Working design for holding tank on a Tiki 30?

[Jordi]

Anyone with a Tiki 30 who has installed a holding tank which can emptied both to sea and pumping station?

Thoughts and/or experience (hopefully positive) to share? Placement? Size? Plumbing? Pump or gravity outlet?

Thanks!

[Budget Boater]

I cannot tell you what size tank to use based on the lack of information you have provided, but here are a couple of schematics on how to do it.

Having installed dozens of head plumping systems, it is important that you do not skimp on the equipment. This system deals with black water. Good hose is very expensive ($10-25 per foot), good Y-valves are $60-150, use AWAB or simlar hose clamps, and the pump is something you will be servicing, so get a good one that has parts and rebuild kits.

I used the second method - LAVAC - on my Tiki 30, as well as several previous boats, and will use it on my current boat.

• Lavac head with pump

• Locking Y-Valve x2

• Hose worth every penny

PDF for download also attached.

[Jordi]

Thanks for the information Budget Boater.

My main difficulties come from the very narrow spaces in the Tiki 30, and the very small freeboard which I guess makes gravity outlet impossible.

What size (LxWxH) and shape is your tank? Where did you locate the head and tank? (My head is at the aft of the sb cabin, and I'm planning to put a commercial rectangular tank just across the bulkhead from it, in the sb lazarette).

Thanks!

[Budget Boater]

Gravity? You cannot rely upon gravity, even if you had a large enough space. You must use a pump, hence my drawing.

I used a 3 gallon poly tank in the stb lazarette, and used the Lavac system shown above. When I sold the boat a couple a years later, the tank was still as new (I never intended to use it, but installed it only because it was a legal requirement to have one.)

If you intend to actually use the tank, it is best to install the largest size you can fit, which will probably be a flexible tank, or a custom fiberglass lined wood tank.

Jordi said:

Thanks for the information Budget Boater.

My main difficulties come from the very narrow spaces in the Tiki 30, and the very small freeboard which I guess makes gravity outlet impossible.

What size (LxWxH) and shape is your tank? Where did you locate the head and tank? (My head is at the aft of the sb cabin, and I'm planning to put a commercial rectangular tank just across the bulkhead from it, in the sb lazarette).

Thanks!

[Jordi]

Thanks for your help, Budget Boater.

The problem with tank size is fitting it through the hatch. I've found a 35-liter one which may fit... barely enough, but it will have to do. I'm wary of flexible tanks, since so many people seem to have trouble with them.

[Budget Boater]

Like anything pliable, a flexible tank must be isolated from chafe. I used cut down foam pool floats against the hull for the tank to rest on and tied out the corners of the tank to minimize movement. Lots of cruising and never lost a tank (I had 3.)

 
Jordi said:

Thanks for your help, Budget Boater.

The problem with tank size is fitting it through the hatch. I've found a 35-liter one which may fit... barely enough, but it will have to do. I'm wary of flexible tanks, since so many people seem to have trouble with them.

[Jordi]

How about pumping out? Doesn't the opposite side smack against the outlet and prevent emptying?

[Budget Boater]

A flexible tank will work 100% when properly installed. There is no magic. If you drop one in a hole (like most people seem to do) then it will not function correctly, and will eventually chafe through. Isolating the flex tank from chafe and movement, which goes hand-in-hand with tying off the tank, done properly will prevent the tank sides from collapsing prematurely preventing full evacuation when pumped out.

Jordi said:

How about pumping out? Doesn't the opposite side smack against the outlet and prevent emptying?

[Jordi]

Thanks a lot, Budget Boater. I'll let you know what I eventually decide and how it turns out.

[Jordi]

5 years later, it's about time I report on this. I installed a rigid tank, gravity-emptied, as per the plan linked below and it has worked flawlessly (except for the gauge sender clogging), and it does not smell if I don't leave it full for more than a few days.

https://ao-nui.blogspot.com/2017/01/waste-holding-tank.html