Wanted: An inexpensive old/ needs repair first sub

[JWLaRue]

Tom is providing some good advice. Ballast systems like the SubDriver are intended to have the ballast tank either completely empty or completely full. Control of the vent valve is not really fine enough to perform exacting trim changes. The ballast system essentially operates just like the 1:1 subs. There are systems that provide a higher level of control, such as the piston, but there are trade-offs for going that route.

I'm one of those that trim my boats such that a full ballast tank (no matter the ballast system I'm using) will put it on the bottom....when I am running in a pool. When running in a lake/pond, I trim such that the top 1/2-inch or so of the conning tower is out of the water with a full ballast tank.

Be aware that Boyle's Law also affects the flotation foam, though to less effect. I have seen boats that are trimmed to be positively buoyant sink to the bottom if they are driven deep enough.

-hope this helps,

Jeff

[salmon]

Be aware that Boyle's Law also affects the flotation foam, though to less effect. I have seen boats that are trimmed to be positively buoyant sink to the bottom if they are driven deep enough.

-hope this helps,

Jeff

And that is one of the contributors to the sinking of my Type XXIII. I made the positive so close to being negative that when it was hit by another person's radio and did a nose dive......it went completely negative. So, one of the failsafes did not work. My fault. That being said, it ran so well I could do a very slow speed and maintain my depth.
sigh....(wiping tear from eye)

[subdude]

Having been present at the tragic loss of Tom's XXIII, I will attest to it's beautiful running characteristics, and good looks. Was it ever recovered, Tom?

[salmon]

Lost.....to this date. The good news is I have collected all the components to build another one. So, it is in the build list.

[sam reichart]

Lost.....to this date. The good news is I have collected all the components to build another one. So, it is in the build list.

I'll follow along. I want to get one in the water as well.

[Ralpharch]

Tom is providing some good advice. Ballast systems like the SubDriver are intended to have the ballast tank either completely empty or completely full. Control of the vent valve is not really fine enough to perform exacting trim changes. The ballast system essentially operates just like the 1:1 subs. There are systems that provide a higher level of control, such as the piston, but there are trade-offs for going that route.

I'm one of those that trim my boats such that a full ballast tank (no matter the ballast system I'm using) will put it on the bottom....when I am running in a pool. When running in a lake/pond, I trim such that the top 1/2-inch or so of the conning tower is out of the water with a full ballast tank.

Be aware that Boyle's Law also affects the flotation foam, though to less effect. I have seen boats that are trimmed to be positively buoyant sink to the bottom if they are driven deep enough.

-hope this helps,

Jeff

That response and Boyle's law may be playing a big role in my son's (Parallax on forum) repeated sinkings of his Permit submarine. His sub is definitely set up for partial ballast tank venting. It is hard to control precisely but he is always trying to get sub submerged at surface with a small part of the sail out of the water. So the venting is done to the point wher a small sail area is out of water before diving actively. From that point on the sub will dive and operate well since trim is pretty neutral, but when the same vent servo is used to blow some air out of ballast (using snorkle for air path with pump) it is very hard to get right amount of air into partially filled compartment. Not to mention that the trim on that servo needs to go from full negative to full positive in order to go hard enough over to right to activate the emergency blow using Propell in cannister. Hence it ends up on the bottom.)

[JWLaRue]

Ralph, we'll keep that in mind when we do the troubleshooting this Saturday, however I'm virtually certain that it would not explain the leaking that is occurring. Those dive modules can easily withstand the pressure at the bottom of the pool we're using.

-Jeff