Fuel mileage efficiency

[Mambo42]

What is it that would block the entire thermostat poppet valve but not a 3 mm hole?

The 3 mm hole is indeed there to avoid air blocks in the system. The hole will equalize the pressure in case there is an air block and since the pressure of the waterpump is so much bigger than the relatively small flow of coolant through that hole, the chance that the thermostat will open late is next to zero.
I have been running this thermostat now for about 60 hours this way and the engine temperature is steady at 78 degrees. Good maintenance practice also tells you to regularly exchange the thermostat, so I will do that every year, just like I change the oil, oil filters, fuel filters etc etc.

 

[Mambo42]

I’ve learned to not trust anyone except myself. Even when I’m gone and dependent upon yacht management I don’t want them to have to scramble if shore power goes down. Perhaps in your situation it may not be possible to be shore power independent. But will say it was a new world and much lower stress being so. Especially when I wasn’t on the boat for significant periods of time.

@ Hippocampus, I now learned that as well the hard way, expensive lesson. No work done on my boat anymore when I am not there. And indeed don't assume that people will do something just because they say they will do it.

Being almost 13.000 km away from the boat at this moment does not help of course.
But when we left at the beginning of June I closed all the sea cocks, so no water can come in anymore. I disconnected all my start batteries and batteries for the stern thruster and pasarelle. Only batteries still connected is the house bank (which is destroyed anyway) and the battery for the bilge pump. Solar power will charge them and shore power is disonnected.

Just a few days ago I called my neighbor, who lives on board his sailing vessel, and asked him if he could check battery status and bilge status. Everything is fine according to him, so in about a month he will check again. But not a single person of this marina will ever set foot on my boat anymore, I don't want any more damage.



So I fully agree with your approach, it is the only way to make sure your boat stays the way it is.

 

[Nomad Willy]

Thought about the hole in the thermostat but now I’m glad I didn’t do it.

My Mitsu started up quickly and warmed up fast. Was up to 190 quickly. My idle speed was higher than most would have it (1000?) as I had a problem early on in Alaska. Started up and backed out of the slip .. pulled the throttle back and before I shifted into fwd gear the engine quit. I think I had the idle speed too slow .. 700 or so. Turned it up to about 1050 when all warmed up. Engine never quit again .. for too slow idle adjustment. I couldn’t think of any reason for a slow idle so that’s where it stayed.

 

[twistedtree]

Thought about the hole in the thermostat but now I’m glad I didn’t do it.



My Mitsu started up quickly and warmed up fast. Was up to 190 quickly. My idle speed was higher than most would have it (1000?) as I had a problem early on in Alaska. Started up and backed out of the slip .. pulled the throttle back and before I shifted into fwd gear the engine quit. I think I had the idle speed too slow .. 700 or so. Turned it up to about 1050 when all warmed up. Engine never quit again .. for too slow idle adjustment. I couldn’t think of any reason for a slow idle so that’s where it stayed.

The only issue with a fast idle is that it’s harder on the clutches when you shift gears. 1050 is pretty high. It might be worth checking what your gear mfg suggests. I would think that 800-850 would be a better compromise.

 

[Bacchus]

Small hole in Tstat plate is meant for allowing air to bleed off preventing air lock and overheating. My mechainic friend suggested I drill one when I replaced coolant and Tstat. When I got the new Yanmar Tstat it already had a hole in it.

 

[Nomad Willy]

twistedtree wrote;
“ The only issue with a fast idle is that it’s harder on the clutches when you shift gears. 1050 is pretty high. It might be worth checking what your gear mfg suggests. I would think that 800-850 would be a better compromise.”

I should have mentioned my engine was not a Lehman or 6cyl Perkins. It was a four cylinder 40hp engine. And I never abuse clutches. Engage and disengage clutches smartly as in quickly.
The trans was a BW designed for much larger engines. I used that transmission mostly because it was original equipment .. mated to a 4cyl Perkins. I had installed a smaller gear on the oil pump as the clutches needed far less pressure to maintain clutch engagement. Worked perfectly.

 

[Lepke]

You can buy a digital flow meter on Amazon or ebay for about $40.
It only measures in one direction so you need 2 and have to do the math.

