The joys of marine plumbing

The joys of marine plumbing

Thursday 12th Nov 2020

We didn’t have a lot planned for today, which is just as well. Shortly after breakfast I was pumping out the forward head (toilet) when it stopped emptying and I couldn’t pump any more. We only use the forward head to pee in and we have it set to pump directly overboard. I wasn’t totally surprised that there was an issue as we’ve been struggling to keep this unit smelling fresh in the past couple of weeks. I decided to disconnect the hoses and approach the problem from the out-flow side rather than dismantling the pumping unit. I found several sections of hose and the anti-syphoning u-bend to be almost completely constricted. What happens is that urine and seawater when mixed result in deposition of some insoluble salts and these build up in the hoses and the diameter of the opening shrinks from 2 inches to less than a quarter inch in this case. (As chemists we are interested in the basis of this.  We think the solids are ammonium magnesium phosphate hexa-hydrate, the ammonia comes from breakdown of urea, phosphate from the urine and magnesium from the seawater. It’s a problem in waste-water plants and in cats and dogs the deposits cause kidney stones.) If this were a blocked artery doctors would perform balloon angioplasty and put in a stent. The marine hose equivalent is a bit more basic. Having disconnected the hoses I jumped in the dinghy and went to the dock where I was able to pound the hoses against a wooden piling. We learned this trick from some fellow boaters a few years ago and it is a strangely satisfying experience. The deposits, which have the appearance and consistency of poor quality cement, come flying out of the end of the hose! All in all it took me a couple of hours to complete the project and the head now works like a charm ... and seems to smell better!

The other boat issue that we hoped to resolve today was our auxiliary microphone for the VHF radio. The “Commander Mic” as it is known … or “Commander Mike” as I like to think of it. Yesterday we were trying to talk with another boat whilst traveling along the ICW and they couldn’t here us clearly until we switched to our back-up hand-held radio. It turns out we have interference on our radio when (and only when) we use the cockpit microphone with the engine running. It is likely due to interference from the alternator. We don’t think this has always been a problem because we have used the “Commander Mic” extensively in the past, but we don’t know what has changed or how to fix it. Any advice would be very welcome.

As if all that weren’t enough excitement for the day, the predicted storms finally rolled in about 3pm with winds gusting to 40 knots and some of the heaviest rain we have ever seen. It’s reassuring to be on a large mooring, but we would have been smart to take the engine off the dinghy before the storm. At one point I got really worried the dinghy might flip and immerse the outboard in salt water. It didn’t and we were able to get the engine back on Cotinga once things eased up. It’s going to take a long time to pump the rain water out tomorrow morning!

There is only one thing to do on a night like this … eat smoked shoulder of ham and watch movies! I'm already in my PJs, having gotten soaked sorting out the dinghy, and it's only 5pm. 

Mike

34 02.727 N, 77 53.386 W

The mooring field behind Carolina Beach. The 8-moorings can be booked on line and cost $20 a night ... more expensive than anchoring, but reassuring when there are strong storms forecast.

Looking across the anchorage during the storm

The view from the stern once things started to settle