|Topic Review (Newest First)|
|04-09-2007 02:46 AM|
Originally Posted by sailaway21
ULSD is made by hydrotreating which makes it more susceptable to gelling. Untreated, it will gel at about 30F but this has nothing to do with water in the fuel. "Winterizing" ULSD involves either blending it with kerosene, which is very expensive for the refineries, or treating it with pour point depressants, cloud point depressants and cold flow improvers.
Hydrotreating also reduces the lubricity of the ULSD so that engine parts wear faster. Lubricity improvers are added to counteract this. Some of the natural antioxidants in the deisel are also removed by hydrotreating so there are antioxidant packages added to prevent gums and sludge.
These additives were used in regular deisel and LSD, it's just that more is used in ULSD. I work for a company that sells these additives and others to the refineries and distributors.
Hydrotreating causes the deisel to burn more quickly, reducing fuel efficiency slightly. Mileage reductions of about 5% are being seen. I'm not sure about ULSD having more affinity for water but I do know that the spec it has to meet for water content hasn't changed. I can find out for sure if someone has a specific interest.
The positive aspects, besides the main one of reducing the amount of sulfur going into the air, is that ULSD improves cold starting (since it burns faster), reduces white smoke during the warm up period and prolongs the period allowed between oil changes (since it burns cleaner).
Biodeisel is a more recent change in deisel. It's very much an emerging market with as much as 20% being blended into some deisel sources. This addresses some of the lubricity issues with ULSD but does not allow kerosene to be used to improve the cold flow properties. Specific biodeisel additive packages are used to ensure that the fuels continue to meet quality specifications.
Better living through chemistry.....for me especially.
|04-09-2007 12:55 AM|
I do not have any sort of official verification of this, but several different marine fuel stations as I came North up the Oregon and Washington Coasts, and the Straits, all said there is no difference between the Highway and Marine diesels except the dye that is added, and the fact that marine diesel does not have the highway fuels tax. I have heard they no longer even dye it.
When the original low-sulpher spec came in, marine and off road diesel were permitted (not required) to have a higher sulfer content. In fact after a few years, the oil co's decided it did not make economic sense to continue to make the older higher sulfer diesel, so they now make only the low sulfer, but sell it in different markets but with different taxes.
This info is mostly from discussions dockside with people who may or may not know.
|04-08-2007 01:50 PM|
This just in.
One of my over the road truck driver buddies just told me that, in addition to there being less energy in the low sulpher, it seems to have a greater affinity for water. It is definitely gelling much quicker in cold weather. Sounds like filtering and water removal are going to be even more important.
|04-05-2007 11:08 AM|
[quote=cardiacpaulBub, they're talking about diesel engines with pistons the size of your head or a pumpkin. not the yanmars, ok? [/quote]
I had a friend of a friend who was a ship's engineer on a 1000 ft grain freighter. He gave us a tour of the ship one weekend when he was on watch including the engine room. The engine was being overhauled at the time. The valves on this engine were the size of dinner plates and the cylinders were about 3 feet across. He said that they run at at ~ 40 rpm.
|04-05-2007 09:23 AM|
Ok, I feel the need to add my .02 as i have driven diesel cars since 85.
the last time the feds changed the sulfur content around 94-96 the diesel fuel was drier or less oily. this caused the diesel pump 'pick-up or boost pump' to dry out.
when the lubricant 'sulfur's job' changes to a dryer mixture more wear occurs.
i have noticed no difference with the new fuel, the fuel changed last year once again. but on an older model pre '96 I expect hard starts, eventually no starts.
cheap fix, diesel fuel boost pump inline from the tank to the engine $45. a gas fuel pump won't work not enough pressure. better permanent fix rebuild the fuel pump $$$
|04-04-2007 09:36 PM|
"Not sure why you woldn't just motor the 4 miles. Thats not very far." For many sailors, it would take an hour to disembark, motor 4 miles (40 minutes under near full power) and tie up at the other end, ignoring any wait at the fuel dock. And then another hour to come back. Two hours of pointless motoring, as opposed to fifteen minutes to stop at a gas station and fuel the jerry jugs on the way to the boat.
"Nice sail over fill up and sail back, no big deal as far as I'm concerned."
IF your fuel dock is someplace convenient to sail to. For many of us, it means "some other inlet or bay" where you weren't planning to spend the day.
"a full tank of desiel should last a long time. Depending on"
Yup. Often a whole season, ignoring any major events that might need a second or third fill-up.
"Also, your marina may frown apon you filling your boat with jerry cans at the dock. " You responsibilities are the same no matter where you fuel. Any reasonably careful sailor will fuel in such a manner that any spill is on deck, rather than in the water. If you are thinking that there's an easy way to avoid that responsibility by letting a pump jocky do it....Sure. But I'd rather use a baja filter and do it the slow way--which most pump jockies aren't going to do. If you can eyeball the fuel going in, and make sure it is going in clean, you can have more faith in the system. (Those of us who don't use a hundred gallons in a clip, anyway.
I think I'd rather ROW the boat than take on a load of diesel without watching it. I *hate* diesel fuel system problems.
|04-04-2007 09:18 PM|
Your point is exactly correct. I would only add that the size of the current engines is such that you have quite enough room to stretch out and take a nap on the crown of a piston. Most of these engines burn heavy fuel oil, HFO, which must be heated just to pump it and is often blended with lighter fractions when the vessel is manoeuvering.
One should consider the age of one's engine when selecting diesel fuel. Some older engines may desire the higher sulpher content of the now outlawed for over the road use high sulpher fuel. The most common place to still find this fuel is your local farmer, or someone else certified for it's 'off-road use'. Another advantage to it is that there are no highway taxes paid on it.
One tablespoon of refined product will create a visible sheen over one square mile. What? That is according to the USCG and they should know. In fact, they have equipment that will do a spectro-analysis, from an aircraft, of the fuel on the water. When complete, they can tell you where it came from, basically right down to the refiner. The notice of discharge fine doubles if you have a spill and do not report it. Given these facts, and our desire to keep the water clean, it is probably prudent to fuel at your local marina. The local marina has gone to significant expense to provide a safe, non-polluting facility for re-fueling and lives under the regulatory ax for any mishaps that may occur. Given the cost of compliance, and the potential liability they must assume, I think it is reasonable to give them your business. As previously stated, it's not like you're fueling the QM2 or even a tug-boat for that matter.
|04-04-2007 06:03 PM|
Originally Posted by sailortjk1
BTW here on Clear Lake, the local fuel dock's diesel is usually about 20-cents per gallon HIGHER than highway diesel.
|04-04-2007 05:57 PM|
|PBzeer||I've yet to see an "on the water" fuel price in the US that wasn't around a dollar more a gallon than at a gas station, diesel and gas.|
|04-04-2007 05:47 PM|
|sailingdog||Umm.. it depends on where you are. In many places the automotive diesel is actually cheaper than fuel at the marinas... even paying the road taxes on it. Go figure.|
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