Thursday, October 23, 2014

A Tale of Two Holes

In case you haven't guessed yet, I'm back on our boat in Deltaville VA.  After the boat show, my wife and I came down to try and get some work done on the boat.  My wife flew back to our house earlier today (can't really call it home anymore...more of our things we intend to keep are  now on the boat) and I needed to take a break so I thought I would try to catch up on my blog writing.

Of course, right now even writing posts is a bit of a challenge.  One of the holes I mentioned in the title is the technology black hole of Deltaville.  The Stingray Point Boatyard, where Rover is currently on the hard, has internet access...but only if you are within about 2 feet of the office building.  Even my Wirie, that can pick up a number of locked signals in the area, can't get a reliable connection to their access point.  And forget about using my cell phone.  Unless you have Verizon (the most expensive wireless carrier in my experience) you are lucky to get any voice coverage and no 2G internet access.

So, sometimes I'll go sit on the chair in front of the office with my tablet in the evenings...until the mosquitoes chase me away.  Or I go to Patti's Diner, who has WiFi, to read some news, research my tasks, look for parts, and upload posts.

If atmospheric conditions are just right, I can occasionally get a local TV channel for news...but most of the time the digital TV is doing it's best Max Headroom impression.  It really is a technology/information black hole around here.  On the bright side, I guess I'm not getting barraged by all the political ads that are probably plaguing the country right now.

The other hole is a hole in the boat.  One of the tasks I left for the boatyard was the replacement of two through hull valves that were seized or otherwise inoperative.  After some other labor snafus and after reading about other Leopard boats that were having electrolysis issues with their through hulls, I decided we would take care of all the through hulls when we got back to the boat.

There's a hole in the boat dear Liza...
I ordered about a thousand dollars worth of bronze parts to replace all the through hulls such that they would arrive at the boat the same day we did.  When we got to the boat, I tried disassembling one of the through hull and seized valves and, as expected, corrosion had essentially welded the parts together.  So, out came the grinder and I was able to remove the entire through hull/valve assembly.  In the process of grinding out the through hull, I was able to determine that my bronze fittings weren't suffering from the same issues that others had experienced so I shouldn't have to replace all the other through hulls now.  So far, so good...but it is a boat so we know that will probably change.

Cut out through-hull and valve
And, it did.  I ordered the shortest through hull I could find and dry-fitting the new parts revealed that they simply would not fit.  The through hull itself is just too long and as a result the valve will not fit under the floor.  I tried all sorts of configurations but it just wouldn't work.  So, I decided we had nothing to lose and cut down one of the through hulls so it would fit.

Here is where we get into the semi-technical explanation of NPS and NPT threads.  Through hulls are typically NPS (straight) threaded so they will mate with nuts or seacocks and can clamp to any thickness of hull (a nut can spin all the way down the threads).  NPT is a tapered thread that only tightens so far before binding and forming a seal. Since there isn't enough clearance between the hull and the floor board, the Leopard through hull goes straight into a 90 degree elbow and then a valve is attached to it.  The elbows are only available with NPT (tapered pipe) threads.  Since many manufacturers are going to this configuration, some through hulls now have a combination thread so the very end of the through hull is NPT and the remaining thread is NPS.

By cutting down the through hull, I removed the NPT threaded end.  I knew this would likely be an issue, but didn't really have much of an option.  Now the elbow would only screw on about a turn and a half before the straight threads would bind in the NPT threaded elbow.  Not a safe option for something that, if it gives way, leaves a 1.5 inch hole in the bottom of the boat.  What I need is to be able to re-thread the through hull so it would again have the NPT tapered thread on the end.  In theory, this should be do-able.  In reality, not so much.  You see, pipe threaders apparently expect a long straight pipe to be inserted in them and the now 2.25 inch long through hull with the mushroom head on one end won't fit in any reasonable pipe threader.

I spent a good couple days trying to find options to get the tapered threads cut, but had little luck.  One machine shop in town said he could setup one of his machines to do it, but it would be several hours of labor to setup the machine and the cost was rather prohibitive...not to mention the hassle if when we ever need to replace the thing again and don't have access to a well equipped machine shop.

Doing a little more research, I found that most people that have had to deal with these through hulls have simply gotten rid of them.  The through hull is the direct discharge for the head and the boat is designed so you can direct discharge through the holding tank so it is somewhat superfluous.  And getting rid of a 1.5" hole in the bottom of the boat is generally a good thing, so I think we will be glassing over the hole and changing the plumbing.  Just wish I had decided this before I bought all the parts and replaced all the hose.

Hopefully I'll get the work that needs to be done finished soon, as the chill in the night air indicates I really need to be heading south.  Of course, with my wife back in Colorado, I need to see if I can find a hand with that task too.

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