Gas vs Diesel

[Art]

I have been on gas boats snd diesel boats, both with fuel leaks.

You can smell fuel long before it is dangerous...usually.

Probably why most explosions are during or right after refueling because people associate the smell to the refueling and not a different problem.

It may depend on the boat, but I dont worry about either. If I was regularly running a gas boat with a well sealed bilge from the cabin, I would make darnn sure the sniffers worked and fuel system was checked regularly......no different than the propane system on my diesel boat.

Years ago, in late evening-dark, upon first arriving to boat, I topped-off gas tanks from wheel cart pump fuel container.

First and last time I will bring marine tanks to full-level that way. In my learned opinion, adding fuel by wheel cart without "filling" the tanks is OK... but completely filling the tanks up with a wheel cart - Is Not OK!

Unlike standard fuel-dock hose plentiful rush of liquid the recognizable very audible sound change of approaching full does not occur... so you don't easily know when to stop filling as fuel dribbles into tank in comparison to fuel-dock pressure.

By using the wheel cart fuel container I topped-off the starboard tank too full, a bit of gas dripped out the overflow.

As I always do, with bilge blower on during adding gas and before any ignition device is used, soon as the fill-up was completed I opened both hatches in salon sole and with portable search light inspected both tanks... as well as leaning down for a whiff. All looked and smelled OK.

We cashed in for the night in rear master stateroom; early next morn was our departure plan.

At 4:30 [my standard wake time]... upon opening my eyes I realized I faintly smelled gasoline. Immediately getting up I woke and alerted Linda to get off boat onto dock and far away.

I then gingerly opened the salon hatches. Gas odor was there but not overpowering. I had portable spotlight and was searching on and around tanks. Turned on bilge blower and called Linda back in... she went back to bed... 4:30 is NOT her usual wake time!

Soooo... I stepped down into engine compartment and quickly realized the odor was coming from starboard tank. Upon quick check I saw moisture on tank top right at the plate for gas gauge sending unit.

Yup... that was it, because tank had been too much filled gasoline moisture had seeped out of that unit's gasket and onto tank top. I placed shop paper towels all around that area and made sure the seep was dry. Watching closely I could see there was a slow moisture increase coming around the plate.

I started stbd engine and in short period of time the seeping was stopped due to gas level going down. I left the engine idle for considerable period to make sure tank level was down somewhat.

Then: I placed wrench onto fastener nuts and found that over the many years the gas gauge plate had loosened just a bit. Upon tightening the nuts sufficiently I could see the gasket slightly compress.

Lesson learned... Make sure all plates atop fuel tanks are well tightened and that gaskets are OK. Also... Big Lesson - Do Not top-off tanks with portable fuel carts.

Happy Boat-Safety Daze! - Art

 

[psneeld]

That's not too lucky either way. Diesel fuel misting like that makes it much more flammable than just a puddle of diesel. Glad to hear it ended well.

I don't know specific numbers, but a lot of work boat fires in the ER are due to little leaks that mist fuel vs big streams of fuel.

First trip south, outside of Beaufort, NC , I developed a visible, misting diesel leak from a cracked injector pipe.

With the posting of a tornado watch, anchoring in the middle of the narrow ICW for repairs seemed out of the question.

Knowing the danger of misting diesel fuel, the easy solution was to tie wrap a piece of absorbent pad around it to turn the mist into a slow drip.

A couple hours later in Beaufort, at the dock, changing out the pipe was easy.

Many emergencies dont have to stay that way when small or creative solutions can be quickly applied.

 

[FF]

"A couple hours later in Beaufort, at the dock, changing out the pipe was easy."

EASY , if you have an on board spare.

Harder if it needs to be flown in from somewhere.

 

[RT Firefly]

Greetings,
Caution: Thread drift... Mr. FF er al. "...if you have an on board spare." I've often wondered why one couldn't make one's own injector lines. I'm sure the raw tubing is available. So, what would be the problems doing a "home made" injector tube, if any?

 

[psneeld]

Greetings,
Caution: Thread drift... Mr. FF er al. "...if you have an on board spare." I've often wondered why one couldn't make one's own injector lines. I'm sure the raw tubing is available. So, what would be the problems doing a "home made" injector tube, if any?

