RE: [PSUBS-MAILIST] Maneuvering

["Smyth, Alec" <Alec.Smyth@compuware.com>]

I had a conversation once with Phil Nyutten about just this topic. Bear
in mind one of his early subs (Sea Urchin) had the rotating thrusters
just like a K boat, so he's dealt with it. He moved to fixed thrusters
in the following configuration: Two thrusters on the sides of the stern
pointing straight back, and two amidships angled down and out. If he
runs only one of the midships thrusters slowly, he moves the boat
sideways, a degree of motion that the K boats lacks. If he runs both
midships thrusters at the same time, he gets vertical movement as if
he'd swivelled the K boat thrusters up or down. And of course with the
two on the stern he can go forward or reverse, or run them in opposition
to turn on the spot. 

Phil gets an additional degree of motion, but the advantage of the K
boat is that you can lose any one thruster and still get home on the
remaining two, while Phil would go in circles. I think a factor would be
whether your sub will ever operate without a surface support boat to
either lift her out or tow her home in case of thruster failure. Clearly
the Deep Workers prioritize fine maneuverability, and are not intended
for long surface cruises.

Saving all the work associated with linkages and through-hulls sounds
very attractive to me. I've twice had Snoopy's thrusters disabled by a
single grain of sand jamming the thruster shaft. Cheeky little things
scratched up the shafts too. They got there when I sandblasted the hull
prior to painting. The shafts rotated freely until weeks later when the
grains must have shaken themselves loose from the o ring grooves. So I'm
inclined to favor electrical through-hulls that have no moving parts,
that way my subs are safe from my sloppy groove-cleaning.


:)

Alec

-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Joseph
Perkel
Sent: Thursday, November 16, 2006 4:51 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Maneuvering

Alec,

      "I had already-built hardware to contend with."......

..... Well I don't yet, but considered the 360 deg rotational capability
enough of a plus to negate the negative of the things "sticking out"
there too much, as well as the shaft seals. ...That was, until you just
said this Alec.

If I were to dispense with the rotating side thrusters, would'nt this
require additional thrusters in lateral and vertical to compensate? Is
decreasing chances of entanglement the main benefit of a fixed approach?
If your thinking is that fixed is better, I surely would be interested
in why while I still have a chance to follow suit.

The thread is tremendously helpful guys....thanks! I love the simple oil
comp rig!
Even modern CAD can't "pretty up" those dinosaur cans Vance.

Joe


>From: "Smyth, Alec" <Alec.Smyth@compuware.com>
>Reply-To: personal_submersibles@psubs.org
>To: <personal_submersibles@psubs.org>
>Subject: RE: [PSUBS-MAILIST] Maneuvering
>Date: Thu, 16 Nov 2006 14:15:28 -0500
>
>Agree 100% on all counts. My next boat will have fixed thrusters, but 
>on the K-250 I had already-built hardware to contend with.
>
>Alec
>
>________________________________
>
>From: owner-personal_submersibles@psubs.org
>[mailto:owner-personal_submersibles@psubs.org] On Behalf Of 
>vbra676539@aol.com
>Sent: Thursday, November 16, 2006 1:04 PM
>To: personal_submersibles@psubs.org
>Subject: [PSUBS-MAILIST] Maneuvering
>
>
>Alec,
>
>I'd be prone to using thrusters of the same size, and carrying a spare 
>that could replace any of them. The JSLs use them pointed athwartships,

>vertically and fore and aft for main propulsion and they're about as 
>good as it gets for close work (considering the weight). However, it's 
>power heavy for transits, as you're steering with the maneuvering 
>motors all the time. Their motors are on and off (1 1/4 hp 28VDC 
>through a planetary gear turning 14" props in a Kort nozzle).
>
>Rudders and planes are nice for transits. You could build the thrusters

>into the things and operate them mechanically from inside (the same as 
>our side units now). Then a fixed lateral on the bow--four thrusters in

