2009 searay 350da vs2008 monteray 350, mph gph cruisng style

[Ethan's Tank]

So with my 09 350da, I've been trying the most efficient and most effective way of cruising. Twin 8.1 375hp stern drives is what drives this
Everyone loves my boat, but mostly hate the amount of gas I burn every time we cruise somewhere since I normally cruise @ 3400 rpm, 23mph in 10+ ft over water, 25 mph in about 6ft and get about .7mpg. When I go to the local beach in my river, about 15 miles round trip, I burn about 20gallons of gas, which translate to about $63...Marina gas is $3.149 per gallon.

So i take a longer trip one day, I think it was almost 2 hrs away, I meet my friend's buddy who has a monteray 350. He said he made the trip in about 1.5 hrs, traveling at 3400 with twin 8.1(same motors), traveling at about 32mph and his boat is 16,000 lbs, mine is 18,000 lbs and he was burning about 28gph I asked him 'how' he drove down, and his reply was once on plane, he set his outdrives up and set rpm to 3400. I don't know his prop type or pitch.

So I'm wondering since I tried it, has any obtain specs like these on their 350s. When I try to raise my bow up, either by outdrives or trim tabs, my mph drops. With my outdrives up, it's a major significant drop like down to 19mph when on plane. It seems like with my bow down closer to the water, I get max speed and better mpg. All the guys at my Marina with the 24-28 ft length, single engines, they drives with their bows up and ride on top of the water....my stern always seems to squat due to the weight, but they travel around 30+ mph.

And I driving it all wrong?

 

[JimT]

Lowering the trim tabs will slow the boat down and force the bow into the water when you are planing. They should be up all the way once you are running at planing speed unless you are trying to balance the boat to offset an uneven load or a lateral wind or current. You can also use the tabs to stay on plane at lower speeds. I use them to help get on plane if I have a full load then raise them.
Trimming the out drives up too far will also result in a loss of performance. A short burst on the rocker switch is all you really need. You will get a small pick up in speed but it's not going to raise the bow much at all. I have found on my boat that there is little performance benefit to trimming the drives up so I usually leave then down. You should be up on plane at 3400 rpms at 23-25 Mph. What is the condition of your bottom? Sounds like your performance issues could be the result of a dirty bottom or a problem with your props.

 

[dmorris800]

I think you picture ( I am assuming your son) sums up boating quite nicely! As for fuel efficiency.... What is your GPH on your engines? I have a 310 with twin 300 (260 HP each) which weighs aprox 12K, at 3500 RPM it is 1.2 or 1.3 mpg with a burn rate of 19-20 GPH. My nose only rises about 5 degrees up once on plain so I think your trim is right.

Dave

 

[Ethan's Tank]

Lowering the trim tabs will slow the boat down and force the bow into the water when you are planing. They should be up all the way once you are running at planing speed unless you are trying to balance the boat to offset an uneven load or a lateral wind or current. You can also use the tabs to stay on plane at lower speeds. I use them to help get on plane if I have a full load then raise them.
Trimming the out drives up too far will also result in a loss of performance. A short burst on the rocker switch is all you really need. You will get a small pick up in speed but it's not going to raise the bow much at all. I have found on my boat that there is little performance benefit to trimming the drives up so I usually leave then down. You should be up on plane at 3400 rpms at 23-25 Mph. What is the condition of your bottom? Sounds like your performance issues could be the result of a dirty bottom or a problem with your props.

If I raise the tabs up to reduce drag, it slows the boat down about to about 1 mph, so when I'm on plane at about 25mph on calm water about 6ft depth, it drops to about 23.5 to 24.x. if I drop the trim down, it cruises at back at maxium speed, although it's not fully down, but I don't have trim indicators to fully know where they accurately sit, but I do see my bow dropping more towards the water.

As for the out drives, my vesselview indicates the precise angle and I've tried them with a short burst to about halfway up and the speed drops significantly, anywhere from 3-5 mph, the best I get is When the drives are completely down.

I do manage to get 23-25 mph as you have mentioned at 3400 rpm, but I'm wondering if anyone has gotten 30+ as the monteray owner has gotten with a boat 35' and up.

