Need info about: Inboard converted to Propane or Natural Gas

[rfdfirecaptain]

I?ve been researching old threads about converting a gasoline inboard over to propane. Some threads offer clever thinking on the topic, but in general, most posters are against the idea, citing the hazards from the physical properties of the fuel. I get that? I am a hazardous materials specialist so I?m not looking for more information about the hazards in this thread.

Several threads I read explored the idea of this conversion back when gas was just $2 per gallon. Now that Gasoline prices have held steady around the $3.50 mark for a few years I think it?s safe to say it?s not ever coming down and the good old days are over.

What I am hoping to achieve by starting a new thread is this. Have you, or has anyone you know successfully converted a marine inboard engine over to Propane or Natural Gas? If so, please post as much information as you can on the topic. Please include the name of the conversion equipment and any photos of you have of it. My review of the threads thus far has not turned up any credible and successful conversion.

Let me qualify the words ?credible? and ?successful?:

CREDIBLE: Conversion equipment that is produced and sold by a reputable company who has a proven record of quality. A reputable company would not be someone who is working out of their garage.

SUCCESSFUL: The conversion equipment has powered your boat?s engine for at least 25 hours while on the water, without any mechanical issues related to the conversion. Powering your boat for 25 hours while tied to the dock does not qualify.

Right now I can go on an ocean cruise about cheap as I can operate my boat for the same number of days. Propane and Natural Gas may not be the answer, but sooner than later the boating industry has got to overcome this problem. If not, you can certainly look for even more boat builders to go belly up!

 

[Speakrdude]

Re: Need info about: Inboard converted to Propane or Natural Gas

Very intertested in the outcome of this thread. I am still wanting to convert my service vans and my personal rides over to Nat Gas. Seems like a no brainer. Have at homw and work already. Runs cleaner, burns better, cost less. Now if only the conversion process is affordable.

 

[mjfink]

Re: Need info about: Inboard converted to Propane or Natural Gas

Are propane and nat gas cheaper than gasoline/diesel (on a BTU/$ basis)? I thought that propane (in particular) was really expensive for the amount of energy contained in it?

I'm not trying to throw a wrench in the works, but I wasn't aware that those fuel types were less expensive than gasoline.

Just did a little research, it does appear that nat gas is significantly less expensive than gas or Diesel fuel. Interesting thread, I'll be curious to see the outcome of this conversation (although, the question immediately pops to mind, how the heck do you get nat gas to your boat and store it safely?).

 

[Struc]

Re: Need info about: Inboard converted to Propane or Natural Gas

how the heck do you get nat gas to your boat and store it safely?).

I don't know about you, but I have a nice big aluminum gas tank under my floor - seems like the perfect place for a CNG cylinder.

 

[rfdfirecaptain]

Re: Need info about: Inboard converted to Propane or Natural Gas

mjfink: If you compare the available btu's there is a significant difference. Here's a chart that gives the comparisons using the Gasoline Gallon Equivalent formula.. http://en.wikipedia.org/wiki/Gasoline_gallon_equivalent

Here?s the theory. Assuming all conditions and factors are identical? If 1 gallon of gasoline will push your boat exactly 1 mile, that same mile will require 1.5 gallons of LNG. Yes, the consumption of LNG to Gasoline is greater. As compared to your current onboard gasoline tank this would result in a 50% increase in consumption of your fuel capacity and a 33% loss in range.

Now you have to make a comparison of the cost of Gasoline to LNG. Currently Gasoline in my area is $3.35/gal and LNG is $1.10/gal. That is almost exactly a 3 to 1 ratio, respectively.

Let?s say I travel 100 miles on gasoline at a cost of $335.00. Assuming all conditions and factors are the same that same 100 miles powered by LNG would cost me $165.00

For the sake of discussion, excluding the issue of ?safety? and regarding LNG and Propane only: I?ve read the concerns about the loss of btu. My question is this. If gasoline has so many more btu?s (and it does) why aren?t we heating our homes with the same stuff that powers our boats?

