving this one I can say that I definitely wouldn't want the 3.0L Merc in a boat this size!
 

TomB985

Petty Officer 1st Class
Joined
Apr 4, 2011
Messages
213
Re: O/B vs. I/O experience

As mentioned, some trim tabs might help with wander. Might help with getting on plane quicker too. As far as blaming that on it being an I/O, well that isnt really fair. I have driven some really slow planing outboards, and some really slow planing I/Os. My Tahoe with a carbed 5.7 lept out of the water. My Caravelle with the 4.3l was pretty slow getting up. My current Monterey is pretty fast, but takes a bit longer to get up on plane. It is a 5.0 MPI. But it is smoother getting up too.

If you live where it freezes, then that will be your biggest issue. Winterizing is about the only really big differance in maintanance. I love the rear deck and huge swim platform. I think you will too.

You're absolutely correct about the swim platform, this is one true advantage!

Don't get me wrong, my boat isn't slow to plane. BoatTest rated it around 3.1 seconds at WOT, which is very fast for any boat! It's that if not trimmed correctly or there's too much weight in the back of the boat it takes much more power. When it falls off plane during a sharp turn it takes far more power to get up on plane again than the light aluminum outboard I used to drive. I'm thinking this may also be a function of the deep deadrise. I do know that 115 HP moved my parents boat really well. Mine is 6" longer, and if I had the 130 HP I/O it would be genuinely underpowered.
 

mnypitboat

Lieutenant Junior Grade
Joined
May 31, 2010
Messages
1,091
Re: O/B vs. I/O experience

You're absolutely correct about the swim platform, this is one true advantage!

Don't get me wrong, my boat isn't slow to plane. BoatTest rated it around 3.1 seconds at WOT, which is very fast for any boat! It's that if not trimmed correctly or there's too much weight in the back of the boat it takes much more power. When it falls off plane during a sharp turn it takes far more power to get up on plane again than the light aluminum outboard I used to drive. I'm thinking this may also be a function of the deep deadrise. I do know that 115 HP moved my parents boat really well. Mine is 6" longer, and if I had the 130 HP I/O it would be genuinely underpowered.

I think there has to be a differance in the way they are rated. Or a lot of drivetrain loss. It may take some getting used to the trim. I guess I have just been driving them so long, I never notice. I trim it to plane and tinker with it the whole time I am on plane. I dont seem to have a problem keeping it on plane in turns though. Maybe its how you use the throttle in these maneuvers. Again, maybe it takes some getting used to.
 

TomB985

Petty Officer 1st Class
Joined
Apr 4, 2011
Messages
213
Re: O/B vs. I/O experience

I think there has to be a differance in the way they are rated. Or a lot of drivetrain loss. It may take some getting used to the trim. I guess I have just been driving them so long, I never notice. I trim it to plane and tinker with it the whole time I am on plane. I dont seem to have a problem keeping it on plane in turns though. Maybe its how you use the throttle in these maneuvers. Again, maybe it takes some getting used to.

This is only when I slow to bring the boat around quickly, not for most turns. I, too, am always playing with the trim to the point where I worry about wearing out my trim pump! I've spent the last month finding the handling limits of the boat and I've been pleasantly surprised with how the hull performs. Rather than aerating the prop and slowing down she just digs in and pulls from any speed. I do have to trim down before getting too frisky though...

I'm beginning to think that much of the differences I'm seeing are due to weight and deadrise. This boat is nearly 1,000 lbs heavier than the Aluminum outboard I've mentioned previously, and it has a steeper deadrise which is likely why it has a harder time planing. Most of the weight difference is due to the heavy engine, but I'm not sure that's the only reason anymore.

This has been a great discussion, I sincerely appreciate everyone's input!
 
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