Solomon - Anyone Else,
This is input on an earlier topic.
I work for Sea Ray Boats in materials development and tool fabrication and before that I worked for ATK Composites before that working composites for the Rocket Motors for Boeing and Lockheed and Aircraft Structures for Vought Aircraft and Northrup-Grumman.
You asked how deep can they go? Answer - It really depends on how much time, effort, and money your willing to spend. Composites are incredibly more complex and fickle than just using isotropic (this means having material properties the same in all directions - ie strength and stiffness) metals or plastics.
Alot of variables tie into making successful composites - especially when these are loaded structures and your life may count on it. Without "FULLY" understanding the material your using and it's capabilities I would never recommend using this in this application.
Am I saying that composites are a bad choice for this application - No. Materials have to be tested and qualified - period. This means coming up with a Laminate Design that can withstand the pressures that it will be experiencing. Note: Laminate refers to how many layers of fiberglass/carbon fiber your using and the directions the fibers run (generally they refer to these as 0/+45/-45/90 directions relative to a given direction - ie bow to stern).
Using fiberglass in this application needs to be engineered and tested!
______________________________________________
This part is technical:
Generally Fiberglass has a coating on it called sizing. This material helps resin (polyester, vinylester, or epoxy) bond and stick to the Fiberglass. Not all resin to fiberglass sizings are compatible. What does this mean - this means that even though it may "look" like a solid laminate with no air or voids in it, it may significantly underperform.
There are individuals that can run the engineering numbers on what the layup should be. But without good testing you'll never know until it's possibly too late. Is this a risk anyone is willing to take?
Metals and Plastics have been run through so much testing and materials are manufactured to standards that provide for reliability and acceptable use.
Using composites (fiberglass) can be used if done right, but BEWARE if you don't follow the right precautions - it's like Russian Rullette. Did I mention - Composites have very poor impact resistance and foregiveness (don't run it into anything) -> flaws may develop that you can't even see.
_______________________________________________
As Ray shows the pressure increases very rapidly with depth. The Bionic Dolphin probably doesn't go very deep because they don't trust it and if there is a failure they may be able to escape.
Any comments are welcome.
Wish Everyone Luck,
Loren
Daniel Lance <lanceind@earthlink.net> wrote:
Solomon,
To be even more precise,
.445 psi per foot of saltwater
.433 psi per foot of freshwater
or just a rough rule of thumb to make quick calculations: 1/2 psi (.500) for
every foot of saltwater.
If you are planning on going much further with a sub project take Ray's
advice and attend a basic scuba class. It will be money well spent.
Dan Lance
> From: Ray Keefer
> Reply-To: personal_submersibles@psubs.org
> Date: Thu, 12 May 2005 18:03:07 -0700 (PDT)
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Fiberglass submersibles inquiry
>
> Hi Solomon,
>
> Water pressure in salt water at sea level is:
>
> 0fsw (feet deep salt water): 1 atm
> 33fsw: 2 atm
> 66fsw: 3 atm
> 99fsw: 4 atm
> and so on
>
> 1 atm is
14.7psi (pounds per square inch)
>
> A good scuba class will cover these basics.
>
> Regards,
> Ray
>
> --- solomon D wrote:
>> I know that laminate hulls for submersibles are not
>> a
>> good idea. I have always liked the bionic dolphin
>> project though and I was wondering what the max
>> depth
>> it can safely reach is? They list something like 10
>> feet on innespace's website. I wanted to get other
>> peoples opinions on the subject however. The hull is
>> laminated fiberglass and carbon fiber I am not sure
>> about the reinforcing structure, it has a 3/4" thick
>> F16 acrylic canopy.The bionic dolphin is very
>> positively bouyant and uses horse power to shove it
>> underwater.So how deep do you think it would dive
>> before the canopy or something else gave way?
>> Supposing
that the engine could run for an extended
>> period underwater (which obviousily it cant).I am a
>> complete newbie at this sub stuff so please forgive
>> my
>> ignorance. I also wanted to find out what kind of
>> pressure water exerts on the hull at a depths of
>> 10,20,30,50 feet etc. I cant seem to find a website
>> to
>> explain it thourghly. Do not worry I am not planning
>> on building anything to kill myself in ;I would just
>> like to educate myself on this subject.
>>
>>
>>
>>
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