 

[Art]

I nearly always shift gears at 1000 rpm, sometimes 100 below or a 100 above... that's according to my old tachs... which I'm confident are not accurate at faster rpm's; so, who knows at considerably low speed??

When first starting boat up with hatches wide open, while I'm listening closely to engines running [warming up]... as I shift tranys' in F and R to test them - the shifting sounds smooth and gentle at 1000 rpm. At below 800 rpm there's a rattle in reverse [not in forward] - more pronounced on port. Rattle disappears above 800 rpm. Have heard of this from other BW VD trany owners. Same rattle has been present for 14 yrs we've owned our Tolly.

Accordioning to my trans specialist shop: An important item in shifting marine transmissions, to help not stress a trany's plates and its other internals, is the "couple second wait" in neutral before altering shift lever position from F to R or R to F. That's easy to say... but in close quarters a second or two can be a long time between the altering of prop direction.

Sooo... To best as possible not stress trany internals [by often doing back and forth shifting] during close quarter maneuvering: I recommend going at things very slowly. Wherein I go from a shift direction and into neutral so far away from striking a point with boat that the couple of seconds wait before going into opposite gear is no problem. Also, if you go into neutral but quickly realize you should go back into the same gear then there is no wait time required.

Happy Trany-Shifting Daze! - Art

 

[Simi 60]

You can buy a digital flow meter on Amazon or ebay for about $40.
It only measures in one direction so you need 2 and have to do the math.

Beat me to it
Which looks identical to the Scintex one for $350

Inline Digital Turbine Flow MetersSPEVINFLO40

 

[SteveK]

You can buy a digital flow meter on Amazon or ebay for about $40.
It only measures in one direction so you need 2 and have to do the math.

This one measures a minimum of 9L/min

Beat me to it
Which looks identical to the Scintex one for $350

Inline Digital Turbine Flow MetersSPEVINFLO40

This one measures a minimum of 5L/min

Unless I misunderstand that suggests that if the flow is less then it does not measure.

 

[smitty477]

I nearly always shift gears at 1000 rpm, sometimes 100 below or a 100 above... that's according to my old tachs... which I'm confident are not accurate at faster rpm's; so, who knows at considerably low speed??

When first starting boat up with hatches wide open, while I'm listening closely to engines running [warming up]... as I shift tranys' in F and R to test them - the shifting sounds smooth and gentle at 1000 rpm. At below 800 rpm there's a rattle in reverse [not in forward] - more pronounced on port. Rattle disappears above 800 rpm. Have heard of this from other BW VD trany owners. Same rattle has been present for 14 yrs we've owned our Tolly.

Accordioning to my trans specialist shop: An important item in shifting marine transmissions, to help not stress a trany's plates and its other internals, is the "couple second wait" in neutral before altering shift lever position from F to R or R to F. That's easy to say... but in close quarters a second or two can be a long time between the altering of prop direction.

Sooo... To best as possible not stress trany internals [by often doing back and forth shifting] during close quarter maneuvering: I recommend going at things very slowly. Wherein I go from a shift direction and into neutral so far away from striking a point with boat that the couple of seconds wait before going into opposite gear is no problem. Also, if you go into neutral but quickly realize you should go back into the same gear then there is no wait time required.

Happy Trany-Shifting Daze! - Art

"At below 800 rpm there's a rattle in reverse [not in forward] - more pronounced on port. Rattle disappears above 800 rpm. Have heard of this from other BW VD trany owners. Same rattle has been present for 14 yrs we've owned our Tolly."

Most likely from the dampener plate.
Typical on 4 and 6 cyl diesels as they go through their power stroke and communicate load lash at lower rpm.
We always had our idle speeds set at about 700 rpm - for 6 cyl diesels.
They shifted and ran fine there but you could always goose the throttles up if you wanted to.

 

[Simi 60]

This one measures a minimum of 9L/min


This one measures a minimum of 5L/min

Unless I misunderstand that suggests that if the flow is less then it does not measure.

The more expensive Scintex package in the video above does the same

 

[OldDan1943]

This is a seasonal discussion.... If it is winter, 'How to keep warm on the boat, open the engineroom hatch.' In the summer, how to keep the ER cooler, 'open the ER hatch.'
I would rather save my hearing.

