Aluminum or Polyethylene Gas Tank?

I am going to rebuild the Gray Marine engine on Papoose and need to replace the gas tank at the same time. I put the galvanized steel tank in there about 20 years ago and would replace it in kind if they still made them, which they don't. So the choice is between Aluminum or Polyethylene as I have read that stainless steel is not approved for gasoline for some reason I would probably prefer not to discover. Aluminum seemed like the way to go until I read how you install them -- two tubes of 5200 to glue them down to your fiberglass base. Obviously I don't have a fiberglass base as Papoose is wood but I guess I could make one up but I am not inclined to glue my tank in place should it ever need to be removed. I also read that even in new boats, aluminum tanks can fail after just 3 years due to corrosion. So that freaks me out if this is true. Ideally, I could mount it suspended by the side mounting ears which would keep moisture off the bottom of the tank but that doesn't seem to be how they are mounted. My tank is 18 gallons, 36x18x7.5 high. This is a common size available in either material. I thought someone on this group might be knowledgeable on the subject. Allen

We like plastic tanks. They are CG approved, [ be sure to get one designed for below deck mounting ] can never corrode, are light and inexpensive. Most have their own hold down clamps, to make mounting easy and very secure. The one BIG disadvantage - they will melt if the boat catches fire. *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184* On 12/28/2011 1:39 PM, Allen Edwards wrote: > > > I am going to rebuild the Gray Marine engine on Papoose and need to > replace the gas tank at the same time. I put the galvanized steel > tank in there about 20 years ago and would replace it in kind if they > still made them, which they don't. So the choice is between Aluminum > or Polyethylene as I have read that stainless steel is not approved > for gasoline for some reason I would probably prefer not to discover. > > Aluminum seemed like the way to go until I read how you install them > -- two tubes of 5200 to glue them down to your fiberglass base. > Obviously I don't have a fiberglass base as Papoose is wood but I > guess I could make one up but I am not inclined to glue my tank in > place should it ever need to be removed. I also read that even in new > boats, aluminum tanks can fail after just 3 years due to corrosion. > So that freaks me out if this is true. Ideally, I could mount it > suspended by the side mounting ears which would keep moisture off the > bottom of the tank but that doesn't seem to be how they are mounted. > > My tank is 18 gallons, 36x18x7.5 high. This is a common size > available in either material. > > I thought someone on this group might be knowledgeable on the subject. > > Allen > > > > > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.925 / Virus Database: 271.1.1/4108 - Release Date: 12/28/11 02:34:00 > -- *Joe DeMers - owner* Sound Marine Diesel LLC SoundMarineDiesel.com <http://www.soundmarinediesel.com/> *phone & fax (860) 666-2184*

Allen, everything I've been learning about the resistance to putting ethanol in higher concentrations into gasoline indicates the ethanol has a solvent property towards the polyethylene compound. I predict in my own opinion, that unless someone comes up with another compound that will not dissolve, the m-brand of tanks will become obsolete. They have great shape options, but so do the aluminum guys. There are mounting brackets available for all tanks. screw-down types. If you wish to glass the brackets in, that is an option. You can also make a glass case to secure your tank in. It's a lot like a battery box. lucky for you, the Lapworth uses a rectangular shape, the fg 36 uses a 5-side compound shape, two of which are under 2 1/2 inches, (water condensation trapped on the under side of the tank plus salt air for 40 years helped rust away that steel bottom side that jams in under the port settee, all fittings on ends, not top, including fill. anytop fittings would reduce 25 gallon tank to probably half. ( Sorry I messed up the type). It will cost us over $250 for any new tank, plus fittings, as I've been researching for a while now. I really didn't want to have one shipped, wanted to take the old one to a manufacturer to get exact, as I've sent specs but the result comes back skewed to a different shape. There are four big mftrs, but only two will answer. (ps: if any tank becomes hot enough, it's a potential for explosion.) Helen ....... If 5200 is the only way to attach, (not allowed on our boats), you could build a mounting frame that is removeable, and use that for the glue down.?? A lot boils down to what it would take to dislodge a 25 gallon (200 lbs approx) tank, what impact, your knottage plus the other guy's speed? Or t-bone(how far away from the bilge chines is the tank).? From: Allen Edwards <al… [at] gmail.com> To: Ca… [at] yahoogroups.com Sent: Wednesday, December 28, 2011 10:39 AM Subject: [Cal_Boats] Aluminum or Polyethylene Gas Tank? I am going to rebuild the Gray Marine engine on Papoose and need to replace the gas tank at the same time. I put the galvanized steel tank in there about 20 years ago and would replace it in kind if they still made them, which they don't. So the choice is between Aluminum or Polyethylene as I have read that stainless steel is not approved for gasoline for some reason I would probably prefer not to discover. Aluminum seemed like the way to go until I read how you install them -- two tubes of 5200 to glue them down to your fiberglass base. Obviously I don't have a fiberglass base as Papoose is wood but I guess I could make one up but I am not inclined to glue my tank in place should it ever need to be removed. I also read that even in new boats, aluminum tanks can fail after just 3 years due to corrosion. So that freaks me out if this is true. Ideally, I could mount it suspended by the side mounting ears which would keep moisture off the bottom of the tank but that doesn't seem to be how they are mounted. My tank is 18 gallons, 36x18x7.5 high. This is a common size available in either material. I thought someone on this group might be knowledgeable on the subject. Allen