I pulled my boat out 3 weeks ago and the bottom is clean, no barnacles or sea life

 

[Ethan's Tank]

I think you picture ( I am assuming your son) sums up boating quite nicely! As for fuel efficiency.... What is your GPH on your engines? I have a 310 with twin 300 (260 HP each) which weighs aprox 12K, at 3500 RPM it is 1.2 or 1.3 mpg with a burn rate of 19-20 GPH. My nose only rises about 5 degrees up once on plain so I think your trim is right.

Dave

Thanks Dave that is my son, Ethan and my boat.

At 3400 rpm, the twin 496 (375Hp each) is burning .7 mph and a rate between 31 to 35 gph, dry weight about 9tons.

I have noticed at my trim set, when I get off plane, my bow dips down pretty low and in no wake zone, stern seems to sit slightly higher than bow

 

[dmorris800]

I don't think your numbers are to far off from optimum. If you look at the stats for the new sun dancer 350 on boattest.com (you may need to create a user to get test data) it is burning about 31 GPH with the same engine package. Of note the new boat weighs 3K less than your weight so I would expect you to burn more. Plus those numbers are optimized (ie 1/2 tank of fuel with limited cargo and people on board). I think you are paying the curse of having to move a beautiful condo at 25 mph up / down the river :smt001

From personal experience, if you want to conserve fuel, run the boat slow (ie less than 9 mph) or on a plane. That in between area kills you on fuel.

the link is:
http://www.boattest.com/boats/boat_video.aspx?ID=2528

 

[Zorba]

I dont know. Something doesn't sound quite right. In my '06 340, which is virtually the same boat as yours, i am getting around .9 mpg at 3350 rpm with inboards. I go slower than you because of the inboards (28mph) but you should also be getting better MPG due to less drag with the outdrives. Even with full tabs i'm only losing about 1-2mph.

 

[Jimmy Buoy]

There seems to be two issues here and maybe it would be helpful to clarify. Outdrive trim settings and Trim Tab settings. These are two independent variables that can really affect the boats efficiency.

Regarding trim tabs… JimT was asking about your trim tab settings that you normally use while cruising and your answer was not really clear to me. It might help to refer the tabs as being zero (meaning raised to their home position) or 10-20-50-75% etc down angle. From your answer, I assume that running tabs at zero gets the best performance and that any additional tabs reduce your speed?

Regarding drive trim… From your description, it seems that your drives are tucked in to the transom as far as possible (zero trim) and any trim applied while at cruise lowers your speed? This is probably the result of the hull design that Sea Ray chose for this model to give it the best ride and handling.

Over the years, I have noticed quite a change with how Sea Ray's IO boats handle. Older ones I've had have needed some drive trim to free the hull from water drag and increase efficiency while newer ones (mid 2000's) don't respond to raising the drive much at all.

 

[Ethan's Tank]

I dont know. Something doesn't sound quite right. In my '06 340, which is virtually the same boat as yours, i am getting around .9 mpg at 3350 rpm with inboards. I go slower than you because of the inboards (28mph) but you should also be getting better MPG due to less drag with the outdrives. Even with full tabs i'm only losing about 1-2mph.

Yep your 340 and my 350 is the essentially the same boat, but my dry weight is 4000 more, not sure if that would make a huge difference...Haha when I dragged a 320 by foot, felt the same amount as my 350.

I go much slower than you at 3350, that would knock me down to about 22-23mph in glass water. Although I figured the out drives would be a major drag since its 2 big ass units hanging behind and under the boat and they're heavy. I just know my stern boat is more agile than the inboards.

Wow do you really go 28 mph, haha that let me keep up with the other folks I cruise with

 

[skolbe]

You either need to bump the RPMs up a bit due to weight, or is the bottom of your boat dirty? I have driven a friends new Sea Ray with outdrives. It seemed like the outdrives just liked a tap of trim. What RPMs are you getting at WOT. You could have the wrong props as well, that would also indicate if the bottom was dirty or another issue. Seems like you should be a bit faster.

 

[Ethan's Tank]

There seems to be two issues here and maybe it would be helpful to clarify. Outdrive trim settings and Trim Tab settings. These are two independent variables that can really affect the boats efficiency.

Regarding trim tabs… JimT was asking about your trim tab settings that you normally use while cruising and your answer was not really clear to me. It might help to refer the tabs as being zero (meaning raised to their home position) or 10-20-50-75% etc down angle. From your answer, I assume that running tabs at zero gets the best performance and that any additional tabs reduce your speed?

