[PSUBS-MAILIST] magnetic base

Tue Jul 16 05:20:08 EDT 2019

 Alan, In my case with E3000, if I have a rope in the prop and am stuck, I would jettison the bottom half of the sub giving me 600 lbs lift.  I also have an enormous air supply from my buoyancy tanks that can be emptied into the MBT's .  At 3000 feet I still have 2400 psi to work with in the tanks.  I bought magnets with 60 lbs holding force and will use two per motor.  I always test stuff like this, so I will test how much pull it takes to break the motors free.  If the force is too great, I can weaken the force by putting thin non magnetic spacers between the magnet and base.  I really like this idea, if it works out, any sub owner could could refit this to their existing mounts.  It is unbelievable the magnet power and choices.Hank
    On Monday, July 15, 2019, 8:08:21 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hank,thinking this through more; if you had your vertical thrusters in a slot thattakes the vertical thrust, then this may impede the detachment of the thrusterif the only force you can apply to the thruster is vertical to break it free fromthe magnets. Ie. If a rope is caught in the thruster & you have blown ballaststhen the pull on the rope would be vertical & against the edge of the slot.   If the magnets were mounted inside the hull & you removed them, then youwould have a lot more chance of getting the thruster to drop off.Alan
On 16/07/2019, at 10:37 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hank,the magnets in my open underwater motor from Blue Robotics are coatedwith a marine epoxy & are used in seawater.There are large free magnets in old microwaves. I have some tiny 1/4"neodymium magnets & they magnetise through an inch of wood.I would experiment with putting the magnets inside the hull, & having a metal baseon the thrusters; that way you could assist in the breakaway of the thruster byremoving the magnets, rather than just rely on pulling power. Additionally  you wouldn't need to paint them  & could experiment more readily with the power by adding & subtracting. Another thought is having magnetic bases that are used for mounting dial gauges; you could turn their switch to remove them.Good idea re magnets Hank, hadn't considered that.  Alan
On 16/07/2019, at 9:10 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Alan, Yes I will make a pocket to take the vertical force.  I think since the magnets are so cheap, I will just replace them when they corrode.  Maybe spray them with WD-40.   I did that with my hatch spring and it is amazing how well it worked.Hank
    On Monday, July 15, 2019, 3:02:24 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hank,If you could mount them in a slot so that the vertical thrust pushes against theedges of the slot, that would require less power from the magnets. ( you wereprobably planning that anyway). Magnets are corrosive so you would have to either coat them or mount themInside the hull. They should magnetise through the hull if strong enough.If the magnets were mounted inside the hull you may be able to knock themsideways out of the way to help release the thruster.I would have some way of pinning the thrusters during transport, & take themagnets off ( some how ) during storage.One thought is that a powerful electro magnet may help with the removal ofthe magnets.Alan
On 16/07/2019, at 8:25 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Hi All,  I want to make magnetic bases for my vertical thrusters on E3000.  The thrusters are mounted to the hull section that jettisons witch is bad.  I figure the best way to jettison the motors in my case is to mount them with magnets that will break away.  Anyone try this?Hank

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