 

[SteveK]

The more expensive Scintex package in the video above does the same

To be clear, if Scintex is not measuring flow less than 5L then it is not measuring all flow. If only the return line is less than 5L then the math is not accurate.
These devices must measure every drop to become accurate. Perhaps floscan went out of business because of the real world flow not being reported

 

[Art]

To be clear, if Scintex is not measuring flow less than 5L then it is not measuring all flow. If only the return line is less than 5L then the math is not accurate.
These devices must measure every drop to become accurate. Perhaps floscan went out of business because of the real world flow not being reported

Following the general bent of questioned "accuracy" mentioned in post above...

Doesn't it seem logical and most often practiced that nearly all boats have two to three primary speeds [rpms] they cruise at? One or two of the possible three being the rpm/speed most often used.

Therefore... by some means of calculation wouldn't the captain of a boat fairly soon accurately calculate fuel usage at each of those often used rpm/speeds.

Soooo... once the calculations have been accurately completed the captain knows how much fuel is being used during travel sequences.

Then, I simply gotta ask: Why would a captain need to constantly be looking at a fuel flow meter to tell him/her second to second report of what he/she had already calculated as an overall spectrum of the rpm/speed relationship to fuel usage?

Seems pretty simple to me without having a flow meter as just another fuel leak point and gauge to eventually break down.

 

[Hippocampus]

Engines burn fuel primarily on the basis of load. Bog an engine (high load low rpm) or over rev an engine (low load high rpm) you aren’t being kind to that engine. Electronically controlled engines do a better job than old school naturally aspirated engines but it’s sill not being kind.
People driving for maximal efficiency try to achieve the proper load (not rpm). That’s why there’s variable pitch props mated with a exhaust temperature gauge. Then you can adjust the three variables ( exhaust temperature, prop pitch and speed) to maintain the ideal load. Even with a fixed prop you know this. Look at burn going into headseas and winds. Compare to surfing and downwind. At the same rpm fuel burn is entirely different. If you keep speed the same then you’re increasing rpm going upwind into the seas to maintain that same speed. Downwind you can go to just enough rpm to not backload the prop and to keep steerage. Load is much less.
This ain’t new. Going back decades since variable pitch become available even before common rail this has been done.

BTW I have two set idle rpms. 600 and 900. The boat is unmanageable at 900. 900 is ok for a slow troll to catch fish. That’s it. Docking you must use 600. The boat is a SD hull so to achieve speeds above displacement they stuck n 540hp. Would suggest the above posts talking about idle speeds may apply to FD hulls or those with lower HP engines but for those of use on SD hulls propped and engined for that use that discussion is not applicable.
Lastly in a truck, car or boat if you’re getting lash the trannie needs servicing.

 

[smitty477]

Following the general bent of questioned "accuracy" mentioned in post above...

Doesn't it seem logical and most often practiced that nearly all boats have two to three primary speeds [rpms] they cruise at? One or two of the possible three being the rpm/speed most often used.

Therefore... by some means of calculation wouldn't the captain of a boat fairly soon accurately calculate fuel usage at each of those often used rpm/speeds.

Soooo... once the calculations have been accurately completed the captain knows how much fuel is being used during travel sequences.

Then, I simply gotta ask: Why would a captain need to constantly be looking at a fuel flow meter to tell him/her second to second report of what he/she had already calculated as an overall spectrum of the rpm/speed relationship to fuel usage?

Seems pretty simple to me without having a flow meter as just another fuel leak point and gauge to eventually break down.

'Then, I simply gotta ask: Why would a captain need to constantly be looking at a fuel flow meter to tell him/her second to second report of what he/she had already calculated as an overall spectrum of the rpm/speed relationship to fuel usage?"

I agree that they are not necessary, but they can be very helpful .....
- detecting boats current bottom condition
- showing the latest prop/running gear status
- finding engine balance in twins
- detecting real time engine issues

 

[rslifkin]

For those with Velvet Drives, even with smooth running engines (like a gas V8), they'll give a terrible rattle if the idle is set too low. But it shouldn't happen at 800. Mine have to get below 600 in gear for it to happen.

