Fluids - June, 2021

Me and fluids have history. My first discrete fluids related memory has got to be my dad teaching me about the wonders of siphons. I recall him helping me put together a science fair exhibit when I was in grade school. I had buckets of colored water magically self-pouring themselves into different pails and containers through a veritable maze of clear plastic tubing. Dad even let me borrow one the pumps he used for his job as a water treatment sales engineer. It was a variable displacement diaphragm pump with a nifty black bakelite knob you could turn such that it would exactly match the siphon rate and refill the top bucket. Except that you couldn't ever get it perfect, and pretty soon the siphon would outrace the pump, or vice versa, and a scowling Mr. McGregor would have to drag his bucket over to that damn Sprague kid's exhibit yet AGAIN to mop up the latest mess. By the end of the fair, I was soaked to the skin, and was proudly clutching a soggy third place prize for "best physical demonstration." It was great.

My siphons taught me about incompressible fluids, what we usually call liquids - gasoline, water, blood. Kites introduced me to compressible fluids, what we usually call gasses, air, helium, nitrous oxide, steam. [note: and then there’s jello] Dad, my brother and I were involved in a YMCA group that built a giant kite one summer. It was perhaps 8 to 10 feet in length with bamboo poles for the frame and butcher paper for the surface. It got aloft, but was unstable. We tied on about 30 yards of tail, which got it up higher, but then it promptly nosedived and crashed into the ground, burying its pole about a foot into the earth right next to a young mother and baby. Dad quickly retired that kite.

In high school, I became infatuated with boomerangs. I learned to build them and studied everything I could find about the physics of their operation. This quickly led me to aerodynamics and compressible flow theory pertaining to wings. Library books taught me about laminar and turbulent flow, vortex detachment, and the alleged benefits of dimpled surfaces. I was convinced that my newfound knowledge helped me make better performing boomerangs, but looking back, I think it was much more likely that my trial & error approach, and copying other boomerangs made the most difference.

Then I managed to slip in the side door to the Engineering program at the University of Illinois. My math skills still weren't quite up to par, and I had to really work hard to keep decent grades. I held my own in most classes, until Fluids with Doc Peters. Peters taught out of Frank White's classic textbook, and graded on a perfect bell curve centered on a grade of 3.0 out of 5.0... half the class was above a 'perfect' C, half below. I ended up as one of those critically important students who selflessly contributed in a fashion that made the upper half of the class possible. I think that may be when the nightmares started.

For most of my life, I have had certain recurring nightmares. The typical “I forgot to go to this class all semester and the final exam is in 8 minutes and I can’t find the exam room” one is common to most college students, but 30 years after my last degree, this one has finally dropped off the list of regulars. The biggie for me is the plumbing nightmare. This one gained steam after we bought our first house, and I became responsible for the aging and corroding pipes. Each nightmare would be somewhat unique, typically reflecting the most recent hellish u-joint or fitting that I had noticed decomposing in some dank inaccessible corner of our basement. Sometimes the dream was triggered by a plumbing job that I had actually tackled with some variable level of success, other times the subject was a real or imagined potential plumbing disaster, biding its time, but sure to erupt at a critically inconvenient time. The scenario usually involved me, armed with a plumber’s wrench and a crowbar, failing to stop a badly corroded pipe fitting from spewing vile and toxic waste all over a home I was trying to protect. I’m not actually that BAD at plumbing, but I’m not great at it and it always stresses me out imagining the damage and/or inconvenience that could be caused by my imperfect repair.

One of my personality flaws is my inability to accept my inadequacies. Most people could have accepted a B+ engineering degree from UofI and felt good about it. I was so bothered by that one D grade, that I felt compelled to take a graduate level Fluid Dynamics class during my M.S. degree. I had no interest in the topic and could have taken any of a dozen more relevant classes, but I signed up for Fluids anyway. I felt a need to exorcise the demon of Dr. Peters, and damn it, I got an A in that class.

I am becoming convinced that getting a boat is a continuation of this same personality flaw. I don’t need to be a good plumber. Now, I can hire a good plumber. But instead, I took the money that could have paid for scores of plumbing emergencies and sunk it (heh) into a boat. Because a boat like the Perseverance is basically a hole in the water filled with plumbing. This boat has potable water pumps, tanks and plumbing. 3 sinks, 2 showers, 2 toilets plus an icemaker in the freezer. The perseverance has 4 black water tanks and associated plumbing. There is gray water plumbing, there is seawater plumbing, there are shower sumps and bilge pumps. There are diesel tanks, filters and lines. There are coolant tanks, filters and lines. There is engine oil, filters and lines. There are three separate hydraulic pumps, each with its own reservoir, filters and lines. To make this boat do anything, some liquid fluid must be pressurized and moved from one place to another place. Apparently, I need to prove to someone that I am a plumbing savant.

So, we’re minding our own business, taking a 20-mile jaunt out around a lighthouse in Green Bay and back. The trip goes great, and Lori docks the boat making liberal use of the hydraulically operated bow thruster. We tie off and shut down the diesel with no alarms, lights, noises, smoke or fire. I took a conference call for work and wandered back down to the engine room to shut off the air compressor. I opened the engine room door and fell right on my keister.

There was hydraulic oil everywhere. The main 1,200 psi pressure line from the crankshaft mounted hydraulic pump was open to atmosphere, and oil was slowly flowing out of the hose and brass fitting, puddling on the floor and dripping down into the bilge. I shut off the main hydraulic valve at the reservoir, stuck my finger in the bleeding hose like the Dutch boy at the dike and hollered for help. Lori grudgingly but promptly forked over her fancy wood, metal, rubber and glass wine bottle stopper, and then we could more calmly assess the situation. Thanks to the valving and Lori’s wine stopper, there was no additional oil leaking out. We shut off the bilge pumps so that they wouldn’t pump the oil out into the lake. The sight glass on the 20-gallon reservoir read somewhere below 2/3 tank, but it wasn’t full before the failure. We put out cardboard to walk on, and I started mopping up surfaces so that we could start the failure analysis.

The blue plastic block on the hydraulic line is for electrical isolation of the hydraulically powered generator. It’s nothing but a block of strong engineering plastic with 1” pipe threads cut into it. Examination of the underside revealed a missing chunk plus about 6 interior female threads showing significant flattening and damage. All we can figure is that the fitting had been slowly unscrewing itself for some time and spontaneously failed by fracture at Lori’s final bow thruster command, or that a pressure surge as the diesel was shutting down caused it to let loose.

Lori left to fetch cleaning supplies, fresh hydraulic oil, a hand transfer pump, a couple 5-gallon buckets and a new plastic isolation block. Davi and I commenced mopping and a first round of cleaning. Lori failed to find an isolation block (turns out it was custom machined) but succeeded on all other fronts. Davi hand-pumped the escaped hydraulic oil out of the bilge into our new bucket, and we were able to pretty successfully suck the water out of the bottom of the bucket so that our new best friend (Dan at O’Rielley’s Auto Parts) would accept the waste oil. It was VERY obvious when the pump switched from moving water to the more viscous and lighter weight oil.

We still had a slight drip from the main oil pump, so I decided to reassemble the existing parts. I determined that if I screwed the brass fitting into the plastic block all the way, that I could engage more threads than had been used during the previous 20 years, despite the missing fractured chunk. I reassembled everything, and we restored the missing hydraulic oil with new. The previous owner came over to check our work and feel sorry for us. We’re going to get some sleep tonight, and tomorrow we’ll fire up the diesel while docked, and see if everything is holding together properly.

Then I’ll only have the aft shower sump, the bow head and the starboard HVAC drain to fix. Am I adequate yet?