Outboard vs. stern drive

J

Jake

New member
Not so much a C-Dory question but general boating. On say a 25 foot single engine boat, what would be some differences of stern drive compared to OB regarding:

1. Steering, forward and reverse. General handling.
2. Steering effort. Stern drive is one finger light but how much effort does a typical hydraulic system require.
3. Noise.
4. General reliability and maintenance.

Many more differences of course, just looking for some real life experiences in the above areas.

Thanks,
Jake
 
My experience with IOs is that the motors are are reliable and easy to work on, or even to replace, but the lower section is problematic., Mine were twin 140 hp 4 cyl Chevy engines. The lower units, from the engine back, were a constant problem. Consider the complexity of 2 90 degree gear boxes, gimble bearings, multiple seals, a "u" joint, rubber bellows, etc.

Besides that they perform pretty much like an outboard. Only difference is you can't lift one off the transom and take it to the shop for repair.

While, since then, I have gone with inboards or outboards, I am sure others have had better experiences. As with everything else, it's a matter of personal choice.
 
Jake":103g9xmp said:
Not so much a C-Dory question but general boating. On say a 25 foot single engine boat, what would be some differences of stern drive compared to OB regarding:

1. Steering, forward and reverse. General handling.
2. Steering effort. Stern drive is one finger light but how much effort does a typical hydraulic system require.
3. Noise.
4. General reliability and maintenance.

Many more differences of course, just looking for some real life experiences in the above areas.

Thanks,

Jake
Click to expand...




1. Same
2. Same
3. 4 Stroke Outboards are QUIET!
4. IO is at least 100% more maintenance. & a properly maintained IO / stern drive is as reliable as a outboard.
 
A good mechanic once told me he would never own an I.O.. That was enough for me. More maintenance engine harder to service etc.
Out boards easier to service such as oil changes, impellor changes, winterization, and the bonus prize no part of an outboard failing can the sink the boat.
D.D.
 
We went from a CD22 with 90hp outboard to a heavy diesel sterndrive 26-footer. Quite the learning curve on setup and maintenance of the Volvo KAD44P engine and sterndrive. Our Yamaha 90 2-stroke had required almost no maintenance over 5-6 years and a lot of hours.

Now that I understand to prop it right and maintain religiously the belts filters etc on the engine, that part is relatively easy. The sterndrive is another matter - especially with the torque of the 260hp diesel, the drive is pushed about as far as it can handle. It goes about three years and 1500 hours between major services (open up, check, replace seals, etc). I do drive lube changes, bellows replacement, and other routine stuff.

For us it's worth it. There are significant advantages, including cabin heat and hot water from the engine, galley and shower with hot water, and much more electric generation capacity with aftermarket alternator and regulator.
 
The latter has a transmission, a straight drive shaft passing through the bottom of the boat, through a support, and having the prop, and the a rudder. That type of drive has very low maintainence issues, except the shaft log (and seal). Main issue with them is similar to the I/O, that being the engine takes up cockpit space unless the deck of the cockpit is raised above the engine. I would have that setup anytime, if it could be encorporated in the c-dory. Main problem though is that the draft of the boat cannot be varied by raising an outboard, or outdrive when in shallower waters.
 
I spent several years boating with friends who had a B-boat. Same length as my Cruiser. Their boat had an IO drive and a Merccruiser marine engine with all the trimmings, the 90 degree gear boxes, the bellows, and the exhaust risers, and the usual cramped to unbelievably inaccessible parts to deal with for maintenance and repair.

It was, admittedly a hefty deep vee hull, and when we got together, it was most often on their boat because of the cockpit room and the full width bench seat aft.

When we stopped at the fuel dock, things were very predictable. If he filled first, I would know exactly what my bill would be..... one half of his. If I filled first, his was always twice of mine.

The only boat I ever actually saw that was sunk at the dock, was an IO that got a bad case of bellows rot, and it broke open from some wave action and went down in an afternoon.

That's just a few of the things I like about my C-Dory with an outboard.

Harvey
SleepyC :moon

IMGP1872.thumb.jpg
 
I have owned 3 gas I/O boats. Issues:
1. corrosion and maintenance of the bellows, with the I/O in the water.
2. cannot raise the lower unit out of the water
3. If you trim the lower unit up, for shoal areas, you cannot run above an idle
4. very difficult access to the engine parts, especially starter.
5. More noise for the same HP, even with insulation of the engine room.
6. More intrusion into the cockpit--less cockpit room, and awkward.
 
Dr. Bob,

Always value your advice. And I feel like if you listed every boat you've ever owned it would take up an entire screen page. :D

I currently own a I/O with about 90 hours on it,purchased new in 2011, kept on a lift in a covered slip on a good size lake. So only routine maintenance and I can change oil and filters from the cockpit with the boat on the lift. And also the boat stays dry and is easy to keep clean. But yes, most any other repairs/maintenance would be tough to access and expensive since I wouldn't be doing the work.

So the current boat is a good fit for the current situation but just looking ahead (as always) to what might be next. Glad to hear noise is not a concern.
 
Jake,
Your use of the I/O is that of least risk to the engine, and out drive. Those two boats I have kept in salt water full time (Calif). Needed new outdrives in about 3 years because of the corrosion issues. I am glad that works for you.

The most recent I/O, was lift kept, fresh water for the last few hundred hards before on the lift. I caught a stick about 1" in diameter between the counter rotating props, after Hurricane Ivan (lots of Debris), at idle speed. That was enough to destroy the gears in the lower unit, and the 3rd boat needed a new outdrive. (The same stick, it hitting an aluminum prop, may have dinged it--but most likely no damage to the gears. With A SS prop, there most likely would have been no damage.
 
