Month: August 2013

Going Down with the Ship: It’s Aeration, Not Suction

Ok, this will seem a little off the wall. Many of you who know me know that I used to be a professional sailor years ago. I worked on everything from small oyster boats to tug-n-barge combos running 600 feet in length. Sailors are great exchangers of tales, and no tale is more horrible and morbidly fascinating than that of a ship sinking. Such tales often feature, in one way or another, the idea that people who aren’t able to swim far enough away from the vessel risk being “sucked under” as it goes down.

That idea never struck me as very plausible. A ship going down creates a void in the water where its mass used to be, and water will rush in to fill that void, but the idea that some sort of suction could be created that would literally pull you down with the ship never made sense to me. I don’t have the technical chops to say exactly why, but it just struck me as wrong. While watching video of a sinking fishing vessel yesterday I thought of an alternative explanation that seems much more reasonable.

As most people who mess around with boats know, a prop that breaks the surface can no longer effectively propel the vessel. The reason for this is a phenomenon known as cavitation. When the prop breaks the surface it pulls air down and aerates the water around it. Aerated water does not have the mass of non-aerated water, and the prop can’t push against it effectively. For the same reason you cannot swim in aerated water. If I put you into a tank of water and bubble air up from the bottom you will sink, however mightily you flail.

Which brings me to sinking ships. They have a lot of air inside them, and when they go down that air comes bubbling up from all the various openings through which it can escape. You can see that effect pretty clearly in this two-minute video of a small fishing vessel sinking. A much larger ship means a lot more air, which in the process of escaping turns the water above into a aerated froth. And as I said above, you can’t swim in froth. So, I think the reality is that when a ship sinks and you are in the unfortunate position of treading water right above it, you don’t get sucked down. You fall.

LinkedIn: Why I Am Not Returning Your Endorsement

Don’t get me wrong, I love you all: the former colleagues from jobs I held eight or ten years ago; the neighbor I have never actually worked with, but who plays a congenial game of poker and is an all-around nice guy. I appreciate that you took the time to go on LinkedIn and endorse me for everything from “Software Development” (because there is no aspect of it I am not awesome at), to SQL Server, ASP.NET, astrobiology, xenolinguistics, and starship navigation. It’s true, I am a master of all those things.

But there’s no way most of you guys could have known that, because, well, we haven’t spoken in a decade or so. I wish that weren’t the case. I’m terrible at keeping in touch. But then, hey, you didn’t call either. I guess, in a way, this puts us back in communication. You took the time to punch that button on LinkedIn, and that means you were thinking of me, or at least stumbled on my bio pic as an artifact of an otherwise accurate search for people you care about. In either event I’m gratified. But I am not going to return the favor, and I thought you deserved to know why before I clear my inbox.

See, in other than a very few cases to which I have already tended, I just don’t know what you’re good at anymore. Ten years ago I was writing C# code, pulling data out of SQL Server, feeding it to ASP’s renderer, writing form-based web apps. When I code now I write Python, stick my data in Postgresql, and use ajax calls to populate pages. That is, assuming I am not writing Java or Objective C for mobile apps.  The world is completely different. If you’ve worked with me in, say, the last year or two then your endorsement might carry some weight, but not after so many years. And the same goes for any endorsement I make in return.

I think there may be some value in LinkedIn’s system of professional network references, but whatever that value is, it is certain to diminish with time. Endorsements are perishable. And given that, regardless of how many I collect, any potential employer is still likely to want me to put on a nice shirt, schlep in for an interview, and prove I actually know my stuff. It’s inconvenient, but it makes them feel a lot better about paying me, so I go along. Fortunately I don’t expect to have to go through it for some time, but then, that’s what we always think isn’t it?

In the meantime, I wanted you to know that I do honestly appreciate your effort, and that my lack of a return gesture does not have a linear relationship to the respect and regard in which I hold you. It’s just that it is exactly that, a gesture. I don’t mind “liking” crap on Facebook or G+ from time to time. After all, what am I really saying? Not much. But an endorsement for a specific skill should mean something, and carry some weight, and I just don’t think that LinkedIn endorsements do.