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Bute Sunday 5th August.

Sunday was a bit different. The tail-wagging excitement was giving way to the more usual sense of being at work and on a mission such as had always pervaded our workshop. By now we knew where our tools were and each had adopted whatever task seemed best to suit them as their own. Jersey Mike had arrived from Jersey bearing pretty much everything we could ever wish for and set up the workshop in a totally organised fashion. The tea tent was fully commissioned now too with each member of the crew having being issued a paper cup on the bottom of which we wrote our names so as not to lose their very own brew mug.

Today it was time to up the ante and start creeping up on getting K7 running at speed again on the water. First thing was to have Stew carry out a static engine run to warm all that metal and blow out the cobwebs and also to give him some engine handling experience from inside the cockpit.

But this was not your standard static because shortly before we left for Bute our engine had developed a problem that we’d thus far been unable to cure. The book says the engine should idle at 3650 rpm. In fact what it actually says is something like 3650.374 +/- 5rpm. How can you have a figure to many decimal places then slap plus or minus five on the end, we asked aerospace? It’s derived from a graph, apparently and so we were often presented with such confusing figures – oh, and don’t forget to factor in ambient air temperature and barometric pressure. We decided that somewhere near 3650 would do for our purposes, especially as the RPM indicator was mismatched to its generator on the engine and read incorrectly until we had it recalibrated by ‘Clever’ Barry Hares. Donald had a similar mismatch and never got his working properly so far as we know.

We’d therefore been happy that, from the first time it ran properly, our engine spun up to 3650-ish and sat their happily turning paraffin into noise. The way the engine is set up is that a lever down in the right hand side of the cockpit is slid forward until it locks into a detent and opens the throttle valve on the engine to thirty-four degrees, which is what’s required for start and idle. The other sixty degrees is controlled by a foot throttle. What you do next is switch on the igniters, arm the start system then hit the start button. There’s a violent whoosh somewhere behind your head followed by the whine of the compressor as it spools up. Soon the RPM indicator flickers and begins to catch up with the accelerating spool until, about three seconds in, there’s a whoomph! as the igniters do their job and the engine starts to accelerate. Now the exhaust gas temperature indicator, having arrived late at the party, suddenly leaps off its stop and climbs rapidly. You have to hold steady on the starter until the needle climbs past three hundred Celsius at which point you can release the button and the whoosh of compressed air ceases instantly. Upwards goes the EXH gauge as the temperature soars alarmingly. Four hundred, five hundred, six hundred until at last its seemingly inexorable ascent is checked by inrushing air hungrily ingested by the compressor. Seventy percent of the air that goes through the engine serves no purpose but to tear unwanted heat from the metals and throw it out the back before it damages something. Push the turbine much over seven hundred for more then a few seconds and it invisibly destroys the structure of the blades and begins to fail at that point. No ifs, no buts, you just wrecked your engine so we drummed the start procedure into our pilots.

However, the problem that now plagued us was that instead of the engine idling at 3650 as it always had, just before we left for Scotland it suddenly began settling nearer 5000 and nothing we tried would have it do otherwise. This was a problem for three reasons.

Firstly, we didn’t know why it was doing this so what if next week it decided instead of 50% it might like to idle at 75% or 100% - then we’d be in bother. Secondly, you can’t start your jet boat in neutral. Once it’s lit it starts to move and as we’d never tried lighting it on water we’d prefer if the process were as gentle as we could make it and whooshing up to 50% was unlikely to prove gentle and, finally, we’d been warned by Lew Norris years earlier about just how efficient K7 is when planing so with our engine stuck at 50% we had doubts about being able to slow down at the end of a run. Of course the pilot could just pull the lever back and the engine would shut down instantly but that would mean no return run unless we moved the whole operation to the other end of the loch to start again from there.

We initially thought we’d just set the linkage up wrong as it’s absolutely impossible to see what you’re doing down there but it is possible to adjust the linkage – just – so we ran the engine and adjusted until we had the idle we wanted. Sorted – except it wasn’t. Once shut down the engine wouldn’t re-start. Investigation revealed that our adjustment had reduced the initial opening to a mere twenty-two degrees, enough for the correct idle once the pressures came up in the system but nowhere near enough to start the engine. We were flummoxed. There’s also an adjuster on the engine called the ‘idle bypass’, which is like the idle screw on your petrol lawnmower only with extremely fine adjustment. It goes in tiny clicks because the difference between flowing lots of kerosene and none at all is minuscule – hence the issue with the incorrect SG of our fuel but no matter what we tried we couldn’t persuade it to have any effect and our friends in aerospace sadly declared it a victim of ‘magic muck’.

Magic muck is a theoretical contaminant that gets into the fine workings of hydro-mechanical fuel systems and prevents something from working properly but when dismantled there’s nothing to be seen and when reassembled it all works as it should. We had no time to go investigating magic muck so by the time we wheeled K7 out of her boatshed that Sunday morning to have Stew perform his static engine run we were stuck with our 50% idle problem and were just going to have to work around it.

