sub newbie

[jk6672]

I just wanted to say hi and get some advise from the experienced guys.
I ran across this site looking for a sub other than the kiddie toys that I’ve been playing with and I'm finding a whole new world out there I didn't even know existed. I just like subs plain and simple and I would like to venture off the deep end and build my first r/c sub. I'm really not sure where to begin. As a beginner I want something that is relatively easy to assemble for the beginner that I am and will function correctly without to much discouragement for being my first. After looking at a few things I think I would like to use a ballast type system instead of the dynamic divers that I thought I would try first.
It also seems that there are various choices for a ballast system. Which type is preferred?
Are there any websites besides the ones I’ve ran across doing a search for r/c submarines on the web? Does anyone have any comments on this sub by ThorDesign http://www.thordesign.com/alfa.html
As I said I’m a beginner and have never built anything except car and plane models as a kid, but I feel I’m up to the challenge.

[captain nemo12]

Hello!

I hear the Thor

Hello!

I hear the Thor Alfa is a good choice for a beginner kit(correct me if I'm wrong guys ) well, I started the hobby with a dynamic diver and am planning to build a static one. I also heard that you could convert cheap plastic sub kits on the market into good looking RC ones. I also think the Robbe U-47 should be a good choice too! Anyways, if you've thought about starting out in the hobby, you are at the right place! Enjoy your stay.

[safrole]

I vote Robbe U-47 (big

I vote Robbe U-47 (big surprise). You get a low entry fee without sacrificing the ability to upgrade later.

I opined on the ballast system question over in the R/C forum. Here is the link to Subconcept's upcoming dive module that inspired that post.

http://www.subconcepts.com/product_p..._ADM_Lite.html

[JWLaRue]

Welcome to a very exciting

[color=#000000]Welcome to a very exciting and interesting hobby!

Please don't be surprised if you get many different answers to your questions...everyone has their own preferences and biases.

The best advice that I believe you will receive is]

[jk6672]

Thanks for the info. The

Thanks for the info. The SubTech Albacore was another choice I had in mind.
Out of the different ballast systems which is the most reliable and the lest expensive to maintain?

[david h]

Have you thought about the

Have you thought about the Sheerline system with the pressurised ballast tank. Very simple.

regards,

dave h

[jk6672]

No, where can I read

No, where can I read about it? Do all these systems have a fail-safe, or is that something you have to do separately?

[JWLaRue]

JK,

>>> Out of the different

JK,

>>> Out of the different ballast systems which is the most reliable and the lest expensive to maintain?

Oh, boy....this will be an interesting discussion!

There are pros and cons to any ballast system and like your question on a good starter kit there will be a whole host of different opinions and quite strong biases. Part of this is due to how each of us might define "reliable and least expensive" for maintenance.

Here's my contribution the discussion:

(We're only talking ballast system types here....not dive module manufacturers, etc.)

The principle ballast system types are:

Propel-based systems - generally very easy to use and maintain. The most common systems use Schrader valves that are actuated via the servo to vent and blow. Seasonal maintenance of the servo linkage seal(s) is generally a good idea. Those who prefer other ballast systems will point out the cost of the Propel and the fact that if you run out of Propel and you're on the bottom, you cannot surface the boat unless you can drive it to the surface. Also it should be noted that as you use Propel, the trim of the boat will change...getting lighter each time. This can be considered a good thing if one starts out with the boat trimmed out to 'periscope depth', thus making it harder to place the boat on the bottom with an empty Propel tank. A good reliable ballast system.

CO2-based systems - not recommended for the beginner! The high pressure of liquid CO2 requires care in handling. Similar to Propel except that a tank of CO2 will likely last you through an entire weekend (or more) and will have virtually no effect on the trim of the boat. Most systems of this type that I've seen use a solenoid valve to control the blow. As long as the high pressure components are maintained properly, these also are very reliable ballast systems.

(Open) Pump-based systems - these systems do not 'suffer' from the change in trim that is part of a Propel-based system however in order to blow the ballast tank, you need to drive the boat up near the surface to get (usually) a periscope exposed....which is actually an open tube that the pump uses to draw in air to empty the tank. Other than the occasional maintenance of the pump seal...no real problems. As to working reliability, also tends to be very good.

Pressurized pump-based systems - similar to the open pump-based systems, these use the dry space of the dive module to 'hold' the air of the ballast tank (when the tank is full of water). The pump typically forces water into the ballast tank, with the air allowed to escape into the dry spaces through a small opening. These systems usually have a 'dive management' system...a piece of electronics....to control the system, including a low voltage gate that forces the tank to empty if there's not enough battery power left...esssentially forcing the boat to surface. Other than annual maintenance of the hose fittings, typically none required. Those that have this system consider it to be quite reliable.

