Fuel consumption with V-drive big blocks?

[mnm99]

Hi guys..I just joined this forum and want to do my research before I upgrade. A little background. I live in the northeast IE saltwater..I currently have a 2001 Monterey 26 ft with a 5.7 Mercruiser. I cruise at around 27mph. I'm looking to upgrade to either a 32-34 boat. I am really hooked on the 31 or 34 Formula PC, but a lot of my friends have SeaRays. One with I/O's and the other with V-drive. Call me still a kid, but I will be selling my AC Cobra to get the boat I want. So I was looking at the formula for the speed aspect too. Formulas only come in I/O. NOW..What I know the V-drive is slower, uses more gas and less maint. The I/O is faster, less gas and more maint. I notices the 30-32 Searays come in small blocks. One of my friends has a 31ft with 5.0's and I/O. He cruises at around 27 at around 20GPH. The other has a 32 with 5.7's and V-drive and he cruises at around 23 not sure what GPH he gets. If I went up to the 34 I see a lot come with 8.1's. Now my question is whats the cruise speed with V-drive and big blocks? Also what GPH are these running?
Thanks all....
Marc

 

[Windjammer]

Generally 22kt @;3400 rpm; 26 gph (combined)

 

[Strecker25]

I like our alphas on our particular boat but I think the key here is the salt you're operating in. For me the inboards would be a no brainer, most of those formulas are BIII and they can have some serious corrosion issues especially in the salt.

Good luck

 

[Madifonzo]

I have a Sundancer 280 with Bravo 3's. mu first season I was intimidated by the drives and all the horror story's surrounding maintaience. Now that I have had the boat 3 seasons I can honestly say that the drives are simply part of my spring routine. I am also looking to upgrade and for a short while would only consider a Dancer with v-drives. I am now open to Io's. I found a nice 310 with Bravo 3 and seacore. Bonus is the axius. We shall see on that. Anyways, I think when you way pros and cons drives vs inboards may be close to even. Nice thing about the drives in a large boat is the massive space in the engine.

side note: we have 2 friends with 31 PC's...boy what a nice layout. Wide beam and great space. There is one for sale in our area and they are rare.

 

[mnm99]

I have a Sundancer 280 with Bravo 3's. mu first season I was intimidated by the drives and all the horror story's surrounding maintaience. Now that I have had the boat 3 seasons I can honestly say that the drives are simply part of my spring routine. I am also looking to upgrade and for a short while would only consider a Dancer with v-drives. I am now open to Io's. I found a nice 310 with Bravo 3 and seacore. Bonus is the axius. We shall see on that. Anyways, I think when you way pros and cons drives vs inboards may be close to even. Nice thing about the drives in a large boat is the massive space in the engine.


side note: we have 2 friends with 31 PC's...boy what a nice layout. Wide beam and great space. There is one for sale in our area and they are rare.

I like my Bravo3, except for the problems I could/will have. My main concern is that stupid steering pin. My current boat I had to repair the pin seal because it was leaking. I ended up putting a new transom assembly on because it wasn't much more than just buying the parts needed and now everything is new at a cost of $3500 installed. My boat is a 2001. I'm looking at 2003-2007ish boats. The $7000 repair if it happens kinda scares me, unless I negotiate it out of the way in the beginning. I know that won't likely happen. The speed and fuel consumption with the Inboard just kills me though. I've been reading the 8.1 V-drive cruise at like 24-25 and burn 30+ GPH. That's a bunch.

 

[Henry Boyd]

MNM,

I've had similar experience. I had to replace a transom assembly because the mounting point for the raw water gooseneck had corroded. $3500 sounds like you made out. Mine was closer to $4500, although I also replaced the starter motor and all of the merc engine hoses.

Previous to that I had done the steering pin, replaced the BIII drive shaft (merc only sells a complete sub assembly and not parts) and rebuilt the upper gear cluster, and let's not forget a couple of bellows replacements. In nearly ten years of ownership the stern drive has been the largest single category expense, more than all winter storage, or general engine servicing, etc.

Our next boat will definitely be vee drives, or straight inboards. I recognize the trade off is speed and fuel economy, but the cost savings in maintenance more than makes up for slightly lower fuel economy.

As for speed that is really personal choice. But keep in mind as the boats get larger they also get slower just because they are heavier. That 300 series he has his eye on is probably 50% (if not more) heavier than his current 280.

Henry


Sent from my iPad using Tapatalk HD

 

[Shtmetal]

Most boaters are very conservative about there fuel burn numbers. A sea ray 340 sundancer with 8.1's are going to burn over 30gph easily at cruise speed. I boat on the Chesapeake Bay and ithink the 340 is the most popular boat here, actually 30 gph ain't bad for a awesome boat like that. I have a 08 310 with v drives and it burns 26 gph at 3600 around 25 mph I would imagine the 320 would be close to my numbers. In salt water v dries are a must for longevity

 

[ziekman@cox.net]

21 kts. 3250 rpms 33 gph .5 mpg on a 36' 330 DA, 15,000 lbs. + gear, 2 people, with no noticeable difference at varying fuel/water/waste levels.