Hippocampus has a good point (and it's one I've referenced here before). On a faster boat with a lot of power and a low revving engine, you can easily reach the point where idle thrust becomes excessive (as idle may be 25% of WOT RPM on a boat that moves fairly fast). Look at a big sport fish or some of the fast express styles with big diesels. Unless they've got trolling valves, some of those things do 7 - 8 kts at idle as a byproduct of having the power to do 30+ kts at WOT and engines with a fairly small RPM range.

When you look at the other end of the spectrum (FD boat with a small, possibly higher revving engine like a sailboat) you often won't have enough idle thrust and you'll be adding throttle every time you put it in gear for maneuvering.

 

[OldDan1943]

An observation: There are only so many upgrades and modification one can make w/o it becoming, difficult to maintain and confusing to you and the next owner.

 

[Hippocampus]

Or-dance with the girl you brought. Some like waltzing, others rhumba, others limbo. All are fun.

 

[Seevee]

As for knowing or not knowing fuel consumption, I could make a STRONG argument for knowing your consumption for a lot of reasons... even in intercoastal cruising.



First, if one is much of a traveler, fuel can be your largest expense, has been for me, over the years. So a difference of 1.5 or 2 mpg makes a HUGE difference over time.


There's times we don't want to stop, but continue on to a better stop, so it's nice to know that we can do that with reserves. With a good flow meter, we can know that exactly.



I don't have one on the boat.... yet, but have had them in planes and they have paid off handsomely.


Occasionally a small speed/power change makes a huge difference and hard to know without a fuel meter.


Question: Does anyone have the Maretron fuel flow meters and can comment about them, especially accuracy at low fuel flow? They look pretty good.....

 

[Art]

Bout 10 yrs ago...

I inexpensively picked up an unused twin engine set of FlowScan fuel gauges; still in the box, from a fellow who'd sold his boat. That's as it sits in my boat's storage draw now. Never did bother to install em.

Be a good "this comes with it too" point of interest if/when selling. :lol:

 

[Nomad Willy]

Seevee wrote;
“ First, if one is much of a traveler, fuel can be your largest expense, has been for me, over the years. So a difference of 1.5 or 2 mpg makes a HUGE difference over time.”

No disrespect toward you as you’re on the high side of respected TF members but I must say perhaps you should consider a smaller SD boat or a FD boat. But also in you’re defense this period of high priced fuel will almost certainly pass
Eric

 

[Hippocampus]

There’s micro and macro management. In this situation don’t see a particular advantage to micro management and therefore adding more meters and therefore complexity. My Cummins tells me instantaneous usage but I rarely even look at it unless it’s on the screen I’m using. Practically I what to know usage at various speeds in various sea states and direction. Once I know that I know my usage and range as I cruise. I expect every blue moon I will do the exercise again to make it hasn’t changed. But there’s multiple other ways to know the health of my engine and machinery so not going to stress on it. Even if I never do it or didn’t have monitoring but just looking at sight guages after completion of my trips I’ll have a real good idea of usage in the real world. Monitoring devices mentioned here give you a snapshot but life is a movie. Wouldn’t go to the expense and labor of adding one.

 

[Seevee]

Seevee wrote;
“ First, if one is much of a traveler, fuel can be your largest expense, has been for me, over the years. So a difference of 1.5 or 2 mpg makes a HUGE difference over time.”

No disrespect toward you as you’re on the high side of respected TF members but I must say perhaps you should consider a smaller SD boat or a FD boat. But also in you’re defense this period of high priced fuel will almost certainly pass
Eric

Thanks Eric, but the price of fuel is NOT an issue for me. I hedged myself with buying oil rights which will pay for all the fuel I'll use for the rest of my life... however, still the biggest expense if one travels much. And, don't believe it will pass soon, with the current administration. We'll have relatively high prices for years to come.... all politics, but I don't care.

 

[Barking Sands]

Not that its entirely needed but I actually prefer the micro-management in regards to this type of info. On my previous boat I really enjoyed the Mercury Vessel View and usually had the app open and configured for my top 5 parameters. Fuel burn info was on there.

