Replacement Water Tanks Oday 34/35

Jul 20, 2020
4
Oday 35 Clearwater
The plastic water tanks in my 1985 Oday 35 are starting to develop cracks. I am looking for alternatives to replace the tanks without having to cut into the fiberglass to install new tanks. Has anyone found a source for bladders that are compatible with the space that is available? Thanks!
 
Feb 21, 2013
4,638
Hunter 46 Point Richmond, CA
Aug 17, 2010
311
Oday 35 Barrington
When I was boat shopping (ten years ago) I looked at an O'day 35 that had a plastic bladder tank on the starboard side. I believe that the owner (carefully) cut the tank into smaller pieces with a sawzall to remove it. He then cut and ground off the plywood mounting brackets tabbed into the hull for the original tank. He laid some form of liner on the hull, and replaced the tank with a bladder that ran the full length of the starboard setee. I don't know how he plumbed it, as I did not buy that boat.
 
Dec 2, 1997
8,709
- - LIttle Rock
I just checked the listing on Amazon....those tanks can't be top quality or even decent quality for that price....at best on a par with Plastimo. "Nautos" is apparently an attempt to mislead people into confusing it with Nauta, which is top quality...check it against Defenders price for a Nauta 35 gal tank. Vetus bladders are mid-quality at a somewhat lower price.

The average lifespan of most bladders is only about 15 years before they start to leak at a seam or fitting...or chafe through unless they're carefully protected from chafing when installed. Like most things, the better the quality, the longer it should last.

I know you don't want to cut into anything to install a new tank, but when you compare the price of a good bladder with the price of a top quality plastic tank, you may decide it's worth the effort. So check out Ronco Plastics... 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, so you may find a shape size that can be swapped out with a minimum of fiberglass surgery. There are retailers who sell Ronco tanks, but Ronco sells direct for a much lower price...and they're great to work with. Ronco Plastics marine Tanks is their current catalog...most people find their previous catalog easier to search so they've left it up Ronco Plastics old marine catalog

--Peggie
 
Aug 17, 2010
311
Oday 35 Barrington
If I were to replace any of the non-fuel tanks on my O'day 35 I would cut the top of the liner off, leaving a 1.5" lip. I would then cut a piece of 3/8" marine plywood to fit the opening so that it fits snugly on top of the lip. I would add ½" stiffeners as needed to the new plywood cover. For the water tanks, I would do this for both the port and starboard setee. For the holding tank, I would do this to the entire V-berth. This would increase the accessibility of working in these compartments.

I got this idea after I was on a Tartan 3500 that, I believe, had come this way from the factory.
 
Jul 20, 2020
4
Oday 35 Clearwater
Thanks to all for your inputs. My initial plan was to install bladders inside the existing water tank shells. Unfortunately, I have not been able to find a bladder that would reasonably fit inside the existing tank shells without creating voids that would collect dirt and lead to the growth of algae. I agree with Peggy that new plastic tanks would be the best approach. Although I am very hesitant to cut into the existing fiberglass liner to the extent suggested by eherlihy, Plan B is to cut the fiberglass liner portion that joins the two existing access openings under each settee in order to provide enough room to slide in new plastic water tanks. The removed portions of the liner could be reinstalled and reinforced after the tanks are in place.
 
Dec 2, 1997
8,709
- - LIttle Rock
I just realized you've been saying tankS (plural), not just "tank ." Are there two in tandem? If so you should be able to find one larger one that'll fit the space, which would simplify the plumbing a bit.

--Peggie
 
Jul 20, 2020
4
Oday 35 Clearwater
I have two duplicate water tanks...one on each side of the salon under the settee. The bottom of each tank is made to conform to the curve of the hull. Each tank is 36” long, 21” wide across the top, 11”:high on one side and 5” high on the other side.
 
Dec 2, 1997
8,709
- - LIttle Rock
Ronco has been the OEM water and waste tank supplier to a number of boat builders...You might want to ask them if they supplied tanks to Oday.

--Peggie
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
Here is how two 30 gallon tanks are mounted in the O’Day 322...one under each settee...


Greg