[PSUBS-MAILIST] Lurker finally surfacing!

Tue Aug 28 21:22:38 EDT 2018

Thanks Allen for that hull calculation!  I hope you're right!  I thought it might be shallower than that without reinforcement.  I've tried to build a good safety margin in all the parts on the boat (using thicker steel in the conning tower, for example, than what the K250 plans called for).  Still, this being my first boat I don't really want to go deeper than I could safely get up from on SCUBA (I've got a 2" flood valve if I ever need to get out while on the bottom).  Plus most of the sea life I'm hoping to see is usually in shallow water.  But you're right, little more investment now may make a difference if I decide to go deeper for some reason in the future.  
THANK YOU again and God bless, Jim   On Monday, August 27, 2018, 2:51:34 PM PDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi Jim,thanks for the introduction, and welcome along.Can't help you with the seals as my motors  are external.I have been making my own thrusters & have contacted seal reps &even emailed the manufacturer for advice on a non standard mountingmethod I was proposing. Normally seals are used on pumps to keepfluid that is under pressure in rather than out as in our case.I did a quick calculation on your pressure vessel & it came out as a 600ftcrush depth. Don't take that as gospel, but it may be worth looking at itin depth if you haven't already. If the 600ft is right you could dive to 300ftwith that hull! For all the work that goes in to building a submarine you mayfind that it is only a relatively small amount of extra effort & cost to giveyou an extra 200 ft of diving capability. I would think about this first beforechoosing a seal as the added pressure may have bearing on your choice.All the best,Alan (New Zealand)
On 27/08/2018, at 4:11 PM, james hughes via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Good evening All,

My name is Jim and I’ve been a lurker on this list for manyyears now.  Long before now I’ve intendedon making my presents known to the whole group (I’ve contacted several membersoff list over the years) but have always seemed too busy to do so… Well, nowI’ve pretty much got all the time in the world and am using much of it tofinish building my sub…

Here’s a little about me: I’m 56.  Retired navy Chief (I was a corpsman).  Just finished earning a BS in marine biologythanks to the GI bill.  Now I’m finallyfinishing the behemoth that’s been sitting in my brother’s backyard for nearly15 years now…

My boat started as a modified K250 (for which I haveblueprints) but morphed into something of a money pit since the day I saw andbought a “real bargain” (a giant pressure vessel) at a wrecking yard.  The pressure vessel that I’m using for myhull is 12.5’ long, 5’ in diameter and 5/8” thick.  It would have cost about $15K new, but I gotit for $300!  My boat will be named“Pipedream” when it’s done because my original idea called for the hull sectionbeing made from a piece of pipe.  I don’tplan on going deeper than 100 feet and will likely stay above 60 feet most ofthe time.
One of the reasons I’ve finally surfaced on this list is toask for help.  Does anyone have a workingplan / blueprint of a through hull connection for a drive shaft?  Or can someone direct me to one?  I’ve got a 10 horsepower motor for propulsionthat I plan on using to turn a 1 inch diameter, 5 foot long shaft with a 12”propeller.  I’ve read all I can findabout mechanical seals and watched all the youtube videos on them that I couldfind…. Can anyone recommend specific mechanical seals and bearings(manufacturer / source or catalog number)? My nephew in Texas works at a machine shop and assured me that with theequipment he has, that he can make anything I ask for if I can only get him a basicblueprint or plans for a part with the seals and bearings that I need inside.  I need to wrap up the issue with the throughhull ASAP as the guy who has done most of my welding is moving next month and Idon’t want to get someone new to put that part in (the welder I have is VERYgood at what he does).  I would be verygrateful if someone could help me with this particular issue.  Thanks in advance for any advice or help!God bless, Jim

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