So far, no one has yet to produce any credible evidence of a successful conversion... so I wait and continue to ponder.

 

[mjfink]

Re: Need info about: Inboard converted to Propane or Natural Gas

] My question is this. If gasoline has so many more btu?s (and it does) why aren?t we heating our homes with the same stuff that powers our boats?

So far, no one has yet to produce any credible evidence of a successful conversion... so I wait and continue to ponder.

Because (from your chart) heating oil has even more BTUs than gasoline. And people heat their homes with that all the time.

I'm also curious about this, sounds like the real benefit is financial (LNG is quite a bit less expensive) than an actual gain in power density. But, the question remains, if LNG is cheaper, why aren't we running our boats/cars on it instead of gasoline/diesel?

 

[rfdfirecaptain]

Re: Need info about: Inboard converted to Propane or Natural Gas

mjfink: I agree you are correct.

I am rebutting the argument (in other posts) that the loss of btu's makes LNG or Propane a less desireable fuel for boats, while at the same time the folks who make that argument would not choose gasoline to heat their homes.

I suppose in a perfect world (excluding green energy) our boats would have diesel powered generators, that power electric motors, to turn our props. Take the rail industry for example: One train hauls hundreds of thousands of tons of weight on a tiny portion of diesel fuel.

 

[HT32BSX115]

Re: Need info about: Inboard converted to Propane or Natural Gas

Howdy,


It probably would be possible to get an engine in a boat to run on CNG. You could increase the compression ratio and get a fair amount of power out of the engine but not as much as you can get out of gasoline or diesel.

Most large boats like you have in your signature hold as much as 80-100 gallons of fuel.

100 gallons of gasoline weighs around 640 lbs. An 100 gallon aluminum tank weighs around 50 lbs. figure approx 700 lbs for fuel and tank.

So, to get at least as much range with CNG, you would need the equivalent amount of CNG. (GGE.....Gasoline Gallon Equivalent)

That would require CNG tanks that hold approx that amount.


Do a search for manufacturers of CNG tanks. I looked and found several, but they all are pretty big and weigh a LOT!


1 15gallon GGE tank weighed 377lbs!


So, to get an equivalent of approx 100 gallons of CNG storage, you would need 7 15 GGE tanks. (they don't make really big vehicle tanks) 7 x 377 = more than 2600 lbs!

The composite cylinders are lighter to be sure but they're not small and they're VERY EXPENSIVE.

The following company claims to have the largest lightest tank available.
http://composite.about.com/library/PR/2001/blatp22.htm

The 21.2 x 120 inch tank weighs 380 pounds. At 3600 psi it has a capacity of 5606 standard cubic feet (SCF) of compressed natural gas (CNG) which is equivalent to 40.3 gallons diesel. It would be LESS compared to gasoline and you'd need 2 of them to have an equivalent of 80 gallons of diesel it would probably take 3 to equal 100 gallons of gasoline.

3 nearly 2ft dia x 10ft long tanks

And hat would be over 1000 lbs just for the tanks! I couldn't find a price but I'll bet they cost a fortune!



CNG ain't gonna happen in a boat....It just ain't!


Propane is a little better, Propane can be stored in liquid form MUCH easier than (L)NG and at MUCH lower pressures, but it still requires a fairly heavy tanks. AND your range is also considerably lower so you need MORE (gallons) than gasoline.


Neither is very practical for a boat.


It's just how it is. gaseous fuels are fine where weight and space isn't a factor. on a boat, it's a big factor.



Regards,


Rick

 

[Speakrdude]

Re: Need info about: Inboard converted to Propane or Natural Gas

SO I need to running my boat on heating oil?

