Skipjack 1/72

[trout]

If you can extend the foam float out a bit that might help break the vacuum hold or add a BB or two to the end of the foam might help. Mark, can you tap the float foam and will that break the vacuum?
Yes I got it to water line or close depending on how much I empty out the ballast. Big portion of my foam is above waterline. So does not affect the surface trim. It is when it submerges that the foam will prevent the rear from sinking.

[greenman407]

Thanks Dave , Ill try that. Tom, Im sure that its not the float as this problem occurs when the float is disconnected as well. As far as the waterline thing is concerned, Ill have to start moving the two cast weights from there designated positions to do that. I was trying to see what could be done with the boat with the weights in there prescribed locations.

[greenman407]

The latest progress on this boat is that I recieved from Caswell an old gas valve. Having that, it was time to begin building my "Emergency Gas Ballast System". As you all probably know, I drive, sometimes in less than desirable lakes and ponds. Therefore, I like the extra insurance that a gas system can provide. Therefore, perhaps,If there are no objections, we can refer to this as a Hybrid system. HWSNBN recommends a very small 1/2" copper pressure vessel to get you out of a jam but also to keep the ballast tank volume to a max. Well...........If Im going to make one, I want it to be for more than one shot......................so, I made mine out of 1/2" copper pipe, but I made it 3&1/2" long. In order to do this I had to make a few changes to the SAS configuration. I pulled the forward ballast tank bulkhead out to give me access to the interior of the ballast tank. I had to move the SAS manifold on top of the ballast tank 1" to the rear to make room for my pressure vessel. Since I have to put the bulkhead back and since the battery compartment is pretty big, I have the option to move the bulkhead forward to increase ballast volume. But , If I do that I reduce internal volume that the SAS uses to blow ballast with. So, Ive got to make up my mind on that one. Also, I had a small leak that I believe can be repaired by expanding the oring seats to give a firmer fit to the inside of the clear tube. Ill do this with 4 or 5 wraps in the bottom of the oring channel with hobby vinyl pinstripe. Ive used it before on the Oscar and it works well.
Ill get some pictures up here on Monday. This posting finds me visiting "Kinfolk" in Dothan ,Alabama. They are wondering what Im doing, hunting and pecking on the computer keyboard.

[greenman407]

Here we go with some pictures
In the construction of the Sub driver, Dave was nice enough to add a hole for the Emergency gas ballast system and covered it with Vinyl tape. I used that hole and moved the manifold back 1". One of the pictures shows the pressure vessal under pressure for testing. I did find one leak that I then fixed. Good thing I tested it. Next, time for install.:

[trout]

Mark, if you attached a plate to the end of the pipe the schrader valve could be attached there so it will line up with the vent pushrod. Then set the servo on radio loss to go to say 120% and have that hit the valve.

[greenman407]

Since these Gas valves seem to be in short supply I decided to make my own for next time.

[greenman407]

Tom, thanks for the advice. In the picture I dont have the gas valve shown installed yet in its rightful place, in its own cubby hole on the inside face of the ballast tank bulkhead. Today itll be there.

[greenman407]

Gas valve in place. The function of the gas system is excellent! Also I stopped the waterleaks from the orings using four wraps of 3/32" vinyl trim tape. Watch it. The 3/32" Tape is really a strong 1/16". If I had bought 1/16" trim tape it would have been less in width. The resistance of the oring fit to pushing on of the end cap is now much stiffer. Perfect. In the process of re-trimming. To keep the battery from shifting I put some foam in there to hold it in place. Bad thing about it is that it reduces internal volume of air for the SAS. Ill come up with sumpin else.

[greenman407]

To hold the gas valve in place there are two set screws, one on top and one on the bottom. The bottom one can be accessed via a predrilled hole in the bottom. The top one you have to drill your own hole. This makes sence, since most people are not going to use it. I drilled a 1/8" hole, set the adjustment and then forgot to cover it. If you dont cover it, your air will leak out and your ballast tank wont work. Needless to tell you, I got it into the bathtub to re-trim the sub and I couldnt figure out why it was going straight to Davy Jones Locker. So , I took the top off of the sub and lowered the rest of the sub down into the water and then it became obvious. OOOPPPSSS! Dryed and cleaned off the area around the hole and then covered it with a piece of high quality Electrical Tape. That fixed it. Dont tell anyone.

[alad61]

Great stuff on the emergancy blow system Mark. Re the battery try using Velcro tabs at the end of the battery and the bulkhead. Seems to work for me and I have done some serious hook turns with no noticeable listing from the battery shifting.

[greenman407]

Thanks for that Alec. Now on to the update. In our last episode, as youll recall, we find our bumbling hero struggling with various issues. Well, Im proud to announce(drum roll please) that I just got my first WHOOSH! Yes , the SAS decided to cooperate. I like it a lot. Ive got the radio set up to allow me to turn on the SAS pump at the stroke of a key and it stays on till I turn it off, using the trim lever and the stick in concert. The rest of the sticks throw allows me to engage the gas progressively, all the way up to full emergency blow. I am aware of the drawbacks to this but we will leave it that way for now. Im also happy to announce that we still have no water leakage since the o ring modification, despite much testing. Testing what? Im trying to get the waterline right. The nose sits a little low and the stern sits too high. I have been progressively installing foam above the waterline a third of the way forward at the rear of the Subdriver area. At the same time reducing foam inside the tail cone. Little bit by little bit. In the picture you can see green oxidation on the brass push rods and drive tube. I believe it was caused by the toxic fumes from the curing silicone seal behind the foam. The next time I dunked it, it disappeared. Also, an absolute necessity is plenty of snacking materials on hand. Im out of chocolate, otherwise you would have seen a picture of a Cadbary bar in there.

[trout]

So Mark, what was it that made the SAS work? This is excellent news!

[greenman407]

Dave recommended that I use air pressure to blow into the subdriver to free up a sticky float valve. Well, since I lost my job, I no longer had access to air pressure. I then went out and bought a Craftsman 1.5 HP x 20 gal. compressor that was on sale. But then, i didnt have a nozzle. But I bought it because I knew I would eventually need it for other chores. My testing continued and eventually it started working and has been ever since. It just needed to get broke in.

[He Who Shall Not Be Named]

It hung-up because of a heavy wad of silicon grease between the nipple and rubber element atop the float -- the gooy stuff stuck the float in the 'flooded' position. You're shot of air shoved the wad out of the way so it would not 'glue' the float in the 'up' position with no water in the unit. All fixi-poo!

Damn, boy ... easy on the snacks, you'll start looking like me soon.

M

[trout]

I am sorry Mark for not comprehending what you were saying, when you were saying float valve my mind was translating that to the SAS valve on top of the sub. Now that I put two and two together, I get it. The foam in the copper pipe container was stuck in the up position (as if water had flooded it) preventing the air to go through.