2007 280ec can you tell me the cruising speed & at what rpm?

anotherboat

I just got a 2007 280 ec with a volvo 8.1GI eng ,outdrive with duo prop. can you tell me the cruising speed & at what rpm? what is top speed & at what rpm?   I am new to a boat of this size and im learning how she works...trim tabs,eng tilt. I just love this boat. I have been out on it 5 times, just cant help throwing the hammer down all the way..someone told me the gps is the best way to tell speed, the speedometer is not as accurate,is that true? I had the gps at 44 mph, the speedometer was lower. now i want to explore.... how far can i go on a tank of gas? the cruising speed & rpm should tell me if i am getting all i can on a tank of gas correct?         thanks for your help & info.   

Babyboomer

TonyWalker

Congratulations on your new 280.  I know the feeling.  My boat is a 2006 and in those days and for the size of our boat, Rinker put out a performance chart that gave GPH vs engine RPM, speed and all that stuff.  For us that continues to be a big help and reference.

I would avoid the hammer down all the way except of an occasional burst.  All the way should give you 4800 rpms plus or minus if your boat has the right prop on it.

Your 44 GPS mph is probably correct.  The water speedo will read less since that is water pressure operated and the water speedo is several feet above the transducer.  Sometimes the transducer gets a load of seaweed and that makes any reading totally meaningless.

Your GPH goes up exponentially with speed.  So the best economy will be below hull speed, for your boat maybe 6 mph, since economy and hull speed is related to the length of the boat that is in the water.  On plane your best economy should be at the speed that keeps you "just" on plane or slightly above that.  At WOT (wide open throttle,) you are really inhaling the gas out of the tank.

Since you asked about fuel economy I strongly recommend you consider installing a fuel flow meter.  It will tell you all kinds of stuff about how your boat is performing and fuel usage.

I know you will get all this stuff down as you gain experience with your new boat.  Have fun

Tony

Salt Shaker 342

brianluck

I second a fuel flow meter, I intend to install them for next season on my boat

anotherboat

what is cruising speed? is it not the speed of the boat when it gets on plane? the gps on the boat does not have a transducer, the 44 mph was from the gps signal. the speedo gets its info from a small hole on the outdrive. hull speed...never heard of that one. sounds like no fun, but i would like to know what that is. I live in NY and would like to explore the canals and that could be handy to know.

brianluck

I like to cruise around 2800-3200 rpms. 

seguir

I have a 280 EC with a Merc 5.7 300 HP.   I find it seems to run its best at about 3800 RPM trim tabs down.... which gets me about 20 to 23 mph.  Anything above this it sucks up gas, 1/4 tank per 1 hour run.  If I slow it down I can run for about 8 hours on one tank.  They call them "Cruisers" for a reason.  Take your time and enjoy.   WOT on our boat is 5200 rpm.   The highest I have had it is 4500 rpm...which didn't get me much more speed.

TonyWalker

I guess cruising speed is what ever speed you like to cruise at.  Just some speeds are more efficient than others.

 

You have two efficient speeds.  One is going fast, on plane and the other, very slow.  As you speed the boat up in the slow mode, your bow wave is what governs.  As you speed up, you will be more and more effected by it until you are at the point where you need to climb over it to go any faster.  This is at your hull speed and it is related to the boat length at the water line.

 

To climb over it you have to add more power and with enough added power you will climb over it and wala, you are on plane.  Us Rinker owners all have flat bottomed boats, ok "V" bottoms but the principal is the same.  With enough power the "flat bottom" will get over the bow wave and get "on top"  If we had round bottom boats, there is no practical amount of power that would get us on top and their speed is limited by the "hull speed"  I will look up a good definition and post it if no one does it first.  Round bottom boats are the most seaworthy there are but they sure can make one seasick!  There are may articles and books written on these subjects.

 

Trust your gps.  It is satellite related so it is all electronic and accurate.

 

We cruised the Erie canal from Troy to the Otswego (sp?) and on into lake Ontario back in 2010.

