2013, the year of the jet drive?

[smclear]

Re: 2013, the year of the jet drive?

I, too, have "heard" that the Sea Doo boats powerplants tended to run into trouble relatively early. Don't know if it's true, but it is one of the reasons I went with a Yamaha.

The normally aspirated 4-stroke engines are quite reliable. The supercharged engines prior to 2008 were guaranteed to fail. It is not a question of "if" but "when". Prior to 2008, they used ceramic clutch washers in their superchargers. They absolutely will fail. When they do, little pieces of ceramic will easily destroy the engine. Beginning in 2008, they switched to metal clutch washers. This is primarily true in their skis, less so in their boats. Much information on this phenomenon can be gathered from Greenhulk.net

Yamaha uses a different type of supercharger and do not have this problem.

 

[supersoaker548]

Re: 2013, the year of the jet drive?

i love my jet boat 2.3mpg 890hp 548BBC

with old motor sold it now run a n/a motor 2mpg 548BBC 680hp

 

[QC]

Re: 2013, the year of the jet drive?

Try loading that twin engin jet and your single I/O to maximum capacities and then compare numbers again....
The jet drive is using "X" amout of hp to produce "X" amount pressure (thrust).
If you run a jet at a given rpm you will use the exact same gallons per hour loaded or empty.
As you load your boat your engine will work harder and your gallons/hour goes down.

Yeah I get all that, but loaded vs. empty I'll still get better fuel economy overall. No biggee, and I usually say so. What, $5 a day difference? So what.

You will rarely see me bash any technology here, but I will describe it. The problem is when I say Inboards are slow, people get all worked up as if I said Inboards are bad. Compared to OBs and I/Os, they are slow for the same power. It's an observation, not an indictment. I used drive a 460 and Olds 455 powered jet often. They are soooo much fun, and in shallows the stress level reduction just adds to the fun. I have thought about one of these Yammie jets a lot. If I boated on the southern sections of the Colorado, that combo would be hard to beat except maybe a single pumper as described above.

 

[smokeonthewater]

Re: 2013, the year of the jet drive?

Try loading that twin engin jet and your single I/O to maximum capacities and then compare numbers again....
The jet drive is using "X" amout of hp to produce "X" amount pressure (thrust).
If you run a jet at a given rpm you will use the exact same gallons per hour loaded or empty.
As you load your boat your engine will work harder and your gallons/hour goes down.

might rethink that...... the REAL difference between loaded and empty is mph... a heavier boat will move slower with the same thrust ie the same fuel burned will make less speed be it jet, prop, or even an airboat...

 

[OrangeTJ]

Re: 2013, the year of the jet drive?

i love my jet boat 2.3mpg 890hp 548BBC

with old motor sold it now run a n/a motor 2mpg 548BBC 680hp

Sweet! They didn't have one of those in stock when I picked up my SX210 from the Yamaha dealership...

 

[Mischief Managed]

Re: 2013, the year of the jet drive?

i love my jet boat 2.3mpg 890hp 548BBC



with old motor sold it now run a n/a motor 2mpg 548BBC 680hp

What's the top speed with those motors?

 

[Part-time]

Re: 2013, the year of the jet drive?

might rethink that...... the REAL difference between loaded and empty is mph... a heavier boat will move slower with the same thrust ie the same fuel burned will make less speed be it jet, prop, or even an airboat...

Rethink what??? I never mentioned MPH or MPG.
The load on a jet boat engine stays the same, always.
The load on the engine on a proped boat will vary with the load = gallons used per hour go up as the engine works harder.

The point I'm getting at is if you just use your boat for fishing or joyriding with just you and the admiral, the prop will be to your advantage for fuel economie (hp/efficiency)
but if you are going to spend the day WOT and pulling skiers or tubes... that difference in hp/efficiency that people always compare between props and jets will quickly disapear.

 

[supersoaker548]

Re: 2013, the year of the jet drive?

What's the top speed with those motors?

blown 548 / 890hp ran 112.4 gps
N/A 548 / 680hp run's 97.8 gps

 

[Howard Sterndrive]

Re: 2013, the year of the jet drive?

On price, I just quickly went out and looked at listed base prices of 21 foot bowriders from Bayliner, Monterey and Sea Ray. With no options and base power (4.3 V6), these started at approximately $32,500, $45,000 and $53,000 respectively. Yamaha's base 21 footer, the SX210, lists at $36,499. At that price, the boat includes things that are optional and will add to price on the others (bimini, trailer, snap out carpet, etc.).

more bewildering that I haven't ever seen one on the lake, I suspect I will see some this summer.

 

[RogersJetboat454]

Re: 2013, the year of the jet drive?

op2:

 

[smokeonthewater]

Re: 2013, the year of the jet drive?

Rethink what??? I never mentioned MPH or MPG.
The load on a jet boat engine stays the same, always.
The load on the engine on a proped boat will vary with the load = gallons used per hour go up as the engine works harder.

The point I'm getting at is if you just use your boat for fishing or joyriding with just you and the admiral, the prop will be to your advantage for fuel economie (hp/efficiency)
but if you are going to spend the day WOT and pulling skiers or tubes... that difference in hp/efficiency that people always compare between props and jets will quickly disapear.

my engines don't use more fuel when the boat is loaded unless I up the throttle and actually as rpm decreases and a given throttle due to load the fuel consumption also decreases.... besides if a person uses a boat for watersports loaded down with people but chooses a prop for an empty boat cruising they have made a poor choice.......
Strictly on the subject of efficiency I don't believe that props have a HUGE advantage in efficiency but I also don't believe that jets have any advantage at all loaded unloaded or otherwise.

