How reliable are modern outboard engines?

[DoubleEnder]

My experience to date is 100% sailing boats and diesel auxiliary engines, 21st century 20-30hp Beta, Yanmar type of thing. I believe these engines to be reliable and easy to maintain.
The next boat could be a small motor boat 6-7m that would be used both on sheltered upper Thames and occasionally in east coast estuaries. My prejudice is for diesel inboard power but I think there may be more choice if I go for outboard power. It would also be helpful, potentially to have high speed available from tim to time, and I guess lighter weight and more beachability too, also desirable.
But. …are modern outboards really reliable enough for coastal work like this? Should I carry a backup little outboard?

And do you service them yourself? If not, how does servicing get done, it would be hard to hump a 40hp engine off the boat?

apologies for dumb questions and thank you

 

[julians]

I think a modern well serviced/well maintained outboard is just as reliable as any well serviced/well maintained diesel inboard.

So if you have more choice of boats by considering an outboard, and the petrol is available in your area then it's a no brainer. Fuel consumption will probably be higher with the outboard than the diesel,but whether that's a problem depends on how many hours you will do.

 

[jakew009]

My experience to date is 100% sailing boats and diesel auxiliary engines, 21st century 20-30hp Beta, Yanmar type of thing. I believe these engines to be reliable and easy to maintain.
The next boat could be a small motor boat 6-7m that would be used both on sheltered upper Thames and occasionally in east coast estuaries. My prejudice is for diesel inboard power but I think there may be more choice if I go for outboard power. It would also be helpful, potentially to have high speed available from tim to time, and I guess lighter weight and more beachability too, also desirable.
But. …are modern outboards really reliable enough for coastal work like this? Should I carry a backup little outboard?

And do you service them yourself? If not, how does servicing get done, it would be hard to hump a 40hp engine off the boat?

apologies for dumb questions and thank you

Modern outboards are probably as reliable if not more reliable than a diesel inboard.
They are generally less complicated and need less maintenance than an equivalent inboard diesel.

The fuel is obviously a bit more expensive because you have to pay full tax on it, but you will save on servicing and no out drives to worry about..

The RNLI stick them on the back of their boats...

Edit: servicing is easy - changing the engine oil is like changing the oil on a lawnmower, changing the gearbox oil is just undoing a plug and let it drain out, fuel filter, maybe the spark plug occasionally. No need to take it off the boat, you could do the complete service in 30 mins.

 

[ontheplane]

In my experience, absurdly reliable unless you go for cheap Chinese or something with the word “Force” on the hood!

Mainly had Yamaha and they rarely if ever go wrong if basic maintenance is carried out... I have never had an issue.

 

[simonfraser]

'sheltered upper Thames and occasionally in east coast estuaries'
you're not going to do monster miles, OB at least as reliable and way easier to access

 

[Fire99]

It does depend on the outboard's age but if you are looking at currently available engines, the 40hp will be fuel injected and have an ECU so likely a fundamentally reliable engine but you may have the odd sensor issue and possible need to electronically diagnose like you would a car. But fundamentally reliable. You are looking at around 100kg (220+lbs) in weight so this is no engine to lift off yourself.
Something like a modern Tohatsu has a fresh water flushing system which makes it easy to flush out the salt.

The other big plus is that the engine is easily accessible to service so no folding yourself in half to do maintenance. Something like a modern 40hp will happily plop along at low revs without sooting up and also be happy on a coastal blast. You don't need to run them fast to keep them running well.

So they are expensive, electronically fairly complicated and very heavy but reliable, easy to service and low-maintenance on the running side too. Just press the button and off you go.

 

[Rappey]

Outboards have a great resale value, it's easy to increase or decrease the size of the engine and they are smooth and quiet.
With a demountable tank you can fill up anywhere . Look at the amount of 40yr plus old outboards still working on the back of boats.

 

[Fire99]

Look at the amount of 40yr plus old outboards still working on the back of boats.

That's true.. My outboard on my tender is a 9.9hp 2-stroke from 1991...

 

[Boathook]

Modern outboards from the main brands are good. I've got a Honda 30, about 15 years old and it still works well. Servicing is easy but mine has 3 carbs that ideally need to be balanced at each service. I've quite happily motored for 16 hours to get across the channel and engine was running well.

