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I would think the distortion factor might outweigh the
costs involved??
Rick
Sent: Tuesday, March 15, 2011 6:36 AM
Subject: Re: [PSUBS-MAILIST] Main Tanks Question
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> 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 -----
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
About 4400 pounds.
----- Original Message -----
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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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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