View Full Version : BoatU.S. Recommends Leaving Your Boat's Gas Tank Full This Winter

09-10-2008, 02:34 PM
Got this press release this morning on the OutdoorWire:

BoatU.S. Recommends Leaving Your Boat's Gas Tank Full This Winter

The Problem with Ethanol Fuel: Phase Separation
ALEXANDRIA, VA, Sept. 9, 2008 -- Ethanol-laden gasoline, dubbed "E-10" for its 10% ethanol content, is now commonplace at marina fuel docks across the country. However, as winter approaches and boaters lay up their vessels for the season, Boat Owners Association of The United States (BoatU.S.) has some recommendations to ensure that spring commissioning will go smoothly. That's because E-10 can phase separate, or form two separate solutions in the gas tank - water and fuel - over a long winter storage period. Once this happens, the engine may not run and internal damage can occur.

BoatU.S. has these recommendations for storing boats fueled with E-10 this winter:

· Top Off: For boats with built-in gas tanks, stop at the fuel dock and top off the tank before you haul out, leaving it nearly full with just a little room for expansion. A tank that is almost full limits the flow of air into and out of the vent, which reduces the chance of fluctuating temperatures adding condensation (water) to the fuel, inviting phase separation. Anglers who fish over the winter should also top off their boat's gasoline tanks between outings to prevent condensation. Draining built-in fuel tanks of E-10 gas, while completely eliminating any chances of phase separation, is not practical and potentially dangerous.

· Freshening doesn't work: Midwest marina owners, who have dealt with E-10 for many years, report that phase separation typically occurs when boats are stored with tanks only one-quarter to one-half full, which cannot be remedied by adding fresh gasoline in the spring. Once E-10 phase separates, the water will remain at the bottom of the tank.

· Additive issues: With any fuel that sits in a tank for a long time, it's important to add a stabilizer. But stabilizers do not prevent phase separation. Once it occurs, additives and water separators can't help. The only remedy is to have the gas and ethanol/water professionally removed from the tank.

· Fiberglass tanks beware: Ethanol is known to chemically react with many fiberglass fuel tanks, which can cause them to deteriorate and potentially fail. Unfortunately, unless your boat's manufacturer can confirm that your fiberglass tank was built to withstand ethanol, your only remedy may be to replace the tank with a non-reactive material such as aluminum.

· Let it breathe: While ethanol does attract moisture, never try to plug up a fuel tank vent to prevent moist air from entering a tank. Without room to expand, the additional pressure could rupture fuel system components.

· Portable gas tanks: Any un-mixed gas (without 2-cycle oil) remaining in portable tanks may be carefully poured into your automobile gas tank. However, if you do have to store gas over the winter in a portable tank, keep the tank out of the sun and in a well-ventilated area away from ignition sources, keeping in mind that gasoline fumes are heavier than air. Recent BoatU.S. Foundation tests of portable jerry jugs confirmed that over time, gasoline can evaporate through the walls of some plastic containers.

· The good news: Next spring when you start the boating season you will already have a tank full of last year's gas, likely saving yourself some money on a fill up.

BoatU.S. - Boat Owners Association of The United States - is the nation's leading advocate for recreational boaters providing its 650,000 members with a wide array of consumer services. For membership information visit http://www.BoatUS.com or call 800-395-2628.

09-10-2008, 03:04 PM
I always store my boat with a full tank, I thought that was common practice. I don't care to deal with condensation.

09-10-2008, 04:16 PM
As do i, fill 'er up and add Stabil, run it and close 'er up for the winter. :)

09-10-2008, 04:35 PM
Never done it and never will. Three ounces of stabilizer and a gallon of gas. Interesting that the same website has two different versions. The main point is stated: "Draining built-in fuel tanks of E-10 gas, while completely eliminating any chances of phase separation, is not practical and potentially dangerous" where eliminating the phase seperation is a certainty but the author has found the risk of draining built-in tanks to be too risky. On my DD, I just pumped out 15 gallons of gas in about 10 minutes and it is as easy as disconnecting the gas line at the carburator and putting it into a gas can. Connect a power source to the fuel pump and away you go. In the spring, I pump out the gallon of stabilized gas and anything else that made its way into the tank and start with fresh gas (and hopefully cheaper). For those who are in the States affected by Gustav, you have a waiver on E-10 for a few more days.



Water Hazards
Ethanol absorbs water extremely well. Marine fuel systems are very susceptible to water intrusion. E10 has the ability to absorb a certain amount of water into solution and simply allow it to be burned by the engine. Here’s the comparison: MTBE gasoline can hold about 60 ppm (parts per million) of water in solution; E10 can hold 6,000 to 7,000 ppm of water in solution. Meaning, if you have a 100 gallon (378.5 liters) tank, it could hold up to .6 - .7 gallons (2.3 – 2.6 liters) of water in solution.

The biggest problem with ethanol for an alternative is with “phase separation.” That’s what happens when the fuel is saturated beyond it’s capacity to hold water in solution. Water and gasoline actually separate, and the gasoline floats on top of the water. With MTBE you could simply pump the water out from under the gasoline, or let your filters remove the water. With E10, ethanol blends more easily with any water. When phase separation occurs in E10, the ethanol is pulled out of the gas and absorbed by water. This results in two solutions, neither of which is good for the engine or fuel system…not to mention the environment. The gasoline left behind is absent of oxygenate. The water left behind now contains a high concentration of ethanol; this solution is highly corrosive and damages any material it may come in contact with in the fuel system. The only solution for phase-separated fuel is to dispose of the entire fuel load, clean the tank, and start over with a fresh tank of E10.

