[PSUBS-MAILIST] GRP hatch

Wed Apr 29 04:04:38 EDT 2020

Hank, which sub is this?  Are you doing another along with elementary?

On Tuesday, 28 April 2020, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alan, true. I am going to put the hull together and throw it in a pond
> with enough weight inside and outside to sink it.  I can hang it off my
> excavator to add weight in stages.  This way I can experiment with it to
> find the sweet spot.  That is the nice thing about this sub-it is so light
> and tiny.
> Hank
> Got the new leg tube on today
>
> On Tuesday, April 28, 2020, 12:44:56 PM MDT, Alan via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hank,
> if it were me I would test it out with a support person & push the conning
> tower from side to side at various stages of descent & ascent.
> If you know it can't turn completely upside down & you are comfortable, or
> get used to it you might want to live with it. After all it's only a few
> seconds of
> instability over the period of the dive.
> Alan
>
>
> On 29/04/2020, at 6:27 AM, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alan, that is exactly the idea I have.  The MBT's can be in an L shape
> with a smaller portion extending part way up the CT. Or like you said an
> independent MBT behind the CT, you can't see behind anyways.  The CT is
> buoyant under water by about 80 lbs so its just a matter of getting under.
> Hank
>
>
> On Tuesday, April 28, 2020, 12:11:15 PM MDT, Alan via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hank,
> what about a ballast tank behind your head outside the conning tower.
> From memory you would probably have the same problem but just not
> as bad if you lightened the hatch.
> It looked to have a lot of floatation in the conning tower area, so you may
> topple over but not turn upside down. Dive & ascent really quickly?
> Alan
>
> On 29/04/2020, at 3:28 AM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hank,
>
> I'm only aware of a couple of subs with composite hulls, and the thing is
> I understand them to be not hand laid but constructed by the
> computer-controlled spinning of a single strand on a big megabucks machine.
> And even then, I'heard they discovered voids when cutting the hull open.
>
> The trick might be just to concentrate on emptying those MBT really fast
> by using bigger valves or more of them. That, or an MBT design that reduces
> the free surface area during diving, or which divides the surface areas
> into smaller ones via internal MBT bulkheads. I'm guessing you have
> something like that in mind?
>
>
> Thanks,
> Alec
>
>
>
> On Tue, Apr 28, 2020 at 10:13 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alec, yes it is a bit out there.  I was thinking I would clamp one to the
> K350 hatch and sink it to test depth for testing.  I figures if there are
> GRP hulls then why not a hatch.  I do have a design for MBT's that could
>  solve the problem.  The sub is fine when submerged.  Maybe that is the
> safest solution
> Hank
>
> On Tuesday, April 28, 2020, 8:05:13 AM MDT, Alec Smyth via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi Hank,
>
> Personally I'd have to research stress calculations in GRP before going
> that route. But even once that were figured out, the build variations in
> hand-laid GRP would make me sceptical of my own calculations. I suppose the
> alternative would be to make a number of them and test to destruction. It
> would have to be a number of them, not just a single sample, because
> evaluating standard deviation would be just as important as confirming the
> depth rating. That's rather painful, so for my part I'd look at
> other solutions.
>
> Thanks,
> Alec
>
> On Tue, Apr 28, 2020 at 9:50 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alec, I think Mike has a submarine parts warehouse lol.  I would like to
> use what I have, just so I don't have to make too many major
> modifications.  Have you ever heard od a GRP hatch?
> Hank
>
> On Tuesday, April 28, 2020, 7:44:51 AM MDT, Alec Smyth via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hi Hank,
>
> May I suggest speaking to Mike Caudle? He has two acrylic cylinder CTs,
> complete with hatches and all, that are beauties but I believe much lower
> displacement than the one on your project sub, and very lightweight because
> they are aluminum. If you can arrange a swap or something, one of those
> might be just what you need.
>
> Best,
> Alec
>
> On Tue, Apr 28, 2020 at 9:17 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi All, I am have some real trouble with my DW style sub mods. If you
> recall it has an acrylic cylinder CT and a K350 hatch.  My problem is, the
> sub lacks volume to support the heavy hatch\land assembly.  I do plan to
> increase the volume by installing a larger diameter leg tube.  This volume
> increase is still not enough to give me enough buoyancy for stability
> during transition from surface to being submerged.  Options are to loose
> the cylinder and go with dome.   Make a lightweight hatch with GRP, or come
> up with a creative MBT that maintains buoyancy longer during submerging.
> Hank
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