Re: [PSUBS-MAILIST] propane tanks revisited

[MerlinSub@t-online.de (Carsten Standfuss)]

Hi Brian.. The small wall tickness is the problem.. 
..for a shallow dive depth sub or an ambient sub maybe.. 

>From the archive: 

What do you thing about the following estimate figures : 

1.) Sub with used propane tank hull : 
14250 $ and about 100 ft dive deep. 

2.) Sub with new propane tank hull : 
15100 $ and about 100 ft dive deep. 

3.) Sub with custom made shell : 
15101 $ and about 1000 ft dive deep.  

Dive deep versus the Dollars : 

No.1.) 152 Dollar per feet
No.2.) 161 Dollar per feet
No.3.)  16 Dollar per feet... 

...

Hmm - seems you save 3 hours for the longitudinal weld and 4 hours
for the cycle weld - but you waste 2 hours to cut one endcap from
the propane tank and give some extra hours for cleaning and 
sandblasting the old colour away.. .. you have to spent some 
extra money for more lead you need - because your propane tank 
shell is so light.. 

Another point: 

If you spent money for a good custom made hull - and save 
maybe money on the other equipment during building your sub 
- you can later spent additional money to purchase better 
or additional equipment - and you will get a better sub. 

If you purchase a cheap propane tank - to save money during 
construction - later no money, no time and even no better 
equipment will help to make the sub better. 

So again - what do you save - really ? 

see you - Carsten

> Brian Cox schrieb:
> 
> Propane Tank investigation:
> 
> I was explaning my design to my diving friend and he mentioned that
> since my pressure hull is around 28" in diameter that I might consider
> a propane tank.  I have always discounted the propane tank idea
> because I felt having to deoderize it wouldn't be worth the effort,
> but then we discussed buying a brand new one -never been used - from
> the factory.   I didn't think that would make any difference whether
> you were buyng a new one from the factory or having one rolled from a
> fabrication plant  -  but  -  he pointed out that since the propane
> tanks are mass produced that they are cheaper !  So I called a propane
> company that I know and sure enough they are a lot cheaper .  For a
> 250 gal  which is approx 30" X 7'  the cost was $850.00    compared to
> $2000.00 (a year ago) having it rolled at a fab plant.  I still have
> to find out the exact specs on the propane tank however,  I'm not sure
> on the thickness  and I haven't confirmed the grade of steel.
> 
> Brian