Author Topic: More fresh water tank questions  (Read 180 times)

SailRxSin

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More fresh water tank questions
« on: July 25, 2020, 03:06:44 AM »
So I have determined that the only way I will get the layer of grime out of the freshwater tanks is to remove some of the glass from the setee and make some larger access ports that I could use to really clean the tanks well.  My problem is what do I do once I get a couple of 6 inch or so diameter ports on the tanks.  From what I've read, nothing adheres to polyethylene very well at all, save for some Marine Tex Flex Set.  Maybe keep the pieces I cut out and then place a splint on top of them to hold them in place while I reseal with Flex Set?   

Any and all ideas apprecitated. 

Has anyone here completely replaced the original freshwater tank system, lines, and all?
Sincerely,
Skipper & Cindy
RxSin
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Dolce_Vita

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Re: More fresh water tank questions
« Reply #1 on: July 25, 2020, 03:01:06 PM »
So I have determined that the only way I will get the layer of grime out of the freshwater tanks is to remove some of the glass from the setee and make some larger access ports that I could use to really clean the tanks well.  My problem is what do I do once I get a couple of 6 inch or so diameter ports on the tanks.  From what I've read, nothing adheres to polyethylene very well at all, save for some Marine Tex Flex Set.  Maybe keep the pieces I cut out and then place a splint on top of them to hold them in place while I reseal with Flex Set?   

Any and all ideas apprecitated.  ...

I've had a similar question for a long time.  From what research I've been able to do, the preferred solution is some sort of flange that relies on clamping a gasket in compression, rather than on an adhesive. 
@(^.^)@  Ed
1977 P-323 #42 "Dolce Vita"
with rebuilt Atomic-4

SailRxSin

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Re: More fresh water tank questions
« Reply #2 on: July 29, 2020, 12:38:53 PM »
I've had a similar question for a long time.  From what research I've been able to do, the preferred solution is some sort of flange that relies on clamping a gasket in compression, rather than on an adhesive. 

Ed, thanks for the input, you definitely a great source of knowledge on this site.  What about something like this:  https://www.defender.com/product.jsp?id=47548

Sincerely,
Skipper & Cindy
RxSin
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Grapevine, TX

Valor

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Re: More fresh water tank questions
« Reply #3 on: August 03, 2020, 08:19:43 AM »
Those inspection hatches need some kind of sealant between the hatch and the deck. The lid seals with an o-ring which is what you want. If you can find something similar but has some type of gasket between the the 2 mounting surfaced you should be ok. This is what you are looking for.

https://www.vetus-shop.com/universal-inspection-port-for-fuel-and-water-p-3452.html
Michael M

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Yanmar 3GM30F

Dolce_Vita

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Re: More fresh water tank questions
« Reply #4 on: August 03, 2020, 11:21:19 AM »
Those inspection hatches need some kind of sealant between the hatch and the deck. The lid seals with an o-ring which is what you want. If you can find something similar but has some type of gasket between the the 2 mounting surfaced you should be ok. This is what you are looking for.

https://www.vetus-shop.com/universal-inspection-port-for-fuel-and-water-p-3452.html


Can't view it.  This link seems to require a login.
@(^.^)@  Ed
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with rebuilt Atomic-4

SailRxSin

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Sincerely,
Skipper & Cindy
RxSin
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Grapevine, TX

Alma

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Re: More fresh water tank questions
« Reply #6 on: August 06, 2020, 03:59:32 PM »
I played around for years and finally cut open the port side settee and made a flange and lid that is stronger than new. You can see Mr. Shaw designed nice beds for the stock tanks. Yes under the tanks is reinforced. I had a new poly tank fabricated at great expense and trashed it two years later. It was impossible to get the lid to stay welded since there was no access to weld the inside of the seam. Sadly it was useless.

I installed a big French bladder tank and it works well. The new bladder flops over the smooth ends well and the added weight over each side is insignificant.

The only problem is air building up and preventing water from filling the bladder if the filling supply is too fast. If overfilled it could bust-up the settee so it is a job for the captain only. I've racked my brain to figure an air vent. Chime in if you think you have an answer without adding another fitting.

The new tank is much larger capacity than the old tank.

A thin stainless steel custom tank would be nice but why bother? The bladder uses more of the under settee space and is so cheap it can be replaced instead of cleaned. The French have the plastic figured-out, it is tough and has no taste or smell at all. The tank is two part, water bag and tough outer shell.

The lid is a little over-engineered but stiff as can be and lightweight too. It is supported by thin plywood I beams that harken Rube Goldberg as well.

It was necessary to build that way for a solid tank that fit the original footprint- The i-beam flanges must go in after the rigid tank was laid in- the flanges are two part and nest together after fitting past the access hole.  Once assembled they tie together the settee and support the lid, sliding plywood berth and any occupants easily.

Starting with a bladder you could cut a small hole, chop up the old tank from within and stuff in a new bladder in an afternoon... That would be my route now for the Starboard side when that 42 year old tank gives problems...

PS there is a a nice cubby hole storage available in front of stock tank area where a door in base of settee or opening in bulkhead from within hanging locker could provide access without the sizable job of removing the cushions, plywood sliding berth base and new engineered lid.

Additional house or windlass battery?
« Last Edit: August 06, 2020, 04:39:32 PM by Alma »
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SailRxSin

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Re: More fresh water tank questions
« Reply #7 on: August 07, 2020, 12:12:32 PM »
That is a great idea and one that I had not thought of.  Love your reinforcements.  I guess you have to fill the bladder from inside the salon?   
Sincerely,
Skipper & Cindy
RxSin
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Alma

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Re: More fresh water tank questions
« Reply #8 on: August 10, 2020, 10:19:11 AM »
The bladder is plumbed to the deck fill. But air in the water builds up and makes a bubble that prevents the tank from completely filling. Since the hose dips on its way to the bladder it traps this air. The solution is to fill slowly so no air is entrained with the water- I usually need to purge this air every 4th fill... The 5MM Birch Plywood is called Tech-Ply. I used to be able to get it from a local flooring supply. It is imported. It is very stiff, lightweight and water resistant. Aircraft builders use it but now it is hard to find and expensive. I was spoiled paying a little more for it than junk Luan ply...
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