 

[rfdfirecaptain]

Re: Need info about: Inboard converted to Propane or Natural Gas

HT32BSX115: You are correct about the weight of tanks due to the extreme pressures of Natural Gas. Believe me I have looked at this from a lot of angles and once I think I'm on to something I hit a snag. The fact that no conversion enthusiast has come forward so far tells me this is still an unperfected science.

I love iboats forums and I have gained a lot of information from this network of boaters. We all post our problems on the site and within minutes some stranger is saving us hundreds of $$$ in repair bills with expert (or trial and error) advice. How cool is that? Even so there is a big pink elephant in the corner.

Oh, occasionally there is a post about it, but I see no evidence that there are any concrete solutions to overcoming the problem. At the very least boat propulsion system engineers had better listen up. The cost of fuel is slowly eroding the use of pleasure boats, which by default is squeezing out many who have long enjoyed boating as a pastime. Pre 9/11 when gas prices were stable and reasonable (around $1.25/gal) some boat manufacturers were still failing to keep their doors open. Since that time boat manufacturer closures have gotten exponentially worse. It?s not the cost of the boat that is driving the customer away, it?s the cost of the fuel to enjoy the thing! The proof of what I am saying is plastered all over the ?boat for sale? websites. Folks are practically giving their boats away just to break even. Doesn?t this mass exodus from the pleasure boating world signify there is a BIG problem out there?

Somehow, someway the boating industry has got to come up with a way to decrease the cost of fuel, by either increasing range or converting to a cheaper fuel. Otherwise, I predict the pleasure boating industry will collapse onto itself leaving behind only the very few who can afford fuel, regardless of the price.

 

[Bondo]

Re: Need info about: Inboard converted to Propane or Natural Gas

SO I need to running my boat on heating oil?

Ayuh,.... You've got it,...

In a motor fuel, that same fluid is called Diesel Fuel, 'n is taxed to beat 'ell....

For the storage reasons noted by Rick,
'n then ya gotta buy a compressing station to tap into a local utility pipeline...
1s I've seen start in price at that of a well outfitted 30-odd foot cruiser....

Diesel is still the Best answer to boat propulsion,....
It's just that the good ole USA won't build piles of decent hp little diesel motors...
What there are, aren't plentiful enough to be Cheap...

 

[mjfink]

Re: Need info about: Inboard converted to Propane or Natural Gas

SO I need to running my boat on heating oil?

We call it Diesel fuel, but yes, if efficiency and longevity are your goals, heating oil is the way to go.

I used to live in a farming community in NJ where a bunch of the farmers would get heating oil delivered into big (500 gal) tanks. They had a little pump on that tank and would use it to fill up their trucks/tractors/etc. Heating oil is a different color, but only so that a police officer can tell if you're running the "taxed stuff" (green) or the "off road stuff without tax" (red).

 

[rfdfirecaptain]

Re: Need info about: Inboard converted to Propane or Natural Gas

I found this video today on Youtube. It's a Volvo Penta that has been converted to Propane.
http://www.youtube.com/watch?v=vvc5HhD9uGg

This looks convincing, but the information is not written in English. Anyone able to translate it?

 

[GA_Boater]

Re: Need info about: Inboard converted to Propane or Natural Gas

It's Dutch. I used Google translate

This is a Volvo Penta 5.7 ​​GXi 300hp V8. This engine is sold to us by a client to replace an old 5.7 liters V8 Mercruiser carburetor. We have this engine on behalf of the customer converted to LPG.

We have done the original injection intake manifold to replace an Edelbrock Performer manifold. On this manifold are then throttle a Holley four-barrel carburetor mounted, and there is then an Impco 425 mixer fitted. The ignition, sensors and wiring harness are transferred from the old MerCruiser engine. This will require a variety of software to support this type of newer Vortec V8 fit. There is also a support made ​​by us to the Impco evaporator and vacuum valve to be mounted, so they sit nicely on the bike.

Exhaust manifolds, remote oil filter, flywheel, damper and starter motor are original this engine.