After Malcolm’s safety briefing we began with the roll out.



Notice the tool benches down the left and the plethora of fire extinguishers on the right. It hadn’t taken us long to get our boat shed into shape. Also on the right in his uniform is Stew Vandal representing the army unit who installed our slipway. He made us so collectively itchy by standing in a very military way in full scratchy uniform and cap for the first couple of days that we begged him to swap it for shorts and flip flops. Stew did just that and became one of the team very quickly.



The crowds had begun to gather by the time our other Stew climbed into the cockpit. We also had a safety briefing for the crowds where we told them to protect their childrens’ ears and secure any loose items that might be swirled away into our engine. Truth be told, it only creates a mild breeze at low power settings but it was all good precautions. The spectators were brilliant and took excellent care whenever we carried out one of these tests.



Once strapped in, Stew spent some time going over the controls and doing practice drills from his checklist. This was a bit of a vertical learning curve for him but he went about it most professionally until, declaring himself satisfied, he closed the lid, gave us the signal that he was good to go and we removed the intake blanks.


It went off without a hitch. Stew followed the start procedure to the letter, the engine lit at the prescribed moment and, though yet again it raced to 50% before settling down, everything ran smoothly. We also got to see for the first time the effect of the jet efflux on the surface of the loch.


Another small glitch we took with us was a small but persistent fuel leak from part of the fuel system that operated at very high pressure. Much of the fuel system we ran on Bute was overhauled original – a seemingly impossible task undertaken for us by aerospace but which created many problems of its own one of which was choosing suitable gasket material. Back in 1959 when it was built, asbestos gaskets were the norm and what an incredible gasket material it is. Mainly because the same microscopic hooks that make it ruin your lungs also grip the sealing faces of whatever you want to seal and don’t let go but of course we can’t have those any more so the one that was leaking had been replaced with some high-performance foil-backed carbon material but unfortunately it wasn’t quite high performance enough and it leaked. You’d think all of this shouldn’t be a big deal but in many cases the thickness of the gaskets between faces of the myriad components affected the stroke of levers or the travel of pistons so it all needed careful redesign in the rebuild process. We later cured this particular leak on the test rig with a new carbon gasket and some aerograde Hylomar but in Scotland with the fuel system largely inaccessible we could only keep an eye on it so John peered in and declared it OK.



Stew’s static run lasted only a couple of minutes to conserve our limited fuel because we had a bigger plan for later in the day but it was a complete success and caused much smiling once he’d shut the valves and the engine had spooled to a standstill and the blanks went back in.



Malcolm did his debrief, all parameters were recorded in our notes then we headed for the tea tent for refreshments and a natter with the crowd who had about a million questions. Stew enjoyed a well-earned photo opportunity.



But no rest for the wicked because our rather bold plan for the afternoon was to get Bluebird onto the water, install lead-pilot Ted in the cockpit, light the engine then have him complete a slow taxi run down to where the loch narrows and then back again. That half of the loch is really shallow and we could all see it clearly from whatever vantage point so it was a good starting point for our on-water running but first we had to prepare our kit to enable us to light the engine whilst afloat.

Yet another incomplete job before our crew training was Bluebird’s on-board air start system. With the help of another sponsor from Aerospace we’d got the original working but not so we could safely use it. It was only tested to a pressure where it would spin the engine for a few seconds but nowhere near enough to start it so we’d designed in an offboard connection but now we had to get our start bottles afloat.



Stew Vandal, now out of his scratchy army uniform and looking a million times more comfy, helps Jimmy Poole (in the boat), operator of Loch Fad Fisheries and skipper of the start boat from the get-go, to try out our arrangement for stability.

We asked Jimmy, who had also been instrumental in arranging a thousand and one things on the island ahead of our arrival, to skipper our start boat as he knew these little boats better than anyone, and soon enough he became so crucial that a run would be delayed if we couldn’t find Jimmy for whatever reason. That’s basically our start rig bobbing about on a boat. It’s two, 50litre, 300Bar air bottles attached to the rapid start system from a Vulcan bomber. It all connects to Bluebird via an air hose and an electrical connection and can be fired by the pilot in the cockpit. Bute Blacksmiths allowed us to steal their 3-phase leccy to run a HP compressor to charge a second pair of bottles from which we decanted air to keep our start boat topped off.

We launched Bluebird



We knew how to do this now – crew training, you see.



One of the regular tasks was to remove the jetpipe cover once the boat was afloat. We always left it in place for the launch or a bout a hundred gallons of water was sluiced straight up the spout. John wades ashore with it.



Then, with us all back on the beach, Sir Malcolm presided over one of his pre-run briefings. We had lots of things to discuss this time as what we were about to do was very daunting and we’d never done anything like it