>all. Mind you, the most successful builder these days is Phil Nuytton, 
>and he mounts verticals fixed and steers with the motor controls on his

>side thrusters (2 or 4 units), also fixed. It's simple, doesn't require

>anything but cable penetrations, and saves a lot of fuss and bother 
>with rotating shafts through the hull.
>
>The bigger Minn-Kotas all have speed controls and lots of other tasty 
>options, including battery condition meters, solid state chargers that 
>could go INSIDE the sub, rather than be toted around, and even a built 
>in auto-pilot on some models. In fact, they have a dual motor unit 
>designed to mount to the topside of an outboard's cavitation plate, and

>I don't see why that couldn't be adapted to fit them on either side of 
>a rudder, and wouldn't THAT be a kick in the tail!!! We'll see what 
>they say, and then look at the price.
>
>Vance
>
>
>-----Original Message-----
>From: Alec.Smyth@compuware.com
>To: personal_submersibles@psubs.org
>Sent: Thu, 16 Nov 2006 11:52 AM
>Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>Vance,
>
>Snoopy came with the side thrusters and I added the stern thruster. I'm

>not certain how many pounds thrust I have on the sides, but I'd guess 
>they're about 40 lbs. Those appear very nicely sized, but I'd encourage

>you to go with variable speed as opposed to my simple on/off. As you 
>might have seen in the cable collision video, Snoopy goes a bit too 
>fast for limited visibility. I wouldn't want them any smaller because 
>they're just right for maneuvering on the surface, but for UW use 
>variable speed would be a worthwhile improvement.
>
>The stern thruster is tiny, just 28 lbs. My reasoning for that was that

>I was envisioning using it UW and wanted something small to go slowly.
>That turned out to be a mistake. The problem is if I'm cruising UW on 
>the stern thruster alone I have no vertical control, so the main use of

>the stern thruster is on the surface, and it's way too small for that.
>The side thrusters, because they rotate, are the ones to use submerged 
>unless you were also putting in a fixed vertical thruster.
>
>Bottom line, I'd go with side thrusters in the 40-50 lb range and a 
>stern thruster in the 75-100 lbs range.
>
>Ah, and the question about currents. Unfortunately in the sorts of 
>tidal currents you have down there in South FL, all of the above are
useless!
>
>:)
>
>
>Alec
>
>________________________________
>
>From: owner-personal_submersibles@psubs.org
>[mailto:owner-personal_submersibles@psubs.org] On Behalf Of 
>vbra676539@aol.com
>Sent: Thursday, November 16, 2006 11:13 AM
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>I remembered the conversation after sending the email, but didn't hear 
>how you had actually done the job. Excellent. Just as plain-dumb-simple

>as can be. I just wrote Minn-Kota about this. They've got the 101# 
>saltwater 36 volters, plus a new electric outboard that is 48 volts.
>I'll have to see whether I can afford a box full, as will take at least

>four motors to do what I want. Which model did you use for Snoopy, and 
>how are they in a current?
>Vance
>
>
>-----Original Message-----
>From: Alec.Smyth@compuware.com
>To: personal_submersibles@psubs.org
>Sent: Thu, 16 Nov 2006 10:38 AM
>Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>That's funny Vance, because you were the guy who gave me instructions 
>on how to do it!
>
>Each trolling motor has two little plastic elbows screwed into the 
>casing, one on top and one below. I have about a foot of clear plastic 
>tubing that is wrapped around the can and ends in each elbow. The 
>tubing being flexible will compress if there are any small air bubbles 
>left in the motor (I've found it impossible to eliminate ALL bubbles, 
>there's always a small one that shows up in the tube). The reason the 
>elbows are on the top and bottom, as opposed to say the sides, is to 
>make it easier to fill with oil. I disconnect the tube from the top 
>elbow, raise the open end of the tube above the level of the motor, and