 

[HT32BSX115]

Re: Need info about: Inboard converted to Propane or Natural Gas

Yeah. That system is fairly "old".

I have a V-8 Impco system out in the shop I thought about putting on my old truck.

I also have a 30 gallon DOT compliant tank. The tank weighs about 80-90 lbs.

They work VERY well and are pretty easy to hook up.

Since propane only contains about 91,000 BTU per gallon (gasoline is around (115,000-125,000), you will use MORE propane in a bigger engine to produce the same HP in a reciprocating engine.

Also, if you want to get that maximum hp, you have to increase the compression ratio and install hard valves and seats (if not already installed.....most engines nowadays have hard seats)

But you still won't get the same HP you would get from gasoline. so your 100 gallons of gas equivalent in propane would probably result in a fuel tank that weighs nearly 3 times as much as a 'regular' tank.

If your boat ran well with a small block engine on gasoline, you would probably need to go to a BB engine to get the same performance.

It simply would not be worth it.

The same problem is coming to aviation gasoline. 100 LL (low-lead) is going to be phased out. (leaded fuel is banned.....AVGAS has a waiver, but not for long)

I think the following fuel would be a great fuel for marine gasoline engines.

http://www.swiftenterprises.com/Swift Fuel.html


regards,


Rick

 

[halfmoa]

Re: Need info about: Inboard converted to Propane or Natural Gas

I converted an old riding mower to propane just to see if I could do it using plumbing parts and redneck engineering. (I should mention it was a 5hp push mower engine with a milled head and swapped pulleys that'd run almost 30mph...) I was getting my tank filled at the local propane place and struck up a conversation with the owner. This guy was a real "Hank Hill". Knew the propane business inside and out and had a passion for what he was doing. If you have a local yokel type shop like that I'd start there. This guy was an absolute library of information on propane conversion!

 

[HT32BSX115]

Re: Need info about: Inboard converted to Propane or Natural Gas

I converted an old riding mower to propane just to see if I could do it using plumbing parts and redneck engineering.

One could probably "redneck" engineer a marine system to run propane in a boat (and run afoul of a fair amount of USCG regs)..............

It would probably be big news when it blew up and killed everyone on board..... Propane is a LOT like gasoline. It's heavier than air, and very easy to ignite AND under pressure! (over 200 PSI at the tank depending on the temp)

I wouldn't want a propane bottle anywhere near a boat! Especially one large enough to run the engine!

 

[wagnerz]

Re: Need info about: Inboard converted to Propane or Natural Gas

I don't know if someone has already started a thread about this. I see people driving around in these Chevy Volts, and it makes me think if the boating industry could make an electric boat? Seems like the amount of batteries it would take would weigh more then the boat itself. Although I think the Chevy Volt only has like a 25-30 mile range. Sorry, I am just typing as I am thinking and realizing we are at least a decade away from an electric boat.

 

[HT32BSX115]

Re: Need info about: Inboard converted to Propane or Natural Gas

Sorry, I am just typing as I am thinking and realizing we are at least a decade away from an electric boat.

More than that! The electric cars are not ready for prime time right now!

 

[Scott Danforth]

Re: Need info about: Inboard converted to Propane or Natural Gas

in addition to the impracticality of gaseous vs liquid fuels, propane conversion engines run hot. on small engines and industrial applications propane conversions usually lead to warping heads and melted pistons. if the timing is off, they tend to backfire thru the intake.

I have spent the last 10 years with propane conversions from small engines all the way up to 1000kW gensets

one small hickup with the vaporizor or any small leak and you have a bigger boom than if you had liquid fuel in the bilge.

you want to exclude the safety aspect at the same time you want to see evidence of a successful conversion. I would state that there is no successful conversion because of the lack of safety of a conversion in a marine environment.

If you want more economy than your current BBC volvo, put in the new LSA marine engine. 425-557 hp and about 3 times the fuel economy.