I just wanted to second Dan's comment about considering polycarbonate (eg.
Lexan) instead of acrylic (eg. Plexiglas). For applications in which you are
not constrained by pressure differentials or optical requirements for
acrylic's refractive index, PC is a much tougher transparent plastic than
acrylic.
-Sean
On Tuesday 15 March 2011 09:36:14 you wrote:
> James,
> I think the acrylic forward main ballast tank is an idea worth trying.
> It is something I have thought of doing to my K-350. As far as
> durability goes I do not think acrylic would be too much worse then
> fiberglass. I encountered a situation while recovering my 350 one day
> where the seas picked up pretty good. The load line on the crane was
> just slack enough for my sub to come up under the stern of the boat. The
> boat being heavily built out of steel did not even flinch the fiberglass
> MBT shattered like an egg shell. Luckily no one was in the sub.This is a
> good reason to have a way of securely dogging the hatch from the
> outside. The MBTs I have were built by George Kittredge so I assumed
> they were made as well as they could have been.
> The most expensive part of making an acrylic MBT is the "form" you will
> need. If it was me I would form the MBT in one piece. Use the K-350
> drawing that gives you the best top looking down view of the forward
> MBT, scale up the dimensions and cut the outline on a piece of 6mm
> steel plate. For a one off maybe you could get away with using a thick
> piece of plywood. You will probably have to start with 10mm acrylic
> because of the thinning that takes place at the apex of the finished
> object. When you are done you will have a thick outer perimeter where it
> really counts.
> Greg Cottrell is the expert in this field maybe he will get involved in
> this discussion. I hope I have not given you any bad advice as far as
> the fabrication aspects.
> Dan Lance
>
> On 3/15/2011 5:57 AM, James Frankland wrote:
> > 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
> >> > <mailto: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. <mailto:Jumachine@comcast.net>
> > *To:* personal_submersibles@psubs.org
> > <mailto:personal_submersibles@psubs.org>
> > *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 -----
> > *From:* James Frankland <mailto:jamesf@guernseysubmarine.com>
> > *To:* personal_submersibles@psubs.org
> > <mailto:personal_submersibles@psubs.org>
> > *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
> >> > <mailto:Jumachine@comcast.net>> wrote:
> > About 4400 pounds.
> >
> > ----- Original Message -----
> > *From:* ojaivalleybeefarm @dslextreme.com> > <mailto:personal_submersibles@psubs.org>
> > *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
> >> > <mailto:landnsea1@hawaiiantel.net>> wrote:> > <mailto:Alec.Smyth@compuware.com>
> > 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
> >
> > *From:* Smyth, Alec
> > *Sent:* Friday, March 11, 2011 5:51 AM
> > *To:* personal_submersibles@psubs.org> > <mailto:personal_submersibles@psubs.org>
> > <mailto:personal_submersibles@psubs.org>> > *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
> >
> >
> > The contents of this e-mail are intended for
> > the named addressee only. It contains
> > information that may be confidential. Unless
> > you are the named addressee or an authorized
> > designee, you may not copy or use it, or
> > disclose it to anyone else. If you received it
> > in error please notify us immediately and then
> > destroy it.
> > *From:* owner-personal_submersibles@psubs.org
> > <mailto:owner-personal_submersibles@psubs.org>
> > [mailto: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************************************************************************
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