For a Lehman, it would be pressing (swaging?) the acorns on the tube ends.

Not sure just how accurate the length has to be, but if within a couple mm, my cabinetry skills suck, so I bet my machinist ones do too......its a me and tape measure thing....

 

[sunchaser]

Well.... I will be banished, but I made the jump. I now own a boat, but it's in no way a trawler or even a cruiser lol. It's a 2000 Glastron SX 195 bow rider. Something to use for the next couple of summers while my 2 year old gets a little older and we can stash some cash for a 40 ft trawler. Maybe I'll make it my tender once I get a trawler haha

Like your new boat, hundreds of thousands of water toy related boats will not work very well with a Lehman.

 

[diver dave]

Greetings,
I've got both, gas and diesels. I've had fuel leaks on both. Neither is a problem IMO.

perhaps then, "I got away with leaks" ?

I'm not jumping into a gas vs diesel argument. But, almost no fossil fuel boats are immune. Here is an interesting read on a "simple" outboard 17' that sustained a bilge explosion. Not due to a far more typical gas in the rodholder scenario.
Need Help- Gasoline Fuel Explosion After Fuel Line Service - The Hull Truth - Boating and Fishing Forum
I've got the same model boat, and with a plastic tank in a sealed bilge, there is nose detectable fumes due to gas permeation through the plastic tank.

The auto ignition temperature is not the metric one needs to look at for gas explosion risk. It's lower and upper explosive limits:

GAS LEL: 1.2%; UEL: 7.1%. Propane LEL: 2.1; UEL: 9.5. Diesel doesn't have these at room temperature/pressure.

 

[psneeld]

Of course one gets away with leaks,.....and spills.

In a lifetime of leaks and spills....never a fire or explosion....neither happen the vast majority of the time. Why? Takes more than a few factors to make either happen.

In a lifetime around the water, yes I have come across boat fires and explosions. But comparing the total number of gas boats I have seen operating normally, or even with leaks....it is such a small percentage...I couldn't fathom the number of decimal places would be in that fraction of a percent.

I worry way more about my health than a gas fire/explosion.

 

[RT Firefly]

Greetings,
Mr. dd. "perhaps then, "I got away with leaks" ?" It seems I did but the fact of the matter is we've had gas boats in the past and I have always been very diligent about inspecting and keeping the fuel system in good order and following proper re-fueling procedures. I do the same and have done so with our diesel vessels as well. For me, as I stated, it is not a problem.

Oh, we now also have propane aboard as did our previous vessel. Difference THIS time is I installed a fume detection system as the design of our current gas locker called for it.

 

[diver dave]

I understand both points here. I've owned gas boats longer than a car. What's interesting in all this is there is a commonality of explosions to glass breaking. No warning and no middle ground. So, as we "risk mitigate" ourselves though life, we really are not developing a great sense on how close we came to disaster. Unlike car accidents, we visually experience near misses, and hopefully modify behavior accordingly.
I suppose my point in all this, is no one monitors LEV, and UEV of gas fumes. Its more insidious.

 

[psneeld]

I disagree...I posted earlier that if I cant smell gas fumes on a boat, I would have sniffers like MANY boats have installed.

So people ARE monitoring the explosive limits as any wiff is usually way below the lower limit and sniffers give a good heads up too.

Make sure when saying all these explosions have a common threead, that they also dont have a common thread where leaks and spills dont get to the explosion part.

Arts example is one that turned out well, not an explosion. Not going to say what more could have been done, but the fact remains, a spill occured without an explosion...like millions more per year ....I would bet.

 

[garycasey]

gasoline vs. diesel as a fuel

I'm new to this list, and am just in the process of buying my first trawler, so I have no experience to draw from, just my engineering background.