My tank is under the cockpit just forward of the rudder post by a fraction of an inch. It is inboard about a foot so it that tank gets ruptured in a collision, the boat it under water at that point so not so concerned with fire. My tank is just kind of stuck in there, not really mounted very well. Someone brought up the idea of a stainless steel tank. That might solve the problem of corrosion and the plastic issues. Yet another option. I had ruled it out as I thought it was not approved for boats. Allen On Thu, Dec 29, 2011 at 11:37 AM, Helen Horn <he… [at] sbcglobal.net>wrote: > ** > > > Allen, everything I've been learning about the resistance to putting > ethanol in higher concentrations into gasoline indicates the ethanol has a > solvent property towards the polyethylene compound. I predict in my own > opinion, that unless someone comes up with another compound that will not > dissolve, the m-brand of tanks will become obsolete. > They have great shape options, but so do the aluminum guys. There are > mounting brackets available for all tanks. screw-down types. If you wish > to glass the brackets in, that is an option. You can also make a glass case > to secure your tank in. It's a lot like a battery box. lucky for you, the > Lapworth uses a rectangular shape, the fg 36 uses a 5-side compound shape, > two of which are under 2 1/2 inches, (water condensation trapped on the > under side of the tank plus salt air for 40 years helped rust away that > steel bottom side that jams in under the port settee, all fittings on ends, > not top, including fill. any* top fittings would reduce 25 gallon tank to > probably half. ( Sorry I messed up the type). It will cost us over $250 > for any new tank, plus fittings, as I've been researching for a while now. > I really didn't want to have one shipped, wanted to take the old one to a > manufacturer to get exact, as I've sent specs but the result comes back > skewed to a different shape. There are four big mftrs, but only two will > answer. (ps: if any tank becomes hot enough, it's a potential for > explosion.) Helen ....... If 5200 is the only way to attach, (not allowed > on our boats), you could build a mounting frame that is removeable, and use > that for the glue down.?? A lot boils down to what it would take to > dislodge a 25 gallon (200 lbs approx) tank, what impact, your knottage plus > the other guy's speed? Or t-bone(how far away from the bilge chines is the > tank).? > * > * > * > * > * > *From:* Allen Edwards <al… [at] gmail.com> > *To:* Ca… [at] yahoogroups.com > *Sent:* Wednesday, December 28, 2011 10:39 AM > *Subject:* [Cal_Boats] Aluminum or Polyethylene Gas Tank? > > > I am going to rebuild the Gray Marine engine on Papoose and need to > replace the gas tank at the same time. I put the galvanized steel tank in > there about 20 years ago and would replace it in kind if they still made > them, which they don't. So the choice is between Aluminum or Polyethylene > as I have read that stainless steel is not approved for gasoline for some > reason I would probably prefer not to discover. > > Aluminum seemed like the way to go until I read how you install them -- > two tubes of 5200 to glue them down to your fiberglass base. Obviously I > don't have a fiberglass base as Papoose is wood but I guess I could make > one up but I am not inclined to glue my tank in place should it ever need > to be removed. I also read that even in new boats, aluminum tanks can fail > after just 3 years due to corrosion. So that freaks me out if this is > true. Ideally, I could mount it suspended by the side mounting ears which > would keep moisture off the bottom of the tank but that doesn't seem to be > how they are mounted. > > My tank is 18 gallons, 36x18x7.5 high. This is a common size available in > either material. > > I thought someone on this group might be knowledgeable on the subject. > > Allen > > > > >

