Just read a comparison outboard, sterndive, jet drive.

[tuffr2]

Glastron now makes a boat with 3 power options. I saw a test of all 3 power options and it proves what I always kinda knew. Outboard power is the best and Jet Drive power the worse. In the test for speed a 150 HP outboard matched 220hp stern drive which was faster than 250hp jet drive.

To be honest I kinda knew this from the old days. Was suprised it is still true in 2018.

The 4 cycle outboard had the best mpg and was also the quietest. Was suprised jet drive finished last again since it has the least amount of underwater drag. They said that in this Glastron set up the jet drive did not have any trim feature. The sterndrive and outboard were able to get more boat out of the water.

They did not talk about jet drive being able to go thru shallow water better.

[Sailmonkey]

A jet drive will always be less efficient because if the way it provides propulsive force. However it has other benefits beyond shallow water operation (really shallow water isn’t the jet drives friend either).

[hobopacket]

Faster and more mpgs aren’t always the pros one needs to look at. I would love outboards. But my old 350 Chevy I/o is crazy easy to work on.

[Fence Man]

I prefer outboards over I/O because there isn't a giant hole in the boat to spring a leak when you aren't looking. But, I'll agree with Hobo on the 350 Chevy. Easy to fix, and parts are easy to get.

[Scout 30]

The comparison left out straight inboards. Way superior to IOs & the best option if you want diesels. Still hard to compete with getting the motors completely outside of the boat. Frees up a ton of room.

[ZULU40]

Originally Posted by tuffr2

Glastron now makes a boat with 3 power options. I saw a test of all 3 power options and it proves what I always kinda knew. Outboard power is the best and Jet Drive power the worse. In the test for speed a 150 HP outboard matched 220hp stern drive which was faster than 250hp jet drive.

jets are more usually just centrifugal compressors and their efficiency or the lack of it described their demise to axial jet engines in the early jet aircraft era. In this case one could compare an open prop to an axial engine sans the shroud. That said they have some solid virtues, not the least of which is a good efficiency off their peak RPM.

more specifically, watch any film about New Zealanders and their jet boats, Im sure any reasonable person would be convinced they fit the purpose in the environment they find themselves in, perfectly.

Originally Posted by tuffr2

To be honest I kinda knew this from the old days. Was suprised it is still true in 2018.

The 4 cycle outboard had the best mpg and was also the quietest. Was suprised jet drive finished last again since it has the least amount of underwater drag. They said that in this Glastron set up the jet drive did not have any trim feature. The sterndrive and outboard were able to get more boat out of the water.

Not so sure here, Evinrude have done a lot of work on the injected 2 stroke that would give any 4 stroke a run for its money, and on power per pound (important for demountable outboards) theyre going to be in front

Originally Posted by tuffr2

They did not talk about jet drive being able to go thru shallow water better.

and heres the rub
where one has the option to choose the definable criteria one can always assert a case extraordinary to practical value.

[Cheechako]

The problem is a 250 HP outboard is $20k and a V8 I/O almost half that. It is nice having the engine out of the boat, but they are also very hard to work on compared with a simple auto engine. You can get a rebuilt long block for a 350 GM for about $1600-1800 when it comes time to replace. Jets are cool but yeah, inefficient.

[denverd0n]

Everybody has their own criteria. Outboard may be the best for you. It may be the worst for someone else. All depends on what you're looking for. (Which is true of almost everything in life.)

[Cadence]

Originally Posted by denverd0n

Everybody has their own criteria. Outboard may be the best for you. It may be the worst for someone else. All depends on what you're looking for. (Which is true of almost everything in life.)

And how deep your pockets are?

[skipmac]

Did the test compare torque, pulling power, time to plane or out of the hole? I know competition ski boats generally use V-8s but inboard. Part of the reason is center of turn and weight distribution in the boat but I think the larger displacement of the inboard is better for pulling you out of the water and holding speed when the skier is digging in for a turn.