An item not mentioned is the possibility of increased fuel leak/fire/explosion hazards in an I/O boat.

Having the fuel consuming engine in the boat where any leaks in the fuel system can get into the bilge increases the risk.

Automotive engines are located under the hood of a car where any fumes/spills can vent into the air. Boats are bowls with closed spaces where the fumes/spill can collect.

A power vent system is mandatory on gasoline inboard engines.

Adhering to ABYC and USCG specs is mandatory to prevent the big boom! NEVER work on the fuel system unless you KNOW what you are doing, and only use MARINE parts for any repairs. Just because the block is a GM 350 block does not mean that the fuel pump, carb, fuel lines, filters, etc are the same as the car versions. NEVER modify any part of an I/O engine fuel or electrical system.

Do not use new or rebuilt automotive starters or alternators. Marine grade starters, alternators, and other electrical components are designed to prevent open sparks which could start that big BOOM.

Lastly, when I worked in the repair shop, we mechanics called the I/Os a "Mechanics Retirement Plan"!

In my opinion, outboards are safer, and less expensive to maintain.
 
An I/O has twice the moving parts as the lower unit on an OB, think Z vis L. This fact alone should steer you away from stern drives.
Also, I see older I/O stern drives converted to outboards all the time, never the other way around.
 
I think Bob's reply was as great as any! FWIW, I've had 3 boats. A pontoon with an OB, a Searay cabin cruiser with an IO, and now my CD-22 with the OB. Outboard hands down. (And I say this even though I felt more knowledgeable and handy with the I/O, as the engine itself wasn't much different from an automobile engine!) Colby
 
Trailer Boat #13 has outboards.
Ditto what Dr. Bob wrote, in spades.
In addition, there are 10 good reasons for outboards:
#1 No outboard parts failure will sink your boat unattended at a marina, while all stern drive engines are sitting way too far under the waterline and hoping for 'good maintenance' and good luck.
#2-#10, repeat the above and get over it.
Cheers!
John
 
gulfcoast john":3qpf9q7q said:
Trailer Boat #13 has outboards.
Ditto what Dr. Bob wrote, in spades.
In addition, there are 10 good reasons for outboards:
#1 No outboard parts failure will sink your boat unattended at a marina, while all stern drive engines are sitting way too far under the waterline and hoping for 'good maintenance' and good luck.
#2-#10, repeat the above and get over it.
Cheers!
John
Click to expand...

:thup :thup :) :D :lol: :thup :thup

Harvey
SleepyC :moon

JC_Lately_SleepyC_Flat_Blue_055.highlight.jpg
 
I normally don't think I have been boating unless I hit something underwater... or fowl a prop.... an outboard is much easier to lift the outdrive up out of the water .....easier and cheaper to replace... plus I never have to worry about those darn boots between the outdrive and the water...

Joel
SEA3PO
 
We have a Volvo Penta D4-260 with a DPH drive at present. The engine and drive are flushed and stored on a trailer unless we are sleeping on the boat, which is 3/4 of the weekends and one two-week vacation per year. We purchased this boat (used) because it was the right machine for our mission, at the condition and price we wanted. The particular setup (gas/diesel/outboard) was secondary.

The efficiency of the D4-260 propulsion package is great. We are somewhere between 3 and 3.5 nmpg at 28-29 knots. Having no gasoline aboard is also comforting. The engine provides cabin heat which we used all summer, and it heats our domestic hot water for use where we have no power.

The drive merits concern for the reasons others have listed. This is not a machine suited for those not inclined to understand how it works, operate it properly, and maintain it properly. The fuel savings offset by the maintenance cost are likely a wash when compared to outboards. Commercial operators and heavy users could see substantial fuel savings with the diesel IO, and I have talked to some with 3700+ hours on a similar power package. My reading indicates the D4-260 id designed for a 5000-hour service life. For the recreational user, the diesel IO purchased new might not pay for itself. We have not experienced any limiting or disabling mechanical casualties.

I personally would not be interested in a gasoline IO, UNLESS the purchase price were adjusted downward considerably. I would likely repower with outboards when the time came. There are some fantastic deals out there in gas IOs right now.

If I were ordering a new boat to possibly sell in the future, I would spec outboards. If I were keeping it long-term or putting on many hours, I would go with a diesel and strongly consider Arneson.
 
You got good advice! As always, listen to Dr. Bob!!!

Regarding steering, it does take more to turn an outboard than an i/o, as you must turn the entire package, whereas with an i/o you just turn the outdrive.

I would consider arneson if I were building a new boat.

I would not be too excited about an i/o, thought most of the boats in our harbor (mostly commercial) have them.

For one, they have more moving parts, and the driveshaft must turn as it connects to the outdrive, then it extends horizontally, then turns vertically, and again horizontally to the prop. An outboard simply mounts the drive shaft vertically down the lower unit and it turns horizontally once to the prop: simpler. Less potential for breakdown, and cheaper!

I think it's easier to work on an outboard on the water, unless it's rough, or you drop something.

But the giant hole below the water line is something I detest the most.

If I were to design a jet boat of any size, I would go for an inboard though. The drive shaft runs horizontally to a horizontal impeller. No turns, and more efficient than an outboard jet that does some convoluted things to suck water up and shoot it out.
 
I'm betting you guys aren't too keen on a pod drive either :) LOL

I love outboards, just haven't ever owned one, which is why I started this thread. Think I asked some specific questions partly because I'm aware of the differences but also had the more general question of why so many small inland lake recreational boats are I/O? I know many of the reasons. Just wondered if I was missing some major non-obvious disadvantage of an outboard. Evidently not.

Thanks for the insights.
 
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