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Diver Box questions w/answers.

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  • Diver Box questions w/answers.

    I received several private emails regarding the clear Diver boxes I’m using, so I told them instead of responding, I’ll post here. As this gnarly, surly, intimidating old Torpedo man (Merriman) once told me, SHARE what you do, give what you’ve been given! My holy mantra now. I do plan to do a walk-thru video on SSN-591 when the weather turns, but I realize for many of us in the northern hemisphere, especially above 40 Latitude, it is build season.

    First off I want anyone purchasing these to be aware of the gasket material they use. I purchased about a dozen since I started, enough to supply all my large boats. One or two had instances where the gasket material did not meet, allowing water entry. I’m the first to admit they may not use Six Sigma Quality control. But then again, it’s not life support or landing people on the moon. Just take a moment to inspect the gasket when you get it in and you’ll see a tiny seam where the ends but in the groove. I found a gap on the one that leaked. Test it! If you do get some water, it can easily be fixed with fine tweezers, gently lifting one end, and with a slight stretch to overlap the other. Easy peasy lemon squeezy. Yes, I also use a thin film of marine grease.

    In the two years I've been running this boat, for HOURS at a time submerged, I DO NOT even get the telltale moisture fog of an annoying “can’t find” leak. Nothing.

    Now to the questions……..

    Q-How do you mount them?

    A-Believe it or not, that’s really up to you, and in saying that, I’ll give you one example.
    I try to avoid using using holes wherever possible. Electrical connections, antenna openings, and servo pushrods are one thing, but you don’t need to add holes for mounting hardware on this baby either.

    Though you can't clamp it down like a conventional WTC as it opens upward, you CAN make do with that large, flat surface area on the bottom! With that in mind you can fabricate all sorts of cross members and adhere it/them to that surface using your glue of choice. Those will actually be the “hold down” interface to the hardpoints you fabricate in the hull. Now this IS acrylic, so I’m going to suggest something from my 1:1 scale sailing days. What you choose is up to you.

    It is the most tenacious, vile, surface grabbing stuff on the planet. Trust me when I say that, it seems to find a way of getting on you no matter how careful you are, and take persistent rubbing with acetone to remove from your skin. I spent enough hours working in the boat yard to attest to that. Those of you who do recreationally boat will know what I mean, to those that haven’t, I introduce:

    3M 5200

    3M Marine Adhesive/Sealant 5200 is a one-part polyurethane that chemically reacts with moisture to deliver strong, flexible bonds. It has excellent adhesion to wood, gel coat and fiberglass. It forms a watertight, weather-resistant seal on joints and boat hardware.

    There is an alternative by Loctite, which funny enough is what I actually use on the models:

    Loctite PL Marine Fast Cure Adhesive Sealant

    Loctite PL Marine Fast Cure Adhesive Sealant is a fast setting, moisture cure polyether adhesive sealant which delivers strong bonds while forming a watertight, flexible seal above or below the waterline once cured. Once cured, it withstands both saltwater and freshwater environments

    Both are a bit pricey (compared to say Irving Lloyd’s sub favorite “GOOP”), take time to cure, and probably overkill. But then again I’m an “over-engineering” type of guy. Skynet Terminator Model T-100 endoskeleton grade ENGINEERING as I like to say! But that’s me.

    What’s the difference between polyurethane and polyether? Some basic understanding from from WestMarine:

    Polyurethane: Recommended for permanent bonding because of its enormous adhesive strength of about 700psi, polyurethane is more of an adhesive than a sealant. It is good for hull/deck joints and bonding thru-hull fittings but incompatible with ABS and Lexan, and does not adhere well to many other types of plastic. Polyurethanes have poor resistance to oil and the acids used in products such as teak cleaners. Do not use polyurethane-based sealants if the bonded items might have to be separated in the future.

    Polyether: One of the most exposure resistant sealants, unaffected by teak oils or cleaners, permanently flexible, and sandable. West Marine Multi-Caulk is an excellent choice for wood, metal, or fiberglass but will attack some plastics.

    You CANNOT paint either, it flexes! Treat like permanent silicone.

    You can get either at Home Depot, Lowes, Ace, Amazon, etc.
    By the numbers on Amazon PRIME:

    Loctite PL Marine Fast Cure Adhesive Sealant, 3 Ounce Squeeze Tube (2020627)
    $8.97 Polyether, 24Hr Cure

    3M 05206 Marine Adhesive/Sealant 5200, White / 1 oz.
    $8.09 Polyurethane, 5-7 day Cure

    3M 05220 Marine Adhesive/Sealant 5200 Fast Cure, 3 oz. / White
    $13.67 Polyurethane, 48Hr Cure

    Again, this is the pricier stuff, go with what YOU like. The above was just an informative suggestion.