 

[harvey38]

Hmmm, I would generally say they are very reliable.......however.
I always flush my Suzuki 2.5hp in fresh water, shut the fuel off and run it out of fuel and put it on the rail mount in a full cover.

I came back to it after four weeks and it has no compression, nothing! It would appear the valve seats are made of chocolate and corroded. Not a happy Suzuki owner?

 

[Bouba]

A super reliable Honda 150 would go very nicely on a 7m boat....it will never let you down

 

[Pleinmont]

Yes modern outboards are pretty reliable and easy to access.

If you do flush your outboard innards with fresh water using a flush port after using (which is a very good idea) just be aware of what is actually being flushed. It seems to vary between motors.

I had a Honda 20hp on a trailer rib for a few years until recently and always flushed after each trip. Was easy to connect a hose pipe and leave it 5mins cleaning itself - manual said this had to be done without the engine running as it didn't provide enough water to cool the motor just clean it inside.
Then started getting overheating shutdowns whilst out at sea which was scary. I took it apart and found the thermostat was completely blocked with salt crystals.
It turned out that as the engine is off and cold, the thermostat stays closed and the water doesn't even pass through and enter the head so the engine stays full of salt water till the next time you use it.
The flush port seems pretty pointless and misleading in this respect.
I replaced the thermostat, cleaned out the crystal deposits and the motor was perfect again.

Much better to flush on tick-over using muffs on the intake and let the engine warm up, then the thermostat opens and fully circulates the fresh water.
Or if easier, run it in a barrel of water (I could never get the muffs to actually stay on whilst the engine was on tickover, used to fall off after a minute or two).

 

[simonfraser]

hm, is this still the case with a modern Honda 150 HP ?

 

[Pleinmont]

Not sure, my 20hp Honda was about 2008 I think, maybe the newer ones (and/or the bigger ones) are better now and allow a full engine flush through via a hose port. It would be good to think they have improved that design flaw.

 

[C08]

Without having any evidence to this effect I suspect modern outboards will be less reliable than older ones. Does fuel injection with its associated electronics improve or impair reliability? Nice to have features like power tilt could be expected to introduce more stuff to malfunction.
My experiences with an outboard main engine have been pretty good but not without problems. My Tohatsu 30hp 2 stroke was totally reliable for 8 years from new but with only about 1000 hours was showing signs of wear mostly paint peeling etc and rust on the non-stainless many engine bolts. My 20HP Tohatsu 4 stroke was totally reliable in itself but there was a break in a power tilt wire at 5+ years that fortunately was down at the time and I was almost back on my pontoon berth after a long summer cruise. There is a power tilt to manual release screw but anyone who thinks that is a saver has not tried to release a screw 1ft under water at the back of a boat-just not possible even in flat water. The engine also had bad corrosion on the prop shaft bearing carrier at 7 years which needed replacing although it did not actually fail it would soon have let water into the gearbox reulting in a trashing of the bottom end. This motor after 8 years from new needed a comprehensive de-rusting and painting before selling and buying a new motor.
My current motor a 25hp Yamaha High Thrust motor is impressively heavily built but when I sounded out dealers about aroutine service I was stunned to find that the boat had to be lifted for them to access the leg and remove the impeller and replace gear oil (no chance of taking a 235lb lump back to the dealer) . So much for a cheaper option than an in board engine.
There are things that appear potentially problematic with outboards, having the power tilt wires underwater. Although these are cable tied to the lower transom bracket there is a cable there that needs to be sealed from water ingress. On my Yamaha there is a gearbox breather, a 6mm plastic tube secured with cable ties at the plastic union you need to separate to drop the leg. Hardly what you want to see a £5k engine dependant upon.
Given the choice I would go for a diesel inboard engine everthing else being equal although on a cat being able to lift the leg when sailing is one advantage. Getting petrol alongside is quite a problem in some areas.

 

[C08]

Outboards have a great resale value, it's easy to increase or decrease the size of the engine and they are smooth and quiet.
With a demountable tank you can fill up anywhere . Look at the amount of 40yr plus old outboards still working on the back of boats.

Although an outboard engine fuel tank is a "portable appliance fuel tank" within the legislation covering cans at petrol stations most fuel stations have their own rules which preclude any container more than 10L and in my experience staff rigidly enforce this so filling a 25L tank at the forecourt is quite difficult now.

