*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: The bite is on at the floating coconut.
I have not bought a new boat ever and every boat that I have looked at or purchased with outboards had a problem that I could not fix and when I got the estimate to fix, it sure seemed like the outboards cost a bunch more to buy and a bunch more to keep.
I have a boat with twin Volvo 290s and SBC 350 engines with Holley dual pumper carbs. The boat hauls butt and seems to be pretty frugal. My only comparison is to a boat I used in the Keys with dual Yamahas that ate my lunch in fuel consumption.
I can repower my boat with rebuilt engines and outdrives (my labor) for less than $6K. Looks like a pair of Yam 250s would cost me about $30K. I can buy a lot of gas for that $24K. What am I missing in my logic? There has to be an excellent reason that everybody runs outboards. I know they take up less room, but I have that great sun deck platform for the beautiful women (that never go fishing with me..). I wonder if the boat manufacturers wanted out of the business of preping for I/O and the I/O manufacturers realized that they could sell outboards that would bolt on to anything and they could sell the engine and outdrive directly to the boat dealers and get a bit more markup.
Can you guys give me a fuel use comparison for a 32 foot open fisherman with I/O vs Outboards?
I like the fact that I can work on the engines and can get to everything even in rough water. I don't know what you do with an outboard that dies in rough water. I am not preaching about the benifits of I/O vs Outboards, but I would like to understand why the transition happened.
I. I/O's are more likely to sink- even at the dock.
II. Outdrives are usually less reliable over time.
III. Outdrives can not be tilted out of the water- therefore they require more maintenance if you keep the boat in the water.
IV. SBC's are great motors, but would you really run at 5,000 PRM all day long? Outboards are meant to run at higher rpm. Higher RPM= higher cruising speed.
V. An I/O's motor sits low in the hull and if a bilge pump fails, the motor is more likely to take on that water.
There are other reasons, but I'll let some other chime in.
Thanks for your comments. Seems that additional speed is the real driver. We can build V-8s to run at higher RPMs, but they start to cost like outboards.... I get that point.
Agree on the sink at the dock thing, but I will never again own a boat that I can not put on a trailer or davits. I know how to raise a boat off the bottom, but I won't tell you why I know....I had a single screw inboard Aquasport that I had a love hate relationship with until I realized that there is a reason to have two props (attached to two enginens) on your boat, other than the spares I had to keep as I was always nicking the bottom.
Not sure about the reliability issue as the lower unit is mechanically the same thing. There are lots of I/Os in the grave yard that sat in the water and disolved, but isn't it the same with outboards?
Agree on the tilt issue.
An SBC running at 5000 RPM is good for about 100 hours and then there will be some big noises, but an SBC running at 3500 RPM might well make it to 2000 hours. My boat will cruise at 30+ at 3200 RPM.
If your leave your boat in the water and the bilge pump fails your boat might well sink as well. Don't buy that arguement, and if it sank, $6K would replace every thing that would need replacing.
For most recreational offshore boats, it is easier to get a 40mph cruise speed with outboard power. Of course you will pay dearly for this extra 10mph. If you are happy with a 30mph cruise, trailer, like to do your own repairs, pay less up front, pay less for repowers, and don't like the idea of 4' of wasted middle transome, then I/O might be for you.
I think the longevity point related to the u-joints, Gimbal bearing and bell housing assembly needed to get the power around that 90 degree turn to the prop. We all agree the I/Os are more maintenance. That becomes a choice....if you can do a lot yourself then they are very economical for the power they develop. I have a Merc 350MAG MPI Horizon mated to a Bravo I.....
it's FWC including the manifolds. The seawater path is through a brass seawater pump, through a brass power steering fluid cooler, through a brass heat exchanger and then into the exhaust elbows. The only corrosion prone item I see in the path is the exhaust elbows. Using SaltAway I think I can expect at least 5 years out of those. Also the engine is rated to 5200RPMs....which seems insane for a small block, but it does have roller lifters. Cruising at 3/4 WOT or lower and 29MPH I think I could expect easily 2000 hours.....if not much more considering how good synthetic oil is these days. And fuel consumption for a 6500lb boat is pretty good at 2.8mpg.
Outboards are lighter, faster and can be tilted out of the water to go shallow.....and are extremely reliable these days. But they also cost a LOT more. As usual you have to pick your poison......
Outotime- I've owned a couple I/O so I am not opposed to them at all. As far as the not buying the bilge pump failing and causing engine damage- I've had it happen. One of my first boats was a Wellcraft 190 classic. It was a 4.3L and had no scuppers. The pump failed, and filled the hull enough to destroy the motor. Granted, I was young and dumb, but it CAN happen.
Truepursit- As far as believing that RPM's push your boat faster. Well, the higher the RPM's are on my boat, the faster it goes. That is a fact. I'm NOT saying it is the ONLY factor to speed, but you can't argue that pushing the throttle further doesn't directly relate to speed. My point is that when you want or need to go faster, running an I/O at higher RPM's for a sustained amount of time is not the most reliable set up. Who runs their SBC powered car at 4,000-6,000 all day long. Not many, and if they do it's not going to last very long. The urge to push the throttle down and go faster is always there, so the potential to wear the motor faster is also there.