    Now with the TESKEY PROTEUS, I merely mounted a rectangular piece of 1/16 thk PVC plate with holes at the corners using the aforementioned Loctite PL Marine. These 4 holes are for the screws which mount it to the hard points you pre-fabricated in the hull. In this case on the ballast tank.

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    Of course it DOES not have to be a big plate like this, two 1”x1/4”x4” would work as well. The size, shape and material is entirely up to you. Depending on the application of course. Just insure the materials you adhere with hold up (IE Marine Sealant) over time and the box is ultimately removable for testing and maintenance. The motor compartment for the 591 uses 2 alignment/hold down pins, and two 10-32 screws! More on that in the 591 Walk-thru video. The limit is your imagination.

    So have at it, and keep it simple stupid. ENGINEERING IS THE FUN!!

    Q-Motor mounting and Drive train for the large scale boats.

    A-First off I’ll start by saying I believe in motor cooling. I do understand many do not, and that’s okay. But I run for HOURs on the same dive, so I’m not chancing a large motor in a very enclosed place, with continuous thermal input. I tested the 591’s motor and after 10 minutes under load it read 105F. Say it’s a mid August day, ambient is around 80, you place the boat in the water with a box at ambient……

    I’m NO thermal engineer, but the ability to passively cool is all around us, and with a little additional work it’s free. Again, no one I know of really does it but me, and I’ve never really heard of issues, but I was taught, cool electronics makes for happy electronics. Something a SIMPLE as exposing the aluminum mounting plate to the water is better than nothing.

    Here you can see the motor, my 2x3 shaft seal, Aluminum mounting plate, and the Motor compartment ready to go.

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    After I carefully made a cut-out “coolant window” to expose the Al mounting plate, I had drilled the through holes with a plastic drilling bit, and temporarily mounted the motor plate with regular silicone to mark the plate for accurate hole alignment. I wanted to insure the shaft would line up with the shaft seal. At least within tolerance of the forthcoming home-brewed shaft coupler (the 2x3 mentioned below).

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    Fabricated parts. FWIW, I did wire-brush and paint that motor beforehand lol. But in the end it’s easy enough to remove should I ever need to replace the brushes. As you notice, I did violate my earlier example note regarding mounting holes, but in this case they were obviously necessary.

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    Ready for assembly. So the through holes in the box are over sized for placement tolerance with the #8 SS self tapping screws, the Al plate holes are drilled the proper size for the #8 H/W to bite into. No issue as liberal use of the aforementioned Marine Adhesive/Sealant WILL keep water out.

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    AIN’T NO WATER GETTING IN THERE. Any thermal transfer from the motor, through the plate, out that “window” into the water, is better than nothing. Just a little extra work and I can even say now “She’s passively water cooled” with the best of nerds.

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    Getting there. Note the thermal resettable fuse. I had originally used that but switched out for an automotive ATC style 10A fuse. I understand tug guy’s use ‘em, but the thermal reset fuse is NOT quick enough for me. If I’m going to get a prop wrap significant enough to blow the fuse, I would probably have to retrieve the boat anyway cause it's anchored there. Therefore I’d rather it go quick and save the motor/ESC than reset to just have to swim out anyway and smell somewhat cooked motor. Another good idea in theory that’s impractical in real life. Application trumps the best of intentions.

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    I want to show what I did to help limit shock to the drive train with respect to large boats.

    Back in late summer 2016, I had just finished 591 in her MOD II configuration, the “Great Annular Ballast Tank Experiment”. It was here I used a 750Kv Brushless motor for the first time. I did not get a chance for Sea-Trials prior to Groton, so when I did get her in the water and tested everything, it worked flawlessly! Until I extreme cycle-tested the throttle (A/A FLANK to A/B Emergency, stop to stop very quickly, several times in quick succession) to insure I wouldn’t have a problem if I had to perform an emergency back down to avoid hitting someone or something. Better to have it fail at test than ram into someones $2K heavily detailed Heavy Cruiser. My 591 as I said before swings a 3-” prop.

    Well it failed of course, literally ending my weekend there on a Saturday morning, but a bad day at Groton is better than a good day anywhere else. For me at least. I ended up replacing the plastic dog-bone with a homebrewed brass one, and programming the ESC for a lowest levell soft start. Needless to say it wasn’t that issue itself which caused me to rebuild the present watertight box MOD III configuration. It’s ease of access to the internals, and compartmentalization that drove that paradigm. Now if I blow something, pop the hatch. The first photo shows the overall internals with the plastic dog bone that blew, the second close up shows the brass one I made. Last shows the MOD II system installed, with like a gazillion inches of drive shaft lol. But I was able to stick a 2nd 3:1 gear reduction at the mid point coupler you see just after the aft 12V battery.