First, hp vs. torque: This argument has gone on forever. Hp is simply torque times rpm, so they're not exactly unrelated. A given hp is able to push a boat at a give speed, period. Of course, the props have to be the same and each engine has to have a gearbox that rotates the props at the same speed. On planing hulls, there is a high hp requirement to get the hull up on plane, and at the lower speed the engine might not be able to rotate the prop at full speed, and therefore the mid-speed engine torque is important. So what? Well, contrary to some opinions, the mid-rpm torque of a diesel engine is often less that that for a gas engine. Truckers call that torque "back-up," or how much higher the peak torque is compared to the torque at peak power. This is true for a variety of reasons, too involved to cover here. Torque just isn't a reason to choose between diesel or gas.

Every type of engine has a "scaleability" characteristic. How well does that type work when scaled up (or down). For detonation reasons, spark ignition (gasoline) engines scale up poorly, while diesel engines, like turbines, scale up very well. Higher hp engines are mostly diesel. Diesel engines have in the past, been much more expensive, but modern technology has made them less so.

Yes, each fuel type can be "safe", but the safety of gasoline is more an "active" thing. One has to take more care to ensure and equal safety level to diesel. So diesel fuel has more inherent safety.

Fuel cost is perhaps the deciding factor. How many hours a year will the boat be used and how long will that usage "pay" for the higher initial cost of a diesel? And for long passages, how much space and weight will the fuel take? I think there is also a psychological factor. If I want to go out to that island for lunch, what will it cost? Yes, I saved money on the purchase of the gasoline-powered boat, but that was yesterday. Today I have to buy gas for it. The same argument can be made for a sailboat - the per-hour cost is essentially zero, so I'm not inhibited in using it. The diesel-powered trawler wins this argument.

So overall, which is better? To each his own.

 

[FF]

Most likely the newest engines that consume diesel fuel will have a spark ignition.

To get the compression temperature required for self ignition requires a high compression ratio , therefor a strong and heavy engine block.

Look first in drones , then in outboards (Merc has them now for Unkle Sam) then if they can get by the air police , in your next car.

 

[RT Firefly]

Greetings,
Mr. gc. Welcome aboard.

 

[Art]

Hello Gary... Welcome Aboard!!


Seems you carry correct tener to make a dent in this forum's threads.


I take it you were [maybe still are] with sail boat?? "... just in the process of buying my first trawler, so I have no experience to draw from ..."


Cheers!


Art

 

[garycasey]

Thanks Art,
Yes, I've been a sailboat(s) owner for maybe 20 years, graduating up to a 34 Hunter. Since then I've been a "borrower", sailing our son's boat (J110) for 2 weeks every year. This Nordic Tug is our first trawler. Looking forward to it!

 

[sbu22]

Diver Dave - you're correct on the LEL/UEL argument.

You're incorrect that nobody monitors it. The Xintex MB-1 (as an example) "gasoline fume detector" alarms and commences auxiliary functions at 0.1 - 0.2 LEL

 

[Baker]

Fuel cost is perhaps the deciding factor. How many hours a year will the boat be used and how long will that usage "pay" for the higher initial cost of a diesel? And for long passages, how much space and weight will the fuel take? I think there is also a psychological factor. If I want to go out to that island for lunch, what will it cost? Yes, I saved money on the purchase of the gasoline-powered boat, but that was yesterday. Today I have to buy gas for it. The same argument can be made for a sailboat - the per-hour cost is essentially zero, so I'm not inhibited in using it. The diesel-powered trawler wins this argument.

So overall, which is better? To each his own.

First off, welcome aboard. And that was a very well thought out post and agree with some of it. I do not necessarily agree with the above portion. Fuel is not the biggest expense in owning a boat. You are thinking like a sailboater... And a sailboat is not zero per hour cost. Sailboats do cost money...and that cost is averaged out of the hours used. They are plenty expensive.

Never have I sweated the fuel costs associated with a particular mission. They day I do is the day I can no longer afford the boat. Because if I am sweating the fuel...read my first point!!...Cheers!

 

[BruceK]

Detection: your nose or an electronic sniffer?

I`ve been told the best sniffer is the one mounted on the face. But I also recall some normally olfactory detected substances destroy(short term) odor detection capability. Does anyone know if gasoline comes in that category? My practical experience says it doesn`t, but you can`t smell what you can`t smell, which could make the electronic sniffer much more necessary.

