What goes in must come out

Binary’s holding tank/s, when installed, have to be:

• Easily accessed for maintenance – Installed vertically in the forward/sail lockers
• Located close to other sewerage – Installed against the locker/head bulkhead, so connection is only 15mm away
• Compatible with 40mm (1 1/2″) rigid components – Supplied with Qty 9 x 1 1/2″ BSP threaded but uncut ports.
• Very robust – Manufactured in 5mm minimum thickness polypropylene
• Inexpensive – Enough to pass the Do I Build It Instead test
• Fitted with minimal inlets and outlets but still cope with environmental laws, current and future

Hence along with a sewerage design to accommodate all environmental laws effecting our home – now and in the future, here and overseas – we have chosen these 120 litre tanks (one in each hull):

I installed it with a single fitting for inlet, outlet to sea, and outlet to pump out, see below:

A bottom (gravity drained) located outlet to sea was considered as well, however I wished to avoid the complexity with structure required for this. I also wanted all ports in the tanks to, by default, have no discharge overboard or into the boat, in the event of a port or valve or human failure.

The single fitting for all (except venting) requires a pickup pipe inserted. Such an item in 40mm only seemed to exist for custom tanks. Or I could have used a 40mm tank flanged port and cut my own hole and then battle leaks… no way, not with sewage. This left my next best option – modify an existing manufactured fitting.

What I needed was a 1 1/2″ BSP nipple with a female 1 1/4″ BSP in one end and a 900mm x 1 1/4″ threaded pipe.

A bastardised answer would be to butt weld a 1 1/2″ BSP to 1 1/4″ BSP reducing bush onto one half of a 1 1/2″ nipple.

The elegant answer lay with the 1 1/2″ nipple having more than enough wall thickness to allow the use of a thread tapping tool. Did you know however that a hand operated tap of that size costs an arm and a leg?

Then I found a little firm in Darwin called AtSea Engineering and at $18 a thread I had 3 (one spare) modified.

Are you still with me reader, a bit verbose? Would you prefer the usual fare, photo after bloody photo?

Below: This is a rare little item! Contact me for one at our special price.

Below: Here it is threaded onto a 1 1/4” pipe.

Below: Here fitted properly to the 900mm pipe with 110mm cut off at an appropriate angle.

This is where I paid for being tricky. After cutting out the correct port I found out how far these port threads go into the tank. Far enough to block my u-beaut pickup pipe, see below.

Below: I therefore had to cut out and cut back (very challenging, being internal) the unused offending port.

Below: Now it fits, and apart from the stuffing about, it also cost another two blanking caps.

Below: The pickup pipe fitted properly.

Below: Now we are back where we started however the tank can now be emptied.