Can't believe my fuel consumption.

[PBJT]

I use to own a 1997 twin engine sea doo jet boat (twin 85 hp) It was a 14ft speedster. I sold it a few years ago just because the fun vs cost of fuel was getting to me. I shy'ed away from boating cause fuel is not getting cheaper but I was getting that boat itch. So we took the plunge and purchased a brand new 2009 Rinker 192 Captiva with a 4.3 MPI V6 thinking we can atleast sit on the boat in the water if we don't want to run it. Well I can not believe how Little fuel this thing uses in comparison to our older 2 stroke twin engine jet boat was......I bet we burn of 1/4 or less fuel we did before. If I had of known these new MPI boats were this good on gas I would have bought a bigger boat .

Any how, thought I would share my pleasure regarding what I found regarding our new purchase and thanks to Iboat for a place to share it.

Pete

 

[abj87]

Re: Can't believe my fuel consumption.

Don't doubt it. Older two strokes are gas hogs, plus that coupled to jet drives its a match made in hell from a fuel economy standpoint. Whats your consumption 4-5GPH?

 

[PBJT]

Re: Can't believe my fuel consumption.

Based on 11.5 hrs I have on our boat I just calculated it out to 4.45 GPH

The exact same type of use with the 1997 seadoo was 18.32

Wow, the calculator was fun, thanks for the question....no wonder I sold it!! But it was fun jumping a 14 foot boat over 3 foot waves

Pete

 

[NelsonQ]

Re: Can't believe my fuel consumption.

I use to own a 1997 twin engine sea doo jet boat (twin 85 hp) It was a 14ft speedster.

If I had a dollar for every time someone told me that I could afford the gas in my two stroke

Actually, I just bought my boat the end of June and since then I've noticed a lot of Sea Doo jet boats. Not surprisingly with the fuel cost on the rise, these boats are selling. That's saying something about fuel consumption on them.

By the way, great looking Rinker you have there.

 

[abj87]

Re: Can't believe my fuel consumption.

The exact same type of use with the 1997 seadoo was 18.32
Pete

that's insane!

 

[bowtie4x4295]

Re: Can't believe my fuel consumption.

Agreed, I just sold my 19.5 with the 175 Black Max. Boat was FAST, but could not go very far. Sold it, bought a 18 foot bowrider with a 4.3 carbed engine. We filled it up, went out 4 times, just cruising around 3000-3200 rpm, few hours at a time. Fuel needle didn't move, called the man I purchased it from to see if it was normal. He advised it was completely normal, the boat just sips gas. I filled up back up and it took 12 gallons. I am so happy I have only had to put gas in the boat 3 times this season. I would love more power and the V8 sound, but the GPH is great.

Mike

 

[Mischief Managed]

Re: Can't believe my fuel consumption.

If I had of known these new MPI boats were this good on gas I would have bought a bigger boat .

It's not really the MPI that's making the boat more efficient, it's the drive and probably the style of operation. It would "sip" gas with a carburetor too.

When I drive jet boats and PWCs, I turn often, go on and off plane, and change throttle settings (often going WOT) constantly. It's fun, but terrible for fuel consumption. Stern drive boats lend themselves to steady-state cruising and since they are pokier out of the hole compared to jets, we don't come off-plane unless we have to.

Glad you are having fun.

 

[180shabah]

Re: Can't believe my fuel consumption.

Agree with MM, half of that difference is in the "design" and the other half is in the usage. How often will you be chasing larger boats jsut to jump thier wake in the new boat.

Case in point - check out Sugar Sand, they make single engine(more effieient than twins) jet boats with fuel consumption that is comparable to I/O's

 

[Irv964]

Re: Can't believe my fuel consumption.

I can relate to that too, when I purchased my latest boat/motor (2007 90 Merc 4 Stroke) I thought the gas gauge was stuck? I said to my wife who was in the boat with me, we had better get back because I think the gauge is not reading right and we have been boating/tubing for a while!
I had no idea what to do except add more gas and see if the guage went up? Too my surprise it did! I couldn't beleive it, we hadn't burnt enough to make the guage move at all.
My last motor I had was a Nissan 50HP 2 stroke and that was great on gas imo but this 90 4 stroke is even better than it................Irv964

 

[NSBCraig]

Re: Can't believe my fuel consumption.

Jets suck down gas.

 

[Bigprairie1]

Re: Can't believe my fuel consumption.

The exact same type of use with the 1997 seadoo was 18.32

....you're kidding...right? 18.32 gph?
I knew jets were thirsty and I assume that two jets are even thirstier but this is really chowing the fuel.
What does that work out to...over a $1/minute to run the boat...yikes. That makes for a pretty expensive weekend in my books and that would definitely slow down my boating activities.
Anyways with that kind of fuel usage that might explain why there seem to be quite a few of them for sale lately around here.
Interesting stuff.
BP

 

[fishingdan]

Re: Can't believe my fuel consumption.

That is a beautiful boat. The 4.3 engine is a very nice package of power with fuel economy if you take it easy. Run it at full throttle and you'll burn through some fuel with this engine too, but you are probably find a nice cruise at around 3000rpm. At that level it is very efficient. As noted above, even the carburated versions do well. My boat has a carburated 4.3 with a 4 barrel carb. We can tube and cruise on vacation for a week without needing to refill the boat. My previous boat had a carburated Merc v6 150hp outboard. On the same trip, we would need to refill the tank 3 times and both boats have the same size tanks.

 

[45Auto]

Re: Can't believe my fuel consumption.

....you're kidding...right? 18.32 gph?

18 GPH sounds about right for a 170 HP jet at WOT. The Rinker with the 4.3 will suck down about 16 GPH at WOT.

The 4.45 GPH must have included a good bit of idling or sitting listening to the radio with the key in the "run" position, just cruising in a 19' will burn around 5 GPH. Pulling 3 tubes ain't gonna improve it any!