>add oil through the tube until it flows out the top elbow.
>
>Obviously to install the elbows you need to take the motor apart, 
>because drilling and tapping the holes creates metal chips that would 
>ruin the motor in short order. You also need to make sure you're 
>drilling in between the magnets, which come glued to the inside of the 
>motor can.
>
>I hope that description is clear. If you see the actual HW it's 
>ridiculously simple.
>
>
>thanks,
>
>Alec
>
>________________________________
>
>From: owner-personal_submersibles@psubs.org
>[mailto:owner-personal_submersibles@psubs.org] On Behalf Of 
>vbra676539@aol.com
>Sent: Thursday, November 16, 2006 10:17 AM
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>Alec, How do you compensate the oil? I'd love to try some of those 36 
>volt Minn-Kotas. They've got a ton of umph, and might get me back a 
>couple of hundred pounds of payload from George's Model-T Rex style 
>thruster cans. And it would be cheap, too. Vance
>
>
>-----Original Message-----
>From: Alec.Smyth@compuware.com
>To: personal_submersibles@psubs.org
>Sent: Thu, 16 Nov 2006 9:39 AM
>Subject: RE: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>I had an email conversation with Carl about a year ago on that topic.
>They're just straight air compensated, with Swagelok SS fittings tapped

>into the trolling motor casings. The reason I'd contacted him was to 
>ask whether he was using air, because some on here maintained that at 
>his depths, the partial pressure of O2 in air would be a fire hazard. I

>think his sub demonstrates it's not.
>
>BTW Snoopy's trolling motors started out air compensated and are now in

>their second season with oil compensation. I have nothing at all 
>against air compensation, and would go with that if my air bottles were

>outside the hull. But the way it was implemented on Snoopy the air was 
>passed through the shafts from the cabin, and there just wasn't space 
>to do it properly along with the cables. What's been interesting about 
>the switch to oil is I can't notice ANY difference. The motors seem to 
>pull just as strong, and even sound exactly the same as before.
>
>cheers,
>
>Alec
>
>________________________________
>
>From: owner-personal_submersibles@psubs.org
>[mailto:owner-personal_submersibles@psubs.org] On Behalf Of 
>vbra676539@aol.com
>Sent: Wednesday, November 15, 2006 11:17 PM
>To: personal_submersibles@psubs.org
>Subject: Re: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>Oil compensated DC motors work just fine at moderate depths. Alvin had 
>problems originally with brushes arcing, but he Hymak 5 hp motor used 
>by Hyco on nearly everything they built was a serious workhorse. You 
>get to tear it down and change brushes periodically as they wear 
>faster, and they'll get the oil dirty, so you'll have to watch that. I 
>was on Karl Stanley's web page last night and it looks to me like his 
>Idabel is using about a case of trolling motors, and they must be 
>compensated, as the sub is rated for 3000 foot service. Maybe we ought 
>to ask him what the secret is, if any.
>Vance
>
>
>-----Original Message-----
>From: DJACKSON99@aol.com
>To: personal_submersibles@psubs.org
>Sent: Wed, 15 Nov 2006 10:35 PM
>Subject: [PSUBS-MAILIST] Oil Compensated Thursters
>
>
>Can anyone support this statement: "Scripps has tried to fill the DC 
>motors with oil, but the oil gets between the brushes and the 
>commutator, where the insulation properties of the oil causes problems.
>Although it would be possible to use high voltage to break through the 
>oil film, the high voltage is a safety hazard for the divers."
>-- www.empiremagnetics.com/articles/deep_sea.htm
>
>I was thinking about 24 or 36 volt oil compensated brushed trolling 
>motors, but after reading the above I looked and could not find any 
>examples of oil compensated brushed motors under 100 volts.
>
>What are your experiences and thoughts?
>
>Thanks
>--Doug J
>www.submarineboat.com <http://www.submarineboat.com/>
>
>________________________________
>
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