 

[Davy_S]

most fuel stations have their own rules which preclude any container more than 10L and in my experience staff rigidly enforce this so filling a 25L tank at the forecourt is quite difficult now.

I cannot honestly say that i have ever come across that problem, simply lift the boot or hatchback up and fill up, half the operators cannot see what you are doing, nor do they care, it was painfully obvious the amount of motorists topping up containers when we had the fuel shortage.

 

[Boathook]

Without having any evidence to this effect I suspect modern outboards will be less reliable than older ones. Does fuel injection with its associated electronics improve or impair reliability? Nice to have features like power tilt could be expected to introduce more stuff to malfunction.
My experiences with an outboard main engine have been pretty good but not without problems. My Tohatsu 30hp 2 stroke was totally reliable for 8 years from new but with only about 1000 hours was showing signs of wear mostly paint peeling etc and rust on the non-stainless many engine bolts. My 20HP Tohatsu 4 stroke was totally reliable in itself but there was a break in a power tilt wire at 5+ years that fortunately was down at the time and I was almost back on my pontoon berth after a long summer cruise. There is a power tilt to manual release screw but anyone who thinks that is a saver has not tried to release a screw 1ft under water at the back of a boat-just not possible even in flat water. The engine also had bad corrosion on the prop shaft bearing carrier at 7 years which needed replacing although it did not actually fail it would soon have let water into the gearbox reulting in a trashing of the bottom end. This motor after 8 years from new needed a comprehensive de-rusting and painting before selling and buying a new motor.
My current motor a 25hp Yamaha High Thrust motor is impressively heavily built but when I sounded out dealers about aroutine service I was stunned to find that the boat had to be lifted for them to access the leg and remove the impeller and replace gear oil (no chance of taking a 235lb lump back to the dealer) . So much for a cheaper option than an in board engine.
There are things that appear potentially problematic with outboards, having the power tilt wires underwater. Although these are cable tied to the lower transom bracket there is a cable there that needs to be sealed from water ingress. On my Yamaha there is a gearbox breather, a 6mm plastic tube secured with cable ties at the plastic union you need to separate to drop the leg. Hardly what you want to see a £5k engine dependant upon.
Given the choice I would go for a diesel inboard engine everthing else being equal although on a cat being able to lift the leg when sailing is one advantage. Getting petrol alongside is quite a problem in some areas.

My Honda 30 is around 15 years old and so far reliable. I had carb problems due to modern fuel and had to get them cleaned. Paint peeling of doesn't affect reliability. In all the years that I have had outboards the gearbox oil at the bottom of the leg has always required yearly replacement. Over the years for various reasons, I have managed to remove the leg whilst afloat and change the impellor and oil. Fiddly I must admit but doable. All going well this winter, the 100kg engine will be off my boat, in the car and dropped off at a Honda dealer for them to work their magic on a service. Not to sure what they do but it has in the past come back running very smoothly, something I struggle to do. I suspect it is due to balancing the 3 carbs plus a few other tweaks.

 

[Rappey]

cannot honestly say that i have ever come across that problem,

I have a 30 litre "demountable" fuel tank. In the past 25 years have only once had an issue where they would not turn on the pump.
The relevant parts on the hse Web site seem to be scattered but I found "plastic container -10 litres. Metal -20l and demountable fuel tank-30litres
30 litres is also the max you can store in your car !
The regulations do not specify the number suitable portable containers that can be filled.

 

[25931]

My experience to date is 100% sailing boats and diesel auxiliary engines, 21st century 20-30hp Beta, Yanmar type of thing. I believe these engines to be reliable and easy to maintain.
The next boat could be a small motor boat 6-7m that would be used both on sheltered upper Thames and occasionally in east coast estuaries. My prejudice is for diesel inboard power but I think there may be more choice if I go for outboard power. It would also be helpful, potentially to have high speed available from tim to time, and I guess lighter weight and more beachability too, also desirable.
But. …are modern outboards really reliable enough for coastal work like this? Should I carry a backup little outboard?

And do you service them yourself? If not, how does servicing get done, it would be hard to hump a 40hp engine off the boat?

apologies for dumb questions and thank you

Even on a sailer with diesel I have normally carried a baby o/b. Once, fairly close to shore an unmarked pot line stopped the engine, needless to say, there was no wind. The dinghy mounted motor got us home safely.