Black Water Tank Access

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Black Water Tank Access

Postby dboyes » Mon Feb 22, 2021 8:40 am

I am thinking of installing a Beckson deck access plate in the top of my black water tank, probably a 6 inch one.

The purpose being to have access to clean tank out with hose now and again.

What are people's thoughts?
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Re: Black Water Tank Access

Postby jimcoleman » Mon Feb 22, 2021 9:17 am

SeaLand makes a Cleanout KIt that requires a 4" hole. I purchased one from Fisheries, but am still building the courage to drill the 4 " hole in the top of the tank. I too feel there is a lot of solid sediment in the tank limiting capacity. Also on my list is the replacement of all the hoses. Anyone have experience with that?
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Re: Black Water Tank Access

Postby dboyes » Mon Feb 22, 2021 9:36 am

Well Jim glad you put me onto the Sealand Cleanout Kit. Best to use something designed for the job.

I think it best to rent a 4 inch holesaw for the job???

I too am nervous about drilling the hole:)

A very capable Camamo owner, Bruce Synder has replaced all the hoses on his tank.

Can't remember if he just told me or actually posted his experience.

He has Chasing Time #84.
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Re: Black Water Tank Access

Postby Bruce » Mon Feb 22, 2021 1:24 pm

Good Morning,
This winter I replaced all hoses,installed a tank level transmitter, removed and cleaned the tank. Regarding the hoses, don't go cheap. Spend the money and get the good flex hoses. Otherwise your wife will likely hear words see hasn't heard before during install. A heat gun is a must as the old hoses will be hard with very little flex and the gun makes it easy for both removal and install especially when it comes to the macerator and vent line connections on the thru hull. Incidentally this would be the time to replace all hoses connected to and from the toilet as well.

Suggested removal steps:
1.If you have carpet anywhere, cover it prior to beginning.
2.Flush holding tank numerous times with clear water
3.Close off all water connections to toilet.These valves will be found behind the inspection door. There will be two of them.
4.Remove medicine cabinet (four screws)
5.Before you attack the hoses take pictures.This will help during the re-install especially in and around the macerator area and cabinet/bulkhead.
6. Remove zip ties as required. Most of the zip ties will need to be cut/removed. You should note here that the ties are the kind that can be attached to the wall. Buy them before you start. A drill that has a 4" driver bit is a real time saver.
7. This next step is a personal preference thing. I cut all of the hoses just behind the medicine cabinet area. This is for removal of the hoses that are connected to the macerator/pump out/vent. This will make their removal easier and has nothing to do with the tank per say. You should plug the hoses with something that will not only stop the smell but will prevent any leakage as well. I used a few plastic plugs. Another way is to use medical inspection gloves. Just place glove over the hoses and then rubber band them tightly.
8. Remove remaining liquid from the tank. Behind the medicine cabinet where the hoses were cut using my trusty wet/dry vac I connected to the large diameter tube coming from the tank. Duct tape and a little plastic pipe did the trick. Don' forget to open the vent line (tank side) by removing the plug or cover. Otherwise you could collapse your tank. Run the vac for a minute or two. Replace your caps/cover when done.
Assuming you are removing the tank which is easy and a good idea for cleaning the tank as well as the area under the tank. Place a couple of rags that can be discarded on the hull under the tank fittings.
9. Remove tank vent line and plug/cap as required.
10. Remove the crap delivery line and plug/cap as well.
At this point you should note that you have two 1 1/2 inch lines remaining. One is the pump out and the other is the pump overboard line.Take pictures noting how the line runs under the bulkhead. This will make it easy when rerouting the lines during install especially behind the cabinet. There are two bronze or plastic elbows that connect the two lines at the bottom of the tank. The elbows are simply threaded into the tank. I heated the elbows where they go into the tank while gently prying up and down in order to break it loose. Once loose;

11. Cut the large lines (one at a time about six inches before the tank connection) place a medical glove over the hose and rubber band it. Do the same with the other
If the elbows broke loose you can rotate them upward. Do no force them. You can leave them in the original position just ensure they are not leaking.
12. Remove tank attaching straps. Two screws/washers. If corroded replace them during install.
13. Lift tank out of its cradle.
Tank Cleaning. I used a pressure washer. After pressure wash completed I filled the tank with two gallons of RYDLYME and two gallons of water. I made plugs for the tank to allow me to rotate the tank every four hours or so. I let it set for several days before draining and pressure washing again. RYDLYME is biodegradable.
If you haven't done so your shower drain filter is also down there and should be cleaned out as well. If you use your shower often this filter clean out should be an annual requirement.
14. Remove all hoses. I cut them right at the wall bulkhead for ease of removal. The heat gun works wonders.
When installing the new hoses do not clamp or tighten clamps or zip ties till entire hose routing is complete.This will become readily apparent when routing the hoses behind the cabinet are as well as through the wall bulkhead. Leave the tank unsecured as well. You will need a little wiggle room to fit the hoses. Use the heat gun to warm the hoses. Plumbers silicone is super helpful as well. Dish washing soap works as well. Extra hose length should be trimmed at the tank. Once you are sure the hose lengths are correct for the tank connection begin the clamping/zip tie process but do not connect to the tank as yet. Start at the macerator by tightening the clamps then the over board hose. Then go to the pump out hose, attach and tighten and finally the vent and toilet hoses. working inboard attach but do not completely tighten the ties as the hoses need room for flexing and so on. Once you are comfortable with the hose fitment, attach hoses to holding tank and begin tightening the ties.

Sorry to be so verbose but wanted to put down all of my thoughts on this. Apologize for any grammar/spelling errors I missed

Regards, Bruce
"Chasing Time"
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Re: Black Water Tank Access

Postby Vector » Tue Feb 23, 2021 2:05 pm

I wonder how the Sealand differs from a screw-in deckplate? I see it includes a gasket where you would usually put sealant on a deck plate.

Non-Camano, but I recently ordered a 30-gallon polyethelene water tank. I had them cut a hole for a 4" Beckson deck plate (4.5" hole) because I had the deck plate on hand (did not have that large a hole saw myself). However for that tank I discovered that a larger hole would be nicer for reaching in (it's 36" long), so I decided to instead install an 8" deck plate that I also had on hand. I was able to pretty easily make the cut with a jigsaw (I was now making an 8.5" hole so larger radius). The deckplate was intended to use sealant to install the outer ring, but I didn't want "goop" in contact with my potable water if not necessary, so I ordered a food-grade silicone sheet from McMaster-Carr and made a gasket instead.

Above is a little bit rambly. I guess I mostly mention it in case a ~4" hole seems a bit small. Maybe it's fine though since the tank is not very large. One tip: The hole will be the largest and easiest to work through *before* you install the deck plate ring. So maybe clean it out good one time after you cut the hole but before you install the outer ring -- especially with the smaller SeaLand cleanout. In future the hole will be smaller (due to outer ring) but then those will just be maintenance cleanouts since you will already have done the big one.

If I ever install a holding tank cleanout, I'll probably contact Sealand to see what other differences there might be from a standard screw-in deckplate (gasket is one obvious one; are there more?)
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Re: Black Water Tank Access

Postby rwidman » Fri Apr 09, 2021 9:55 am

I did just what you are planning and cleaned the tank once or twice. I haven't touched it since. It seems pretty pointless, it will just fill with poop again.

And marinas don't like you rinsing the holding tank and then pumping it overboard. It's still "sewage", just diluted.
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