Real test numbers:

http://www.boattest.com/oem/test-results.aspx?ID=857&lp_id=&from_gi=yes

Edit - Is the 11.5 hours the time on your engine meter or the total amount of time you've spent out on the water??? - makes a big difference!

 

[jkust]

Re: Can't believe my fuel consumption.

I had the same experience regarding fuel consumption. I moved from an older 2 stroke 85hp that went through both six gallon tanks easily in one day. When I moved to my 4.3 carb mercruiser, my common sense told me that I would burn through the 35 gallons very fast. The gas gauge would stay at full for hours of hard and slow plowing engine use so, naturally I thought it was broken. I would go fill it after a full day of boating, only to find that I would only put in 9 or so gallons. It makes me wonder how much more gas in paractical terms a V8 would use. I could easily accept half the economy as the V6 if the 8 improved performance a large amount. My outlook on how expensive boating was supposed to be and how cheap it really is an eye opener.

 

[ufm82]

Re: Can't believe my fuel consumption.

Keep in mind that nearly 33% of the fuel that goes into a 2-stroke engine goes right out the exhaust. That alone makes a huge difference between a 2-stroke and a 4-stroke. New 2-strokes that monitor fuel and inject the fuel as opposed to simply dumping it can improve usage numbers immensely. Even though my 150 is fuel-injected, it's basic EFI and isn't a whole lot better than a carb. (Think showerhead.LOL) Unfortunately, the difference between buying a new 4-stroke or 2-stroke versus running my gas-hog is so high that I'd spend years before the savings evened out. So, a 2-strokin' I will go. I've never figured out fuel burn on a time basis but I get about 2-2 1/2 mpg out of my ride. :-(

UFM82

 

[jkust]

Re: Can't believe my fuel consumption.

Keep in mind that nearly 33% of the fuel that goes into a 2-stroke engine goes right out the exhaust. That alone makes a huge difference between a 2-stroke and a 4-stroke. New 2-strokes that monitor fuel and inject the fuel as opposed to simply dumping it can improve usage numbers immensely.
UFM82

Earlier this year Boating magazine did a comparison of a 20+ year old fully tuned up 2 stroke to a brand new equivalent HP direct injection 2 stroke. I seem to recall mileage was about 1/3 better with the new engine. Funny how no one cared when gas was .99/gallon.

 

[lkbum]

Re: Can't believe my fuel consumption.

Older wave runners are the same (really bad on gas). I have a neighbor who bought tow late 90's 1100 cc yamaha's for the kids to "save money" on tubing. After a month of $200+ per weekend for gas they sold them and went back to pulling them on the tubes. Waverunners are usally run wide open constantly and they will suck down 12 gallons in about 1.5 to 2 hours.

 

[PBJT]

Re: Can't believe my fuel consumption.

My 11.5 hrs is on the meter and is only engine run time. I also cruise my new boat at 3900 - 4000 rpm cause 3000 is just to slow for my attention span. Also a good bit of that time was at WOT cause I like the feeling of speed on the water.

When I sucked back 330 Litres of fuel on my twin engine jet boat in one day of boating on the Bay of Quinte .... we repeated the day after I bought my new Rinker 192 and the fuel guage droped 1/4 of a tank from full and a visual of the fuel tank it looked pretty full still. Conditions were the same sunny and calm with no jumping and minimal tubing. Both boats topped out at the identical speed.

Either way I could not expect everyone to believe my fuel story cause I myself can not believe the enjoyment of using the much bigger boat with more hp and far less fuel!!

Pete

 

[45Auto]

Re: Can't believe my fuel consumption.

Congratulations on your great fuel economy. I don't believe it either!

Just think how good the economy could have been if you hadn't totally ignored the break-in procedure on your new engine, particularly number 3. It might have been twice as good!!

Mercruiser 20-Hour Break-In Period:

IMPORTANT: The first 20 hours of operation is the engine break-in period. Correct break-in is essential to obtain minimum oil consumption and maximum engine performance. During this break-in period, the following rules must be observed:

1) Do NOT operate below 1500 rpm for extended periods of time for the first 10 hours. Shift into gear as soon as possible after starting and advance the throttle above 1500 rpm if conditions permit safe operation.

2) Do NOT operate at one speed consistently for extended periods.

3) Do not exceed 3/4 throttle during the first 10 hours. During the next 10 hours, occasional operation at full throttle is permissible (5 minutes at a time maximum).

4) Avoid full throttle acceleration from IDLE speed.

5) Do NOT operate at full throttle until the engine reaches normal operating temperature.

6) Frequently check engine oil level. Add oil as needed. It is normal for oil consumption to be high during the break-in period.

After Break-In Period

To help extend the life of your Mercury MerCruiser power package, the following recommendations should be considered;

Ensure that propeller allows the engine to operate at or near the top of the specified WOT rpm range (Refer to Specifications and Maintenance) when at full throttle with a normal boat load.

Operation at 3/4 throttle setting or lower is recommended. Refrain from prolonged operation at WOT rpm.

Change the oil and oil filter. Refer to Specifications and Maintenance.

 

[PBJT]

Re: Can't believe my fuel consumption.

Gotta love the "manufactures break in period" They should really say...don't break in your boat the way you are going to run it its whole life but rather break it like an old man till we no longer have to warrantee it then re-break it in on your own dollar.....No thanks, ehh, If she is going to let go she had better do it in 1yrs time bearings and rings these days are not the same as the 50s boys.

Before I use to have to fill the boat and maybe gas the truck, now I gas the truck and don't touch the boat-it is great pulling up to a pump with the boat and truck and leave with out a huge bill

Loven the boat tho.

Pete