Engel piston-based system - possibly the most mechanically complex type of ballast system, but if the piston tank is purchased (e.g. through Engel) most of the work is done for you. These systems are used in *dry* hull boats....meaning that there is little to no free flooding space within the hull. The air space in the hull is used to take up the air from the piston tank when water is forced into it. (Similar to the pressurized pump-based systems) The downside to this is that the overall weight of the boat is greatly increased in order to counter the extra buoyancy of all the extra 'dry' space. There is a principle advantage in the use of this system - namely the ability to adjust the ballast tank (water) volume to hover the boat at a given depth. Only the pressurized pump-based system can come close to this type of fine control. While this is a somewhat more complex ballast system, the maintenance is only slightly higher than that of the pump boats. The piston seals need to be maintained as does that of the inegrity of the dry hull.

.....okay, that's enough for a once-over. I know that others will chime in with their views on this subject!

-hope this is useful,

Jeff

p.s. There are other ballast systems out there, for example Art Broder has created a very nice system using an inflatable bladder...essentially a variant on the pressurized system...only instead of creating an over pressure, this system creates a negative pressure. (Art: if I've got that wrong, please correct me!) In any case, the above are the main system types that I am aware of.

[Guest]

Jeff, and others interested in

Jeff, and others interested in ballast systems,

Thanks for mentioning the RCABS, or Recirculating Compressed Air Ballast System. It is the Simple Ballast System that is described in the most recent issue of the Report. Issue 56, p 50.
Basically, a small onboard 6V air compressor pumps air from the rigid WTC out to a rubber (Neoprene) bladder in the wet hull, forcing water out of the wet hull. Sub surfaces. The air is then released (recirculated) back into the WTC allowing the sea water back into the wet hull. Sub submerges.
Simple, inexpensive to make and maintain, and fun to watch it work. See it at the Subregatta in RI this July 24 & 25th. Also see Documents on My Webpage

[captain nemo12]

Hi Jeff,

You forgot about the

Hi Jeff,

You forgot about the membrane ballast tanks, these tanks use a flexible membrane, a motor and thread to push the water in and out, I saw this system on the Subs on Display page. From these principle systems, there are different variations of them, I believe the membrane ballast tanks are based upon the piston ones. Subs on Display

[thordesign]

While I would love to

While I would love to sell you an Alfa, in my opinion, Skip Asay's Albacore is BY FAR the best beginners model out there. Nothing comes close to it, if you ask me. Skip spent years working out the kinks in that boat. I do not think that can be said of the other vacuum formed boats on the market.

[JWLaRue]

>>> You forgot about the

>>> You forgot about the membrane ballast tanks....

Depends on how you 'classify' ballast systems.

As I noted in my earlier response, I place the membrane-based systems (including Art's RCABS) in the same *general* category of the pressurized ballast tank systems. True, not all of them rely on a pump, but we're talking basics.....as well as what are perceived as the more common ballast system types.

-Jeff

[anonymous]

I have been reading the

I have been reading the various replys to your post, and as you can see, ask a hundred guys, get a hundred opinions. Jeff LaRue gave a very good overview of available options, and Dr.Art Broder and Matt Thor are giants in the field. I would sure listen very carefully to Matt Thor when he recommends Skip Asays Albacore. It gives you a fast and inexpensive way to build a very successful model without breaking the bank. When you have a little sub driving experience under your belt, you will build other boats, and for them I highly recommend Art Broders RECAB ballast system. I'm using it in an Engels boat that I am rebuilding, and think it's the most foolproof, reliable, maintenance free, and inexpensive system out there.
Good luck...keep it simple and your gonna love this !

[david h]

The sheerline system is also

The sheerline system is also that used by OTW. Look up their website and you will see pictures of the set up. Have a look at Dean Naibs site on RC boats and look at the Sheerline Akula and there are some good photo's of the set up.

It is simply a sealed tank with one inlet that is attached to a windscreen wiper pump. The line froom the tank to the pump has a servo with a roller attached to the arm that "pinches" it. The Servo arm moves to one side pushing a switch that turns the pump on. The pump forces water into the tank, pressuring the air behind it,The servo arm returns to the pinch position and holds the water inside the tank. The boat is dived, the servo arm is then moved in the opposite direction and the pressuried air forces the water out.

It is very simple to make ,simple to operate and very reliable. and for some reason not very popular in the states, I don't know why? It's only real drawbacks are that it is quite a drain on the battery and that it is a slow system especially to surface. i haven't had any problems with it.

regards,

dave h

[safrole]

Hey the Engel website (here)

Hey the Engel website (here) says they have sold 30,000 piston tanks. Of course that doesn't make them the best, but it does say they must be doing something right, and for some time.

Here is a page where you can see an installation in a Robbe U-47. (It hasn't been updated for a while, sorry.)

http://www.modelbrass.com/U47Modifications.htm