we have        a 13m  alloy    pontoon    houseboat   with watertanks   as part of the hull    A build   up of  Aluminum Hydroxide    caused filters to block   .   When we opened the tanks   corrosion was eating into the alloy    .  We cleaned and treated with   carboline 891 . epoxy coating   .   Some think this was caused by chlorine in the water   Any comments   ?    
Regards,
Emil from New Zealand                   d     

Chlorine is highly corrosive, so the chlorine in the water water will most certainly corrode any aluminum tank over time...the more heavily chlorinate the water, the faster it will occur. It doesn't take a high concentration. But on average the life of an aluminum water tank is =/- 20 years...a few years longer if the inside of the tank is coated...a few years shorter if a little bleach is added to each fill in a misguided effort to prevent "funky" water.

Coating the inside of the tank will only delay the inevitable...a PE or PP liner, or a bladder would be the best solution.

I HOPE the other uncoated pontoon isn't your waste holding tank...or if it is, that you  haven't had a need to use it in OZ...'cuz urine is SO corrosive that chlorine seems benign by comparison...it typically eats through a weld at a seam or a fitting within about 2-5 years...and typically will turn aNY metal--even 316 stainless--tank into a colander within 10 years. If you do have to use the tank, stop immediately! Thoroughly clean out the tank, then put a plastic linr or bladder tank inside the pontoon.

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

Were safe to use chlorine in an aluminum tank if we just want to clean it out and sanitize the plumbing in the boat once a year, correct?

-------------------------
1990 16x78' stardust
Eastern Ky

While bleach (chlorine) IS corrosive, it’s effects are are cumulative. So the effect of an annual or semi-annual "shock treatment" is negligible compared to the cumulative effect of holding chlorinated city water in the tank for years. Nevertheless, it's a good idea to mix the total amount of bleach in a few gallons of water before putting it into either a stainless or aluminum tank.

And it’s that cumulative effect that makes it a VERY bad idea to add a little bleach to each fill. Not only does it damage the system--taking an average of 5 years off the life of an aluminum tank and the rubber parts in the water pump...but unless you add enough to make your water taste and smell like a laundry, it’s not enough to do any good. Even if it were, any “purifying” properties in chlorine evaporate within 24 hours, leaving behind only the corrosive properties.  

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

Peg

I bought a 1998 Thoroughbred house boat last year. I have both water tanks and holding tanks made of aluminum. The boat's water tanks have had minimum water use as the previous owner never took it out of the slip and had the city water bypassing the tanks and running the boat's water system. However, I know that the holding tanks were used.

Is there some way for me to know the integrity of the metal of the holding tanks, or is it a "Wow, look at that!" type of thing that tells you it is time to replace the tanks?

Thanks for your input.

-------------------------
I use to be "Its About Time"

Edited: 05/06/2009 at 07:38:08 PM by CastingAway

If holding tanks were in constant use I would consider a change out to poly ASAP.

-------------------------
OLD HOUSEBOATER

I wouldn't rush to do anything yet. The water tank is most likely still in good shape, so  recommissioning the system is prob'ly all it needs. The holding tank may or may not be on its last legs, but 'fortunately holding tanks don't just "let go"...the first sign is likely to be seepage at a weld and odor in the area where the tank is. So keep a close eye--and nose!--on it for signs of stinky moisture and be ready to replace it when they show up. Meanwhile, relax and enjoy your boat.

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

Are you 100% sure the black water tanks are aluminum? Kinda surprised that Thoroughbred would of used aluminum for holding tanks. Or does it have gray water tanks that are aluminum?

The fresh water tanks should be fine for along time given the boats age. Ours is a 1990 and I peaked inside the tanks this past winter and they still look new. Pretty sure theyve not been used very much and they are drained in the winter.