Regarding drive trim… From your description, it seems that your drives are tucked in to the transom as far as possible (zero trim) and any trim applied while at cruise lowers your speed? This is probably the result of the hull design that Sea Ray chose for this model to give it the best ride and handling.

Over the years, I have noticed quite a change with how Sea Ray's IO boats handle. Older ones I've had have needed some drive trim to free the hull from water drag and increase efficiency while newer ones (mid 2000's) don't respond to raising the drive much at all.

My trim tabs are about 70% down, thus raising my stern slightly and lowering my bow, from what I've researched it creates hull resistance. Although I'm not positively sure since I do not have trim tab indicators.

As for my power trim, it's tucked completely down, zero trim. Everyone that I've talked to said to raise the trim to get better speeds while on plane. I've always tried different positions ands it's always been best at zero trim. I never set it too long (about a minutes worth) cause of gas consumption, but everyone said wait it out, just never know how long before it helps any.

As for my bottom, it's clean and bottom painted

Hope that helps you to help me:thumbsup:

 

[Bucit]

Once on plane trim tabs fully up. Trim the outdrives (with maybe 11-2 second bursts) and watch your rpm's. They should go up along with your mph. You fuel burn should get better. And BTW, it really doesn't matter if you're in 6 feet or 10 feet of water. The boat only cares when it runs out of water and hits bottom.

 

[Ray Ray]

Yep your 340 and my 350 is the essentially the same boat, but my dry weight is 4000 more, not sure if that would make a huge difference...Haha when I dragged a 320 by foot, felt the same amount as my 350.

I go much slower than you at 3350, that would knock me down to about 22-23mph in glass water. Although I figured the out drives would be a major drag since its 2 big ass units hanging behind and under the boat and they're heavy. I just know my stern boat is more agile than the inboards.

Wow do you really go 28 mph, haha that let me keep up with the other folks I cruise with

ET: I'm right next door to you at Hope Springs, and have seen you out on the creek/river. I agree with Zorba, something doesn't sound right, either with your description of what's happening or how you're actually running. I'm in an '07 340 setup identical to Zorba, although I don't think I'm getting his exact numbers. But I do run in the same area as you and know the surroundings.

With the throttles in the same position, approx. 3350-3400 rpm, I too, have noticed speed changes based on certain depths and spots running in/out of Aquia Creek, and thought it was just me. There's definitely something to it, most likely the slight current pushing or pulling with or againt the muddy bottom, especially when the tide is low.

Regardless, your numbers or description still don't sound right, and I'd be interested in trying to help you figure it out. PM me if you'd like to hook up.

 

[Ethan's Tank]

ET: I'm right next door to you at Hope Springs, and have seen you out on the creek/river. I agree with Zorba, something doesn't sound right, either with your description of what's happening or how you're actually running. I'm in an '07 340 setup identical to Zorba, although I don't think I'm getting his exact numbers. But I do run in the same area as you and know the surroundings.

With the throttles in the same position, approx. 3350-3400 rpm, I too, have noticed speed changes based on certain depths and spots running in/out of Aquia Creek, and thought it was just me. There's definitely something to it, most likely the slight current pushing or pulling with or againt the muddy bottom, especially when the tide is low.

Regardless, your numbers or description still don't sound right, and I'd be interested in trying to help you figure it out. PM me if you'd like to hook up.

Hey Reg, pm incoming

 

[NorCal Boater]

You cannot compare inboard (v-drive) performance to outdrive performance in the same boat. Just the drag and the added weight of the drives alone will lower speed, and increase fuel consumption.

Ethan, you have a heavy boat and a propulsion system that is not the most efficient on your size boat. Also you have a lot of weight sitting in the aft end of your boat. Again, not the most efficient design.

When trimming your boat while on plane you have to remember that the least amount of wetted surface area (friction) will produce the best speed. Examples....unlimited hydroplanes, stepped hulls, catamarans. So what you should be doing is, get the boat on plane as quickly as possible using the Trim Tabs in the down position and your outdrivestucked "in" or "down" all the way . Once on plane bring the tabs all the way up and trim the outdrives "out" or "up" away from the hull. You don't need trim gauges. While at plane look over the side of the boat at your wake. Note where the wake coming off the hull Now give the drives a couple seconds of "up". Did that wake move furhter aft along the hull? The boat should also feel a bit looser or less "stuck" to the water. Now let that run a bit and make note of the RPMs and speed. If your feeling adventerous, give the drives another second or two of "up" and see how things look and feel. What happened the RPMs and speed? What happened to where the wake is coming off the hull?

