Propane conversion

[DAVECAD2.0]

With all the trouble mariners are having using Ethonol fuel mixes, and I've had my share, and still do. I'm thinking about converting to Propane. My 1980 Santa Cruz has twin 25 gal. saddle tanks. With them removed I'd have plenty of space for two large Propane tanks.
Zero fuel issues. No gunk, no sludge, no filters, engine oil stays clean, and Propane virtualy lasts forever. Readily available at most marinas.
It seems like the perfect solution for anyone who doesn't use a boat that much with large tanks.
Has any one done this? Will the Coasties have a problem?

Your thoughts.

 

[ezmobee]

Re: Propane conversion

This is too interesting to leave buried in the carver yact section. Hopefully you don't mind that I moved it to general boating.

 

[haulnazz15]

Re: Propane conversion

The weight of the tanks empty would be a big downer in iteself, those things weigh a ton. The other side of it is the volume, since LPG tanks are usually 3-4 times the size of gasoline tanks to hold the same volume of fuel. Lastly, a pressurized tank of explosive gas in an environment where one spark can set it off, or a leak in your custom fuel system. Kablooey!

Sorry, while I can see the merits of LPG/CNG on large vehicles (like trucks/buses), there just isn't enough room on most boats to fit those systems in. Also, maybe it's different here in Okla., but I haven't had any problems with fuel mixes and carburetors/dirty oil in my boats or cars with as much as 10% ethanol. I think the ethanol blend gets a lot more heat from people than it desrves, but I'd still rather have 100% gas.

 

[DAVECAD2.0]

Re: Propane conversion

Down sides, much lower BTU rating (less power per gallon) meaning you need much larger tanks. In addition, you will see a reduction in Horse Power your engine can produce. Installing the tanks may be an issue because the enclosure MUST be power vented (blower) and you will have to install propane gas detectors. Keep in mind propane tanks have a pressure releif to vent all the propane from the tank in a case of over pressure.

You should also talk to your insurance company. I doubt they will go along with a "home grown" solution like this.

Well actually the BTU or more precisely the caloric value delta is 20%. 20% larger tanks the issue is space since propane tanks are cylindrical. But, factoring in the price differential. No highway taxes. And the marinas don?t rip you off on propane like they do on gasoline. (Not yet) Every marina I?ve ever been to charges at least 25% more for gasoline above what you?d pay at a car pump. And remember there?s? no highway tax at the marina! Propane only runs about 10% more. It?s cheaper per mile/threm/calorie etc. At least here in Florida at current prices. Then factoring in the savings on maintenance; I?ve done the math part. As far as enclosures go, much safer. Not only is propane not as volatile, the tank isn?t vented to atmosphere like gasoline. Also it doesn?t lie in the bilge to get pump overboard. And everyone else (except the oil burners) are currently using the most volatile, explosive vapor fuel available. Gasoline!
Took your advice, and just heard back from my insurance guy. Not an issue. ?Just have a certified tech do the connections?.
Thanks for the input. I need this kind of feedback so I can consider everything. Sometimes my brilliant ideas have a way of going south. Hey. Wait. I live in Florida. Damn!

 

[skargo]

Re: Propane conversion

I converted a Toyota Landcruiser to propane a few years ago, everyone told me I'd lose a ton of power and it would get terrible MPG's, they were wrong.

I had idle issues once in awhile, but I had used used components, when I rebuilt them, it ran like a top.

I am interested in seeing how this goes for you.

 

[bomar76]

Re: Propane conversion

This was covered in depth a few years ago on this forum. I though it was a REALLY REALLY bad idea then and since that time my opinion of it has plummeted.

Use the search (whenever it works).

 

[smokeonthewater]

Re: Propane conversion

I agree.... propane in a truck is pretty nice but any fumes fall to the ground and drift away.... in a boat they collect in the bilge and mix with air..... gasoline leaks are dangerous too but not as likely and gasoline does not vaporize nearly as readily (instantly) as propane does... propane on a boat is possible but scares me....

Oh and on the ins.... make an inquiry to the legal dept of the company.... the "clerk" who sells you the policy doesn't really know and "he said" won't hold up in court nearly as well as "this letter from...."

 

[QC]

Re: Propane conversion

Just a couple of general points, because there are a few misconceptions here along with some solid facts.

Don't mix-up LPG and CNG in the same discussion, different animals. CNG requires 3 -4 times the space for the sem amount of energy. Propane about 1.8ish give or take depending on Tank size etc.

Propane and Methane both are higher octane so they actually "allow" for higher performance. In use though, depending on the engine rating, they actually can displace some available air, so there can be some power loss, but that's only in the highest output ratings.

Propane is heaver than air, but has a narrower band of air fuel ratio for combustion than gasoline, so it is effectively safer. FWIW, CNG (Methane) is lighter than air.

Unless you are paying around 35% less per gallon you are effectively paying more per unit of energy. No savings.

You'll never get your money back in maintenance savings. High fuel users with a good differential (more than 35% less) maybe . . .

 

[haulnazz15]

Re: Propane conversion

To be honest, I don't think I've seen a propane tank at any lake marina, so I think it would be difficult to find fuel except on the coasts.

 

[Paradise David]

Re: Propane conversion

Propane expands as the temperature rises. So the BIG tanks you install, you can only fill them to 80%.

 

[ovrrdrive]

Re: Propane conversion

Propane and Methane both are higher octane so they actually "allow" for higher performance. In use though, depending on the engine rating, they actually can displace some available air, so there can be some power loss, but that's only in the highest output ratings.
. .

