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James Adcock
06-06-2003, 01:45 PM
Dudes, Got a question about fuel tanks. Are fuel tanks for 18-2+3's a standard size? What I would like to know is if I can purchase one before
splitting the boat in half. If so, where?

James Adcock
06-06-2003, 01:47 PM
Sorry about not writing a thank you. My big a__ fingers got button happy. Jamie

MOP
06-06-2003, 05:07 PM
If the newer plastic tank will fit I would use, alot less issues then aluminum.

mphatc
06-06-2003, 10:17 PM
Hasn't anyone created a fuel cell / flexible tank to faciltate this repair on the older boats? It seems like a much easier solution to this problem !!

Mario L.

knee deep
06-06-2003, 10:22 PM
I'm putting my new aluminum tank in on Monday, I did some debating and decided that a tabbed, bolted in aluminum tank was the only way to go. I had it custom made to fit and paid 350 for it, although, to be honest I wish I had had the guy come over to measure it to gain what little extra capacity I might have. Sorry not a plastic fan here.

mattyboy
06-06-2003, 11:06 PM
James
FMT-23DZ original tank for an older 18( before they went to 40 gallons) from florida marine tanks,
MOP is there a plastic equal???? from what mfg???
James drop me a line if you have any questions


Matt

Rootsy
06-06-2003, 11:17 PM
I dont want this to turn into a debate at all so i am just gonna say a few things that i know about blow molded tanks cause i do it every single day for a living...

plastic tanks are all fine and dandy, HDPE is a very good polymer for containers. HDPE is lighter, does not degrade (unless purposely made to do so by additives), is extremely solvent and corrosive resistant, can be molded in about any color and shape, has excellent abrasive resistance and has good toughness and good fatique and thermal properties. it is also unaffected by moisture. as with anything you must provide the proper process and testing methods to verify the integrity... this is why most of the containers you see today are HDPE (High Density Polyethylene). Gas cans, fuel cells, FUEL TANKS IN ALL CARS, HVAC ducting, detergent bottles, cleaner bottles, windshield washer tanks, coolant tanks, dang near anything you can think of, take a look around, turn it over til you find the recycling label.. if it says PE or HDPE thats it. If temperature degredation is an issue then you use polypropylene. the downfall is the flexural stiffness, COLD temperature properties, pressurized burst strength and overall strength vs aluminum + SIGNIFICANT tooling and manufacturing cost. Especially for LOW volume product

That being said, does anyone manufacture a TRUE CUSTOM form fitting HDPE tank for a donzi classic? I have never seen one, doesnt mean they aren't available... but a true fitting tank is what we are discussing here...

The fact is, you must manufacture expensive dedicated tooling to manufacture a tank.. and we are talking a BIG mold and A BIG blowmolding machine, on the scale of likely 100 ton clamping force. A mold this size, say a 30 gallon tank (16 classic), with no compression molded tabs or punched holes and a few domes to be removed would probably run you in the 50,000 - 75,000+ dollar range (depending upon complexity, cores, punches, materials and size) and have a lead time from the tooling manufacturer of around 8-12 weeks. This is for a single product line, say a 16 classic tank. you would have to have another for an 18 and another for a 22, etc etc etc. Plus all of the variations in hulls over the years... PLUS you have post finishing operations such as trimming and cutting holes, all of which cost capital and eat up manpower to operate, etc. therefore, eventhough blow molding is more economical than other methods, you must have the sales volume (as with automobiles and consumer goods) in order to justify the initial tooling, machinery and labor costs over the life of the product...

therefore it is way more economical and a heckuva lot easier to find a custom manufactured aluminum tank that will fit the hole like a glove in your classic. granted support must be provided for both polymer OR aluminum in order to keep it rigidly in place and from rubbing and flexing or jumping right out of place... although on the spans we use in our classics flexure is honestly not that huge of an issue, especially if you use adequate wall thickness on the aluminum.

therefore, and this is just my opinion, aluminum will be the way to go, not because it is the best material but because it is the economical and most convenient way for the volumes and variations required. Aluminum will have no issues lasting 30+ years as many have if installed correctly so that moisture is not retained, initiating corrosion and it is allowed to have air flow around it.

if anyone else has any other thoughts on this fire away eh...

MOP
06-07-2003, 07:38 AM
The aluminum tanks have done darn good, I have gotten to like the plastic as they have proven trouble free, and a fair bit less expensive. A lot of this is preference, a good install on either type will last many more years than most would even want to own any particular boat. Me if I were going to split the boat, I would not hesitate to lengthen the tank cavity to accommodate the 40 gal tank. That to me is light work compared to splitting the boat. I doubt if Donzi has changed the width between the stringers. I would use the new stock 40 gallon Donzi tank.

MOP
06-07-2003, 07:45 AM
Added note if you go with the aluminum tank do not use rubber under the tank, most rubber will over time absorb moisture and many have corrosive properties. There are many tech articles to bear this out. A lot of the guys I know and myself use Starboard strips running length wise. The strips should be firmly glued to the tank this prevents moisture from getting between the strip and allows for the expansion and contraction which is slight.

BigGrizzly
06-07-2003, 08:12 AM
When we did our 1966 16 in 1972. we pulles the tank we copied it and in stalled te tank just like the origional- no rubber it is foamed in and it is still there today with no problems. I will not debate which was is better because none is better than the other. Just secure the tank well and have fun with the boat. While at the Donzi factory in 1968 than in 2001 and seeing how they installed the tank than and how much more secure the old one is then it is to day, I wonder if it was origonally over engineered.

oldLenny
06-07-2003, 11:32 AM
Mphatc,..."fuel cells"...yes they do....Geoo has one in his X-18.

Here is the company. This stuff does NOT look cheap. They hail from Oregon...

http://www.fuelsafe.com/

...and while we are on this topic,...GEOO, what model or "style" did you go with for your X, I assume you gave them measurements and they sticthed it for you, and dare I ask,...what did it cost?

Tony
06-08-2003, 10:25 PM
Here's their 29 gal. rectangle:

PC129 29 Gallon Pro-Cell
Dimentions: 24 1/4 in. x 24 1/4 in. x 12 3/4 in. Price: $ 1,267.50