holding tank

J

jim99

Well-Known Member
Joined
7 Sep 2005
Messages
154
Visit site
Rules, rules... I need to install a holding tank in my Vancouver 27. Not done it before. I have a manual Lavac Popular. If anyone can direct me to installation plans, online or elsewhere, that others have used I would be most appreciative. Cheers
 
You have two basic choices. Systems can be either gravity or pumped - the former has the virtue of simplicity and (lower) cost, but is constrained by the location of the tank, which must, by definition be above the waterline and close to the toilet. Vetus do some standard size bulkhead mounted gravity tanks or you can have a custom design. This type of tank is commonly used on new boats where it can be designed in.

The alternative is a pumped system which allows more flexibility in the location of the tank but inevitably adds complication and cost. Again you have a choice of standard or custom taknks, but it is not easy to find space for a standard size tank with adequate capacity. You need to look at the choice of standard tanks to see if there is one that will fit your space.

As already said there is a lot of useful information on system design on the Tek Tanks site. They also have a list of boats where they have patterns for custom tanks, but your boat is not currently listed. However they may have details. There was a good article in PBO a couple of months ago on fitting a custom pumped system in a Moody Eclipse, which will give you a good idea about what is involved.

I have fitted two gravity systems, both custom and one with a Lavac. Simple and works well. You need to give thought to the design and layout - for example making sure the access hatch is above the outlet so that you can clear blockages easily (not that their common but best to be prepared).
 
Tranona said:
You have two basic choices. Systems can be either gravity or pumped - the former has the virtue of simplicity and (lower) cost, but is constrained by the location of the tank, which must, by definition be above the waterline
Click to expand...

Why must a gravity tank be above the waterline? My long term plan is to put a tank in my very deep bilge with a connection for mechanical pump out and a manual back up. Am I missing something (often happens!)
 
"Gravity tank" as used here means that the tank can be emptied into the sea by opening a valve and allowing gravity to do the rest. If the tank is below the water line then the sea will flow into the tank (and possibly beyond) instead.
 
Dave_Seager said:
"Gravity tank" as used here means that the tank can be emptied into the sea by opening a valve and allowing gravity to do the rest. If the tank is below the water line then the sea will flow into the tank (and possibly beyond) instead.
Click to expand...

Gotcha! Many thanks, had my builders hat on I think.:rolleyes:
 
If you have it below the waterline and open the outlet it will fill with seawater and not drain!

Gravity tanks are usually fitted to a bulkhead in the toilet department. One new boats you often find them behind a vanity unit and immediately above the outlet seacock. The toilet pumps into the tank and the waste exits by gravity through the seacock, which can be closed so that the waste is held in the tank. Not always possible to arrange in an existing boat, hence the popularity of pumped systems where the tank can be in a locker - under a bunk in an adjacent cabin for example. Downside is cost, complication and longer pipe runs. Your proposal is of this type - toilet will pump waste into tank in the bilge and will be pumped out with a motor or manual either via its own seacock, or if you use a diverter valve through the main toilet outlet. Some people use a macerator and a separate outlet which can then be smaller diameter. Not always easy to provide shore pump out with a bilge located tank - another advantage of a bulkhead tank - short pipe to deckhead pumpout fitting.

Lots of choices which are covered in the Tek Tanks guides on design.
 
You must log in or register to reply here.

Share this page

Top