Tag Archives: yarrow

Friday 13th – unlucky for us, and performance data

Lady Luck

Took Befur out for a tour of the lake yesterday, enjoying a day of early autumn sunshine. Conscious that it was a fated day, I was expecting some drama!

Lou managed to (very narrowly) avoid a dunking while we were boarding, so I thought we might of escaped. However, bad planning on my part resulted in us getting blown onto a jetty on the lake, which was (unbeknown to us) fitted with large bolt ends projecting out to catch people in exactly our predicament – so more filling, sanding and re-painting required over the winter to repair a pair of gouges in the hull – bugger!

Performance Testing

One of my objectives for the trip, was to collect some performance data, and the map below (click the link and it should open in google maps) shows the route and the waypoints with speed, direction etc. (clicking on these will give performance data for each bit of the trip).

https://www.google.com/maps/d/u/0/edit?hl=en&hl=en&mid=1qv-Q4JREXMB5lKKMXQmANtZhy-Hxu3DD&ll=54.607108645724125%2C-2.8355938095091915&z=16

The net of this experimentation produced data on two “stable modes” of operation.  All of this at a boiler pressure cycling between 185 psi and 225 psi.

For the record we are now operating with a gear-up ratio from engine to propeller of 1.45:1 and a 21″ x 19″, 3 bladed, left hand prop.

At “cruising speed”

At this speed we are operating with a HP pressure of 60-70 psi, and an LP pressure of around 16 psi and a vacuum of about 10-inches. The engine is turning at between 175 rpm and 125 rpm (when alternator is charging). The map tells us we are moving at about 3 mph (2.6 knts), it was running into fairly light winds, so this data seems realistic.

At “flank speed”

This is about as fast as I feel happy running the plant, and is resulting in the engine slightly outrunning the boiler with a sustained boiler pressure of about 170 psi.. HP pressure is 135 psi, LP pressure 28 psi, vacuum of 14-inches. The engine is turning at 300 rpm and the log tells us she is making between 6.5 to 7.2 mph.

…so with a computed hull speed of just under 8 mph we still have a way to go on the performance stakes.

Those with better maths than I might be able to turn this into some meaningful performance data for the engine hull.

We also had the time to check the depth sounder and it certainly seems to work, with the audible alarm providing some confidence for the helms-person when we are running out of water!

…onwards, it will be “dragging out” time in the next few weeks, and then we can fix the outstanding mechanical issues, ifx the knocks and bangs, fit the mast and figure out how to stop the water getting into the cabin roof!

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Burner Fixes

Just a quick note to record the changes we made to the burner, following the failures on Windermere and Ullswater.

The conclusion was that these failures were mostly heat related. But also we fitted three new control boxes to the burner before we found one that worked!!…

The solutions were:

  • Fit a heat absorbing blanket to the outside of the boiler casing to reduce the radiated heat impacting the burner.
  • Fit an external duct to cause the intake air to be drawn via the control-box and ignition transformer assemblies (to help cool them)
  • Strip and rebuild the burner, fitting new magic eye, solenoid, control box, ignition transformer, motor capacitor and a somewhat worn pump drive coupling.

As noted in an earlier post, this seems to have done the job, so here are some pictures:

A Goal Achieved!

Well that worked!

It would appear that the work on the burner paid off. Yesterday we had a fine day’s trip on Ullswater, from the marina at Watermillock, all the way to Glenridding without a single problem – virtually the full length of Ullswater. (About 3½ hours steaming). The first time we have managed the full length of the lake!

We took most of it at a leisurely pace, with a couple of bursts of speed to avoid yachts out racing…. Continue reading

A final video: Everything running on the bench

First Fix the Bugs!

Following on from the Boiler test, and a quick trial we identified just over 20 items that needed some attention. So a week later, with all these items fixed (from leaking valves to painting and plating valve gear components), we are ready to try again. Continue reading

A Boiler Full of Steam

Well the 10th November 2017 marks a major milestone – the boiler passed its initial inspection and steam test, and is now certified for use. (big smiles all round).

Picture of Engine, Boiler Etc. ready for test

Sadly, everything was too frenetic to take pictures during the steam test – but here it is just before we pressed go!

John, our inspector from SBAS Ltd (the SBA’s Boiler Inspecting Company) had been booked to arrive at 3:00pm – at 9:00am I set about final sealing of the try-cocks on the sight gauge – at 1:30pm I nearly called to cancel the appointment as no amount of fiddling and fitting would make them seal, with a constant drip from each of them at anything above 50psi 😦 Continue reading