Suggestions for emptying blackwater tank with no pumpout available

[Scott Fuller]

We have purchased a boat that has been on the hard for a couple of years with blackwater in the plastic holding tank. Now that the temperatures are rising, the stench is as well. A previous owner did a horrific job of replacing the tank and hoses, a photo of which I have included as supporting evidence of my assessment. The entire system needs to come out and be done over. The previous effort included eliminating the overboard discharge, and the boat is on the hard in a yard with no portable pump out. As we are several weeks from launch, and after launch have a 500 mile delivery I would very much like to have this project completed prior to launch. I'm looking for suggestions as to the best solution for emptying the tank while it is in place.

Thank you,
Scott

[Mr B]

Sludge pump thru the centre hose fitting and have a tank or large container on the ground outside the boat, You can rent a sludge pump and hoses to suit,
The sludge inside the tank will be solid and stuck on the bottom of the tank,
Not a pleasant job,

[meridian28]

Check with s septic tank pump out company

[Sailmonkey]

Ugh. I can see the permeation on the bottom hose!

[Kalinka1]

What we did before y valve. Was use a portable manual bilge pump (Henderson Plastic) with a pvc 1 1/2 threaded fitting and manually pumped the tank out at sea. Could be used to pump out and into a barrael or such on the ground. Or you might be able to et up a syphon to do the same thing. have fun.

[jtsailjt]

I’d disconnect the bottom hose that I assume leads to the pump out fitting at that fitting that’s located above the level of the top of the full tank, and use a diaphragm pump such as a Whale Gulper to empty it either overboard or into a portable tank on the dock. Then, when you have time, add a y valve to that outlet line and use this same pump (now permanently installed) for overboard discharge.

[jtsailjt]

Diaphragm pumps work well for this purpose because they are self priming so can be located above the tank level and they don’t clog easily and are easily cleared if they do clog. Also, since you can mount them above the tank level, if you have to remove one to work on it, you don’t risk the contents of the tank or outlet line leaking out through the pump. If your tank has been sitting full quite awhile, once it’s first emptied you’ll probably want to spray in additional water through the tanks inlet to help flush out any settles solids. This is what I use for my holding tank pumpout and I find it to work much better than the old macerated pump did.

[Bill O]

Are you changing the tank or keeping it? How about cutting in a clean out port in the top of the tank. Then you have options to drop down a pump into the hole. Will agree you will have hardened sludge on the bottom.
This will additionally give you can easily rinse it out at the end of the season.
No matter how you do it will be a messy job.

Since you have no idea how old the hoses are, you will need to replace the hoses. Most hoses are only rated for a few years for permeation. If possible, change over most of the tubing runs to schedule 40 PVC and eliminate permeation in these areas. We did it a few years ago and it made a big difference.

To all: the OP is in the Great Lakes and it is a no discharge area. The OP wants to eliminate an overboard option and not add one. This could be done later if needed.


Bill O.

[Boatyarddog]

Since you'll be installing new hoses, how about installing a macerator in the 1 1/2"discharge bottom hose probably goes to the deck pumpout fitting and pump it into a portable RV or other tank outside the boat.
Just need the pump and a battery.
Cheers
SV Cloud Duster

[basssears]

Find a local company that rents and services porta potties for construction sites, one of them did a pump out on my very full holding tank when we were on the hard after purchase.

[captlloyd]

Sorry, had to say it, go to a composting unit, problems solved.

[Scott Fuller]

Thanks for the suggestions - I have contacted a septic pumping company near the boat who says they can do it for $125.00. Kind of spendy, but none of the alternatives are very attractive either . I would probably lean most toward buying a Whale Mk-V pump which I plan to do anyway, and connecting it to the pumpout hose and emptying the tank overboard into something. Since I don't plan to re-use the tank, I could cut a hole in the top and use a cheap sump pump I suppose, but that seems to have more risk of stuff getting where I'd rather it didn't inside the boat.

My intention is to replace the tank and hoses using good quality hoses and couple large vents, using a tank that actually fits in the intended space instead of protruding into the cabin where it's sight is the first thing that greets you as you come down the companionway.

Although we are in fact on the Great Lakes, I do want to have the capability of pumping the tank out overboard (which the boat does not have now). Generally at the end of the season we have the tank pumped at the marina, then flush a couple tanks of bleach water through it once it's on the hard.

[rbk]

Ya that tank should be junked. No bottom fittings pickup tubes off the top. One wrong step and that tank will empty into your cabin.

[peghall]

Ronco Plastics Ronco Plastics marine Tanks (no relation to the VegoMatic Ronco) is your best source for a tank. They make TOP quality thick-walled water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank.


And I''l be glad to help your spec out the new system.


--Peggie

[roverhi]

I'm going to a C-Head desiccating toilet to replace the holding tank. $800 dollars delivered. If you can plug the hoses, leave in place for the delivery or remove entirely and go with a desiccating toilet. Might think about going that route as it sounds like you'll be doing a total replacement Holding tanks are a stinking PITA, expensive if you have to replace, and take up valuable space that is needed in my case.

Desiccating heads aren't without some issues but with a little care seem to be able to easily handle a months use by a crew of 2 or so without servicing. Best thing is they are super easy to install and don't require any plumbing.