Helen, this article says ethanol does not effect polyethylene. I buy vodka that comes in plastic bottles and I think that they're ethylene. I've been using a generic six gallon plastic fuel tank for my boat for the last 15 years, and the tank still looks new, ....Jerry PS: Wow, fuel tanks, plumbing, rigging, polyethylene in appropriate density and formulation, what's not to like? My mainsail halyard is 1/8" gray Amsteel, it's still looks great after six years, altho maybe I sold have gone one size larger? I wouldn't use it in standing rigging because of "creep", and it is a bit slippery at that tiny size, but the newer stuff has even less stretch and creep than the stuff I have. Here's an article on tanks: http://www.iboats.com/basics/ethanol_fuels.html http://www.iboats.com/basics/ethanol_fuels.html From: Helen Horn <he… [at] sbcglobal.net> To: "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> Sent: Thursday, December 29, 2011 11:37 AM Subject: Re: [Cal_Boats] Aluminum or Polyethylene Gas Tank? Allen, everything I've been learning about the resistance to putting ethanol in higher concentrations into gasoline indicates the ethanol has a solvent property towards the polyethylene compound. I predict in my own opinion, that unless someone comes up with another compound that will not dissolve, the m-brand of tanks will become obsolete. They have great shape options, but so do the aluminum guys. There are mounting brackets available for all tanks. screw-down types. If you wish to glass the brackets in, that is an option. You can also make a glass case to secure your tank in. It's a lot like a battery box. lucky for you, the Lapworth uses a rectangular shape, the fg 36 uses a 5-side compound shape, two of which are under 2 1/2 inches, (water condensation trapped on the under side of the tank plus salt air for 40 years helped rust away that steel bottom side that jams in under the port settee, all fittings on ends, not top, including fill. anytop fittings would reduce 25 gallon tank to probably half. ( Sorry I messed up the type). It will cost us over $250 for any new tank, plus fittings, as I've been researching for a while now. I really didn't want to have one shipped, wanted to take the old one to a manufacturer to get exact, as I've sent specs but the result comes back skewed to a different shape. There are four big mftrs, but only two will answer. (ps: if any tank becomes hot enough, it's a potential for explosion.) Helen ....... If 5200 is the only way to attach, (not allowed on our boats), you could build a mounting frame that is removeable, and use that for the glue down.?? A lot boils down to what it would take to dislodge a 25 gallon (200 lbs approx) tank, what impact, your knottage plus the other guy's speed? Or t-bone(how far away from the bilge chines is the tank).? From: Allen Edwards <al… [at] gmail.com> To: Ca… [at] yahoogroups.com Sent: Wednesday, December 28, 2011 10:39 AM Subject: [Cal_Boats] Aluminum or Polyethylene Gas Tank? I am going to rebuild the Gray Marine engine on Papoose and need to replace the gas tank at the same time. I put the galvanized steel tank in there about 20 years ago and would replace it in kind if they still made them, which they don't. So the choice is between Aluminum or Polyethylene as I have read that stainless steel is not approved for gasoline for some reason I would probably prefer not to discover. Aluminum seemed like the way to go until I read how you install them -- two tubes of 5200 to glue them down to your fiberglass base. Obviously I don't have a fiberglass base as Papoose is wood but I guess I could make one up but I am not inclined to glue my tank in place should it ever need to be removed. I also read that even in new boats, aluminum tanks can fail after just 3 years due to corrosion. So that freaks me out if this is true. Ideally, I could mount it suspended by the side mounting ears which would keep moisture off the bottom of the tank but that doesn't seem to be how they are mounted. My tank is 18 gallons, 36x18x7.5 high. This is a common size available in either material. I thought someone on this group might be knowledgeable on the subject. Allen

