Hunter 33 : black water tank

[polac]

Hello,
The black water tank seems cracked and it is not possible to move it
Do you know if the rear cabin wall is structural
It is divided into 2 parts vertically
The upper part is "embedded" in the stratification (google traduction)
The lower part is screwed on 2 places
The sides are not fixed
I want to make an opening to remove the tank
Your opinions ?

 

[RoyS]

If it is a C33 like my 1980 the rear wall in the head compartment is removable. On mine I had to disassemble most of the cabinetry around the vanity to permit the plywood rear wall to be removed. This is time consuming but you can do it with a screwdriver. Once removed your access is excellent. I installed a 25 gallon holding tank in mine this way.

 

[SailormanDan]

Hi Polac,
Some more information would be helpful:
- The year of your boat - my 1981 H27 has a molded-in fiberglass tank with a screwed on lid, others tanks from different years may be stainless steel, aluminum, or plastic.
- Different pictures of the crack from different angles see people can see what you mean.
- Pictures of the "rear wall" also.
I'm sure it's not a hard fix, but it's also not good to put holes in the hull.

 

[polac]

The crack is probably under the tank, there is nothing wrong on the sides and on the valves
It is possible that the tank has twisted in the heavy weather.
It happened to me that the front tank is totally disconnected in big wave conditions
I will take pictures in 10 days when I return on the boat
I removed the 3-way valve, the macerator and I do not see any possibility to take out the tank by the current hatch

 

[SailormanDan]

I'm guessing that the bow and anchor locker is on the other side of the wood in the photo. Look for screws hidden inside on the back of the wood, they will be along the edges, that whole panel should come out. Not easy, but possible. The tank is probably a separate unit (piece) from the wood bulkhead.
I have a borescope for my smartphone that can look into spaces where I can't, it might help:
https://www.amazon.com/gp/product/B015F53LUK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[polac]

On the other side, there is the fuel tank
The problem would be the same to get it out
To answer the previous question, the tank is made of plastic
I had thought of making a very liquid resin that could cover the bottom of the tank, but I know that nothing sticks to polypropylene

 

[Ed Caldwell]

On the Hunter 340, the older (I'm guessing) sister of your boat, the center of that aft wall is not structural, and comes out with the removal of some screws holding vertical slats covering the joints. See here: https://hunter.sailboatowners.com/mods.php?task=article&mid=32&aid=8133&mn=340 where one owner added a hatch for easier access through the removable part.

I know, not your H33, but I wonder how much Hunter construction techniques changed for this sized boat...

 

[polac]

Indeed, on the internet link, it seems that the access door is wider because you see the tank on 10 cm which is not the case on mine.
It may be enough to simply enlarge this access without breaking everything
Thank you all for your kind responses

 

[Peggie Hall HeadMistress]

To answer the previous question, the tank is made of plastic
I had thought of making a very liquid resin that could cover the bottom of the tank, but I know that nothing sticks to polypropylene

Most likely your tank is polyethylene...nothing bonds permanently to it. However, if a PO had a custom welded made, those are often polypropylene, which can be glued. But regardless of which it is, replace the tank...don't even think of trying to repair it.
Ronco Plastics Ronco Plastics Marine Catalog (no relation to the VegoMatic Ronco) is your best source. They make TOP quality thick-walled water and waste tanks for a very reasonable price and has 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.

 

[polac]

You are right.
It will first be necessary for me to be able to extract it from this place.
Regards,

 

[Scott B]

Most likely your tank is polyethylene...nothing bonds permanently to it. However, if a PO had a custom welded made, those are often polypropylene, which can be glued. But regardless of which it is, replace the tank...don't even think of trying to repair it.
Ronco Plastics Ronco Plastics Marine Catalog (no relation to the VegoMatic Ronco) is your best source. They make TOP quality thick-walled water and waste tanks for a very reasonable price and has 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.

It's a 2005 ( checked his profile page) same as mine. I'm surprised it would crack? or could it have possibly worn through a spot from movement if not 100% secured or came loose?

 

[polac]

Yes, 2005 but bought in 2006
The tank was well fixed. I do not understand why it oozes.
All the pipes are OK, it is the tank that leaks

 

[Peggie Hall HeadMistress]

A blocked tank vent can crack or even explode or implode a tank. Continuing to flush against it can pressurize the tank enough to do it. A strong pump out pulling against a blocked vent can crack or implode a tank. Hunter's OEM tanks didn't have very thick walls--1/4", if that thick, but enough pressure or suction can damage even the strongest tank... I remember a poster here several years ago who managed to burst a seam in a brand new stainless tank because he kept pumping the toilet against ever increasing back pressure--apparently trying to clear what he thought was a clog.

Btw...my current book includes step-by-step instructions for installing tanks and replacing hoses.