E10’s ability to absorb water has yet another drawback; it can absorb water directly from the atmosphere through the vent while simply sitting in the tank. In just 100 days at 70% humidity, E10 can absorb enough water to phase-separate. The shelf life of E10 is only 60-90 days if left without treatment.

Another important fact to remember is that gasoline “oxidizes” when exposed to air. That is, it loses its volatility over time. A good non-alcohol fuel stabilizer is highly recommended at all times in your boat’s fuel. *The key is to not leave a boat for long periods of time with a large load of fuel aboard.

Department of Energy's Situation Report

• On September 5, the Environmental Protection Agency (EPA), in collaboration with the Department of Energy, issued a multi-state emergency fuel waiver, due to the consequences of Hurricane Gustav and the pending shortages and damage expected from Tropical Storm Hanna. EPA moved to waive the 7.0/7.8 psi Reid Vapor Pressure (RVP) maximum and ethanol additive federal requirement for gasoline in the States of AL, FL, GA, LA and NC through September 15. Both FL and LA received extensions to their previous waivers. The waivers will allow the use of 9 psi RVP fuel. The justification for the EPA waiver is that shutdowns of several Gulf Coast area petroleum refiners and widespread power outages in LA caused the curtailment in production and delivery of low volatility gasoline. On August 31, EPA waived the requirement for reformulated gasoline in the state of Texas through September 8.

09-10-2008, 05:59 PM
Fortunately, we have not been getting E10 her in Mississippi so a non-issue.

I filler up and stabil it myself. Hate to even think about the fact that I have to do that anytime soon. Hope to get plenty of riding into Oct..

09-10-2008, 06:18 PM
Like Outback said the E-10 seems to be a rare thing down here in the south! I have only seen it once and it was 60 miles away from the house. Maybe they don't want to sell it in a high humidity enviroment???

09-10-2008, 08:05 PM
we just don't stop riding. as long as there is soft water, we will ride. keeps the fuel mixed up!

09-10-2008, 09:58 PM
Good point year round.
we don't get any REAL cold weather here until dec or jan if any.. Probably could set up a warming lamp to suffice in the mean time.. but rarely does it get below freezing over night and stay below freezing during the day.
Gotta figure up quick winterize plan..

09-10-2008, 11:17 PM
ethanol just sucks all the way around...
but that's another story..
we have a couple of stations here that still sell straight gas without blending, so I guess it's time to fill up for the last couple of runs with their gas. that should help purge all the e-10 out. then just leave a full tank with stabil and away we go next spring.

09-11-2008, 12:07 AM
Thanks for the letter. This is just a way for the goverment to make us pay for its bad decision. In Oregon some older boats have exploded because now they have to pump E-10 as gas stations (except a very short list of stations). The solution was for boat owners to check their gas tanks and fuel lines for leaks E-10 could cause and replace. Anyways long story. Guess i need to now buy a fake a lake so i dont have to haul my boat to the gas station then to the lake just to turn her on and back home.

09-11-2008, 02:11 PM
Try home depot for the fake a lake..
yeah. go get a decent toilet plunger, and then go to the lawn/garden section and get a plastic quick release garden hose fitting (use the male part).
Drill a hole in the plunger a touch smaller than the size of the male qr fitting, put some soap in the hole and force it in.. Voila, $5 Fake a Lake. works for me!

09-11-2008, 02:58 PM
Did the same here. Don't put it near the toilet or someone will get an eye full. I had to cut part of the handle off too.

09-11-2008, 10:13 PM
I am rolling laughing at that one.. I left mine in the garage, but could only imagine what would happen if someone tried that in the toilet!!!!

09-11-2008, 10:30 PM
That is a good idea. Good think i live along or that could be really funny. humm might just have to leave it at my friends house one day :).

james yarosz
09-11-2008, 11:00 PM
FWIW,I've had 3 inboards over the last 30 years.All carburated. When I winterize I fill the tank with gas and put the boat in storage.(no Stabil) Every spring my boats have always started and ran fine.I've only ever had one carb apart and that was when my kids put gas in the boat with an old dirty gas can.JMO

09-22-2008, 01:57 AM
Just saw something today that I thought I'd pass on to every. I was out gather supplies to winterize my boat when I saw something new. Sta-bil now has a fuel stabilizer formulated for ethanol blend fuels. It's blue instead of red.

09-22-2008, 12:10 PM
FWIW,I've had 3 inboards over the last 30 years.All carburated. When I winterize I fill the tank with gas and put the boat in storage.(no Stabil) Every spring my boats have always started and ran fine.

Fascinating. Got me Googling. According to the Sta-bil site, the problem seems to be oxidization. So, with the tanks full, maybe there is is no oxidization? So maybe we're collectively spending scads of $'s for nothing? Maybe just the air exposed fuel sitting in carbs that's vulnerable with carbed engines, but with EFI that shouldn't be a problem.

Other I-net hits suggest overall, the problems are: evaporation, oxidation, and contamination (usually by water via condensation as temperatures fluctuate).

Maybe with the tank filled at storage time, there's no problem? Anyhow, it's part of the Dealer's winterization, so I'll toe the line, but James over 30 years has saved a fair chunk by avoiding it.

My dirt bike wouldn't start one day. Friend said drain the float bowl; problem is stale gas. I did so and bingo! I said it had only been 3 weeks. Friend said gas goes stale in as little as 2 weeks. The stuff that ran down from the tank was fine, but maybe the air exposure in the float bowl rendered that bowl gas unusable. Dunno.

(Ethanol blends...I gather that's a different story altogether).