[PSUBS-MAILIST] Alec's test

Fri Apr 14 08:41:04 EDT 2017

Oh I'm not celebrating yet - the sub hasn't made any dives! I was just
puttering around on the surface and only submerged in shallow water where
there were still six inches of the CT showing when I reached the bottom. It
might have been possible to dive, but I'd rather try it once the
water-blocking issue in the plumbing is addressed.

On Thu, Apr 13, 2017 at 11:24 PM, Alan James via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Congratulations Alec,
> How deep did you dive? Are you busy selecting a sound track for the video?
> I am wondering if you were turning toward the tunnel thruster because
> thrust can
> push out to the side without the restraint of a kort nozzle!
>    I have done a preliminary drawing for a solenoid operated ballast valve
> based on the top hat design that Vance gave out in Islamorada. With it
> being
> electrically operated you could control it with a gyro sensor using a board
> that controls quad copters. That way at the flick of a switch you would
> descend horizontally. (in theory).
> Did you use the new lights?
> Cheers Alan
>
>
> ------------------------------
> *From:* james cottrell via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Friday, April 14, 2017 2:58 PM
>
> *Subject:* Re: [PSUBS-MAILIST] Alec's test
>
> That sounds great Alec! Congrats on a great build. I'm sure you'll iron
> out the minor venting issue.
>
> Greg
>
> ------------------------------
> *From:* Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.
> org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Thursday, April 13, 2017 10:47 PM
> *Subject:* Re: [PSUBS-MAILIST] Alec's test
>
> Hi Greg,
>
> Well here's how it went - much better but there's one more issue to
> resolve.
>
> The change to a raft configuration for the MBTs has solved the surfaced
> stability issue. It was great, I could walk around to any edge of the deck
> without excessive list. The longitudinal trim was slightly down by the
> stern when empty, and trimmed out to perfectly level when a person was
> lying in the front half of the boat (stability was calculated for the boat
> with crew). She floats in water only just over waist deep, 38 inches, and
> the freeboard is 24 inches. The thrusters and their controls worked
> beautifully, and the "tank drive" is really, really intuitive.
>
> After launching I drove around on the surface a bit. I didn't get a
> measurement of speed but would say while slower than a K350 she's decidedly
> faster than Snoopy. I tested a prototype kort nozzle by mounting it on one
> of the stern thrusters only and then giving both thrusters equal throttle,
> to see which way the boat tracked. Surprise, the un-shrouded original prop
> was more efficient because the boat would turn toward the side with the
> kort. So I'm just going to put on standard prop guards, at least for now.
>
> Part of the surface running I did lying down and looking through the bow
> dome. The view is ridiculously good! From the CT it wasn't bad either, and
> I was surprised how the flat domes made objects appear closer, something I
> didn't recall from the flat bow dome in Snoopy. In this one, the leading
> edge of the deck as seen through the CT viewports seemed only a foot away.
> The dome is something else entirely, and optically seemed to have the
> opposite effect of making things appear further away, but maybe that was
> just in contrast to the CT viewports I'd been looking though moments before.
>
> And so here is the new problem. The raft MBT consists of a collection of
> aluminum tanks, each of which has SS tubing coming out the top and
> gathering at a manifold, which is piped to the ball valves on the CT. As
> some of the tanks are off on the edges of the raft, some of the tubing runs
> side to side at an angle (up to 90 degrees) to the centerline. When you
> start flooding MBT, invariably one side will begin to fill slightly faster
> than the other. The side that is flooding faster will be lower in the
> water, and the effect of this list on the opposite side is that the tube
> connecting tanks to their manifold is now sloping downhill instead of up.
> This blocks the high side from letting out air, which exacerbates the
> initial list. It's really obvious when you see it, I should have thought of
> this effect. But luckily the solution is obvious too. There are two ways to
> fix it; remotely actuated valves right on the tanks, or new manifolds that
> are high enough to keep all tubing going uphill at reasonable angles of
> list. My initial impression is that the simpler of the two methods is to
> modify the plumbing.
>
>
> Best,
>
> Alec
>
>
>
>
>
> On Thu, Apr 13, 2017 at 10:10 PM, james cottrell via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
> Did anyone hear how Alec's test went today?
>
> ------------------------------
> *From:* Alan via Personal_Submersibles <personal_submersibles at psubs. org
> <personal_submersibles at psubs.org>>
> *To:* Personal Submersibles General Discussion <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>>
> *Sent:* Thursday, April 13, 2017 9:34 PM
> *Subject:* Re: [PSUBS-MAILIST] Oil Compensator
>
> Jon,
> an easy solution is to take the thruster, or that section of the thruster
> in to a plumbing merchant or hydraulic repair shop & ask for something
> compatible with a barbed hose fitting. Sometimes a metric option will
> fit in an imperial thread, & so they may know of not so obvious solutions.
> Alan
>
> Sent from my iPad
>
> On 14/04/2017, at 12:53 PM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
> Hi Hank,
>
> No, I don't have the shaft, I purchased just the lower head.  A 36 inch
> shaft is $28 but like you said, I really only need a few inches of it so
> don't really want to purchase it that way.
>
> Jon
>
>
> On Thursday, April 13, 2017 8:27 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.
> org <personal_submersibles at psubs.org>> wrote:
>
>
> Jon,
> Do you have the shaft that used to screw into the motor?  if so, you can
> cut it down to a couple inches long and put a waterline compression fitting
> on that.   Then reduce from the compression pipe thread.  Or you can thread
> the inside of that stub shaft with a pipe tap and reduce from that,
> providing it is the heave fibreglass shaft.
> Hank
>
>
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