For me, trimming the boat has always been about "feel." I've been able to feel what the boat is doing. It takes practice and really letting yourself concentrate on what the boat is doing. Give some of this a try and let us know what happens.

Shawn

 

[Zorba]

You cannot compare inboard (v-drive) performance to outdrive performance in the same boat. Just the drag and the added weight of the drives alone will lower speed, and increase fuel consumption.

Ethan, you have a heavy boat and a propulsion system that is not the most efficient on your size boat. Also you have a lot of weight sitting in the aft end of your boat. Again, not the most efficient design.

When trimming your boat while on plane you have to remember that the least amount of wetted surface area (friction) will produce the best speed. Examples....unlimited hydroplanes, stepped hulls, catamarans. So what you should be doing is, get the boat on plane as quickly as possible using the Trim Tabs in the down position and your outdrivestucked "in" or "down" all the way . Once on plane bring the tabs all the way up and trim the outdrives "out" or "up" away from the hull. You don't need trim gauges. While at plane look over the side of the boat at your wake. Note where the wake coming off the hull Now give the drives a couple seconds of "up". Did that wake move furhter aft along the hull? The boat should also feel a bit looser or less "stuck" to the water. Now let that run a bit and make note of the RPMs and speed. If your feeling adventerous, give the drives another second or two of "up" and see how things look and feel. What happened the RPMs and speed? What happened to where the wake is coming off the hull?

For me, trimming the boat has always been about "feel." I've been able to feel what the boat is doing. It takes practice and really letting yourself concentrate on what the boat is doing. Give some of this a try and let us know what happens.

Shawn

I agree that there is no comparing outdrives vs. inboards but you generally don't hear o/d being slower and less efficient than inboards at the same RPM. That's why I was suggesting something sounds amiss. Whether it be improper use of tabs and trim or something else it doesn't quite sound right.


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[Zorba]

Yep your 340 and my 350 is the essentially the same boat, but my dry weight is 4000 more, not sure if that would make a huge difference...Haha when I dragged a 320 by foot, felt the same amount as my 350.

I go much slower than you at 3350, that would knock me down to about 22-23mph in glass water. Although I figured the out drives would be a major drag since its 2 big ass units hanging behind and under the boat and they're heavy. I just know my stern boat is more agile than the inboards.

Wow do you really go 28 mph, haha that let me keep up with the other folks I cruise with

Dry weight is 15,500 so more like 2500 weight difference which will make a difference. I'm not sure if they changed the dynamics of your hull but our LOA, Beam, and dead rise are the exact same. Now I'm just wondering where the extra weight is coming from.






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[WDCboater]

Ethan

Your speed sounds off, but your MPG sounds fairly accurate.

My 2010 350 is a bit lighter than yours, but I have twin 8.1 HO's, but V drives vs outdrives.
I cruise about 3400-3500. I get about 25-27mph. My mph creeps up the longer I cruise as my fuel tanks empty. I average about .7 MPG. These engines are definitely not fuel efficient.

Also, when comparing to other boats look at total weight, not just dry weight. Do you cruise with full water, fuel etc? Also, when was the last time your boat was out of the water and the bottom was cleaned? I know the river creates a slime and I practically get a beard on my bottom. (Even with paint). This will impact your performance.

I obviously can't trim my props, but I do use my tabs to get up on plane if I have a full boat and then I put them back up once on plane.

Also, comparing current models with newer 8.2's to our boats doesn't work. As I understand it, the newer 8.2's are more efficient.

 

[Bob a Buoy]

I think Jimmy makes an important point, drive trim will depend on hull design. My '04 300DA requires no drive trim. In fact, any more than a few quick shots of up trim and I can feel performance start to lag. I don't need tabs for anything other than leveling. I usually just leave the drives down until I'm ready to anchor up. My best cruise seems to be around 3400 rpm at 27-28 knots. I'm not sure about fuel burn. The boat is new to me and I'm still figuring out the smart craft system. From what others have said, it should be around 1.3 mpgs.

 

[Ethan's Tank]

Does driving on cruise control at 3400 rpm makes a difference? Would it throw all these rules out of the window?