[Jammer]

If you are going to play in the river or other places where it is shallow then a jet boat is what you want.

Stern drive vs. outboard much depends on what the hull is designed for. Big outboards require a hull designed for a very heavy load aft of the transom. Stern drive less so. Once you have an outboard that is large enough that you cannot lift it off the boat for maintenance they become a huge hassle to work on and expensive enough that it is rarely cost effective to repower an older boat.

For runabouts in the 20-24' range it is my experience that the stern drives just make for a nicer boating experience. Quieter motor, uncluttered sight lines. These days it seems everyone has pontoons but I'd rather be on a ~22' i/o bowrider if I were just bumping around seeing the lake.

On a smaller boat I prefer to get rid of the console and use a tiller-steer outboard that is small enough to lift off and work on inside.

[tuffr2]

In this test the 150 HP 4 cycle outboard was quieter than the 220 HP stern drive.
Agree that the advancments in 2 cycle outboards like the E-Tec G2 would have been the 4th comparison but it was not tested.

I saw a E-Tec G2 engine at idle. It was quiet and smooth. No vibration that I could see.

For speed, the 150HP outboard pushed the boat as fast as the 220HP stern drive. The 250 HP jet drive was 7 mph slower. Like 50 mph outboard/stern drive vs 43 mph for the jet drive.



The Glastron did not have tilt/trim on the Jet Drive

[Cheechako]

It does depend a lot at where in the planing cycle as far as noise goes. The 4 stroke OB's can be very quiet at idle/low rpm for sure. They grind hard under planing power. at a smooth plane the inboards can be at least no worse.

[a64pilot]

Originally Posted by skipmac

Did the test compare torque, pulling power, time to plane or out of the hole? I know competition ski boats generally use V-8s but inboard. Part of the reason is center of turn and weight distribution in the boat but I think the larger displacement of the inboard is better for pulling you out of the water and holding speed when the skier is digging in for a turn.

A four stroke outboard usually doesn’t have good low end grunt like a two stroke does, Mercury Supercharged their Verados to fix that.
Another reason ski boats have big auto motors is mass, a heavy boat isn’t effected much by a skier on a slalom course, where an outboard powered Boat you can feel the skier slow the Boat.

The reason outboards got so popular way back when was because they were light and cheap, they aren’t so light anymore and certainly are not cheap, however you see many big Sportfishermen repowered with multiple 300 HP outboards, which due to their cost, confuses me.
I would expect due to cost to see a resurgence of inboard boats, but logic doesn’t drive what sells, popularity does, or you would not see so many four wheel drive SUV’s on the road, especially say in Florida where snow is unheard of.

[ZULU40]

Originally Posted by a64pilot

A four stroke outboard usually doesn’t have good low end grunt like a two stroke does, Mercury Supercharged their Verados to fix that.
Another reason ski boats have big auto motors is mass, a heavy boat isn’t effected much by a skier on a slalom course, where an outboard powered Boat you can feel the skier slow the Boat.

The reason outboards got so popular way back when was because they were light and cheap, they aren’t so light anymore and certainly are not cheap, however you see many big Sportfishermen repowered with multiple 300 HP outboards, which due to their cost, confuses me.
I would expect due to cost to see a resurgence of inboard boats, but logic doesn’t drive what sells, popularity does, or you would not see so many four wheel drive SUV’s on the road, especially say in Florida where snow is unheard of.

The popularity of sport fishing is a pervasive force that keeps high power outboards popular. Fishermen like to make the best use of their available time by having very fast boats, and when it comes to stuffing 900hp on the ass of a boat fishing requires clearer decks than multiple inboards can afford.

Outboards also allow you to tilt or raise dead engines out of the water, as do stern drives, but for some reason stern drives have not overcome the disastrous corrosion problems that have beset this power delivery principle.

Such is the variety and uniqueness of platforms, outboards and their conveniences are set to be with us for a long time to come, and irreplaceable in many roles.