Ballast tank

**bob the builder** · 01-05-2004, 06:56 PM

The ballast tank needs to

[color=#000000]The ballast tank needs to be able to "lift" anything that is above the waterline therefore]

Edited By Bob the Builder on 1073343749

**uss silversides** · 01-05-2004, 07:59 PM

Thanks Bob! I'll do that.

Jonathan

Thanks Bob! I'll do that.

Jonathan

**skip asay** · 01-06-2004, 01:11 AM

Here's a much simpler method

Here's a much simpler method -
Build your boat to the extent that everything is done except the ballast tank itself. Put it in your test tank and you'll almost certainly discover that it's light. Add whatever weight is necessary wherever necessary to get it to JUST submerge - not sink like a rock - and sit as level as possible. Something like just enough weight to have it float with just the top of the conning tower out of the water and then add just enough to get it to completely submerge. At that point, a couple of quarters would probably suffice.

Now add square or rectangular foam blocks under the hull until the boat sits at its proper waterline. Since it's a round bottomed boat, you'll have to start by building a cradle (use foam) so the foam blocks won't just roll out from under. Make that cradle and the foam blocks you put under it approximately 4" - 6" long. When the boat is at its proper waterline, determine the cubic volume of all the foam (including the cradle) by multiplying length X width X thickness. Then convert that to the volume of a cylinder (3.14 X radius squared X length). Like Bob said, a 2.75" ID cylinder is 5.94 cubic inches per inch of length.

Another benefit to this method is that by sliding the foam fore and aft, you can determine the EXACT location for the tank.

Yes, when all is said and done, you'll have to remove weight equal to the weight of the ballast tank itself but that's a small price to pay. Plan ahead when you're adding the weight to begin with - don't make it all permanent.

Skip Asay
SubTech

**bob the builder** · 01-06-2004, 11:40 AM

Another thought....

You'll have to subtract

Another thought....

You'll have to subtract from your ballast tank the volume of your pressure vessel, which I just remembered is mounted inside your ballast tank. It takes up space so you'll have to allow for that.

**uss silversides** · 01-07-2004, 05:08 PM

Thanks Skip, actually I kind

Thanks Skip, actually I kind of planned on using this method, but what I really wanted to know is what size tank I should leave room for.

And yes Bob, I thought of that too.

Now that you guys have given me all these ideas, I have decided for the time being to make my sub a dynamic diver. Yes Bob, you finally convinced me My reason for deciding this is: one, the price, two I really, really want to have it running by the end of the summer. The nice thing though is that I can (or at least I think I can) later add a ballast tank since I'm using Greg Sharpe's cylinder.

So, any dynamic diver suggestions?

Jonathan

**bob the builder** · 01-07-2004, 05:46 PM

Good plan, Jonathan. Looks like

[color=#000000]Good plan, Jonathan. Looks like you've cut yourself down to three channels]

**uss silversides** · 01-07-2004, 08:04 PM

Well, I still plan to

Well, I still plan to use a 6 channel radio in the cylinder (for future subs). And I would like the stern planes operating off the radio. Oh, and the bow plane retract, which I already have worked out.

The only thing I really don't like is the waterline thing. I want my sub to look scale. Any ideas on how I could make it a scale looking dynamic diver? (probably a hopeless question)

**Guest** · 01-08-2004, 06:47 AM

Can I make a suggestion

Can I make a suggestion here?

Buy a different model!

Seriously.

Get yourself one of Skips kits (Albacore or Marlin), or perhaps the little Delphin from Norbert Bruggen.

This way you'll get into the water without too much hassle, and you'll learn what works and what doesn't.

At the moment, you have so many questions and doubts it sounds like you could easily be heading for failure and that can be disheartening.

Keep your Gato, and do it 'properly' when you have gained more experience and knowledge.

Cheers

Andy

**uss silversides** · 01-08-2004, 09:42 PM

OK, I admit, I probably

OK, I admit, I probably should have started with something a bit easier. But quitting would be almost as disheartening as failure. And even if I did start with something easier, I would not build from a kit. I enjoy building the hulls myself (so does my wallet ).

I really don't have a lot of doubts; its just that I want to do things in the best possible way.

You said it sounds like I could be heading for failure; what besides my numerous questions, makes you think so? From seeing my pictures, is there something I'm doing wrong on the hull?

Thanks anyway, I know you're just trying to help out.

Jonathan

**Guest** · 01-09-2004, 06:49 AM

Nope, the hull is just

Nope, the hull is just a shell. The real submarine is the WTC sitting inside it.

The reason I state you may be heading for problems, is that you are asking very basic questions, like calculating the size of the ballast tank, how to drive two shafts etc. etc.

No problem with that, after all that is what this forum is for.

But I personally think that these things should fall into the 'automatic' understanding category before taking on a scratchbuilt project.

A kit gives a good grounding, and can be quite cost effective in the long run. Plus if you make a good job of building it, you can always sell it on as a turnkey sub, probably for more than you paid for it.

Cheers

Andy

**uss silversides** · 01-09-2004, 10:51 PM

As I said before, I

As I said before, I really should have started with something easier. But even though I could start over with something new, that would be very discouraging to me.

And as far as asking a lot of simple questions, there seem to be a lot of simple answers, and I just want to go the best route (which is probably now]http://www.subcommittee.com/forum/icon_biggrin.gif[/img] ).

Let me ask another simple question. What would you guys do (as far as the dive system)? Maybe the best option would be get her finished and run her as a surface runner; get used to what works and what doesn't.

Need some advice from the experts here.....

Jonathan

**bob the builder** · 01-10-2004, 11:38 AM

A surface runner is really

A surface runner is really the same thing as a dynamic diver. If you're going to make the sub into a surface runner, it's not much more to allow it to dive dynamically.

Just make sure that all of your expensive electronics are sealed nicely and you should be fine.

**Guest** · 01-10-2004, 12:16 PM

If you're hellbent on sticking

If you're hellbent on sticking with the Gato, I'd recommend against a dynamic diver route.

Sure it's the simplest type of sub to make, however you'll have to run at a ludicous speed to get it to submerge and/or ballast the boat beyond it's scale waterline.

It's the wrong sort of boat for dynamic diving IMHO.

Your best bet is to see if anyone in the club (you are a member, right?) has the same boat as you, and ask how they set it up for static diving. This should put you in the right ballpark regarding ballast tank size, best choice of motor/drive etc.

Do bear in mind that a little boat like Norbert Bruggens Delphin would only take about a week of evenings to complete, and is a superb little dynamic diver (#### fast too).

Cheers

Andy

**uss silversides** · 01-10-2004, 09:12 PM

If you're hellbent on sticking

If you're hellbent on sticking with the Gato, I'd recommend against a dynamic diver route.

Sure it's the simplest type of sub to make, however you'll have to run at a ludicous speed to get it to submerge and/or ballast the boat beyond it's scale waterline.

It's the wrong sort of boat for dynamic diving IMHO.

You're right.

When I announced my intentions of making it a surface runner I guess I left out that I do also plan on eventually outfitting it with a ballast tank.

To reduce complications, I've also brought my channels down to 4.

Jonathan

Edited By USS Silversides on 1073783655

Ballast tank

Ballast tank

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