Lazy Easdale Sound Sunday

We were feeling a bit ropey this morning as we had been at the opening of the new pub in Ellenabeich last night . . . very nice, microbrewerey & restaurant. Had a meal with friends and drank 'till midnight then cycled back over the hill by the light of the full moon. Got up this morning a bit groggy needing to get out to the boat before the  tide dropped too far to get off the mooring. (It probably wouldn't have, but it's equinoctial Spring tides and tides in the bay can be a bit unpredictable anyway)

So - first time through Cuan Sound this season . . . low water, Kathy was driving (no wind) and got a little close to the Cleit - showed 1.8m under the keel. Once clear of Cuan we throttled back and drifted a bit while we cleaned the Winter grime from the cockpit and stern of the boat, then headed on over to Easdale Sound.

Cleit Rock

Into Easdale Sound, never showed less than 2.5m going in - chart shows 1.8 at LAT and we  draw 1.05, so this isn't such a low spring tide after all. Picked up the Eilean Easdale mooring near the pier and read the paper while Kathy cooked sausages, mushrooms and eggs. Very civilised.

I rowed ashore to collect friends while Kathy tidied up and cleaned down below. Chris, who has an engineering workshop in Ellenabeich, had volunteerd to witness/assist with the installation of a new thermostat, which I hope will cure the temperature fluctuations and overheating the engine is still exhibiting.

I brought Ruth back to Fairwinds first while Chris finished a job in the workshop. Drank coffee and stuck some sail tape over the damage on the mainsail (batten pocket at 3rd reef torn at the inner end). I had intended to sew it, but there was a gusty wind on the mooring so decided tape would have to do for now.

Easdale Sound, early Spring

I then went back in the dinghy and picked up Chris. We changed the thermostat and impellor then went for a bit of a sail, but the wind died . . . we drifted about for a bit, but were being carried on to the Southern shore of Insh, so we had to start the engine and motored back. The engine seemed to run steadily at 60 to 70 deg with no rapid temperature fluctuations.

Once back in Easdale Sound we went ashore briefly to get the air cleaner beadblasted and blown out in Chris's workshop. Rushed off to try to get home in time for the brand new series of Dr Who. Willie gave us a tow out to the mooring with the Easdale ferry, which sped things up.

Raining and a light breeze bang on the nose, so motoring for Cuan. Too early for a real spring tide thrill ride - we picked up just two or three knots on the way through - but the water had an interesting look about it at the Cleit.

North Cuan

Once through Cuan we got the dinghy in and tidied up ready for a quick disembarkation. The engine was back to running at just under 80 deg for most of the way back up Seil Sound(boat speed of  of 4.5 - 4.8 knots), but as I cut the corner going into the bay (HW, wouldn't normally do it) the temperature started climbing and by the time we were almost back to our mooring it had reached 90 deg. I cut the throttle and it plummeted back down to 50deg - think it was some sucked in weed from my short cut over the kelp beds, but time will tell.

Got home just as Dr Who was starting. That's the boat ready for a cruise during the school Easter holidays now - a leisurely circumnavigation of Mull is the plan. Watch this space.

Distance - 8 miles

Engine Hours - 2.5

Total for season - 18 miles

9:16 PM - Mar. 26, 2005 - post comment

Themostat in MD6

Hi Nick
I'll be interested to know how you get on with the new thermostat.

I believe that a modern thermostat in a raw water cooled engine will always give temperature fluctuatons. Consider the following sequence of events.

The engine is started from cold. The thermostat is closed. All the cold water from the pump will pass straight through the Tee piece on the manifold, into the bottom of the thermostat housing, pass behind the thermostat, out the top of the housing and along the hose to the exhaust and overboard.

The engine has been working for a while. The thermostat is still closed. There is no circulation of water through the engine. The temperature gauge sensor, and the thermostat will eventually become warm as heat is conducted from the much warmer water around the combustion areas. There may be some thermal circulation within the block waterways but there will still be a temp difference between the hottest water and the thermostat.

The thermostat now opens. Some cold water will now flow from the tee piece into the engine, and the warm water will flow through the thermostat and out of the top of the housing to the exhaust.

The warmer water from within the block will now reach the thermostat which will open fully.
The maximum amount of cold water will enter the block, but will not reach a very high temperature unless the engine is working flat out, and will cause the thermostat to close fully.

This cycle will continue, showing great fluctuations on the temperature gauge.

When the engine is working hard, there will be less fluctuation, as the stat will not close fully.

The engine would have origionally been fitted with a themostat with a wax capsule which would have reacted much more slowly than the snap action of a modern thermostat.

The thermostat will have a tiny hole in the outer rim, which may allow some circulation when the stat is closed, but it's real purpose is to allow air to escape and prevent airlocks when filling a closed system engine.

I have opened this hole to 3mm to encourage a flow of water past the capsule of the stat and hence reduce the fluctuations. I believe that this does help, but should be bigger, say 5mm or even 2 holes at 5mm. This modifation will have the detrimentatal effect of making the engine slower to reach operating temperature in the first place.

Does anyone have any experience of this mod, and know the correct size of hole?

Ashley Smith
Mistral
Vega1789

Anonymous - 4:45 PM - Mar. 31, 2005

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