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New to the Forum... and to Subs

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Re: New to the Forum... and to Subs

Postby Sub culture » Thu Mar 07, 2013 5:20 pm

The answer to all those questions, is yes.

With a wet hulled vessel, the hull shape has an affect on the dynamic handling characteristics, and I suspect the Surcouf will be a bit of a pig in this regard. That is where the influence ends however.

Some modellers still prefer to use the hull as a pressure vessel with flat hatches bolted down to seal it. It does work, but I don't like that method of constuction
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Re: New to the Forum... and to Subs

Postby Lash151 » Thu Mar 07, 2013 5:44 pm

What are the main problems with using the hull as the pressure vessel? It does seem like a more natural thing to do...
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Re: New to the Forum... and to Subs

Postby JWLaRue » Thu Mar 07, 2013 6:39 pm

Lee,

Yup!

-Jeff
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Re: New to the Forum... and to Subs

Postby Lash151 » Thu Mar 07, 2013 8:01 pm

JWLaRue wrote:Lee,

Yup!

-Jeff


Hi Jeff... Do you mean you agree with me about dry hulls being the natural choice?? I would be interested to hear from someone who likes the hull being the pressure vessel.
Lee
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Re: New to the Forum... and to Subs

Postby JWLaRue » Thu Mar 07, 2013 9:47 pm

Lee,

Sorry, I wasn't clear. (Obviously!)

I was agreeing with your statement that the r/c sub is the sub is just the WTC. Of course the WTC could be the hull in the case of a dry hull.

I'd offer the observation that the choice of wet vs. dry hull depends on a couple of factors. For example, the larger the sub the heavier it's typically going to be. On the other hand, for smaller subs, the weight penalty is pretty much offset by being able ti use the entire interior of the hull for the operating components. For those looking to buy a hull kit, the choice may be made for them if the type/class of sub is only available in wet- or dry-hull. Another factor for some in choosing the wet-hull is that the dive module can be moved from hull to hull, thus reducing the cost associated with having a fleet of r/c subs.

Curiously, there is a definite preference 'split' between folks in North America (wet hull) and continental Europe/Germany (dry hull). I suspect this has at least something to do with what vendors were available to the local modelers.

-Jeff
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Re: New to the Forum... and to Subs

Postby Sub culture » Fri Mar 08, 2013 9:40 am

Lee, go and build the boat e.g. the hull. Build it so it separates equatorially, like the OTW hull. Decisions on what dive system/pressure hull to use can be taken when the hull is complete and ready to be fitted out.
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Re: New to the Forum... and to Subs

Postby Sub culture » Fri Mar 08, 2013 10:24 am

What do you mean by 'build half the hull'?

If you want to make a GRP hull, you have to build the whole hull, unless what you're building is totally symmetrical, and the Surcouf is nothing of the sort I'm afraid.

GRP is a very good material to use in sub construction , but I've seen good subs made from all manner of materials. It's best if you choose a material you are experienced and comfortable working with. If that is wood, then use it, just make sure you seal it very thoroughly.
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Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: New to the Forum... and to Subs

Postby Lash151 » Fri Mar 08, 2013 10:26 am

Sub culture wrote:What do you mean by 'build half the hull'?

If you want to make a GRP hull, you have to build the whole hull, unless what you're building is totally symmetrical, and the Surcouf is nothing of the sort I'm afraid.

GRP is a very good material to use in sub construction , but I've seen good subs made from all manner of materials. It's best if you choose a material you are experienced and comfortable working with. If that is wood, then use it, just make sure you seal it very thoroughly.


Hi... yes, I deleted that post...sorry, i was talking rubbish...
Lee
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Re: New to the Forum... and to Subs

Postby Chuck Chesney » Fri Mar 08, 2013 11:47 am

Hi Lash,
Just to give you a little real life perspective on the wet hull/dry hull issue, my favorite sub, an Engles Patrick Henry SSBN, has been both. It started life as a stock dry hull, piston ballast tank, 6 volt boat. In that iteration it worked fairly well, but it was HEAVY. With a dry hull, the opposing forces of buoyancy and the need to provide weight to allow the model to submerge and maintain a proper surface waterline result in a very heavy boat.

About ten years ago I decided to convert it to a wet hull, 12 volt system. I have used a home built WTC in it ever since, with a couple of ballast systems including a RCAB, SNORT, and water displacement pumps, with good results from all of them. By using the wet hull scheme the weight of the boat was reduced by about fifty percent, the ability to dive and surface has been dramatically improved, and surface waterline fidelity is easier to achieve and maintain. The wet hull system simply works better in my opinion. The exterior hull does,in reality, become a fairing, while the WTC is the actual submarine. That makes maintenance and modification of various components much easier, and helps to prevent built-in obsolescence.
I am a firm believer in the wet hull system, and you might consider it in your final building plans although I know that dry hulls are a very popular option in the UK and mainland Europe.
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Chuck
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Re: New to the Forum... and to Subs

Postby Lash151 » Fri Mar 08, 2013 12:04 pm

That is great, it does make a lot more sense to go the wet hull route.

I found this video series on the web. Episode two explains the lost foam process... I really like the look of this method.
You guys probably already know all about this, and probably seen the video...
http://www.youtube.com/watch?v=mjmYb1qG870
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Re: New to the Forum... and to Subs

Postby Sub culture » Fri Mar 08, 2013 12:32 pm

I actually consider the Engel Gato to be a wet hull sub- as much of the hull free floods. They just use a large box inside, which makes for a chunky boat. A truly dry hull boat has no free flooding areas in the hull.

Although the Gato has been revised over the years, the design of that kit dates back to the 1970's, which meant lead acid batteries for any decent running time- compare them with modern lithium batteries which offer about seven times the density. Not easy to see how you can shrink down the space required. Plus it's a virtuous circle, as a lighter boat will need less shove to get it moving, so you can usually use more modest motors etc.
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: New to the Forum... and to Subs

Postby Lash151 » Fri Mar 08, 2013 12:41 pm

Sub culture wrote:I actually consider the Engel Gato to be a wet hull sub- as much of the hull free floods. They just use a large box inside, which makes for a chunky boat. A truly dry hull boat has no free flooding areas in the hull.


So you could have a box area which is built into the hull and the rest of the boat free flooding?
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Re: New to the Forum... and to Subs

Postby Sub culture » Fri Mar 08, 2013 1:31 pm

Yes.
'Why are you staring at an empty pond?'

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Re: New to the Forum... and to Subs

Postby Thor » Fri Mar 08, 2013 3:38 pm

Wood makes a great material for a surface hull, and a terrible material for a submarine. If you can work up a wood pattern, spend a few extra days and pull a quick FRP mold off of it and lay yourself up an FRP hull. That is how I would do it, but that is just me!

Matt
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Re: New to the Forum... and to Subs

Postby Lash151 » Fri Mar 08, 2013 3:52 pm

Hi Matt... yes, I am thinking that wood might not be a good idea. I was erring towards making the hull using the lost foam method... That seems like a good way to go... and within my capabilities. I posted a Youtube video earlier of someone making a very good job of a hull this way.
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