 

[Portage_Bay]

I've also been told the face mounted sniffer is more sensitive than the electronic sniffer. That's why I always open the hatches and sniff before starting my gassers. But, the electronic sniffer does what I can't do, or am unwilling to do. It's on duty the entire time the boat is running, never taking a break.

 

[Art]

I`ve been told the best sniffer is the one mounted on the face. But I also recall some normally olfactory detected substances destroy(short term) odor detection capability. Does anyone know if gasoline comes in that category? My practical experience says it doesn`t, but you can`t smell what you can`t smell, which could make the electronic sniffer much more necessary.

About sniffing odors...specifically, gasoline on a boat:

I recall a friend of dad's named Ken Wilsey. Back in early 1960's Ken was owner one of the first generation Viking brand boats. She was a 38' twin screw gasoline powered, sedan, fly bridge woody; he purchased her new. Unfortunately Viking had trouble with building quality standards at that time... but that's another story.

So... back to the human sniffer. Ken lost his olfactory sense when he was in late 40's, after purchasing the Viking boat. I always figured he must have become afflicted with diabetes as that is said to sometimes affect the olfactory nerves. Anyway, as I recall, Ken gave up boating not too long after his loss of smell due to his inability to smell gasoline and knowing the severe danger aboard a gas powered boat when you could not detect a gas leak - by smell!

Luckily my sniffer is working great in my mid 60's. However, if I do lose my sense of smell.... my gasoline powered boat may need to go up for sale... for safety sake!!

 

[saltcod]

For me, at least, fuel is the least expensive component of boating. Moorage is the most expensive, at $6600 a year. I would have to cruise a lot to burn that much fuel. If it is fear of fuel costs holding you back, unless you are on the water constantly, you'll find other boating expenses more costly.

 

[garycasey]

I certainly agree with the posts above that disagreed with my post about fuel cost. Yes, if you are rational and spread the cost of operating a sailboat over the miles it has traveled it is pretty expensive. After all, a new main can cost $5,000. But I'm talking psychology. The dollar you spend today, say on fuel for your gas-powered cruiser, is more painful than the thousands you could have spent last year for that diesel-powered trawler. And for those that say they don't care about the fuel cost because it is a small part of the total? Well, to me a dollar is a dollar. I can also hope that I can eventually get most of what I spend on the boat back, but fuel cost? Gone forever. Psychology from an amateur psychologist. FWIW. Time to go to the boat.

 

[BandB]

I can also hope that I can eventually get most of what I spend on the boat back, but fuel cost?

The only chance you have of that is that you don't keep accurate records. Insurance, taxes, dockage? Maintenance costs? Upgrades? Haulouts? Painting? Divers?

 

[Nomad Willy]

I get tired of hearing fuel isn't the biggest cost of boating. For a very high number of people it's a very big expense. If I had the boat I'd like and cruised a lot more it would sure be enough to whine big time on TF and elsewhere. But out of necessity I don't have that boat and have no need to whine.

But as trawler people taken as a whole this fuel burn issue is big for many. Couldn't be otherwise w all the verbage, posts and threads directed at fuel consumption. There's even a thread on fuel prices. I'd say fuel IS a big expense and those that say it's not could be bragging a bit about how much money the've got. Generally speaking of course.

 

[smitty477]

FWIW - we have travelled between 1,000 and 1,300 miles a season in the NE over the past 10 years. Our boat (47') was diesel but you could have also found one with gas engines as well - we mostly travel on plane but do cover maybe 30% of the distance at trawler speeds. Our costs for diesel fuel are about $26,000 less that if it were gas over these past 10 years - or about $2,600 per season.

 

[Art]

FWIW - we have travelled between 1,000 and 1,300 miles a season in the NE over the past 10 years. Our boat (47') was diesel but you could have also found one with gas engines as well - we mostly travel on plane but do cover maybe 30% of the distance at trawler speeds. Our costs for diesel fuel are about $26,000 less that if it were gas over these past 10 years - or about $2,600 per season.

"...between 1,000 and 1,300 miles a season..." = an average of 1,150 miles / $2,600 averaged fuel savings at figuring the 1,150 averaged miles = an average of $2,080 +/- [this is a very loose number] annual fuel savings... so:

1150 annual miles at $2,080 fuel savings = approximately $1.81 dollars per mile saved during 10 years running time - which = $20,800 [another loose number].


