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-   -   Holding tank or Fuel for Jeanneau (http://www.sailnet.com/forums/gear-maintenance/11327-holding-tank-fuel-jeanneau.html)

Myblueheaven 02-28-2005 09:31 AM

Holding tank or Fuel for Jeanneau
 
I had a large stainless steel holding tank made for my Sun Odyssey 51 as it did not have any when i purchased her. She is a 1991 from the Caribbean so holding tanks are not required in most ports?

The tank could also be for fuel with little modification. I have not checked the capacity but it is large. I designed it to go under my forward cabin bed area. There is a molded fiberglass triangular area perfect for a tank. I have pictures for the are and the tank for anyone else interested in doing the same thing. The dimentions are: 60" long by 35" wide at the widest part of tank (aft) and 14" deep with an additional 5" tapering to 3" trough/gathering well in the bottom aft of tank( where the pickup tube is place)

maybe Beneteau 50''s have the same are in the forward cabin sole. My email for questions is Myblueheaven@att.net The guy who made mine can make more easily. It took just a week for mine and it is very strong.

Jeff_H 02-28-2005 01:32 PM

Holding tank or Fuel for Jeanneau
 
I hate to say this at this late date but stainless steel is an extremely poor choice of material for a holding tank as the acids in the waste burn through SS rather quickly and allow odors to escape and eventually leaks to occur. Heavy wall plastic is the recommended material for holding tanks.

Also, when full a tank that large is somewhere around 900 to a 1000 lbs. That is an enormous amount of weight located right up in the forward end of the boat. Even for a 51 footer this is critical area of the boat to carry that much weight.

Jeff

Myblueheaven 02-28-2005 08:48 PM

Holding tank or Fuel for Jeanneau
 
I was made to understand by waste tank makers that Plastic was the best material then stainless was second. And that regular steel was the worst due to corrosive chemicals in human waste. In any case, at 18 gauge it isn''t going to corrode anytime soon, and ( very importantly - despite what makers of plastic tanks say, all plastic based tanks get odor permiated and smell through the plastic, just like the best hoses do.. But there was another consideration, the cost. I contacted two of the biggest and best plastic tank makers...Ronco and the other escapes me. Both wanted around 2000 dollars. Mine was built for a third of that!

Lastly, you are right about having so much potential weight up in the bow area...if the tank were full or even half. But the point of a holding tank ( for me anyways) was to have the convenience and legality of a place to store wate ONLY while at the dock or in a harbor. I , like most anyone I know would certainly pump-out at a station in harbor before setting sail, or dump legally beyond the 3 mile limit, so the weight up front is not an issue.

It would be for a fuel tank. But your estimated weight of 900 pounds I believe was way off for a 50 to 65 gallon tank. The bottom line is in 50 foot jeanneau''s where the builders were more concerned about quick turn around chartrs in waters not requiring holding tanks, there are few practical options of legal sanitation devices that would serve a live abord like me well at harbor or anchor( without having to go to the pump-out dock every few days. Jeanneau has a optional 5 gallon holding tank you can buy but you have to give up you closet as that is where it goes with its plumbing too. That''s it! 5 measily gallons. No, I''ll take a NON smelling huge stainless tank hidden away over the factory idea. But I would like to hear from more on the stainless holding tank corrosivness.

dman 03-01-2005 03:34 AM

Holding tank or Fuel for Jeanneau
 
Every plastic holding tank that I had eventualy failed around the area of the fittings but I don`t know if the stainless would have lasted longer either.

RichH 03-01-2005 03:58 AM

Holding tank or Fuel for Jeanneau
 
Unless you use one of ''modern'' very costly 2000 series of stainless you are going to be VERY dissatisfied after you use a 300 series of stainless as the material for a sewage tank. There is NO way that you cannot avoid welds and the corrosion into these ''heat affected zones'' plus the extreme attack by acids and products of fermentation will make your tank a ''swiss cheese'' especially along the weld lines ... in a very short time. Even if you grind all the welds smooth and electropolish and ''passivate'' the internal surfaces. The correct metal for such an application is hastalloy, etc. .... and that cost would be absolutely prohibitive. Sewage fermentation (an anaerobic process) in a tank consumes all the available oxygen (needed to keep stainless stainless) and unless you also plan to ''sparge'' air into the tank continually, eventually ALL wetted weld areas will fail due to an accelerated ''crevice corrosion''. Stainless is a BAD idea for such a tank that isnt continually injected/pumped with air/oxygen ... as would a standard fermentation vessel.

