Oday 28 Holding Tank Replacement

[DYFLWD]

I will be replacing my Holding Tank on my 1983 Oday 28. It is yellowed and "crusty" and I cannot see the level even with a flashlight. It is also shows signs of overpressure due to a plugged vent thanks to the spiders. I will be replacing all the hoses too. Its dims are 9H x 12W x 30L. Very odd shape and since the access hole is only 10 1/2 x 22 1/2 I may have to cut a bigger opening. The capacity is currently 15 gal and I want to upgrade to a 20 or so. Should be a nasty job!! Any tips would be greatly appreciated.

 

[DYFLWD]

Also why does it have 2 vent ports? 1 is on the top (logical) the other appears to be on the bottom in the back though it is hard to see that area (see photo)

 

[Peggie Hall HeadMistress]

I'll answer your second question first. A port at the bottom of a tank can't be a vent...I suspect it may be a separate dedicated port for a macerator pump to dump the tank at sea.

Now...about a tank replacement. Your best source is Ronco Plastics (no relation to the VegoMatic Ronco) Ronco Plastics Marine Catalog They make TOP quality thick-walled water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank. Once you've picked a size/shape, I'll be glad to help you spec the fittings sizes and locations. From your photo, it appears to be under the v-berth, which is the best place for a tank unless that would make the run from the toilet too long.

Replacing a tank and/or hoses and toilet doesn't have to be a nasty job...the key is in the prep BEFORE you begin taking anything apart. You'll find step by step instructions in my new book, available from the online store here...scroll to the bottom of the page to see a link to it.

 

[DYFLWD]

Peggie, Thanks for the info, I have purchased the Kindle version of your book and reading it now. The vent line comes from the hull vent down to a tee near the tank. One line goes to top of tank (vent) the other goes to bottom on the back but I cant see exactly where it goes. If it does indeed go to bottom of tank I assume there must be a stand pipe. I guess I will find out after removing the tank. I have looked at Ronco and definitely where I will purchase. The inlet and outlet hoses are 1.5 and the vent is 3/4.

 

[Peggie Hall HeadMistress]

The vent line comes from the hull vent down to a tee near the tank. One line goes to top of tank (vent) the other goes to bottom on the back but I cant see exactly where it goes.

I have NO idea what the person who "designed" that bit of plumbing had in mind, but I am pretty sure he was clueless about how to vent a waste tank...and maybe where to put the rest of the fittings too, but that much is forgiveable 'cuz boat builders don't either.

Btw...Increase the vent on your new tank to 1".

 

[Apex]

let me know what tank you get, and if it fit well. I will have the same project. A PO closed in the v-berth inset area and shelves in the v-berth, and stuffed a rectangular tank there. I am NOT happy with the installation, esp with the pushlok fittings and screw cap that is glued shut.

 

[DYFLWD]

OK I will increase vent to 1" where do I find a vent for the throughhull

 

[DYFLWD]

Funny they are all 5/8 and some dont even list size..finding this very typical of boat products. Frustrating

 

[Peggie Hall HeadMistress]

You won't use a "vent" thru-hull....they ARE all 5/8" and they're designed to keep sea water out of the fuel and water tanks, which makes 'em completely unsuitable for waste tank vents. You want a 1" open bulkhead thru-hull..the same kind your bilge pumps drain out of. You'll find photo of it on page 41 in my new book.

 

[DYFLWD]

Oh, got it ...thanks. So I just remove old vent and enlarge hole and install the 1" thru-hull. very cool. I think I should read the whole book now and a lot of ?? will be answered!

 

[njlarry]

Please post pics and tips as you progress. Hope to also replace mine for all the same reasons. The 34 is very similar to the 28. Also has 5/8 vent hoses and a fore and aft vent fittings connected to the same vent on the starboard side. I believe that I also have the same size tank and may have cut some glass to install a bigger tank.

 

[DYFLWD]

The next time I get out to the boat wont be until this weekend. I plan on removing the tank and all the hoses at that time. The nice part of this project is it doesnt disable the boat so I can squeeze in some sailing! I promise to post pics and my progress.