-------------------------
1990 16x78' stardust
Eastern Ky

Thanks  for your reply, I forgot to mention that our boat   is only 4 years old !    and the corrosion was about 2mm deep  !  
Are you familiar with the coating I mentioned ?   
It was applied by a specialist  and supposed to last forever.     
Regards,
Emil.              

Jeepster04, think about it - what material do houseboat manufacturers have the most of? They weld odd pieces of sheet aluminum together to fabricate their tanks - both fresh water and black water. It's simply a matter of economics.

I just got off the phone with Thoroughbred. Yes, the holding tanks are aluminum with no coating on the inside. You are correct that they have the material and just weld up the tanks as needed. They now have plastic replacement for whenever the tanks start to "smell".

When we leave the boat, I open the front and back hatches, put a box fan in the back, set to low, blowing into the bilge (downstairs) area. I also put air filters over the front hatch to catch all the dust. This keeps the air moving in the boat and collects the dust as well. If a weld starts to go, we should be able to pick that scent up as soon as we walk into the boat.

As for the water tanks, as I said, the previous owner never used them. I gave them a shock of Clorox last fall. One gallon to 252 gallons. Let it sit and then ran two rinses through. We fill the tanks with water and use them even if we just stay at the dock. I figure if we continually cycle water through, when we go out, the water will be fresh. Now I have to worry about city clorine.

Dang.... it's always somethin'!!

-------------------------
I use to be "Its About Time"

Weeeellll....You managed to startle your system a bit, but a ratio of 1 gal bleach/250 gallons of water isn't nearly enough to shock it. A shame this site doesn't seem to have any archives...if it did, I could just give you the link to the directions for recommissioning a fresh water system instead of posting em again.:

Although most people think only in terms of the tank, the plumbing is actually the source of most foul water, because the molds, mildew, fungi and bacteria which cause it thrive in damp dark places, not under water. There are all kinds of products sold that claim to keep onboard water fresh, but all that’s really necessary is an annual or in especially warm climates, semi-annual recommissioning of the entire system—tank and plumbing. The following recommendations conform to section 10.8 in the A-1 192 code covering electrical, plumbing, and heating of recreational vehicles. The solution is approved and recommended by competent health officials. It may be used in a new system a used one that has not been used for a period of time, or one that may have been contaminated.

Before beginning, turn off hot water heater at the breaker; do not turn it on again until the entire recommissioning is complete.

Icemakers should be left running to allow cleaning out of the water feed line; however the first two buckets of ice—the bucket generated during recommissioning and the first bucketful afterward--should be discarded.

Prepare a chlorine solution using one quart Clorox or Purex household bleach (5-7% sodium Hypochlorite solution)/50 gallons water tank capacity.. With tank empty, pour chlorine solution into tank.Complete filling of tank with fresh water. Open each faucet and drain cock until air has been released and the entire system is filled. Do not turn off the pump; it must remain on to keep the system pressurized and the solution in the lines

Allow to stand for at least three hours, but no longer than 24 hours.

Drain through every faucet on the boat (and if you haven't done this in a while, it's a good idea to remove any diffusion screens from the faucets, because what's likely to come out will clog them).

Fill the tank again with fresh water only, drain again through every faucet on the boat. To remove excess chlorine taste or odor which might remain, prepare a solution of one quart white vinegar to five gallons water and allow this solution to agitate in tank for several days by vehicle motion. Drain tank again through every faucet, and flush the lines again by fill the tank 1/4-1/2 full and again flushing with potable water.

An annual or semi-annual recommissioning according to the above directions is all that should be necessary to keep your water tasting and smelling as good as anything that comes out of any faucet on land. If you need to improve on that, install a water filter. Just remember that a filter is not a substitute for cleaning out the system, and that filters require regular inspection and cleaning or replacement.

To keep the water system cleaner longer, use your fresh water...keep water flowing through system. The molds, fungi, and bacteria only start to grow in hoses that aren't being used. Before filling the tank each time, always let the dock water run for at least 15 minutes first...the same critters that like the lines on your boat LOVE the dock supply line and your hose that sit in the warm sun, and you certainly don't want to transfer water that's been sitting in the dock supply line to your boat's system. So let the water run long enough to flush out all the water that's been standing in them so that what goes into your boat is coming straight from the water main.  

