Are fuel flow meters worth it?

[merlin]

If I'm burning 1,000 gallons of diesel a year, do I need a fuel flow meter or should I just keep my rpm/s below 2,400?

I guess it's a balance between fuel savings and cost of the installation.

How much fuel has it saved all of you?

 

[Happy Hour IV]

I burn gas so my results are probably a little different. Based on the fuel flow meter (1 switched between 2 engines) I was able to decrease my fuel burn by 10-12%. Oddly this also allowed be to go faster. It helped me tune in my trim tabs. I was also able
to determine that 200' of chain in the locker gave me better efficiency than without.

I also noted an ignition problem in one engine that came up but I had not noticed it otherwise.

Bottom line I think they are worth it.

Besides, when I fuel up I tell them exactly how many gallons the tank will take.

 

[Pietro]

They are worth it for more than one reason.
They tell you what you are burning helping you finding the best RPM –cruise speed and trim.
You can check if both engines are in the same mechanical conditions and if something goes wrong you will soon notice an anomalous fuel consumption.
What I like the most is that you can really keep tabs on how much fuel you have burned and thus how much is still in the tanks with just 1% to3% error!
I would definitely suggest to install them!! :thumbsup:

 

[Great lakes pirate]

What does it take to install fuel meters?

 

[Henry Boyd]

GLP,

If your gas engines are Smartcraft capable the feature already exists. This could mean a gauge upgrade if you do not already have sc gauges installed.

Otherwise, and for diesel engines, you would have to add a fuel flow device that would consist of some type of flow sensor in the fuel line and a gauge.

Using the flow numbers allows me to trim 2-3 GPH off the burn rate at cruise speed. So we ran the boat 85 hours this past season. Figure 40 hours at cruise and call it an average savings of 2 gph and $ 3.65 per gallon for gas yields a savings of $ 292.00 this season x 3 seasons = $ 876 in fuel savings.

So, yah, I'd say flow meters are worth it.

Henry

 

[Alex F]

Does anyone know what this mod costs for diesel boats that don't have SmartCraft?

 

[Henry Boyd]

Does anyone know what this mod costs for diesel boats that don't have SmartCraft?

I priced a single engine Floscan meter and sensor for gas before I did my Smartcraft upgrade, and it was about $ 500 installed (in 2008). Since this is a liquid flow device that is not dependent on an ignition system, I would think a diesel set up should be about the same.

Henry

 

[fwebster]

I guess I'm going to be the voice of decent on this one...........

With 3126's you will need to plumb senders into both the fuel supply and return lines which means the cost for installation is going to be close to 2X what it is on a gas boat. Every place you break into a diesel line is one more place for a leak.

Aside from the cost, I also question the need on a Cat powered boat. I use Caterpillar fuel tables and find them to be right on the money as far as GPH. On a 300 gal fill up, I am usually within 5-10 gal of what I expect and have computed from the tables.

Using a fuel flow meter to spot something wrong........? On a diesel if you are observant, you will hear or see problems quickly by smoke, smoke color, sooting, starting problems, acceleration problems, etc. many times before you see it in fuel flow.

As far as using fuel flow to tweak running attitude, keep your eye on the ball here: set the rpms at the fuel burn you are comfortable with (from the Cat tables), then trim the bow up or down until you achieve the maximum speed at that rpm setting. That is a lot easier than investing $1200 and 3-4 days installing fuel flow meters and it gets you the same result.

 

[Alex F]

I like your aproach, Frank. I guess, the only trick is to learn the signs "....smoke, smoke color, sooting, starting problems, acceleration problems, etc...."

 

[Turtlesboat]

They are worth it for more than one reason.
They tell you what you are burning helping you finding the best RPM –cruise speed and trim.
You can check if both engines are in the same mechanical conditions and if something goes wrong you will soon notice an anomalous fuel consumption.
What I like the most is that you can really keep tabs on how much fuel you have burned and thus how much is still in the tanks with just 1% to3% error!
I would definitely suggest to install them!! :thumbsup:

I don't think I would care to run my tanks down to 3%... I have 20% fuel sensors. So when I hit E, I've got roughly 80 gallons of fuel. I even get nervous with this. and what i've found with my CAT's is that they will tell you if you aren't running your boat efficiently. Even throttling up too fast will produce a puff of smoke. So I keep an eye out for any and all kinds of smoke. As far as tabs, what else are you going to do on a long trip besides play with your tabs to squeak out the last tenth of a knot?

 

[The Bill Collector]

"As far as using fuel flow to tweak running attitude, keep your eye on the ball here: set the rpms at the fuel burn you are comfortable with (from the Cat tables), then trim the bow up or down until you achieve the maximum speed at that rpm setting." fwebster

Exactly what I do without FloScan....

We went 10 days up into Canada last summer and based on my chart plotting n. miles totaled and fuel burn estimated, I was within 10 gallons. I had been debating but after last summer's trip the debate is over. I do not need to spend the $ on them.

