As I write, we find ourselves in the Netherlands, and another project is on our horizon; I should not tempt fate now, but suffice that it's quite interesting. In the meantime, what's been happening on Vanguard over the last week and before our impending departure?
HVAC: Webasto Blue Cool Connect
This has proven reliable throughout the hot Mediterranean summer months but has remaining issues that must be rectified.
Firstly, the Turkish agents unintentionally built themselves into the control loop. Getting to the administrator screens or adding members requires authorization via some mostly unanswered Turkish email. That needed to be changed.
Secondly, multiple slow but annoying coolant leaks under the insulation caused a pressure drop within the coolant circuit, requiring a top-up every 6-8 weeks. Intolerance is useful, and we engaged a local contractor (MTSea) to investigate. Sure enough, the problem was down to installation in the form of 3 hand-made rubber gasket seals that had swollen and disintegrated. No tightening will fix this.
Other common problems are a taper and parallel pipe thread in the same connection and reliance on metal/metal joints that are intolerant of vibration and thermal cycling. They may work temporarily, but the seals never last; O-rings are generally better.
Lastly, the technicians from MTSea reported that the system was cyclically going into a high-pressure alarm and ramping down the output, which was then restored to full as the alarm automatically cleared itself. The cause was traced to fouling of the seawater cooler, and the remedy was a thorough acid clean.
The system was drained, seals were replaced with Webasto stock spares, and the thread forms matched correctly. We then refilled with an antifreeze mix and checked the freeze limit temperature (a pleasant (-)16deg.C!)
Problems should not be simply "fixed" but eliminated going forward.
The metal cone fitting was replaced with an O-ring, the homemade seals disintegrated, and the mixed joint threads were replaced.
Engine Room Access.
We have two access points for the engine room. The swim platform is great for access in the harbor, but at sea, it's out of sight of the helm. The aft cabin is safe and enclosed but tends to wake anyone sleeping.
A third option was to use the engine room deck hatch, so we created a guard rail and access ladder to facilitate this. It seems to work quite well so far.
Idling engine propeller shaft.
When transiting the Med, we often ran with just one engine. In calm weather, we can run at about 8KN in this configuration, with fuel consumption around 3-3.5l/NM. Our concern was that the propeller for the idle shaft was windmilling. This causes unnecessary drag and wear to the shaft and gearbox bearings.
A thought was to replace the shaft break systems that were fitted when we initially used Bruntons Autoprops. However, in conversation with Bruntons, they suggested that our new Bruntons Varifold props must be stowed when the engine stops. The blades had remained deployed and caught water flowing around the hull with resultant windmilling. The correct process is a short, slow-astern command before stopping the engine. This results in the blades folding as the hull still moves ahead with a positive flow across the blades, forcing them to stow. To make a long story short, it works perfectly, and they move no more, even when the other engine is at full power. The net improvement in speed under one engine is between 0.1 and 0.2KN, so it is noticeable, and there is no more wear!
Thoughts on long skinny hull forms
On a recent passage from Menorca to Mallorca, we drove through 2.5/3m seas and 30KN winds on our bow. That long, skinny hull sliced through most of it, pitching a little bit without slamming. The speed penalty was about 1KN at what would have been 8.5KN in calm water. The foredeck got rather wet, but it blew a Force 6, and very little traffic had ventured out that day.
One facet also worth mentioning is that attention to detail pays dividends when running a vessel with low drag and installed power. Small details make a difference because no great propulsive force pushes you through and obscures the losses. We have investigated this a number of ways and to summarise the results at an easy cruising speed of around 8KN:
Stopping the windmilling propeller: 0.1-0.2KN
Aligning the rudders to the flow stream: 0-2-0.3KN
Stowing the stabilizers in calm weather: 0.5-0.7KN
Slight 50-75mm trim by the stern: 0.1KN
I don't know the totality, as savings are not directly additive. Still, it suffices that we gain about 1KN cruising speed or 12.5% improved fuel consumption by paying attention as we motor along.
Lastly, stopping the HVAC at sea to save 5kW? ---- the threat of life as a single man if I try that trick again; sorry, Sebrina!