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    Now the Brushless motor worked fine after it was tweaked. I did need to gear it way down (9:1 for that prop, the original 3:1 plus a second inline 3:1) or she porpoised uncontrollably above 60% throttle. But she did have a quite a bit of power budget savings. Yet too be honest, I wasn’t happy with the “low” end performance, sure gobs of power, but not what I look for. They just can’t spin at low RPM like a brushed motor. I’ve seen the venerable Pittman Motor in direct drive spin a prop as slow as single digits per minute! Sang like a canary, but impressed the $#*! Out of me!! I just love that “control”. I just dig maneuvering about in close quarters practicing my seamanship and docking skills.

    “Conquest is easy. Control is not.”
    Kirk, James T. Capt. USS ENTERPRISE (Fictional)
    Episode "Mirror Mirror" (one of the best)

    Sorry, nerd reference.

    It’s all about the APPLICATION man!

    Now my 1:96 ALFA??? THAT will be a different story, I plan to break speed records after I refit her.

    I loved today’s (January 2020) Live Cast by Bob Martin, in truth I love them all, if you’re not subscribed to his channel, you’re doing yourself a great disservice.

    The point is, just watching newcomer questions makes me smile, but only with fondness. I do envy those experience this for the first time.

    It it expensive?
    How Much?
    What Boat?
    What Radio?

    In the end, the answers are REALLY up to you, because it’s what YOU want. Bob of course can, and is there to help with choices and guidance, Dave is there to help with “how to” extending beyond most skill levels. These two make a great team. In fact, like a well known "Big Bang Theory" Halloween dress up episode, I'd like to see one dressed up a Superman, and the other as Aquaman....or maybe he'd be better as "Davy Jones" from "Pirates of the Caribbean" I leave it up to you to guess which is which. But again I digress....
    Many others out here offer help as well.

    Work smarter, not harder! More boats in the water that way!!

    There are NO silver bullets in doing this. It depends on many factors to obtain the end result YOU want.

    So to say this method, or that method, or this brand or that brand, or that radio, or that frequency is the best, is kinda meaningless. What’s best for your what you want to do?

    My only real advice, is have the application fit.

    For guidance on that, speak to Bob and Dave. Do it and LEARN from experience to find what YOU like. Someday you pass on what you learn, and we grow.

    Sorry, I have a tendency to get wrapped up (NO $#*!) in myself.

    Anyway, my great friend Ray Mason came up with a suggestion regarding the torque shock to the drive train on a large prop boat. It wasn’t really a suggestion as much as he gave me a component that’s used in those “gas” go-fast boats many of us dread sat the pond. This two-piece machined Aluminum beauty limits the stress.

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    Not sure what they’re called (Drive Shock Absorbers?) or where to get them, but I also knew I could easily replicate it, and in fact, improve on it as this particular one forced you to have perfect alignment. That shaft seal you saw is my “3x2 Shaft Seal”. Uses 2 “cup seal” o-rings between 3 Rulon bearings. The shaft seals are designed so that the shaft rides “true” to the seals on the three bearings, also the main and backup seals are well lubricated for the season. The motor shaft and propeller shaft need NOT be 100% aligned to it to work.

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    Plus it was just too long for my Motor compartment, I like spare room. (Pudgy fingers). So I grabbed some appropriately sized wheel collars (2x ”, 2x 3/16” here), solder two together as shown with the set screws opposite of each other, and use regular pan head screws! Connect them with ⅛” o-rings (⅜” ID here) at each end of the shafts that will connect the drive train…...DONE! They even allowed for the different size shaft. The 1/4" REDMOND Motor, and the 3/16" shaft for the shaft seal.

    The Large Screw, High Torque, Low impact solution to ALL your big boats! Perfect alignment to the shaft seal is not necessary.

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    Finally, the Motor Compartment mounted and ready to accept the dog bone connecting the prop shaft. The box has two ” brass alignment pins underneath forward that line up with brass tubes in a support bulkhead. I drop it in, slide it forward to the stop, add those two screws aft and she’s in. Just another method I was trying.

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    In conclusion of another, rather long post, I hope that what you take from here is not how I do “it”, but fuel to fire how YOU want to do “it”. It’s ALL about the application in the end man.

    Now I’m off to practice what I preach and apply something…………

    May all your surfacing's equal your dives.

    v/r "Sub" Ed

    Silent Service "Cold War" Veteran (The good years!)
    NEVER underestimate the power of a Sailor who served aboard a submarine.

  • #2
    Another EPIC post, Ed. Thanks so much for taking the time. Great stuff in there. I particularly love the driveline shock absorber! Beautiful!


    • #3
      For brushless motors, if you use BLheli_32 esc's, they have a soft start function on them which reduced snatching, and will be kinder to the drive train. The slightly cheaper Blheli_s controllers lack that refinement. Both types give excellent low speed running, the best I've ever seen with sensorless motors.
      Last edited by Subculture; 01-19-2020, 07:34 AM.
      DIVE IN! Go on, go on, go on, go on, GO ON!


      • #4
        Ed, amazing post!
        I learned a lot and making me think. Thank you!
        If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.