 

I suspect this is far more stuff than you were expecting.  But you brought it up!  LOL

 

Tony

Salt Shaker 342 

anotherboat

I guess I seem like the guy who likes bugs in his teeth when he boats. correct me if i am wrong.cruising speed is at a certin speed & rpm when the boat will go up on plane, at that moment there is less boat in the water and less drag =s the best speed to gas. so if I know what mph & rpm this happens at, and I put the boat at those #s then I know my boat is on plane. If the #s are off then I must trim the boat until they are correct.   RIGHT?     If the boat is not trimed right it will take more gas ,rpms more speed to get on plane or cruising speed......if the boat is trimed and egine is perfect at what speed and rpm will a 2007  280ec be on plane or be at cruising speed?   same token at wide open throttle if I knew the max speed my boat should be able to do and at what rpms it should be at I woud know the boat is trimed proper and everything is ok  

TonyWalker

I guess we are going for two different purposes.

I consider cruising speed to be what makes the boat feel good and me feel good.  Displacement speed for me is about 7 mph.  I have done a lot of that.  I use our boat for traveling.  On plane I guess we are going around 22 mph.  The boat is happy doing that.  So I have a many an hour at that speed.  I think I get 22 mph at around 3500 rpms.  My purpose in boating is to get it to be economical, last as long as possible and take me to places.  I can make it go much faster than that but it is noisy and it burns much more gas.  I have noticed I can get maybe one or two mph more by adjusting the tabs so I do that.  I find if I fool with the tilt of the out drives, not much happens that is an improvement.

Everything you said is basically correct.  You will get the feel after a while.  The numbers (RPM's etc.) are what you will have when you get it doing what you want. 

I guess I would have been a transport pilot if I would have gone that way with my life.  Slow but haul lots of stuff.

What canals are you planning on traveling?

Tony

seguir

To answer your question as to "how far can I go on a tank of gas". Assuming your tank is the same size 100 gal.  With 2 persons, full tank, water none, gear minimal.

at: 3500 RPM - 23 to 25 mph - approx. 180 miles

at 5200 WOT - 40 To 45 mph - approx. 100 miles

lastly

at 2000 RPM - 8 to 9 mph - approx. 170 miles (not on plane)

hope this helps.

TonyWalker

Seguir, am I glad you came to my rescue with some numbers!  I hesitated to give numbers because our boats are so different in size, hp, weight and gas tank size.  I should have said a much.

But your numbers are so close to mine it is unbelievable.  The only thing different is it takes my 2x the gas to do all that.  LOL

Tony

seguir

TonyWalker, It didn't take me that long to find the "sweet spot".  (My boat does best between 3500 to 3800 RPM's dependant on conditions.) Anything over you can watch the gage go down.  The numbers I post are appox.  I live in Toronto Canada and had to convert my numbers from metric.   I take it you have twin engines.    

TonyWalker

Yes, it is a 2006 342. Love the boat.  Had her since new. The boat and I (we) have bonded, so to speak.  900 hours total time.  Just recently changed the trash XDP outdrives for the OceanX ones and since they had to remove the engines to make that conversion, I replaced them too.  The originals were 280 hp on the 5.7 liter block and these new ones are 300 hp on the same block but has far more software in them than the originals.  I only have 4 hours so far on these wonderful puppies.  Tracks and takes off like a jackrabbit compared to before.  It is a "new" boat in a 7 year old "skin."

Been to Toronto on a number of occasions during my working life.  We did the Trent-Severn aboard the Salt Shaker in 2010.  Would we ever love to do that trip again!  Our normal cruising waters are in the Tampa Sarasota, FL area.

Tony

 

 

OldDogNewTrix

I would add that at 1400 rpm, you'd probably be in the 225 mile range. Our 340 drops off significantly at 1800-2200 rpm's.

TonyWalker

Getting near "hull speed" at 1800 rpms.  LOL

We do a lot of 1200-1400 rpm cruising.  A lot of it because of unfamiliar congested waters but even more because it is very pleasant.   And as you say, the fuel burn is much more attractive.

On open water, 3500-3600 is about right for us. Puts some wind in our hair or what is left of it in my case.

Tony

MarkB

My best fuel economy is around 3600 rpm, which is about what I need to keep it on plane. Works out to around 22 mph. I get 2 mpg at this speed.

TikiHut2

With a Garmin fuel flow meter connected to our chart plotter I get absolutely identical numbers to what Seguir posted above for our '04 FV270 w single 300hp 5.7merc, No bottom paint, running in saltwater. I only add that saltwater note because the boat is slightly more sluggish in freshwater. Go figure. It's a bouancy thing I guess, or maybe i was draggin' a gator.
Mike