That isn't exactly true. Octane doesn't have anything to do with the btu or stored energy in a fuel. It is simply a measure of it's resistance to predetonation. It's true that you can get more out of a higher octane fuel but only in a high performance motor that needs to run the timing advanced to make power and that requires a high octane fuel to do so...


I'm not trying to get in a gunfight carrying a knife, but that's my understanding of it.

And I've always heard that fuel mileage goes down when running on propane. My uncle used to work for a gas company and his company truck ran on both. He always ran the propane until it was empty because he got it for free from work but he complained about the mileage he got with it on trips compared to gasoline.

 

[Lion hunter]

Re: Propane conversion

A lot of good comments here.

1. It is true that your mileage will go down. There is not the same amount of "power or work" in a gallon of propane as a gallon of gas. But it is generally cheaper so the cost savings would have to be calculated.

2. Propane is heavier than air so there would have to be a fail proof way to remove it from the bilges. This would be my biggest concern. We have seen the results of not using a blower on a gas motor. I can't imagine if your blower fails with propane.

3. I think that QC is correct that effectivly propane has a higher octane (A resistance to detonation) and is a safer fuel when used in the right circumstance. But a closed environment like a boat hull ain't it

Ultimately I think this is a bad idea for an i/o motor. It would make an interesting experiment for a 4-stroke OB where you could in theory mount the tank in a manner where any gas would not settle in the boat and the source of detonation would be outside of the boat.

Maybe someone that deals with fire fighting could chime in here but I always thought that the best course of action for a propane fire was to let it burn. And that trying to shut valvles could result in fire being drawn back into the tank. Is this true? How effective would someone be at controling a fire from a propane source on a boat with only a fire extinguisher?

 

[smokeonthewater]

Re: Propane conversion

Propane and Methane both are higher octane so they actually "allow" for higher performance. In use though, depending on the engine rating, they actually can displace some available air, so there can be some power loss, but that's only in the highest output ratings.

That isn't exactly true. Octane doesn't have anything to do with the btu or stored energy in a fuel. It is simply a measure of it's resistance to predetonation. It's true that you can get more out of a higher octane fuel but only in a high performance motor that needs to run the timing advanced to make power and that requires a high octane fuel to do so...

That's exactly what qc was saying.... it doesn't make more power but it allows for a higher performance engine with more compression and timing advance which could make more power but with the lower energy density you have less potential energy for the volume of the cylinders but that only comes into play in the highest performance engines

 

[madurodave]

Re: Propane conversion

Do it. I have been a GM for a large propane retailer for years. make sure you do it right. dont let anyone tell you different, propane is a clean, less expensive, high btu alternative. Clean fuel USA is installing filling stations all over the US. Go check it out. also check out the new propane powered Roush Ford F250....talk about one bad mofo.

 

[bekosh]

Re: Propane conversion

Here is an article on BoatUS.com on what is required for a propane system on a boat. http://www.boatus.com/boattech/casey/18.htm

Here is a quote from the article about how the tanks must be installed. Basically they have to be above the waterline, vented overboard & sealed off from the interior of the hull.

Propane Tanks
The best place for propane tanks is on deck. If you want them out of sight, the locker you put them in must be vapor tight and separated from the boat's interior. It must open only above deck and have a drain at the bottom to let leaking gas escape over the side. Be sure the drain outlet is not located near any other hull opening and that it is always above the water, even when the boat is heeled. Aluminum tanks are more suitable for the marine environment

Here is a link to the ABYC standards for LPG systems.
www.abycinc.org/committees/A-01.pdf

 

[skargo]

Re: Propane conversion

Do it. I have been a GM for a large propane retailer for years. make sure you do it right. dont let anyone tell you different, propane is a clean, less expensive, high btu alternative. Clean fuel USA is installing filling stations all over the US. Go check it out. also check out the new propane powered Roush Ford F250....talk about one bad mofo.

That F-250 is not propane powered, it is a diesel with propane injection, huge difference, as a diesel head and someone who has converted a vehicle to propane, believe me

*edit*
well color me wrong, I knew rousch offered propane injection, but it looks like you were right, my apologies.

http://www.worldcarfans.com/109012316496/2010-roush-liquid-propane-injected-ford-f-250-unveiled

 

[ezmobee]

Re: Propane conversion

well color me wrong. looks like you were right, my apologies.

I'm going to always remember I was here when......

 

[skargo]

Re: Propane conversion

I'm going to always remember I was here when......

Come AWN, I always admit when I'm wrong. It's when I'm right when people have to watch out.

 

[Cap'n_Half-hitch]

Re: Propane conversion

A propane conversion sounds like a great idea to me for just the reason you mentioned. Propane doesn't go bad, no matter how long it sits in between uses. Sure, you'll probably have to sacrifice some range, but that might be a good trade-off for not having to worry about water in your gas tank. And sure, it costs some money, but if money were the only concern nobody would have a boat, would they?

Propane on a boat is no more dangerous than any other combustible. Most cruising sailboats have a couple of propane tanks installed in the cockpit above the water line and vented overboard. You already have a blower in your motor enclosure, marinized engines by definition have spark arrestors wherever necessary, and for extra peace of mind you can get a propane detector with an alarm if you want.

 

[skargo]

Re: Propane conversion

Another added benefit is how clean it burns. You can put 5000 miles on a car engine that's propane fueled and the oil will look as clean as the day it went in.