fuel flow computer...good idea?
- Thread starter chazaroo
- Start date
bliss
New Member
A friend installed FloScans on his twin 454s. No small expense. Nice toys but after a while most pilots know within a few rpm where "the groove" is on their boat. In his case, he had had the boat for years and all the new instruments did was confirm what he already knew.
It's really up to you.
I have Smartcraft and it gives the fuel flow. I am just not sure how valuable that information is. Sure, I guess I can feel good by going slower and seeing my GPH "increase" but the reality is I run the boat where it feels the most "comfortable" to me not necessarily where I get the best GPH. Now if you are considering a Navman for other things like GPS mapping, then I suppose you could also buy the harness and fuel flow sensors too. After all it's only money. :wink:
I have Smartcraft and it gives the fuel flow. I am just not sure how valuable that information is. Sure, I guess I can feel good by going slower and seeing my GPH "increase" but the reality is I run the boat where it feels the most "comfortable" to me not necessarily where I get the best GPH. Now if you are considering a Navman for other things like GPS mapping, then I suppose you could also buy the harness and fuel flow sensors too. After all it's only money. :wink:
Northern Ivy
New Member
- Dec 4, 2006
- 6
Installed the 3100s as well
I had the 3100s installed last year as well. The port sensor never has worked properly. We did extensive trouble shooting and the only thing that we could come up with was that there was a bad sensor from the factory.
I also agree that after a certain amount of time you can easily map out your speed vs. burn curve; once this has been complete the real use of the gauges is to tell you more realistically how much fuel you have remaining. I know that my 3100s are much more accurate then the mechincal fuel level guages on our 310.
I had the 3100s installed last year as well. The port sensor never has worked properly. We did extensive trouble shooting and the only thing that we could come up with was that there was a bad sensor from the factory.
I also agree that after a certain amount of time you can easily map out your speed vs. burn curve; once this has been complete the real use of the gauges is to tell you more realistically how much fuel you have remaining. I know that my 3100s are much more accurate then the mechincal fuel level guages on our 310.
boatrboy
Well-Known Member
I have installed the Navman 3100 last year. While I am not really disappointed, I am not sure I would convince someone to run out and install one either. I really wanted to see how conditions, tab settings, trim settings, etc would effect fuel consumption. I spent a lot of time getting the unit calibrated. Most of this was my fault, like leaving the fuel dock and forgetting to take the time to reset stuff. Anyway, the unit seems to work well but it tells me what I thought I knew, in gals/hr. I really see such little effects from fine tuning trim and tab settings that it did not pay for itself as many would think. Guess what, more throttle burns more gas :smt043
I have mine hooked up to my GPS. I have attached a pic of how I mounted it on my dash after moving my stereo controls. I have pics of the rest of this install if you are interested.
Mark
I have mine hooked up to my GPS. I have attached a pic of how I mounted it on my dash after moving my stereo controls. I have pics of the rest of this install if you are interested.
Mark
Attachments
- Mar 10, 2004
- 5,113
I had the navman system 2 years ago and hated it. Last year I put a Lowrance LMF400 system on my boat and am in love with it. I don't think any boat should be without one :thumbsup:
Check out the LMF-400 w/ep-10 fuel sender. It not only does fuel flow, but it will display just about anything else on your boat if its nmea2000 compatible.
http://www.byownerelectronics.com/store/product.php?productid=19804&cat=0&page=1
Check out the LMF-400 w/ep-10 fuel sender. It not only does fuel flow, but it will display just about anything else on your boat if its nmea2000 compatible.
http://www.byownerelectronics.com/store/product.php?productid=19804&cat=0&page=1
sr360aft
New Member
admin said:
I put in the LMF 200 and found I could cut my fuel burn by 40% at cruise by slowing down by a knot. I went from 10 gph at 10kts to 6gph at 9kts. The Lowrance units can display lots of info, in fact it can accept up to three fuel sending units allowing for accurate genset consumption as well
boatrboy
Well-Known Member
sr360aft said:
I am very surprised. If I recall correctly, I would run around 28 -30 mph at about 15 gal/hr. Slowing down to about 26 mph only gave me about 14 gal/hr, so I would just say, for another 4 bucks/hr, I am getting there faster!
I didnt realize the big boys have such a delta at 1 knot :smt089
I also agree with Northern that the gas gage feature is nice as a back up to my regular gas gage. I also like the large display of the Navman so I don't need struggle reading it without my reading glasses on.
sr360aft
New Member
boatrboy said:
I was too, my fuel burn goes up quite a bit after hull speed is exceeded, I burn about 36 gph at 25kts
- Nov 26, 2006
- 7,628
- Boat Info
- 2008 44 Sedan Bridge
- Engines
- Cummins QSC-500's
Straight Drives
If you look at the drag curve for a standard boat (one that planes out), as you accelerate from zero knots and move along the scale from left to right, the drag goes from zero up a fairly steep grade until the hull begins to plane at which point the drag drops down into a valley. The bottom of the valley represents the minimum drag speed on plane.
As you continue to accelerate, the drag goes up fairly steeply again. Drag equates to fuel consumption. The engines require a given amount of fuel to produce a set amount of power. At a stable speed, the power required is dependent on the drag produced.