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

This discussion made me check out the holding tank/pontoon on our houseboat.  It is aluminum and it is not lined.  In fact the previous owner just welded a discharge port and a 3" fitting for the toilet along with a vent into one pontoon.  I don't think it has developed any leaks yet but it sounds as if it won't be long until it does.  The only access to this pontoon is a 3" inspection hole.
 Help. I need advice.  We usually only use this boat for a couple of months a year but  often we stay out for 6 weeks at a time.

I doubt if one more season's use is gonna make much difference, so I'd wait till the boat  is out this fall to do anything. Meanwhile, you might want to start thinking about how best to do it--a new tank in a different location...open up the pontoon to insert a tank.....talk to the builder and the yard about your options and the costs.

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

I have pontoon houseboat with the pontoon as the waste tank it is a 1987 seahawk and the tank seems fine as of yet, here 22 years later could it be the grade of aluminum? I went to the 2008 HB show and it appears they are still building them this way and when asked they seemed to shrug it off saying they havent had any problems. Although I think they were no more than salesmen and didnt give a ........ . I wish i could find out if it is going to turn into a colander soon.

-------------------------
Cheap Houseboater

We keep our small houseboat on a trailer in dry storage so access is available.  One of the options we are considering is a new holding tank.  The only place to install a new tank is under the bed.  This under bed storage area is directly through the wall behind the toilet so it is close and accessible.  However this will require a new toilet since gravity will no longer work.  I am not familiar with these types of toilets.  What would be a good setup?  Since we like to travel a good distance on Lake Powell and stay in remote areas we need a large holding tank.  A toilet that uses small amounts of water would also be a plus but the Sealand EcoFlush is too pricey for our budget.  I am handy and familiar with household and RV plumbing so I can install this myself.  Thank you for the replies and I look forward to your suggestions.

We thought about a head briefly until we checked into costs and heard about the issues stated above. We also have a pontoon houseboat that's more like a camper. And with the costs and issues involved we went with a higher capacity porta potti for our use. Finding a porta john or a public park facility to empty it is not that difficult or inconvenient the water where we boat in. Since the discharge of gray water is legal also in these waters we could not justify the expense of a full blown system for our weekend warrior. If it's not too inconvenient for your application it may also work for your uses. Here's a couple you could consider http://www.defender.com/produc...51|806|81394&id=435205 or maybe this if pump outs are available http://www.defender.com/produc...51|806|81394&id=105225

-------------------------
Respect Our Outdoor Recreational Resources
Leaving Only "Footprints in the Sand"

2003 5.3 Chevy P/U
1972 35' Crest Pontoon Houseboat
2007 90 hp. Yamaha

Hello Peggie ,
how can I send you some fotos of what happened to the tanks    ?   
regards,
Emil.                    

Send me a private message and I'll reply with my email address.

However, I don't know how it will hlep you for me to see the pits in your aluminum...'cuz  there's nothing I know of that would fill 'em. But if you still want to send me photos, please reduce the size to no more than 640 for the larger dimension.

-------------------------
Peggie Hall, Moderator
Specializing in marine sanitation since 1987, Author: "Get Rid of Boat Odors--A Guide to Marine Sanitation Systems and Other Sources of Aggravation and Odor."
[L=http://shop.sailboatowners.com/books/detail-books.htm?sku=66438&cat=1304[/L]

2mm is over 1/16" ... that much aluminum corrosion in only 4 years, I'm thinking there may be some sort of electrolysis problem...??

-------------------------

1988 SkipperLiner 53x14
1995 Tracker Party Cruiser 32 *for sale*
2003 Chaparral 260 SSI
2000 Allegro Bus 40' DP