installing holding tank

[ncfathom]

OK, I have an older 38c and need to install a holding tank. Has anyone been through this? Any info would be greatly appreciated.

[primecut]

NC I'll take a stab at it since I have poked around a 38 and kinda know your options are limited. When I was looking at the 38's....At least at the time I fiqured a bladder would be the way to go. they can fit just about anywhere and are very durable..good luck

[Fanfare]

On our older boats you pretty much have to install a holding tank anywhere you can. When they were designed all of the usable space went for as much fuel or water as possible.

I have a 50MY, with about the same interior layout as the later 53MY. My first attempt to comply with the MSD requirements, around 1972 or so, was to install 3 of Raritan Engineering's self-contained LectraSan macerator/disinfectant units, one for each head. This was expensive, but at least the units were fairly small. They work very well, particularly in places such as the Bahamas, where I have yet to see a pumpout station. Then the Feds went to their silly no discharge rules in the Florida Keys. Tests show that my MSDs actually treat sewage better than many of the Key's land based sewer plants, but.....never mind. Unfortunately, this mindset will probably doom these efficient units in future years.

About this time I re-engined, and the larger exhaust claimed the middle LectraSan space. I got a heavy plastic (polypropylene?) 30 gallon rectangular holding tank and installed it in my forward port generator room. The pumpout goes behind my refrigerator up to a fitting cut into the front outdoor seat area. You will also need to add a vent fitting. Mine has a carbon filter (Sealand) to minimize tank odors. The heat from the generator does not favor this location as it seems to promote fermentation. This is in my port engine room. I also have a Headhunter diaphram tank pump to empty the holding tank at sea. The main drawback is that I Have Groco seawater heads, and they pump out a lot of water, fairly rapidly filling the tank. Also, the convolutions of the Sealand sewage-rated hose is something. Luckily it has not plugged up. But what else is there to do? It is very tough to adapt an older vessel to these constantly changing and frequently foolish requirements.

I considered a bladder tank, but I was worried about odor permeation and the danger of rubbing or puncturing the tank. I have used both fuel and potable water bladders from Nauta, but not for extended times. I did tear a grommet on the 55 gallon water bladder once while transporting it. I don't think I would like this with sewage.

Good luck.

[DCMY #92]

A few years ago I bit the bullet an added a holding tank to our 41DCMY. I ended up cutting a hatch in the V-birth sole and installing a rigid tank there between the stringers. I don't know if this is a possible location in the 38 or not.

I bought a custom made tank from Ocean Link.

http://www.oceanlinkinc.com/tanks/waste-water.htm

They have many many different size and shape tanks you can customize for the position, number and size of openings you want. Their planning and installation information is first class. Even if you don't get a tank from them you should read what they have to say.

You won't get the capacity out of a rigid tank that you will a bladder. The problem is that a maximum rigid tank that will completely fill the available space won't fit through the doors, hatches, etc. needed to get it into place. Had I built a tank in place I could have gotten close to a 35 gallon capacity, but with tank shaped for the area under the V-birth cabin and capable of being installed the best I could do was 22 gallons.

I went for the compromise of a rigid tank with limited capacity due to my fear of leaks from a bladder.

I also installed a compressed air system to pump fresh air into the tank to minimize anaerobic bacteria and reduce odors. A significant consideration in my choice of location was the ability to continuously slope all hose to avoid any undrained low spots. Trapped waste in hoses will create odors no matter what else you get right.

I have attached a sketch of the tank I had built. You will see that it has two dip tubes - one for the deck pump out, and one for a through hull pump out. You will also see threaded fittings for fresh air supply, a spray nozzle to rinse down the inside of the tank, vent line, etc.