The problems of interconnected systems

I’m not writing about IT or programming here (although there can be similar problems).

By this I’m thinking of Single Point of Failures (SPOF) and taking that a bit further. By SPOF I mean the danger of one item failing and causing a cascade of failures. For example suppose your hot water comes from the engine, your emergency bilge pump is powered by the engine shaft, your battery charging comes from the engine alternator, your hydraulic system for bow thruster, windlass and winches is powered by the engine. Then there would be lots of simple small failures that would cause everything on the boat to fail eg some dirty diesel blocks the fuel filter, the sea water cooling fails in any one of 10 different ways.

One of the shocking things when you look for SPOFs is how critical to your safety some very small items are. So far too much of Vida’s systems relied on the engine working (battery charging and hot water being obvious examples). Although the engines themselves tend to be very reliable there are far too many individual things that can stop a diesel engine from working (on boats the most vulnerable things are fuel supply and water cooling).

Generally though on boats as old as Vida (42 years) things were not very integrated. Modern boats will have far more integration of electrics (eg electric toilets, so any electrical failure and you can’t go to the loo) and also electronics (where all the instruments talk to each other but if the main data cable fails due to corrosion nothing works).

However, the area that is proving most challenging in terms of interconnected systems on Vida isn’t about direct connections, it is about space.

Back in the 1970’s boat hull shapes were very different to modern boats. They were much narrower overall and the stern particularly was much narrower (in fact modern 38 foot boats will have a stern that is about the same width as Vida is at her widest). Typically the sides are much more vertical with a hard(ish) transition from the side to the bottom, Vida is more of a wine glass shape. The modern boats have a lot more height above the water (less depth below the water but not by as much).

All this means that there is far less interior volume to fit everything in. Our centre cockpit exacerbates this problem (but is still a design feature that we love and a key reason for choosing Vida).

So getting to the point, the over all boat shape combined with the centre cockpit and through access to the aft cabin means that they suffered from a real lack of space for “machinery” (engine, batteries, water systems, bilge pumps, autopilot, fridge compressor). I suspect that if the production run had been longer than about 6 boats they would have made changes (indeed one of the drawings shows making the galley larger so it is a U shape rather than an L shape – that would have helped this problem a lot).

What the lack of space for all the “machinery” did was create a whole host of problems caused by the various systems getting interconnected by being squashed into a very limited and inaccessible space.

They wanted to have a cockpit locker on the port side as the passageway to the aft cabin means there is no space for one on the starboard side. Storage for gas bottles, sails, fenders, rope etc etc is very limited so they made the locker as big as possible. However, that meant squashing all the “machinery” either under the cockpit locker floor (diesel tank and batteries) or forward of it (underneath where you stand when steering).

What we have found that this meant was that we couldn’t inspect, maintain or replace lots of machinery directly because you couldn’t get access until you had removed other items.

For example to remove the hot water tank (calorifier), which the electrics for heating were condemned in the survey, we had to do the following:

  • Empty the contents of the cockpit locker
  • Remove two levels of floor in the cockpit locker (and all the stuff hidden under the first floor)
  • Disconnect and remove four 12 volt batteries,
  • Disconnect and remove one (very rusty and leaky) paraffin fuel tank for the heating system.
  • Disconnect and remove the pump for the domestic water system
  • Remove the wooden shelf for the water pump
  • Cut out a wooden post supporting the cockpit floor where the person steering stands
  • cut away the top of the wood cradle for the hot water tank
  • disconnect the wiring
  • disconnect the domestic cold water in and hot water out
  • disconnect the two hoses from the engine (which used the hot water from the cooling system to indirectly heat the domestic water)

Having removed all this we now have access to be able to replace the bilge pump hose, also to replace the hose for the cockpit drain (perished where it clamps to the drain and also clearly partially blocked), also to get to the vent hose for the main water tank.

My point is that, because all these systems were packed into such a tight space, with inadequate access, they all became interconnected. If anyone of these failed while at sea a repair would be very difficult. Potentially dangerous so many potential failures could disable the boat completely (at least if a repair was attempted).

There would be no point in carrying a service/repair kit for the water pump if installing it would mean taking all the batteries out of the cockpit locker and the heater fuel tank in order to be able reach it. To do all that while at sea would be very dangerous (eg no engine or instruments while the batteries are disconnected; let alone the danger of lifting heavy lead acid batteries out of a locker onto the deck in any kind of rough weather).

This is why our new plumbing system is not using the engine for hot water (and also because eventually we won’t have a diesel engine anyway) and is all being located under a seat in the saloon. We lose a very useful food storage space but suddenly all the plumbing is accessible.

Obviously we are potentially creating a new set of SPOFs by relying on electricity for everything (cooking, navigation, heating, water heating etc). However, we are trying to minimise this by the way we do things. For example:

  • Using busbars to connect 3 batteries in parallel means any one battery can be easily disconnected without affecting the wiring of any of the others, without affecting the voltage (just the capacity).
  • Using multiple solar panels and multiple MPPT controllers
  • Using two 2,000 watt inverters instead of one 4,000 watt
  • Using two individual 2,000 watt hobs instead of a double hob

We are also very focused on making sure we have easy access to everything. That is helped by getting rid of stuff which took a lot of space and needed to be accessible (hot air heating ducts, seacocks for toilets, basins, sinks, gas bottles, hoses and cut off taps).

Living aboard a boat and sailing it around is often likened to “doing boat maintenance in exotic places”. It is amazing how much YouTube video time is taken by shots of people stuck in lockers or around the engine trying to fix things. Also the jokes when experienced people look at potential boats and joke about how much time they will spend in the “engine room” and how comfortable or not that will be.

So I’d much rather have far less integration of space (and systems) so that when maintenance is needed it is simpler and less potentially dangerous. Against this the cost of losing some storage space to make things more accessible is a small price.

Fortunately, it seems that the more sustainable choices have a nice side effect of reducing this integration and dependence Composting toilets are a great example. They have no integration with or dependence on anything else (eg no plumbing connections at all). So lots of nasty (as in particularly smelly) points of failure are eliminated. Plus no need for any access to or maintenance of hoses, joints, pumps and seacocks.

As is often the case sustainable choices have all kinds of side benefits 🙂

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