 

[Pietro]

I don't think I would care to run my tanks down to 3%... I have 20% fuel sensors. So when I hit E, I've got roughly 80 gallons of fuel. I even get nervous with this. and what i've found with my CAT's is that they will tell you if you aren't running your boat efficiently. Even throttling up too fast will produce a puff of smoke. So I keep an eye out for any and all kinds of smoke. As far as tabs, what else are you going to do on a long trip besides play with your tabs to squeak out the last tenth of a knot?

I also would never run my tanks down to 3%, for sure. That is the precision of these instruments. This allows you to know exactly how many gallons you have burnt in total.
I agree with you all that charts and some calculation can give the same results...but I’m way too lazy when I’m afloat, so just a look at the flow-scan needle and the gallon total display is way too simpler :grin:

 

[tdschafer]

I also would never run my tanks down to 3%, for sure. That is the precision of these instruments. This allows you to know exactly how many gallons you have burnt in total.
I agree with you all that charts and some calculation can give the same results...but I’m way too lazy when I’m afloat, so just a look at the flow-scan needle and the gallon total display is way too simpler :grin:

I'm with you my man. Whatever I can do to increase the relaxation factor is a winner in my book!!:thumbsup:
BTW, Thanks for the winshield trim drawings!!

 

[Great lakes pirate]

Is this what I need? My engines are 6.2L MX 2003 MPI's. They are smartcraft ready but my Tach, Speedo ect are not. Am I better off buying the individual gauges or this unit.

http://cgi.ebay.com/ebaymotors/Merc...0758243QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

 

[jason78]

Is this what I need? My engines are 6.2L MX 2003 MPI's. They are smartcraft ready but my Tach, Speedo ect are not. Am I better off buying the individual gauges or this unit.

http://cgi.ebay.com/ebaymotors/Merc...0758243QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

You could get that but for Twins you would be MUCH better off getting the triple gauge setup or even Vessel View if you want to spend the extra money. I have seen several tri-gauge sets for under $250 on ebay. I am not sure if you can leave your 4-in-1 Gauges setup or not. If not, they will have to be replaced with 4-in-1 SC System Link Gauges. These are available too fairly reasonable- if you get the generic Merc ones. The SR Logo gauges are a little pricy.

Henry Boyd did this upgrade. He should be able to tell you everything you will need.

 

[Great lakes pirate]

So if I purchased the set of tachs and the sync gauges that were smartcraft ready I could just plug them in with the same multi pin connections that came from the factory?

 

[jason78]

So if I purchased the set of tachs and the sync gauges that were smartcraft ready I could just plug them in with the same multi pin connections that came from the factory?

As I understand it, with some different connectors it is fairly easy. Henry Boyd did this conversion so he should be able to give you some great advice about the connections.

 

[shadow9999]

I installed a flow scan system this past summer. You can read all about it in my post on the subject here.

I believe they are indispensable. However, that is due to the type of boating that I do. The vast majority of my boating is trips to destinations, some of them being very far away. So having fuel flow information is very important to me. I installed the NMEA2000 system from Flowscan. This allows me to interface the system to my GPS and my NMEA2000 marine instrument display. This gives me information as to fuel levels, fuel consumed, how many miles I can run until empty under current conditions, etc. I have found that fuel consumption varies from day to day based on current boat conditions (full/empty water, number of people on board, weight of provisions and other gear, etc) as well as sea and wind conditions. These fluctuations can be non trivial in rough seas and heavy winds.

 

[ktcanuck]

Aside from the cost, I also question the need on a Cat powered boat. I use Caterpillar fuel tables and find them to be right on the money as far as GPH. On a 300 gal fill up, I am usually within 5-10 gal of what I expect and have computed from the tables.

Frank, I have looked everywhere (inc Boat Diesel) for fuel flow tables specifically for the 3126TA 420hp version without success. Can you point me to them?

I found a number of sets of data for prop demand but none for this particular model except for three RPM points. I plotted what I found and can deduce the likely burn.

Keith

 

[Henry Boyd]

Is this what I need? My engines are 6.2L MX 2003 MPI's. They are smartcraft ready but my Tach, Speedo ect are not. Am I better off buying the individual gauges or this unit.

http://cgi.ebay.com/ebaymotors/Merc...0758243QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

GLP,

I've done the Smartcraft upgrade and will be glad to help. It's a little more complicated, but do able as both cost effective and as a DIY project. Why don't you start a new thread in the gas engine forum posing the question, and we can take it up there?

Back on topic,

I was thinking about Frank's comment, and as always, he is correct. I guess the significant point is not whether flow meters are necessary, or cost effective, but rather whether accurate fuel consumption data is. I gather from all of the responses that that answer is a yes. As a result, it would seem that if accurate published flow data is available, the added cost of a flow meter might not pay off, or perhaps be more of a convenience than a necessity.

On the other hand, for those of us who do not have access to such data the installation of a flow meter(s) can be economically justified.

Henry