That is applaud worthy savings. The $20.8K saved in a decade will surely assist in the $60K plus dollar replacement of twin diesels. And, seeing as my calcs show that if you average 13 knots that during the entire 10 years you would only be putting some 960 hours run-time on the engines that replacement cost will probably not be necessary for at least a few decades time.

Bravo to you on your engine choice!

The example above is clear representation why for boats that do have relatively substantial use at relatively high planning speed diesel is the way to go [especially for boats over 40' - IMO]. It is also clear representation that for boats [40' and below] cruising at below hull speed, with not too many hours use per year, gasoline engines become quite financially efficient.

Ain't boating fun!

 

[smitty477]

"...between 1,000 and 1,300 miles a season..." = an average of 1,250 miles / $2,600 averaged fuel savings at figuring the 1,250 averaged miles = an average of $2,080 +/- annual fuel savings... so:

1250 annual miles at $2,080 fuel savings = approximately $1.66 dollars per mile saved during 10 years running time - which = $20,800. That is applaud worthy savings. The $22.8K saved will surely assist in the $60K plus dollar replacement of twin diesels. And, seeing as my calcs show that if you average 13 knots that during the entire 10 years you would only be putting some 960 hours run-time on the engines that replacement cost will probably not be necessary for at least a few decades time.

Bravo to you on your engine choice!

The example above is clear representation why for boats that do have relatively substantial use at relatively high planning speed diesel is the way to go [especially for boats over 40' - IMO]. It is also clear representation that for boats [40' and below] cruising at below hull speed, with not too many hours use per year, gasoline engines become quite financially efficient.

Ain't boating fun!

Thank you - just thought a real data point might help some folks.

FWIW - we have saved about $26,000 over 10 years with an average mileage closer to 1,100 nmiles each season at about 105 hours a year. I do not have our logs with us but I have done this math exercise before for some folks considering doing the loop. The savings come from both less fuel used as well as a lower price per gallon when we have added fuel. We traveled extensively with many other boats both gas and diesel so we got accustomed to the average fuel use and prices on many boats. And FWIW I do not include the costs of running a genset in the comparison - we back that fuel use out by estimating 0.1 gph per KW used so those fuel uses would be an additional drop.

 

[Art]

Thank you - just thought a real data point might help some folks.

FWIW - we have saved about $26,000 over 10 years with an average mileage closer to 1,100 nmiles each season at about 105 hours a year. I do not have our logs with us but I have done this math exercise before for some folks considering doing the loop. The savings come from both less fuel used as well as a lower price per gallon when we have added fuel. We traveled extensively with many other boats both gas and diesel so we got accustomed to the average fuel use and prices on many boats. And FWIW I do not include the costs of running a genset in the comparison - we back that fuel use out by estimating 0.1 gph per KW used so those fuel uses would be an additional drop.

I'm really pleased that you posted your real world numbers for us all to see.

There appears no doubt that depending on boat use parameters there are times most economical for both diesel and gasoline engines. In the overall context/scope of boating I'd guestimate that regarding situational differences of boat and travel conditions diesel engines hold some 70% of being the correct motor type to use. Gasoline engines holds the remaining 30% position as most economical. The term economical used here represents not just fuel costs but also engine costs and maintenance costs.

Happy Boat Engine Daze! - Art

 

[ranger58sb]

I get tired of hearing fuel isn't the biggest cost of boating. For a very high number of people it's a very big expense.

I'd say fuel IS a big expense and those that say it's not could be bragging a bit about how much money the've got. Generally speaking of course.

Can't be helped, in many cases. We also fall into that category where our marina fees are higher than our fuel costs... by maybe almost 50%, depending from year to year. Annual insurance is sometimes higher than a year's fuel.

Haven't seen too many folks say it's NOT a big expense, just that it's not the biggest, for many. Sometimes, by a lot.

Can't see what use it would be to brag about stuff like that. It is what it is, for many.

Generally speaking, of course.

-Chris