About 6 months ago I installed a new old stock Floscan on the current Trawler with the Perkins. Its the simpler version with an analog needle gauge and totalizer. I dont really love it because the needle pointer is just not accurate enough to make great calculations. However I just picked up another NOS Floscan with the multifunction digital gauge. It must have been a late model product prior to Floscan shutting down because it has inputs for NMEA 0183 GPS speed as well as wiring for an additional toggle switch to toggle one read out between GPH and MPG with the latter using GPS speed in the calculation. I still need some info on it but if it pans out Ill install it and see how I like it. It happens to have an hour meter which i needed, tachometer which I needed, GPH/MPG and totalizer. For $400 and free labor it cant hurt too much. An additional tach and hour meter would have been $100-200 anyways.

 

[twistedtree]

I think accuracy is the challenge with fuel flow measuring, and expect that’s why the better systems are expensive. I know with the Maretron system you need to carefully select the sensors based on the flow range that’s expected. Outside the published range, accuracy drops off. And when you are measuring flow in and out and taking the difference between the two, errors are additive so 5% accuracy turns into 10%, and 10% turns into 20%.

 

[Hippocampus]

Thanks TT. If you measure fuel before you start a trip and again when you stop you know without any monitoring systems how much was burned. Basic sight gauges are sufficient. Think most of us preplot or use the tract function of our charting systems so you know distance traveled. Will admit I do glance at my instantaneous readings but don’t think that changes my behavior. I’m more concerned by other factors. Things like timing to make use of favorable currents or achieving landfall at a desired time. So I’ll speed up beyond displacement speed to get my whole 6 h of favorable current or slow down to to arrive at a particular time or avoid a unfavorable current. Yes I know the “happy rpm” for my engine and now given fuel costs that’s my go to if other concerns aren’t operative. So my question is:

How does your monitoring system effect your behavior in running your boat?

 

[psneeld]

As for knowing or not knowing fuel consumption, I could make a STRONG argument for knowing your consumption for a lot of reasons... even in intercoastal cruising.



First, if one is much of a traveler, fuel can be your largest expense, has been for me, over the years. So a difference of 1.5 or 2 mpg makes a HUGE difference over time.


There's times we don't want to stop, but continue on to a better stop, so it's nice to know that we can do that with reserves. With a good flow meter, we can know that exactly.

I don't have one on the boat.... yet, but have had them in planes and they have paid off handsomely.


Occasionally a small speed/power change makes a huge difference and hard to know without a fuel meter.


Question: Does anyone have the Maretron fuel flow meters and can comment about them, especially accuracy at low fuel flow? They look pretty good.....

Agree 1000%.

Having spent 2 careers that dealt with emergency or critical response in the air and on the water....

The ability to accurately determine endurance/range was crucial to good decisions/risk management.

True it isn't always about money, just sometimes convenience or even somewhat critical.

That's why when I took out the steel tanks with crap fuel gauges and put in poly tanks where I could always see fuel load and use accurate markings to accurately determine fuel burn under a variety of conditions.....it was one of my favorite modifications.

I can see where it's not necessarily important to some, as carrying large amounts of fuel and pretty consistent and predictable fuel burns bring less worry.....for me....it's just I'm my blood after all these years, plus to gain engine room space on my trawler, I dropped from 400 gallons to 112.

 

[mvweebles]

Agree 1000%.

Having spent 2 careers that dealt with emergency or critical response in the air and on the water....

The ability to accurately determine endurance/range was crucial to good decisions/risk management.

True it isn't always about money, just sometimes convenience or even somewhat critical.

That's why when I took out the steel tanks with crap fuel gauges and put in poly tanks where I could always see fuel load and use accurate markings to accurately determine fuel burn under a variety of conditions.....it was one of my favorite modifications.

I can see where it's not necessarily important to some, as carrying large amounts of fuel and pretty consistent and predictable fuel burns bring less worry.....for me....it's just I'm my blood after all these years, plus to gain engine room space on my trawler, I dropped from 400 gallons to 112.

When I was delivering along the Pacific Coast, fuel/risk management was absolutely critical. That said, I would never rely on an owner's statement of fuel burn. They were always optimistic. I'd still be dead-in-water off the coast of Big Sur if I listened to owners.

But for the standard TF crowd who seems to mostly weekend dawdle, or do the Loop or the ICW, claiming risk-management is a wild exageration. Knowing fuel burn/capacity within +/- 20% or so is all about convenience, nerdish hobbyism, bragging rights, and economy. Sure it effects planning to know when you need to fuel-up. But way down the list is any safety-related concern.

Peter