 

[berner73]

Might find one of these useful to have on hand when removing the old hoses

http://www.amazon.com/OTC-4521-Hose...&redirect=true&ref_=oh_aui_detailpage_o00_s00

 

[Peggie Hall HeadMistress]

Maybe not. It looks like it can dimple a fitting, and if that happens the new hose can't seal.

Warming the hose makes it a lot easier to get off a fitting....also makes it a lot easier to put ON a fitting. You don't have to worry too much about over heating the hose you're removing, but you don't want to overheat the new hose. So while a heat gun is ok to use on the old hose even if you're not all that skilled at using one, a blow dryer is a better choice on the new hose. Lubricate the new hose with dishwashing liquid--or better yet, K-Y surgical jelly...it's slicker than dishwashing liquid, and also water soluble, so it dries out. Don't use Vaseline or any grease...the last thing you want is a greasy hose that can slip off the fitting.

 

[Eduard]

I have same tank on O'day 272. You my have 2 vents on top (each), like I have-one on front, one rear. You may can't see it because pipe from bow side going down.

Will take pics on my this weekend ( just removed)

 

[DYFLWD]

Ok success today! Everything but the toilet removed and already smells 200% better down below. I cleared the plugged vent line at the thru hull (damn spiders) and flushed the system thoroughly with fresh water and pumped out as much as possible. All the lines came off by hand, no need to cut any off. Being careful I bet I didnt spill more than an ounce of sewage. The difficult part of the project was removing the tank because it is a very tight fit through the access hole. It was necessary to remove the inlet and discharge elbows from the tank, they are threaded and just turn out. Also, the wooden tank mount had to be taken apart and slid aside to allow more room. Just required removing 5 wood screws that where easy to get to. So close! Still, I had to pry out just a little with a screwdriver. The big surprise was the vent and the drain hole plug on the back of the tank were installed wrong. Somebody, I assume the manufacturer, put the vent elbow on the bottom and the drain plug on top! Good thing there were 2 vents, the one in front did all the work while the one in back must have filled up to meet the tank sewage level all the time. See the picture..note the TANK IS TURNED UPSIDE DOWN IN THE PHOTO AND I HAVE THE ELBOW REMOVED.

 

[DYFLWD]

The dimensions of the factory tank are 29.25 long, 9 high and 12 wide. That equals 14 gallons, not 15 as advertised in the owners manual. Now I have to decide on the tank size. If I go larger I definitely have to widen the access hole. But I can only go a few inches forward to the beginning of the blue tape that I have marked because there is a stiffener that runs across underneath. If I go wider the tank must be shorter unless I have it specially made to a V in front. The only option I see is going higher as there is plenty of room for that but how high? If I can add 2 inches to the the height that will give me 17 gallons. Maybe I will make a wooden box at those dims and make sure it will fit. Should I have the intake on top? The pumpout on top with a standpipe? I know I want a 1" vent on top.

 

[DYFLWD]

Any suggestions on good hull liner..this stuff has to come off!!

 

[DYFLWD]

let me know what tank you get, and if it fit well. I will have the same project. A PO closed in the v-berth inset area and shelves in the v-berth, and stuffed a rectangular tank there. I am NOT happy with the installation, esp with the pushlok fittings and screw cap that is glued shut.

Can you post some photos of that?

 

[DYFLWD]

Made a template from some art board. 30L x 20W x 10H. Will go to the boat on Wednesday to see if this will fit with minimum trimming to the access hole. I am hoping that if I raise the tank higher the extra 8" width will fit at the front (V). If so I will order a Ronco HB163 25 gal. If not I have to go with less width and less volume. Should I put the inlet on top? If the discharge is on top can I have them install a tube that reaches the bottom of the tank or just do a side discharge with the tank slightly canted towards discharge elbow? I want a 1" vent on top per Peggys advice. Also, this is the thru-hull I am considering. Overkill????