Today Scotty from La Conner Maritime Services arrive at my Port of Edmonds and did the final install for my engine's Low Speed feature.
Summary:
Time to install the hardware, calibrate the software, configure the various user settable settings via computer laptop for the throttle engagement, dry testing things at the slip while stern tied down securely when engaging forward throttle and two sea trials was 4 hrs.
It works.... :lol: Lowest speed with Auto pilot holding a heading (slack tide, wind at 6 mph, calm seas) was around 1.5 kts. Any slower than 1.5 kts the Auto pilot struggled holding the heading and issued warning msg that flashed up a few times indicating the Auto pilot's pump was stalled. The highest speed achieved while the engine was in Low Speed mode was around 3.2 kts. Beyond the Low Speed throttle setting/range the transition to normal throttle use was seamless with no sudden increase in engine RPM. Scotty was concerned that the transition from the Low Speed range to normal Throttle use might cause a sudden and uncomfortable RPM increase; this did not happen.
Details:
Firstly, the way the Low Speed feature works is quite simple. Basically, the rotational speed (RPM) of the prop shaft is controlled by a hydraulic set of valves that controls the amount of pressure the output clutch plate/disc is applied to the engine's output clutch plate disc. The slower speed is achieved by applying less pressure between the two clutch plates and more pressure for faster speeds, up to the point when full pressure is applied to cause no slippage between the two clutch plates. My engine has around a 2:1 ratio meaning the engine RPM are twice that of the prop shaft RPM. The normal idle engine RPM is 700. When the Low Speed mode is engaged (via a button on the throttle base with the engine in neutral) and then moving the throttle lever forward past it's first indent the prop shaft can be lowered from 350 to around 100 (my estimate and could be more or less). As the throttle lever is pushed further forward the hydraulic valve(s) increase the pressure between the two clutch pad discs to raise the prop shaft RPM up to the 350 level. Pushing the throttle further forward disengages the Low Speed mode and from this point on the engine's RPM can be raised all the way up to 3650 as desired.
After Scotty installed the hardware (the two-piece Reluctance plate/ring and the magnetic pulse pickup component that was set to be around .5 mm from the Reluctance plate's teeth), Scotty manually turned the prop shaft to ensure the Reluctance plate/ring was properly centered and none of its teeth rubbed/collided with the magnetic pulse pickup device. The 'pulses' are created by the teeth as they pass by the magnetic pulse pickup. These pulses are communicated to the Low Speed's software in the engine's EVC computer so it is aware of the prop shaft's RPM.
At this point Scotty wanted to do a sea trial to ensure the Low Speed operated as claimed by Volvo.
As an aside, before the sea trial started we had some engine alarms going off which took Scotty some time getting a grip on. The engine alarm for 'water in the fuel' was sounding and no matter what Scotty did trying to deactivate it and clearing the recorded error codes in the engine's software, the alarm persisted. Scotty thought the sensor for the water in fuel had faulted or that there was water in the fuel. Scotty release the sensor from the base of the secondary fuel filer to check for water and none was found. So Scotty was thinking the sensor was bad or had a transient error issue. Bad news, as Scotty did not have a spare sensor on hand. What to do ? It was decided to continue on with the sea trail.
We got out onto the water and started to employ the Low Speed feature. By golly, it had no affect on the boat's speed. Hmmmm, what to do ???? No matter what we did the Low Speed feature was not doing what we expected, even though the Volvo engine display indicated it was engaged. Scotty, then admitted that he had forgotten to calibrate and configure the Low Speed software he had previously installed a week ago when the boat was up at La Conner. Basically, the engine's EVC computer had no clue it had the software installed. (ha ha)
😱 So it was back to port so Scotty could grab his laptop from his parked van.
Back at the slip, Scotty fired up the laptop, connected to the engine's VODIA (Volvo's Diagnotic application) port and started the software calibration and most importantly the settings for Low Speed feature. Of course there are default settings but one of which controls the amount of speed the Low Speed software will allow. The default was 10% which Scotty thought would allow a decent low speed to be delivered. We tested this by securing the boat's stern to the dock, engaging Low Speed with throttle in neutral, and pushing the throttle to the first indent and a bit further in increments while Scotty observed the prop shaft's rotation. With this 10% setting there was not much reduction to the prop shafts rotation speed.... Hmmmmm, so maybe the default 10% was insufficient and we decided to raise it to 70%. In short, this did the trick and we were both happy with the result.
Sometime while Scotty was adjusting the settings the laptop software indicated the power to the engine needed to be turned off and back on after a few seconds. This apparently was to allow the software setting that had been made to be 'burned' into the EVC's EPROM chip. This was done a couple of times.... and strange as it may sound, the 'water in fuel' alarm that was persisting throughout most of the activities so far stopped and never ever again disturbed us... a real gremlin if you ask me.... and looking at Scotty he felt the same way.... software can be finicky at times I guess. No matter, it was a relief to both of us that this alarm was now gone and were left with really not knowing why it
messed with us in the first place. :?
So now we went out for the 2nd sea trial and this time we had success. It was possible to run the boat as low as 1.5 kts with Auto pilot engaged and holding a heading. At a lower speed the Autopilot struggled a bit and threw out 'Auto pilot pump stalled' msg at times. The max Low Speed was at around 3.2 kts as controlled with the throttle. Transitioning from the Low Speed throttle range/angle to normal throttle operation was smooth with no sudden RPM increase and the engine could be run up to WOT and 3650 RPM.
Both Scotty and I were in agreement the Low Speed feature was now operating as Volvo claimed it would, and headed back to home port.
All done in a 4 hr window... and Scotty and I were very happy.
😀 😀 😀
Photo album here...
https://www.icloud.com/sharedalbum/#B1A5qsTcwP8u58
So the real test/benefit for this Low Speed investment will be if I now can catch my Salmon limit multiple times to cover the cost of having the Low Speed installed.... :lol: :roll:
One last thing: what is the maintenance aspects involved with having the Low Speed hardware/software ? I did ask Scotty about this and the response was... "basically no maintenance required." Also, one might ask what are the side affects of having Low Speed feature installed? Again, Scotty replied... "a little more heat will arise due to the clutch plate's combined friction slipping heat... but really no worry as the transmission is cooled to take care of that aspect, and that the clutch plate's wear maybe will be a bit higher.". I quizzed Scotty about running the engine at 700 RPM for extended periods while trolling for fish.... and Scotty additionally replied with some information that addresses another recent post elsewhere here about WOT being used at times and was it necessary ? Scotty said it was very useful to run at high RPM periodically to raise engine temperatures to 'burn off' oily/carbon residues in the Turbo conduit connections and the Turbo vanes as well as the charged air unit (the big finned green box hanging on the upper aft port side of the engine). The charge air unit has many small diameter tubes inside and the moist air mixed with some exhaust oily/smutty fumes will over time build up on the tube's outer surfaces and affect the ability to cool the charged air. Running at high RPM periodically will cause sufficient heat to be built up that will deal with these items and keep the residue build up to a minimum, allow the engine to run smoother, and provide a cleaner exhaust.
Scotty ended up saying, just wait until you have to deal with diesel engines having to have catalytic converters similar to what autos have today. A lot of engineering magic will and is needed to avoid clogging the converter and running a
hot engine will be a necessity at times.
