Skipjack 1/72

[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.:

[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]

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.

[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.

[He Who Shall Not Be Named]

Sounds like the safety float-valve is stuck closed. Remove the Schrader valve, and pressurize the inside a bit (hold the motor-bulkhead and forward bulkhead so they don't pop off). That will break the seal within the safety-float valve -- likely too much silicon grease in there. Sorry bout that.

M

[greenman407]

Thanks Alec. So Tom, You say that you have got yours to ride the inscribed waterline in the hull by shifting weight and foam and still having good submerged trim? As far as the safety valve is concerned, it doesnt matter whether I use the snorkel valve or a pluged off piece of hose. The vacuum inside the Subdriver only slowly equalizes unless I hit the schrader valve in the endcap.

[alad61]

Ditto with the aft high issue. It drove my starkers trying to get the rear end to sit down. Like Tom I added, reduced and shifted weight around' In the end I just kept it on a level trim both submerged and on the surface. What I did find was that once the sas had raised the boat proper I then opened the vent for a bit so it would sit just below the waterline mark and then add a little rise on the rear plane as I cruise on the surface which helps the prop bite better.

[trout]

Yes, Mark, I went through that! I shifted the weight back to the aft end (not adding more weight). Then adjusted the foam to compensate.
As far as the valve, if no water is getting sucked in, the seal is good, but is it sliding down O.K. Is your foam float rubbing against the sail? Does it travel just by turning your sail upside-down?

[greenman407]

Also there is NO WHOOSH! When you operate the SAS and bring the boat to the surface there is no Whoosh. After 30 seconds or so you hear some groaning and other weird noises as the pressure equalizes. If I were a betting man I would say that the Safety valve is bad. I wonder what the prospects are of getting another one?

[greenman407]

Youll notice that some of the additional weight had to be moved off of centerline to counter a list in the boat to port. Now its dead on. I dont know if anyone else is having this problem but, Im having trouble getting it to float at the design waterline. I have trimmed it for perfect submerged trim, but when you surface it it sits too high in the rear. If you were to add weight to the stern to get it to sit lower in the water then you would upset the submerged trim. The stern would sink like a rock. Its functional as it is, its just off the design waterline.

[greenman407]

Where am I?.................Who are you?...............OH....I Remember now! SORRY! OLd Tmers is setting in. Just an update to this thread. I didnt have enough of the supplied hose to plumb the SAS so I substituted some silicone hose. It worked OK but then I found some of the good hose so I have replaced it since this picture was shot. Note also the placement of additional weight and foam.

[greenman407]

If all goes according to plan Ill have this thing in the water in a couple of weeks. No paint until all bugs and adjustments are nailed down. In the meantime she and the Albacore are staring each other down. Actually, I think that they are good buddys, they just dont want me to know it.

[He Who Shall Not Be Named]

proceed

M

[greenman407]

As for the other little bugger, Im going to say that it goes forward. Just behind the torpedo nest area. You can see a circular depression formed in it, possibly for clearance to the Subdriver. AM I RIGHT??!! AM I RIGHT??!! HUH, HUH???

[greenman407]

Im going to take a stab at this. Nobody laugh! OK, so you know I bought the foam and weight kit for my little Scamper here. Only thing was somebody forgot to include instructions as to where everything goes. Dave helped me earlier with the weights. Now for the foam. There are two purpose built shapes of foam. Using my massive cerebral powers of deduction(ahem..ahem) I deduce that the smaller one goes back in that very difficult spot to conform foam to, the rearmost point of the waterline which I believe is the purpose for this scribed line in the hull. Notice the neat little cutout for the magnet attachment thingy. Unless I hear differently Ill be attaching that to the underside of the upper hull just in front of the hold down screw.