On another graph, picture fuel consumption as a function of power output. It goes up at an ever increasing rate to max burn (the curve goes up and curves up until it reaches max power).
The variable is the speed of the hull compared to the fuel consumed. That will be different for each boat on the water. However, the valley in the first curve represents the best speed over water for the minimum drag. If you want to go far and relatively fast, find that minimum speed on which you can stay on plane.
If you just want to go far, and you have a trailing current, go at idle. If you are fighting the current, go back to that minimum plane speed. If the current is significant, push it up a little above the minimum plane speed (continue to read for a discussion on that).
Current - If you cruise at 24 knots, and 24 gph, you get 1 nmpg (nautical mile per gallon). Let's say you push it up to 30 knots, and burn 32 gallons per hour doing it. You now get .94 nmpg. (Random example)
Now, add a 6 knot current in the face. At 24 knots, you make 18 knots SOG, at 24 gph, or .75 nmpg. At 30 knots, you make 24 knots SOG and burn 32 gph. You get .75 nmpg. In this example, you get to cruise 6 knots faster (SOG) for free! Other samples will show an increase in fuel economy at higher cruise speeds when fighting the current.
8 knot current - 24 yields 16 at 24 gph = .67 nmpg
8 knot current - 30 yields 22 at 32 gph = .69 nmpg, and you're cruising 38% faster!!!!!!!!!!!!!!!!!!!!!!
You get the idea.
With a trailing current, shut the engines down and drift - it's all free. But realistically, boats usually get similar mileage at idle as compared to min plane speed (for boats that truly plane out). But a trailing current will increase your idle speed significantly (double or more) while only increasing your cruise speed relatively modestly (by percentage).
As you continue to accelerate, the drag goes up fairly steeply again. Drag equates to fuel consumption. The engines require a given amount of fuel to produce a set amount of power. At a stable speed, the power required is dependent on the drag produced.
On another graph, picture fuel consumption as a function of power output. It goes up at an ever increasing rate to max burn (the curve goes up and curves up until it reaches max power).
The variable is the speed of the hull compared to the fuel consumed. That will be different for each boat on the water. However, the valley in the first curve represents the best speed over water for the minimum drag. If you want to go far and relatively fast, find that minimum speed on which you can stay on plane.
If you just want to go far, and you have a trailing current, go at idle. If you are fighting the current, go back to that minimum plane speed. If the current is significant, push it up a little above the minimum plane speed (continue to read for a discussion on that).
Current - If you cruise at 24 knots, and 24 gph, you get 1 nmpg (nautical mile per gallon). Let's say you push it up to 30 knots, and burn 32 gallons per hour doing it. You now get .94 nmpg. (Random example)
Now, add a 6 knot current in the face. At 24 knots, you make 18 knots SOG, at 24 gph, or .75 nmpg. At 30 knots, you make 24 knots SOG and burn 32 gph. You get .75 nmpg. In this example, you get to cruise 6 knots faster (SOG) for free! Other samples will show an increase in fuel economy at higher cruise speeds when fighting the current.
8 knot current - 24 yields 16 at 24 gph = .67 nmpg
8 knot current - 30 yields 22 at 32 gph = .69 nmpg, and you're cruising 38% faster!!!!!!!!!!!!!!!!!!!!!!
You get the idea.
With a trailing current, shut the engines down and drift - it's all free. But realistically, boats usually get similar mileage at idle as compared to min plane speed (for boats that truly plane out). But a trailing current will increase your idle speed significantly (double or more) while only increasing your cruise speed relatively modestly (by percentage).
Whitenights
New Member
Installed floscans in mine when I bought it. I was hoping to find the sweet spot, which I did, off 
But what I think makes it worth it is it is very acurate so I can run without having to fill up my tanks each time. I have found it to be within a couple gallons per 100 I burn so now I just put in 100, reset the meter, and I know how much is remaining without having to rely on gauges. Saves me from hauling around more than I need.
But what I think makes it worth it is it is very acurate so I can run without having to fill up my tanks each time. I have found it to be within a couple gallons per 100 I burn so now I just put in 100, reset the meter, and I know how much is remaining without having to rely on gauges. Saves me from hauling around more than I need.
bliss
New Member
I think that is a really valid reason. Gasoline weighs 6 lb/gal. Helps with gph. However, one could argue that the only time you have to much fuel is when you're on fire! JS
I hate it when I start reading a thread for 5 minutes and then figure out it's 12 years old....damnit !!
boatrboy
Well-Known Member
So since it's so old-I'll update my position (now twelve years later)
My nema 0183 Navman unit has been working great. I really like having a back up fuel gage so to speak. I like even more getting fuel and knowing within a couple of gallons how much I will take - sometimes within one gallon!
Since I know my fuel burn I can tell if my trim tabs may have accumulated some barnicles and I need to jump and and clean the and props.
My new opinion is I would replace it if it broke for sure.
)My nema 0183 Navman unit has been working great. I really like having a back up fuel gage so to speak. I like even more getting fuel and knowing within a couple of gallons how much I will take - sometimes within one gallon!
Since I know my fuel burn I can tell if my trim tabs may have accumulated some barnicles and I need to jump and and clean the and props.
My new opinion is I would replace it if it broke for sure.