Common Sense

The other day I was trying to disassemble Tarwathie's emergency manual bilge pump because I couldn't draw enough suction to prime it. The going was tough. Parts were stuck and not coming free. Access space was very limited. The rubber parts I wanted to replace seemed to be glued in by a sealant. Worst, I feared that after success in taking it all apart, it would be hell to try to put it back together.

In the midst of that, my mechanical common sense kicked in. I had not been terribly thorough in trying ways to prime the pump. I had assumed that whatever the problem was, that I could not figure it out without first disassembling the pump and looking at the parts.

But wait, the functioning of a diaphram pump is very simple, and obvious by just looking at the pump. It was not common sense to presume that I didn't know how it worked. There are two rubber check valves with two diaphrams between them. Either the diaphrams were cracked or the valves leaked. I felt around and determined that the diaphrams were OK by touch.

I took of the discharge hose and used my palm as a secondary check valve. Aha, within seconds I was pumping water. There was nothing wrong with the pump, more than the valves were a little dry. If I prime it once per month and keep the rubber flexible, it will be OK. I can also use my palm as a backup priming device if necessary.

I realized that having spent four decades as an analytical engineer working on the theoretical side of things made my mechanical hands-on type of common sense atrophy. Worse, my confidence eroded to the point where I presumed that I couldn't figure out how mechanical things work and presumed that I couldn't fix them. Being a volunteer fireman in recent years helped me regain part of that. Maintaining my boat will force me to restore the rest. The pump was a good object lesson.