Polyethylene (or polyethyelene prepegged to a fiberglass backing panel) is about the only way to go. Polyethylene of normal structural thickness doesnt have the ''intersticies'' in its macro-molecular structure to permit stink transmission (vapor pressure pathways) and is quite suitable. You can buy sheets of fiberglass panels already pre-bonded with polyethylene if you want to make your own poly-lined FRG tank ... if you know how to weld polyethylene at the seam lines.

If you have already built a stainless tank for such a purpose, be absolutely sure that you apply a very LARGE cross section atmospheric vent to assure an aerobic fermentation and a vent large enough so that the external ''wind'' can help sweep out the heavier than air ''blanketing gases'' that naturally form.

Sorry.

RichH 03-01-2005 05:29 AM

Holding tank or Fuel for Jeanneau
 
Next time you install a large plastic tank be sure that ALL connections to the tank are so designed and arranged so that stress cannot be transmitted through such joints. This can be accomplished by using ''stress isolators'' such as ''bellows'' connections, short runs of corrugated piping, etc. These are available through industrial and plumbing supply sources.

Jeff_H 03-01-2005 09:15 AM

Holding tank or Fuel for Jeanneau
 
The 900 lb to 1000 lb estimate was figuring a 5''x 35"x14" tank (17 cu ft without the trough/gathering well) using 64.5 lbs per cu foot (which is the approximate weight of water) would result in a full tank weighing roughly 1088 without the weight of the tank itself. Diesel fuel is slightly lighter.

17 cubic feet results in a 151 gallon tank.

Jeff

Myblueheaven 03-01-2005 05:21 PM

Holding tank or Fuel for Jeanneau
 
No, the dimentions are not a rectangle at all. It is a elongated triangle where from the point( front end) to the other end (aft) is 60" and there it is 35" wide. So, 60 inches long and 35 incheas wide at the aft end...a long kinda narrow trinagle, 14" thick. The two 60" sides are equal but the aft end is not equal at 35". How many gallons is that? My math sucks.

It occurs yo me now that I suppose I could have sent the tank ( now built) to ronco and they could have lined it with there plastic as they kind form their tanks using a mold anyways. But I don''t know for sure.

geohan 03-01-2005 05:35 PM

Holding tank or Fuel for Jeanneau
 
We have been very happy for the last 10-years with a stitch-and-glue holding tank of 1/2-inch plywood. Coated inside and out with two coats of epoxy, it now looks the same as when first constructed. It even has a six imch see-thru port in the top for inspection and maintenance shoud maintenance be needed. There are no odors and no leaks. They can easily be built to custom fit the alloted space and while ours is only thirteen gallons the estimated cost was about $20 including the bronze fittings. I would foresee no problem with doubling or trippling the capacity. Just add baffels to break up the free-surface area.

captxtina 05-05-2009 01:18 PM

Quote:

Originally Posted by geohan (Post 49162)
We have been very happy for the last 10-years with a stitch-and-glue holding tank of 1/2-inch plywood. Coated inside and out with two coats of epoxy, it now looks the same as when first constructed. It even has a six imch see-thru port in the top for inspection and maintenance shoud maintenance be needed. There are no odors and no leaks. They can easily be built to custom fit the alloted space and while ours is only thirteen gallons the estimated cost was about $20 including the bronze fittings. I would foresee no problem with doubling or trippling the capacity. Just add baffels to break up the free-surface area.

This is very interesting!! We have a Pearson 28, and the bladder used for our holding tank has been relieved of duty. We are now looking for different solution. The space that the bladder was in was not an even rectalinear cube. The recess in the lazarette designed to hold the bladder can be described as a cube-and-pyramid-combined space. We haven't done the math yet, but we think the bladder held about 6 gallons.

Question: Does this plywood-and-epoxy solution really work?! If so, this may be a good option since the standard holding tanks which are cubular will take up precious space in the lazarette (since it won't fit nicely into the space previously dedicated to the holding tank).

Sharing your experiences regarding this is appreciated.
thanks.


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