Prototype DDB ballast

[bigdave]

Sorry I have not posted for a while.
I am not building any cylinders at this time but I am doing some designing.

I am working on a DDB ballast module for my 2.5 system.
It stands for Dynamic diving, Decks awash, Ballast.

It is for someone that wants to have a dynamic diving boat, but still would like a scale waterline.

I built my version of the ingenious ball valve system Skip Assy used in his kits.
It's all scratch built and just a prototype module.
It works on the bench and will hopefully work in a sub too.
Here are a few photos of the module. BD

[bigdave]

I am installing the DAWB (Decks a wash ballast) module in my Skipjack.
I modified the mounting to accept the module. I had a R module in when I did the install.
This is the hull that I mounted all the components to the upper half.
So what you are looking at is the top hull.
I am trying to get it ready to test at our year end outdoor run.
BD.

[salmon]

Cool!
Small piston in the ballast tank?

[salmon]

Cool!
I see the valve system, but what is the fine tuning done with?
Small piston in the ballast tank?

[bigdave]

It is a dual ball valve system. Very ingenious design Skip Used in his kits.
It allows the water pump to be the only per-say moving part of the system.
If you don't include the balls.
I will have to draw something up that shows how it works.
My version is untested in a boat but works on the bench.
But as we all know they always work on the bench. BD

[scott t]

Come on Jim use your words! Spoken in voice of Dr. McCoy "Bones"

Best guess of how it works:
Tank full of air sitting on surface top ball valve and end of brass pipe lower than bottom of tank holds air in tank.
Turn pump to fill tank with water and air is pushed out short black tube to top ball valve and exhausted out brass tube pointing down.
Tank full of water pump off decks awash.
Turn pump to empty water and the vacuum sucks air from surface through bottom brass tube past lower ball valve and fills vacuum with
air allowing all water to be evacuated from tank.

Did I get close? Oh yeah, very neat system. Kudos to you and skip.
Scott T

[bigdave]

You bet cha.
That's it in a nutshell. BD

[bob_eissler]

I came across this link on another site :https://www.youtube.com/watch?v=2YsI...ature=youtu.be
Looks like he has some interesting things going on.

[bigdave]

Nice find Bob.
Cool video. A little different way to design it to do the same thing.
Thanks for posting that. BD

[bigdave]

I ordered some Lexan block from McMaster and will try the video design.
It's much easier to make than mine. BD

[bigdave]

First prototype built and tested.
Seems to work very well but I need to make the ball holes smaller.
I ordered some smaller O rings.
I think it would work OK built with the larger holes but I don't like it.
Now to test the valve in the sub. BD

[bigdave]

I have had a question on how and why the seal assembly is used.
But in a nutshell, it allows you to use a standard pump.
Not a pump like a parasitic type that will hold the water and pressure in the tank.
If you had no valve on a standard pump the water would just flow in till the pressure was equalized by pushing the air out the vent.
Just sitting the tank in the water the water will not flow in as both balls are sealing the vent.
Starting the pump to fill will push the one ball off its o ring to let the air escape so the water can flow in. At the same time pushing down on the other ball keeping it sealed.

Starting the pump to empty will suck the other ball off its o ring to allow air back in via the vent to let the water out. At the same time sucking the other ball against its seal.

A pump as you know will not suck out the water with a vacuum in the tank.
But it will suck the ball off its seal.

I hope this helps. BD

[bigdave]

Who says only the Japanese can miniaturize.
Same valve only about 1/3 the size.
I will test it after the RTV sets up. BD
f
Well, 1/2 the size anyway.

[bigdave]

Here is the latest iteration of my DAWB system prototype.
With the smaller external valve all the operating gizmos mount to one cap.
I changed the brass ball on the input side to plastic.
The vacuum attained by the pump was having a hard time lifting the brass ball off the O ring.
Now to reinstall it in the Skippy to try it in the sub.
On the bench it works great.
But they usually do. BD

[tommydeen]

That's very cool. After I saw the vid I made two of these valves, very easy to make. Dave I have a Q will these vales work for the DAWB system only? What's the down side of these system
Tom