New project - Neptune - a fantasy boat project

[DrSchmidt]

Good news, WTC is water tight and the ballast system works fine! Just the snorkel missing and then trimming.

[DrSchmidt]

Thanks. Proper CAD designing prior to a built helps allot ;-)

[SubDude]

Finished the WTC for my little fantasy boat Neptun. Ballast system uses a peristaltic pump with a float and a water switch to turn the pump off when the tank is full. Pump controlled by a Brüggen BTS and auto-leveler by Engel. 3s lipo as power source, corona receiver, and a outrunner brushless to drive the prop. I like how compact is turned out...

Looks very clean and well thought out.

[DrSchmidt]

Finished the WTC for my little fantasy boat Neptun. Ballast system uses a peristaltic pump with a float and a water switch to turn the pump off when the tank is full. Pump controlled by a Brüggen BTS and auto-leveler by Engel. 3s lipo as power source, corona receiver, and a outrunner brushless to drive the prop. I like how compact is turned out...

[DrSchmidt]

The sealed pressure ballast system is a tried and true method of ballast control in RC subs. OTW and Sheerline have been using it for decades. Engel boats also pressure up the dry compartments of their boats during piston tank actuation.

The lost volume of the ballast tank is less of an issue with the large boats that typically use these systems. They're not suitable for small boats where space is at a premium, but for big boys, they're a completely valid alternative.

Bob

Exactly......the air from the tank goes into the dry space of the wtc and the pressure rise is accebtable. Sealing off the tank and pumping water into it till the pressure of the pump is maxed out is just hard on the hoses, conections, the pump, and last but not least the battery, as the pump will draw allot of current when working againts the pressure in the tank.

[RCSubGuy]

The sealed pressure ballast system is a tried and true method of ballast control in RC subs. OTW and Sheerline have been using it for decades. Engel boats also pressure up the dry compartments of their boats during piston tank actuation.

The lost volume of the ballast tank is less of an issue with the large boats that typically use these systems. They're not suitable for small boats where space is at a premium, but for big boys, they're a completely valid alternative.

Bob

[DrSchmidt]

Well I have a Phd in physics and know about compressability. The question is, why would I pursue an approach that puts immense pressure on tank, pump and hoses while leaving 20-30% of the tank empty.

[redboat219]

How do you fill a closed tank? The Air has to go somewhere.....

Gases (Air) have
nice characteristics, one of the is compressability. As you fill the tank with water the air gets compressed and it's volume decreases. So it's still inside the tank.Look up Boyle's law.

[DrSchmidt]

Would it be simpler to use a close tank than venting into the WTC?

How do you fill a closed tank? The Air has to go somewhere.....

[redboat219]

https://forum.rc-sub.com/forum/tips-n-tricks/134757-this-is-how-it-all-came-together

[redboat219]

Would it be simpler to use a close tank than venting into the WTC?

[DrSchmidt]

The pressure switch is works differentially - it senses the pressuer difference beween two points, in my case the inside of the wtc and the inside of the tank. When the tank fills, the air moves freely into the wtc and both tank and wtc pressure are the same. When the tank is full, the valve shuts off the tank, but the pump tries to force additional water into the tank. The tank pressure rises above the wtc pressure shutting the pum off. Norbert Bruggens way of doing things....

[redboat219]

Good Day Doctor,

Can you expound more about your 2nd technique, using David Merrimans float valve with a pressure cut off switch. I assume the the float valve will be inside the tank and shuts off the water intake when the water level reaches a certain level ( like in a car's carburetor). What then trips the pressure switch?

You could try this https://youtu.be/T-qimkJsjBg
He also uses a peristaltic pump but instead of a bag he utilized a water tank with a floating piston that's free to move. When the piston reached the end of the tank it trips a microswtich cutting power to the pump.

[DrSchmidt]

So after a while I'm back working on this boat. It was pretty much done when I stopped, but looking at it today, I don't like the original ballast system anymore. It's based on a rubber sack that is filled and emptied by a peristaltic pump. When the sack is full the pressure in the feed line rises, triggering a pressure switch which then switches off the pump. Nice system, but well, I don't like the sack.

So I decided to replace the sack by a 3D-printed tank that vents into the wtc. Now how do we switch off the pump? There are two ways and I'm going to try both. First method is to utilize a float switch. There are tiny ones available for little money. I printed a housing for it and installed it behind the motor. When the tank is full, the housing of the float switch is flooded, the switch is toggled and the pump gets shut of. In addition I installed two gold pins that act as a water sensor. Same effect...shuts off the pump. Second method will be to close the tank by one of David Meriman's neat little float valves and again to shut off the pump by a pressure switch.













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[DrSchmidt]

Photobucket changed their terms and now don't support 3rd party hosting for free users anymore. I guess, I'm not the only one affected. Nevertheless, all pics can be found here:

http://s1262.photobucket.com/user/MaschinenMusik/library/Neptune?sort=9&page=1