I LOVE driving my 10' jeboat but it uses fuel like it's going out of style ... sure it uses the same fuel per hour with 1 or 3 people but if it goes 40 with just me and 30 with 3 people, to go 4 miles would take 6 minutes at wot with just me and 7.5 minutes with 3 people... that means 25% more fuel.... An I/O would be the exact same situation

I understand the difference between a pump and prop but I don't see it giving the jet a mpg advantage

 

[QC]

Re: 2013, the year of the jet drive?

my engines don't use more fuel when the boat is loaded

Fuel use goes up when load increases at the same speed in both examples. Jet or I/O (or OB or Inboard). Has to. Yes the RPM and fuel use "curve" is linear when it comes to driving a water pump (jet drive), but RPM will increase to maintain the same speed with more load. Has to. Please reread carefully before commenting. Mo stuff going same speed, or same stuff going faster requires more fuel. Period. That's what horsepower is. This is like Newton type stuff guys. Equal and opposite reaction? Mo stuff (load) requires mo equal and opposite reaction (power). Mo power requires more fuel. I know of no exceptions.

 

[frantically relaxing]

Re: 2013, the year of the jet drive?

Jets- the only boats with brakes!

I remember a guy in a beautiful green Berkeley jetted picklefork many years ago, used to come straight at the shore at WOT, everyone on the shore (and in the boat) with jaws and eyes wide open, then about 100' from the shore, he'd let off the gas, pull the handle back and stomp it again for about 2 seconds-- this buried the nose and shot water about 80' in the air, drowned everyone in the boat! -- and the boat would be totally stopped about 10' from the beach, with the water still falling from the sky...

Can't do THAT with no I/O!

I had a '77 Makiakona 20' mini with the wimpy 460 Ford for a summer. It wasn't the hot rod some of the others were, but I totally loved the thing!

Worst experience I had was digging the ski rope out of the impeller. But I've done that with props too..

And, this ain't no Yamaha OR Berkeley, but it IS definitely a JET boat!

Check out the webpage and video!

 

[jkust]

Re: 2013, the year of the jet drive?

I can say of the dozens of times I boated last summer I saw one jet boat. It must have been 22 feet, looked brand spankin new, was very tall and wow they were having a lot of fun on it. I like the social swim platform set up on them...sort of reminds me of the open kitchen concept in houses the last 10 or 13 years. You spend most of the time in the kitchen...and for us most of the time on the platform and lounge pad so jets from a pure lounging perspective to me make a lot of sense. I could not care less about fuel usage as long as it lasts a whole day and am aware of the tow sports down sides, and the other issues but from a acceleration and plain old fun stance, I can see owning one.

Now to me the issue is that you can get a formerly 30k - 45K, 19 foot i/o for pennies on the dollar, 5 years old from top end all the way down to Bayliner and Stingray...they are everywhere. The same can't be said of jet boats for us used buyers. On the lake at least there must be 1 modern jet boat to 1000 non jet bowriders. I also never boat on shallow lakes as most of the ones you want to recreational boat on are deeper.

 

[smokeonthewater]

Re: 2013, the year of the jet drive?

Fuel use goes up when load increases at the same speed in both examples. Jet or I/O (or OB or Inboard). Has to. Yes the RPM and fuel use "curve" is linear when it comes to driving a water pump (jet drive), but RPM will increase to maintain the same speed with more load. Has to. Please reread carefully before commenting. Mo stuff going same speed, or same stuff going faster requires more fuel. Period. That's what horsepower is. This is like Newton type stuff guys. Equal and opposite reaction? Mo stuff (load) requires mo equal and opposite reaction (power). Mo power requires more fuel. I know of no exceptions.

I'm not the one who needs to reread.... you just said the same thing I did.... at a given throttle ("unless I throttle up") load does not increase fuel gph but DOES decrease mph so thus both use more fuel to carry more weight. as you said, no exceptions

 

[QC]

Re: 2013, the year of the jet drive?

Maybe we were saying the same thing, just didn't seem like it. Not trying to be snarky, it was more of a can't do more work without more fuel whether it's a jet or a prop. In fact both jets and props are pretty linear when it comes to fuel and load, but theoretically slip increases slightly when more load is on for the same RPM. All good. Like I said, we are probably saying the same thing

 

[smokeonthewater]

Re: 2013, the year of the jet drive?

YUP we worded it differently but we're on the same page.... LOL

 

[Mischief Managed]

Re: 2013, the year of the jet drive?

blown 548 / 890hp ran 112.4 gps
N/A 548 / 680hp run's 97.8 gps

That's awesome. Must be a riot to operate.

 

[smokeonthewater]

Re: 2013, the year of the jet drive?

I love how 210 hp only gains 14.6 mph ... that really demonstrates how much more power it takes on top to make just a little more speed.... (in ANY boat not pointing fingers at jets)

 

[OrangeTJ]

Re: 2013, the year of the jet drive?

I love how 210 hp only gains 14.6 mph ... that really demonstrates how much more power it takes on top to make just a little more speed.... (in ANY boat not pointing fingers at jets)

It is pretty crazy. Similar effect in the Yamaha jets - my SX210 makes 220 hp and will run 47. A 212SS has the same hull but makes 360 hp and will run 55-57. A 64% increase in power for a 21% increase in top speed.