We’re done with commissioning. We met with Dave yesterday to go over things. The hydronic is done! We have unlimited hot water and five zone heat. It’s a beautiful unit.

Dave also worked out an innovative solution to get the hydronic hot water playing nicely with the 11-gallon domestic hot water tank and the engine heat exchanger loop.

We also made some quality of life upgrades.

The water maker is working and we made 50 gallons yesterday as a test. We replaced the undersized nylon line on the rode with 150’ of chain for a full 500’ of chain. The weight made no difference to how the boat rides in the water and there’s plenty of room in the chain locker. We also got some hoses for the washdowns and a thousands other small things.

There were several items on the commissioning list we didn’t get done – we just ran out of time. We never plumbed the BBQ and there are a few cabinet latches that need to be fixed. Lots of small things we can figure out once we get to a new home port.

We’re departing Blaine for the San Juans this morning. Still lots of stuff to get organized. But, we’re officially casting off for the next couple of weeks.

This blog is intended as a document of the nuts-and-bolts aspects of the boat – not as a cruising blog. But, some cruising stuff may leak over.

Shakedown was a big success. We spend the night in Echo Bay, took the dinghy to shore to explore the China caves, and had our tasty first boat meal. We got hit with wind directly out of the SE and there were some big rollers through the anchorage over night, but the Rocna held amazingly well and the kids slept right through it.

Stuff that worked well – the boat handles amazingly (we spent some time with a professional captain to learn how to handle a single screw. Thanks, Gerry!), the basic electronics are solid (we got the autopilot configured, charts, and radar work great), the amenities are really nice – hot shower, laundry, stove, etc. And, of course, our Rocna holding us solid through some big seas. The boat cruises and “lives” incredibly comfortably. The generator is really quiet and worked well to get a load of laundry done and heat some water for showers (the always-on hydronic isn’t working, yet).

We compiled our list of gremlins, as anticipated – the battery monitor is reporting nonsense, as are the blackwater tank monitors. There were several other minor annoyances that Dave will work on this coming week.

Lot’s more progress. We’re targeting Saturday for a shakedown cruise. Not everything will be done, but we’ll be seaworthy, with most of the Quality of Life stuff ready. We hope for 90% of the commissioning to be done by August 10th or so.

Also, just found out that I need to apply for my own MMSI number and Ship Station License from the FCC to get my AIS broadcast ID. As usual, trawlerforum has been super helpful.

Burrow does a really nice job with their furniture. It’s not high-end, but it’s modular and durable. I’m not sure how else we would have gotten a couch on a boat. Everything fit in our SUV and went together in about 10 minutes without tools.

I just found out people besides my family read this blog. Howdy, strangers! Hope it’s helpful.

I’m not sure I got all of this right. But it helped me get my head around the basic design. In most cases, the system should “just work”. The only wrinkle is when the engine has heated the water in the domestic hot water tank and the hot water heater power is off. When that happens (and the hydronic is on), we need to open the water heater solenoid manually using a switch on the panel. Otherwise, it’s closed automatically because the hot water tank is off. For the hydronic solenoid, it’s open by default and can only be closed using a breaker switch. That way, if the hydronic system is off but the domestic system is on, we can bypass the hydronic.

Use cases

Manual interventions in italic

  • Summer on shore power: No cabin heat. Water heater is on, hydronic system is off. Water heater solenoid open automatically. Hydronic solenoid closed from the panel.
  • Summer under way: No cabin heat. Water heater is off. Engine heats the domestic hot water. Water heater solenoid opened manually from the panel. Hydronic solenoid closed manually from the panel.
  • Summer at anchor: No cabin heat. Either run the generator and configure similarly to summer on shore power. Or, put the hydronic system into “summer mode”. Water heater solenoid closed automatically. Hydronic solenoid opened automatically. Diesel boiler provides on-demand hot water.
  • Winter on shore power: Cabin heat. Water heater is on. Hydronic system is on. Water heater solenoid opened automatically. Hydronic solenoid opened automatically. Water is heated by both water heater and hydronic.
  • Winter under way: Cabin heat. Water heater is off. Engine heats both water heater and hydronic. Water heater solenoid is opened manually from the panel. Hydronic solenoid is open automatically. 
  • Winter at anchor: Cabin heat. Hydronic is in normal heat mode and diesel boiler is running. Water heater is off and solenoid is closed automatically. Cabin heat and hot water both provided by hydronic. When generator is started and hot water heater is powered, solenoid opens automatically and boat is configured like winter on shore power.

The hot water and cabin heat are designed to be flexible and configurable, but it’s leading to some complexity, which we’ll need to streamline for every day use.

The domestic hot water heater runs on 120v shore power or the generator. But, it also has a heat exchanger connected to the main engine, so any time we drive it will heat up. This is a pretty standard configuration and it’s already pretty versatile and flexible.

The hydronic system is more complex. It’s core functionality is a diesel boiler that runs on the 12v system. This heats a fluid (basically antifreeze) which is pumped to five locations around the boat. Each location has a heater core (that looks like a radiator with a fan), which is controlled by a local thermostat and fan speed switch. So, each zone has it’s own heat and the whole thing can run on the batteries. The hydronic system also has a heat exchanger connected to the main engine, so the boiler can be heated while under way without having to fire it up.

So, when we’re under way, we’ll have hot water, cabin heat, and pilothouse window defrost for “free” by capturing waste engine heat.

Now, the hydronic system also has a fresh water heat exchanger, connected to the domestic hot water loop in line with the domestic hot water heater. This is designed to be an “instant on” system that delivers hot water on demand (as long as the boiler is hot). It also adds some complications. First, when the fresh water heater is off (say we’ve been at anchor for 12 hours), the hydronic system will heat water in-line and then dump it into the domestic hot water heater (11 gallons) – which will be room temperature at that point – cooling it before it reaches the faucet. The same is true the opposite way. If it’s summer and the water in the domestic tank is hot, while the hydronic boiler is off, we’d have the opposite problem (though the hydronic tank is smaller).

Dave’s solution to this is to install a couple of in-line solenoids on the fresh water hot loop. If the domestic heater (120v) does not have power, the solenoid will close and the instant hot water from the hydronic tank will bypass it. This will be closed by default. There will be a similar solenoid on the hydronic fresh water loop which will stay open by default. Each of these can be controlled by a switch in the pilot house. The only wrinkle in this system is if the fresh water in the domestic hot water heater is hot because the engine has been on, the solenoid will be closed and we’ll need to open it manually using a switch (no sense in burning diesel if we already have 11 gallons of hot water sitting in the tank). Also, when in their non-default mode, the solenoids will draw a small amount of power.

Finally, the hydronic system also has two 1500W electric heater coils, so you can heat the water in the boiler without burning diesel. But, given these draw about 15 amps each, they’re really only an option for when we’re on 50-amp shore power or running the generator.

Oh, the hydronic system also has a “summer mode” where you can use it only as an instant on water heater. You simply close the valves on the ship-wide anti-freeze system so the boiler only heats water internally.

So, on the one hand, we’re very pleased with the options for heating the boat and unlimited hot water – in particular, the option to use engine heat, diesel, 12v power, or AC power. (We don’t want to waste any heat generated by the boat if we can redirect it to heating the cabins or the hot water.) On the other, there are so many ways to use it it will be hard to optimize. I’m working on a diagram and some simple if/then scenarios.