I actually think it is diesel that has a problem with older design polyethylene tanks. I think they line them now so that it is OK. That is a very nice article. Says straight up, don't use aluminum although I think Helen's recommendation of 1/4 inch would pretty much make the tanks last. One article I read said that most of the problems were with 0.090 thick tanks and .125 tanks seemed to do much better. Certainly .250 tanks would be much better still. An option I had not considered is Stainless Steel. I thought that was not allowed for gas but Odin, a Cal34 and 40 owner recommended it to me and I take his recommendations seriously. So, I had two choices, and now I an down to three, Poly, 1/4 inch Aluminum, and Stainless. Great... Allen On Thu, Dec 29, 2011 at 10:34 PM, Gerald Sobel <so… [at] yahoo.com>wrote: > ** > > > Helen, this article says ethanol does not effect polyethylene. I buy vodka > that comes in plastic bottles and I think that they're ethylene. I've been > using a generic six gallon plastic fuel tank for my boat for the last 15 > years, and the tank still looks new, ....Jerry PS: Wow, fuel tanks, > plumbing, rigging, polyethylene in appropriate density and formulation, > what's not to like? My mainsail halyard is 1/8" gray Amsteel, it's still > looks great after six years, altho maybe I sold have gone one size larger? > I wouldn't use it in standing rigging because of "creep", and it is a bit > slippery at that tiny size, but the newer stuff has even less stretch and > creep than the stuff I have. > Here's an article on tanks: > http://www.iboats.com/basics/ethanol_fuels.html > <http://www.iboats.com/basics/ethanol_fuels.html> > > <http://www.iboats.com/basics/ethanol_fuels.html> > http://www.iboats.com/basics/ethanol_fuels.html > > > <http://www.iboats.com/basics/ethanol_fuels.html> > > ------------------------------ > *From:* Helen Horn <he… [at] sbcglobal.net> > *To:* "Ca… [at] yahoogroups.com" <Ca… [at] yahoogroups.com> > *Sent:* Thursday, December 29, 2011 11:37 AM > *Subject:* Re: [Cal_Boats] Aluminum or Polyethylene Gas Tank? > > > Allen, everything I've been learning about the resistance to putting > ethanol in higher concentrations into gasoline indicates the ethanol has a > solvent property towards the polyethylene compound. I predict in my own > opinion, that unless someone comes up with another compound that will not > dissolve, the m-brand of tanks will become obsolete. > They have great shape options, but so do the aluminum guys. There are > mounting brackets available for all tanks. screw-down types. If you wish > to glass the brackets in, that is an option. You can also make a glass case > to secure your tank in. It's a lot like a battery box. lucky for you, the > Lapworth uses a rectangular shape, the fg 36 uses a 5-side compound shape, > two of which are under 2 1/2 inches, (water condensation trapped on the > under side of the tank plus salt air for 40 years helped rust away that > steel bottom side that jams in under the port settee, all fittings on ends, > not top, including fill. any* top fittings would reduce 25 gallon tank to > probably half. ( Sorry I messed up the type). It will cost us over $250 > for any new tank, plus fittings, as I've been researching for a while now. > I really didn't want to have one shipped, wanted to take the old one to a > manufacturer to get exact, as I've sent specs but the result comes back > skewed to a different shape. There are four big mftrs, but only two will > answer. (ps: if any tank becomes hot enough, it's a potential for > explosion.) Helen ....... If 5200 is the only way to attach, (not allowed > on our boats), you could build a mounting frame that is removeable, and use > that for the glue down.?? A lot boils down to what it would take to > dislodge a 25 gallon (200 lbs approx) tank, what impact, your knottage plus > the other guy's speed? Or t-bone(how far away from the bilge chines is the > tank).? > * > * > * > * > * > *From:* Allen Edwards <al… [at] gmail.com> > *To:* Ca… [at] yahoogroups.com > *Sent:* Wednesday, December 28, 2011 10:39 AM > *Subject:* [Cal_Boats] Aluminum or Polyethylene Gas Tank? > > > I am going to rebuild the Gray Marine engine on Papoose and need to > replace the gas tank at the same time. I put the galvanized steel tank in > there about 20 years ago and would replace it in kind if they still made > them, which they don't. So the choice is between Aluminum or Polyethylene > as I have read that stainless steel is not approved for gasoline for some > reason I would probably prefer not to discover. > > Aluminum seemed like the way to go until I read how you install them -- > two tubes of 5200 to glue them down to your fiberglass base. Obviously I > don't have a fiberglass base as Papoose is wood but I guess I could make > one up but I am not inclined to glue my tank in place should it ever need > to be removed. I also read that even in new boats, aluminum tanks can fail > after just 3 years due to corrosion. So that freaks me out if this is > true. Ideally, I could mount it suspended by the side mounting ears which > would keep moisture off the bottom of the tank but that doesn't seem to be > how they are mounted. > > My tank is 18 gallons, 36x18x7.5 high. This is a common size available in > either material. > > I thought someone on this group might be knowledgeable on the subject. > > Allen > > > > > > >

On 12/28/2011 1:39 PM, Allen Edwards wrote: > > Aluminum seemed like the way to go until I read how you install them > -- two tubes of 5200 to glue them down to your fiberglass base. > Obviously I don't have a fiberglass base as Papoose is wood but I > guess I could make one up but I am not inclined to glue my tank in > place should it ever need to be removed. A number of years ago, the aluminum holding tank on our local schooner corroded and began leaking--right under the captain's berth. It was a high-priority repair. We used a tick-stick to make a wood/epoxy replacement that was of larger capacity than the aluminum original because it fit the space better. But wooden boats are not rectilinear constructions, and we couldn't actually see under the new tank to assure that it was going to fit perfectly, uniformly supported. So I laid down some tape on the frames and stringers that the tank would sit on, then squeezed a very thick bead of sealant (not 5200, which is not allowed on the boat now--probably polysulfide rubber). When the tank was set in, it squeezed the sealant more or less, depending on tolerances, giving uniform support and also allowing a bit of give. The tape assured that the sealant would not actualy act as an adhesive, just as a flexible gap-filler. Chris Campbell >