The only running gear maintenance in 7 seasons has been cutlass bearing replacements on both sides, after season 6.

This season, with lower fuel prices was real nice! But, the 8.1s have been exceptionally reliable, move the boat effortlessly, and combined with the v-drive setup, deliver pretty precise close-quarter handling.

 

[mnm99]

View attachment 42470

This was on my last trip. The smart craft rounded up the number, obviously, but over 300 miles, I averaged .92 mpg running at 3450 RPM. Our speed ranged from 28 to 30.5 depending on fuel load.

I am running ACME props though, with the OEM props, the best figure I ever obtained was .88 mpg overall.

If I could cruise at 28 at 30GPH I would be sold. What is you exact boat and specs? What is the difference from a ACME prop? I'd be willing to change props if I had to. My last boat I went through 4 sizes befor I got it right though. That sucked.

 

[mnm99]

My boat is exactly as shown in my credentials and signature photo. 2007 340 DA, 8.1 V-drives. The ACME props are CNC machined and have a bit more blade area than the OEM props. Michigan Wheel also produces a CNC prop which is very similar and I've been told, yields similar results.

Sorry I'm still getting use to the site. Can I ask what size and pitch you went with?

 

[BigBoysToys]

I have 8.1's in a v-drive configuration on my 08 330. I cruise at 28mph burning 36gph. One thing to note though is that I have a lot of gear onboard from tools and spare parts to cases of water and alcohol. It all adds up.

 

[JVM225]

View attachment 42470

This was on my last trip. The smart craft rounded up the number, obviously, but over 300 miles, I averaged .92 mpg running at 3450 RPM. Our speed ranged from 28 to 30.5 depending on fuel load.

I am running ACME props though, with the OEM props, the best figure I ever obtained was .88 mpg overall.

Those are great numbers for big blocks in your boat.
On a recent 280 mile round trip I averaged 1.3 MPG cruising at about 29 MPH with carb small blocks and Alpha 1 drives in my 1987 300 Sundancer.

 

[j98052]

In July I bought a 2008 Sundancer 330 (35.5') with 8.1 Horizons with V-drives. In salt water, at 3400-3500 RPM with mostly full fuel & water, with 2 adults, it cruises at about 22-24 knots (depending on currents & wind), and burns about 34-35 GPH.

At first I was hesitant to buy the boat because of the larger engines, thinking it would cost more in fuel, even though it was fully loaded, in great shape, and the owner was motivated to make a deal. After doing some research and talking to owners of similar boats, I learned that the fuel economy on the 8.1s is not too different than the 350s, as they run at lower RPM for the same speed, and they have better reliability.

The engines had 135 hours on them when I bought it, only 10 hours since 2013, so I had a full baseline service done right away. I didn't check the fuel consumption before I had the service done.

I just moved it to fresh water, and it seems a hair faster. Might be because I know I don't have to wash the salt off when I get back to dock

 

[CliffA]

After doing some research and talking to owners of similar boats, I learned that the fuel economy on the 8.1s is not too different than the 350s, as they run at lower RPM for the same speed, and they have better reliability.

not sure where you were doing your research but the statement that the big block 496's are more reliable than the small block 350's is very questionable.....the 350 engine has been one of the most reliable engines in both the automotive and marine world for a very long time from all the info I have heard and read....

i am sure both engines are great but without documented facts the claim one is more reliable than the other is misleading....

cliff

 

[Ididntdoit]

I have had a 2005 300 with 5.0/BIII for the past 8 seasons - for 6 of those it was wet slipped year round in NE - My drives were just off the boat last week and they are still perfect - no corrosion, including the bearing carriers, etc - but yes, the maintenance does take time and diligence - zincs, fluid changes, trilux, mercathode as well as inspecting bellows/gimbal/etc - for me, in the NE, the tradeoff was worth it, the boat jumps right up on plane and I cruise at 27kts at 3800 RPM with MPG of 1-1.2 depending on sea conditions and load - In Florida, I have to be far more careful - the boat is generally rack stored and does not spend more than 2 months at a time in the water. Remember, a v-drive boat is not immune to problems, numerous members here have had to replace transmissions cutlass bearings, etc.......With all this said, for the way I boat now, I would prefer a boat with shafts over I/O......The idea is to educate yourself and choose the propulsion package based on what makes the most sense for how you intend to use your boat....

 

[cfd95]

2003.5 and up 340 8.1 Horizons V Drives Hands Down.
It is an awesome boat .
You're boating in Saltwater and unless you plan on keeping the boat on a lift i would avoid sterndrives.
I went from a 290 with sterndrives to a 310 with V's.
The maintenance on the sterndrives was nuts.
I will never own a sterndrive boat again.