I loved my I/O boats, but I would not want to keep one in the water all of the time. I wouldn't argue that they are not reliable if maintained well. No doubt they can provide great fuel economy and good cruising speeds as well. I'm just too throttle happy if the conditions permit.
I think you also see a lot more outboards because that what is offered by so many manufacturers. This being a very fishing related site, many of these guys boats available as outboard power only.
I would much prefer a twin engine I/O diesel CC than one with outboards. I used to be dead against I/O's. Until a few years ago I went from twin O/B's to twin I/O's. I did loose speed but damn sure not my wallet on fuel.
For most recreational offshore boats, it is easier to get a 40mph cruise speed with outboard power. Of course you will pay dearly for this extra 10mph. If you are happy with a 30mph cruise, trailer, like to do your own repairs, pay less up front, pay less for repowers, and don't like the idea of 4' of wasted middle transome, then I/O might be for you.
Often times you'll give up that same 4ft of deck space for the I/O.
outotime30 - 7/28/2008 7:18 AM
I can repower my boat with rebuilt engines and outdrives (my labor) for less than $6K. Looks like a pair of Yam 250s would cost me about $30K. I can buy a lot of gas for that $24K. What am I missing in my logic?
A better comparison would be to compare the cost of complete new IO's to new OB's.
I would not put used or rebuilt engines or drives on my boat. Saltwater eats everything in an engine over time and you just don't know when a used block will fail.
Someone once told me that an I/O has all of the disadvantages of an inboard plus all of the disadvantages of an outboard, without the advantages of either. I've never owned an I/O and have been very happy with outboards. Different strokes for different folks...
had I/Os all my life-- last one had 2500 hrs and fell victim to broken clamp on water PU-- however do own work and did replaced bellows and U Joints on a regular basic -- also boat in fresh water and trailer-- purchased new 70 suzy in 06 for small bass boat -- love it-- it would be a hard decision if purchasing new-- These new boat with a 30 " tramson are almost like an I/O in following waves while trolling slow for eyes in Lake E-- Warranties are great ie 6 years
Fresh water, I/Os are great and will last forever if properly maintained. Salt water is a different story, even with regular flushing your replacing manifolds and risers every couple years and if one fails chances are you'll be buying a new long block.
The main reason I own outboards is safety. Pretty much NO chance of underdeck explosion. I have never been comfortable with my engine(s) running at several hundred degrees at certain manifold points, and having 50,000 volts of electricity within a few inches of 200 gallons of fuel and fuel vapors (hopefully totally controlled). I like having the fuel below and the motor above out in the open. Never heard of an outboard catching fire or exploding at the gas dock.
__________________ 1st Cav Div Air Assault Infantry RVN
-Can Do........ and .......Carry On -
Outboards have caught fire. And where are the batteries and battery switches, etc. If they aren't "ignition" protected then they can ignite vapors....not likely but possible. When you see ignition protected in marine electrical parts it means won't ignite vapors.
Thanks for the replies. Seems that there is almost concensus about Outboards over I/O. I have a boat that I am trying to sell and seems that the lookers decide they want outboards. My suggestion to them is to put the outboards on my boat, but I can't justify the high cost versus the cost of repower. By the way, I have had excellent luck with reman engines. The SBC marine version is a $750 cost and the machine work is dead on.
lol there is no part of my I/O engine that runs at "several hudred's of degrees" you are on drugs if you think that because your boat is an outboard it has pretty much No chance of an "underdeck explosion" Anywho if i had the money i would probably be a fan or outboards. but i can do the work myself on my I/O and can afford to replace the motor in it if it takes a crap. i had a 1985 mercruiser alpha 1 set up with a raw water cooled sbc 350 ran it the balls out of it until last year when it took a crap, but thats still that is 22yrs of running raw water through it! it would run 3500rpm at 27kts all day. thats not fast but was also decent on fuel. i would prefer a straight inboard over a I/O and outboard too..
__________________ B.O.A.T - Break out another thousand
Fresh water, I/Os are great and will last forever if properly maintained. Salt water is a different story, even with regular flushing your replacing manifolds and risers every couple years and if one fails chances are you'll be buying a new long block.
The main reason I own outboards is safety. Pretty much NO chance of underdeck explosion. I have never been comfortable with my engine(s) running at several hundred degrees at certain manifold points, and having 50,000 volts of electricity within a few inches of 200 gallons of fuel and fuel vapors (hopefully totally controlled). I like having the fuel below and the motor above out in the open. Never heard of an outboard catching fire or exploding at the gas dock.
the only reason manufactures use outboard power is the easy installation. drill 4 blot holes and wire it up. I have a 454 bravo 1 (310hp) on my 24cc since 1996 just re-powered 2007. salt water cooled in florida I maintained it.
I/O vs Outboards 
1st Cav Div Air Assault Infantry RVN
