Head installations- how much capacity, what type of tank, etc?

[Seafarer]

I seem to have a theme going with the boats I buy. None of them ever come with heads! I need to build holding tanks for both of them, and have some questions regarding this.

How much capacity should I have? Say, per person per day, or per person per week?

I will be doing the IP26 first since it is much easier to access the location of the previous tank and I'll likely be using the head on that boat more anyhow. Its intended purpose is to take me and some friends day sailing / weekending and occasionally a month-long trip with no more than four people aboard- more likely just one or two. I can do two things: 1) a plastic pre-made tank on a shelf, or 2) build a box from plywood and glass and put a plastic or rubber liner in it. I've had experience with rubber bladders before and that experience is that they can really stink. I don't think this will be much of a problem on this boat since the location is vented into the cockpit or head and not the cabin, but I'd still rather avoid smelling it until it gets pumped out. I am leaning towards option #2 and would appreciate sharing any knowledge about different types of bladders. I will most likely install a Lavac on this boat, since I've already bought intended for use on my bigger boat. I can buy another for that boat later, and this way I'll be familiar with the mounting and plumbing method.

On my big boat, there is only a 7 gallon plastic holding tank which I deem inadequate for a live-aboard / cruising boat that seems no time at a dock. I will strive to find some place to put a bigger tank. To be entirely honest, I'm leaning heavily on removing one of my two 90 gallon fuel tanks, and probably shortening the other to a "mere" 50 gallons. These lie next to each other under the saloon floor, and while one is easily accessible I'll probably have to remove the entire dinette to get at the other. Since the dinette is directly aft of the head, that is where the new waste tank will go, probably with the shortened fuel tank aft of it so I can use the easily accessible space for storing heavy items (spare anchors and chain most likely). Anyhow- since there is already a box-shaped object down there I suppose a plastic holding tank would be my best bet for this application. Again, any knowledge about which tanks are the absolute best would be appreciated.

[CharlieJ]

I can give you my time experience with a 5 gallon Porta-potti, plumbed for pumpout , vented outside the hull. Solid wastes only, never used for urination, except incidentally.

Full time use-

Two people, pump every 7-8 days.

One person- pump every 14-16 days

You can extrapolate needs on larger tankage from that I hope.

[JWalker]

heads stink, and are a pain to deal with.

we did the MSD and were very happy with it. It uses WAY less water per flush, so you need less tankage.

I also built a composting toilet that we used at home for a month and it worked well.

We went with the MSD because I wasnt sure about the keys/boot key harbor and a homebrew composting toilet.

search the forum for Catn K's free compost toilet thread.


What a crappy topic  ::)

[Seafarer]

I'll look at making a 20 gallon tank for the IP26, figuring I might be living aboard it during the week and taking 6-7 friends out for daysailing and possible weekend trips. Some of them will be sleeping in tents ashore, on deck, or in hammoks in the rigging. A hardy bunch of climbers used to primitive camping for a week straight, they'll think a crowded boat is a luxury. Anyhow, I'm hoping that *should* be enough tankage if I pump out before any busy weekends. Enough to go a month between pumpouts if it's just me.

[JWalker]

Keep in mind that a normal head uses 1/2 gallon per flush to clear the head, so with a 20 gallon tank you probly get between 20 and 30 flushes.

The MSD was very convenient in the fact that we could dump it w/o pumpout when available, so we paid nothing for that.
We were discrete, and never had a problem.

We had the small msd, and priced another tank to add but didnt end up with it. it was $61 to double our tankage. That would put the whole system at $170ish.....AND you can add water tankage instead of holding.

I doubt that the large holding tank would cost much more than the small one we had priced, but with two of them for the msd that you can switch out you'd have 12 gallons of holding, and barley any water for flushing.

Just a thought.

[Seafarer]

According to the Lavac website, "A typical flush will use approximately 3 pints of water". A half-gallon is 4 pints, so the Lavac is still a low-volume flusher. I'm also doing this with resale in mind. I should be able to ask for more with a quality head in the boat than a porta potty.

[Captain Smollett]

We have a 14 gallon holding tank in Gaelic Sea.  With four people aboard (2 adults and 2 children) and using the head exclusively, we can go 7-8 days.

We don't use water to flush liquid waste, and minimal water to flush solids.  

Using the head only at night, that is 'off the boat relief' available during the day, we've gone 6 weeks or so between pump-outs.

I consider it an advantage to have a holding tank plumbed to be able to pump overboard (where legal).  That is, my head is NOT plumbed to flush overboard - all effluent from the head goes to the tank.  But the tank can be pumped out either at a facility or overboard via hand pump.

Odor:  Use some form of positive ventilation and good quality hoses/fittings, and odor will not be a problem.  Our ventilation is via two vent lines, one led to either side of the hull, rather than the one you usually see in plumbing drawings.

Look up and read Peggy Hall's writing online; her tips have worked for us.