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RE: [PSUBS-MAILIST] Main Tanks Question

I would avoid this, you should build a boat of any kind to get seriously banged around no matter how tenderly you may intend to treat her. Snoopy has had her front claw entirely ripped off, shearing three quarter-inch bolts in the process, in a grounding while under tow. The MBT scraped and gouged against rock walls. Minor bangs against piers, trailer, and support vessels. The viewports are two inches thick, and in a less exposed spot, but the probability of a thin acrylic MBT holding up would have been 50/50, and a breached MBT is a serious problem.
 
Alec

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Frankland
Sent: Tuesday, March 15, 2011 5:57 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Main Tanks Question

Hi Dan\Glen.
 
i think saddle tanks would have been the best way to do things.  Similar to Nemo sub.  But ive already made the through hulls for the standard tanks and i dont want to start cutting into my hull again, im done with all that now so im just going with what i have.
 
Im investigating if its going to be financially viable to have a clear forward tank made.  I cant do it myself so i'll have to get a company in the UK to do it.  I'm thinking It could be made in sections and glued together to make it easier to fabricate.  Stachiw's book shows an acrylic sphere that was made in sections, glued together and tested to destruction.  It did not fail at the glued joints.
 
The one thing im concerned about is that the entire tank may be too brittle and crack if crashed.  At least glass fibre has a bit of give in it.
 
Anyway, im waiting for some companies to get back to me with some prices.  Will probably be too expensive.
 
Regards
James

On 15 March 2011 06:18, Glen Brown <gbrown091@gmail.com> wrote:
James
Acrylic saddle tanks could be a way .One could purchase acrylic tubing  this way one  could monitor the contents ,have more stability and better view ,even if its slightly distorted.
Glen
----- Original Message -----
From: Dan H.
Sent: Tuesday, March 15, 2011 12:44 AM
Subject: Re: [PSUBS-MAILIST] Main Tanks Question

James,
 
A clear forward MBT sounds real interesting.  Most of the time you'll be looking down but to have a totally unobstructed forward view would be nice.  You should be able to vacuum form something from sheet material.  It would take a big oven and a pretty elaborate pattern to form into.  It would probably just about disappear in the water.   Look into Lexan also.  I've formed it in small molds before and it works well.  It's tougher and shouldn't be as prone to cracking. 
 
Forming big parts from plexi or Lexan probably isn't easy but neither is making molds and laying up all that fiberglass.  Maybe Greg Cottrell can advise you. 
 
Dan H.
----- Original Message -----
Sent: Monday, March 14, 2011 7:35 AM
Subject: Re: [PSUBS-MAILIST] Main Tanks Question

Hi Dan\all,
 
I dont actually know what im going to do with the main tanks yet, so i think i'll make them first and then fabricate the mounting arrangement afterwards.

>I discussed my MBT alterations with Kittredge before I built them.  He cautioned me to be careful enclosing to much of the bottom so I wouldn't find myself in a situation where the sub was nose or tail >up like a buoy, with no way to vent the air from the upper MBT and no way to hold air in the lower MBT.  
 
Yes, i'd heard of that somewhere before, maybe from you.  Makes sense.  I'll do the same as you with the vent holes. 
 
What about this for an idea?
 
As you probably know, ive modified the front viewport to be a large dome.  I've been thinking of how i can make the main tanks as near to the originals as possible but without losing visibility through my port.  How about getting the orward main tank fabricated completely from say about 1/2 inch clear acrylic and having a completely clear front main tank.  Protect the tank with some crash bars.
 
Otherwise glass fibre tanks with maybe some acrylic ports on similar to Doug Privit's sub Delta.
 
Any thoughts on that anyone? Completely clear main tank made out of acrylic.  Sounds expensive.....
 
James
 
 
 
n 13 March 2011 15:03, Dan H. <Jumachine@comcast.net> wrote:
About 4400 pounds.
 
Sent: Friday, March 11, 2011 11:07 PM
Subject: Re: [PSUBS-MAILIST] Main Tanks Question

Off the subject, but how much do those K boats wiegh on land?
 
Brian

On Fri, Mar 11, 2011 at 9:22 AM, Land N Sea <landnsea1@hawaiiantel.net> wrote:
Hi James,
 
I am building a K-350 and have always admired Dan H. beautiful job he did on his MBT,s. I was planning on glassing in the bottoms of mine as well with a 6" opening in the centers  or one in the front and one in the rear of each one to prevent the "burping action" when towed by a boat.
I see what you were saying about where the MBT,s interface with the pressure hull as well as the problem with the strap that holds them in place.
I have done some glass work in the past but wasn't looking forward to this step in the future as I don't think I have the talent to make the finish look as nice as Dan's but what the heck.
I would love to see any/all pictures of your MBT,s  and any advice on how you formed them, got a fair front curve on them etcetera.
 
Thanks
 
Rick Patton

Sent: Friday, March 11, 2011 5:51 AM
Subject: RE: [PSUBS-MAILIST] Main Tanks Question

James,
 
I have the standard tanks, but based on using them this is one area where I would suggest you consider a significant departure from the plans, and not just to make them look better. Specifically, I would close the bottoms and provide downward stovepipes. But you will find that hard to do with the standard method of attaching the tanks with a strap around the hull (I actually glassed in the bottoms in an attempt, but ended up undoing it). I would suggest giving the tanks three sides and a bottom, as opposed to using the pressure hull as one of the sides, and bolting them from underneath over supports that will need to be a little different than the standard ones. Just something to think about.
 
Thanks,

Alec


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From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Frankland
Sent: Friday, March 11, 2011 9:49 AM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Main Tanks Question

Hi All.
 
Im finally at the stage where i am starting on my main tanks.  Ive decided just to stick with the ordinary ones shown on the plans, but i'd like to jazz them up a bit like Dan H has done as i think they look a lot better.
 
Question is:  For those of you who have "modified" K350 main tanks, did you make the framework as per the plans and adjust the tanks to fit, or make the tanks first, and modify the framework to fit the new shape.  I suspect the latter.  I was hoping to be able to get the metalwork complete and then get the sub painted.  If i have to make the tanks first, it will mean more time unpainted.  Anyway, any thoughts suggestions always welcome.

Many thanks
James