Navman fuel flow meter- Any experiences?

I posted this on the PBO R to R forum but no reply im afraid.

''Anybody out there fitted a D.O fuel flow instrument to a single inboard Volvo TAMD 41P engine.
Have been thinking of connecting the Navman fuel management system to my GPS but think I would prefer a stand alone unit which is probably a lot simpler to fit.
Are the benefits of being able to see the most fuel efficient running profile of my boat by fitting one of these instrument really tangible ,are the intruments that accurate. Any recommendations on type / maker / models for D.O engines gratefully received. ''

Lets see if you do better on here .

Cheers
 
... just opened this months mbm mag and guess what..! Test report on the Navman 3200

Got four stars out of five.
 
We have the system fitted and been using it about one year. We wrote the article for MBM (June 2008 issue just out)! Any particular questions? I will do my best to answer them for you.
 
Great thanks-

Has the system been reliable?
Have you been able to verify the accuracy of the readings?
Did it actually help in determining an optimum cruising speed or at least what is not an optimum speed! What sort of consumption variations did you find?
Did you manage to check the fuel flow figures for your engines (in the feed and return pipes that is) before you bought the system to make sure they were within the spec for the 3200? This is where I'm having some problem deciding as Navico can't advise if suitable for any particular engine.


Nick
 
I have been running them hooked up to my chartplotter. Navman sensors linked to a Northstar 657 plotter.

Works really well, you can see instantly updated info on fuel use of each engine.

Shows litres per hour and MPG.

Found my optimum MPG to be a little faster than I thought. So that means SWMBO cant tell me off for going too fast /forums/images/graemlins/grin.gif

Also, allows you to balance the engines a little better, as the rev counters may not be as accurate. Assuming the fuel flow is accurate and engines producing similar power etc.
 
I fiited this last year to a boat with twin KAD43's and I have to say it works very well. I opted for the stand a lone display as I was running a Raymarine plotter and anyway, I dont like having one unit for all the data.

The system install is reletively easy, the only difficult/expensive bit is having the fuelines adapted to fit the flow sensors. I found the MPG read out very useful, but also the fact that it monitors every litre in and out of the tank, so you have a 99% accurate measure on exactly how much fuel you have in the tank in litres or gallons. Also, it will give you the effiective range in miles for the current speed and conditions.

The only trouble I had with it was I found the sensors to be very suseptible to clogging if there were even small deposits in the fuel. This is easily cleared by blowing air through them, it just happened too many times and became a bit of a pain. We couldnt locate the sensors after the fuel fileters, so if you can then I suggest you place the sensors after the primary fuel filters to avoid this issue.

All in all, a good system - reccommended
 
Has the system been reliable?
We had some initial teething problems but Navman was very helpful and worked closely with Landau (Hamble Point) who did an excellent installation. Navman even visited the boat to ensure all was well. It turned out that we had a faulty sensor that was replaced and then all worked as it should. One absolute must is that a very clean fuel line cut is required – any particles will cause problems.
We found that one of the read outs fluctuated rapidly whilst underway. This was solved by altering the damping (a function in the display). The system now works very well and helped us to diagnose a prop pitch problem.

We have correlated the amount of fuel put into the tanks with the amount the system says we have used. It seems very accurate. The system gives us valuable cruising data
- digital fuel gauges
- range of the vessel whilst underway (at that speed and in those conditions)
- fuel used (each tank and total, amount remaining)
- economy (miles/litre)
- accurate rpm for each engine to help make them match

The economy function is useful. You can see how much fuel is being used and can adjust speed to be more economical. For us consumption v rpm is a straight line but we know how much fuel we can save by dropping from say 2500 to 2300 rpm and a couple of knots speed! It is quite a lot.

Don't forget though that any fuel used by a generator or heating system will not be measured by the system so build that into the calculations.

As for compatibility, I think it is best to ask Navman about that.
 
Thanks for very helpful responses guys, I think I'll go ahead with a single engine unit to start with. I'll fit to the engine/tank that doesn't feed the genny.
Although my engines are bigger than Navman say in their brochure (they say up to 400hp) according to VP the fuel flow rate for the 74p is well under the 400l/hr max in the feed line(they reckon 190 ltr/hr) . The one I'm not so certain about is the return line, which must be more than 25 ltr/hr, as there doesn't seem to be a spec for this. Will only be a potential problem at off load tickover though so not a real issue.

Nick
 
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