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[1967Brutus]

Engine is out, and this situation:




has to somehow change into something like this:




I did some off the cuff calculations, which suggest that in the direct drive situation, the prop demanded about 1 Nm of torque to maintain 1500 RPM, at the pitch setting the engine would still pull at that RPM. Just as an indication: that is about the torque a 10 kg servo pulls.

Although intuitively one might think, that a reduction gear increases torque, this is not the case, it is the load that DETERMINES torque. The prop now spinning 3,7 times slower, means that the prop demands a lot less torque.


Meanwhile, firing up the trusty old Electric Jigsaw, because I have some carpentry to do, in order to install that gearbox.

[1967Brutus]

The rusty old electric jigsaw still functions well, so about 1,5 hrs (most of it "curing time") later, I basically ended up with this:









To my eye (I have a very vivid imagination, did I allready tell you guys?) it starts to look more and more like a true marine Diesel...

The boltholes are slotted to allow for alignment, and the bracket is built to be plane-parallel with the flywheel. That should make it possible to align the gearbox parallel and concentric with the crankshaft. to within a sufficient small margin.

One or two hours more to allow the aliphatic to thoroughly cure, I will slap on two coats of pore filler, and then two more coats of polyurethane parquet lacquer for oil and waterproofing.

The blocked portside cooling tube turned out to get unblocked very easily so now that we have ample cooling capacity, it also is time to install a controlled cooling bypass, which can be done in the meantime the coating of the gearbox-bracket is curing.

The way this is going, I expect to be able to do a bathtub-testrun tomorrow evening, which opens up tyhe possibility to take part in a Demo on Saturday.

[1967Brutus]

I know this pic is a near duplicate of one posted earlier, but it really is not.



The gearbox in its final installation.
The construction is strong enough to turn over the engine acting on the gearbox output shaft (against a 3,7:1 increasing gear ratio, takes considerable force) so I am more than positive that this will hold, and alignment seems to be quite OK.

Also did a quick 'n dirty bypass control valve for temperature regulation, no pics yet, will be posted later.

[1967Brutus]

https://www.youtube.com/watch?v=eZqfwz1ecFU

Not the prettiest video I've ever made, but I'm absolutely very satisfied...
Unfortunately I can't measure any bollard pull in the bathtub, but the first impression suggests that I've made considerable concessions in that area, but judging by the propwash the speed is still OK.

The engine runs a bit rougher and more irregular due to the lower torque load and especially the reduced inertia in the driveline, but this could also be a carburetion issue, because the engine is now running in a completely different load range.

I was a bit afraid of a lot of gear whine, but that's not too bad.

But then the advantages: WOW! I have "pitch control" like I've never experienced before with this boat. Stop is stop, and everything reacts immediately to small changes, whether forward, backward, or "a little more or less".
I've set everything up so that in forward position at 65% stick, the pitch is at full tilt. From 50% onwards, throttle is added as well.
The first part of the stick deflection is therefore purely pitch at more or less constant speed, the second part is mainly "speed controlled".
Where previously with the propeller in neutral position there was a lot of turbulence in the water, this has now almost disappeared. I think the "prop walk" has now also almost disappeared (previously Woutertje was turning on the spot at a fairly fast pace when stopped).

The temperature control also works brilliantly, responds well to the settings, only those settings are a bit "coarse".
In the bathtub test I saw the temperature go up and down by 2 degrees at most, where it was striking to see that when I gave full throttle, due to the higher speed (and therefore higher pump speed) the temperature first dropped by 1 degree.
When adjusting the control point, a reaction was visible within a few seconds, but the smallest step is soon 4 or 5 degrees.
I now have a temperature of between 74 and 76 degrees, one step higher and we soon see 80 degrees, one step lower and the whole thing goes to 70 degrees plus minus.

I have been running without a superstructure for a while, I see no strange vibrations or oscillations in the driveline, I think this is going well.
What I unfortunately did NOT see was oil circulation in the gearbox, but it could be that there was a bit too little oil in it.

I am happy, and this afternoon I will go to the club pond to test on open water, and then we will also do a bollard pull test.

[JimG]

Really good work there, I don't know if you use Facebook or not. If you are on Facebook there is a group Model Engines - Old and New whose members would be really interested in seeing your work. It is a private group so you need to join it before seeing anything. Engines include I.C and steam.
Jim

[1967Brutus]

Really good work there, I don't know if you use Facebook or not. If you are on Facebook there is a group Model Engines - Old and New whose members would be really interested in seeing your work. It is a private group so you need to join it before seeing anything. Engines include I.C and steam.
Jim

Hi Jim,

I have too many groups and pages to attend to as it is allready, but you have my full permission to link to this thread, as well as the "gasoline Alexandra" thread in the sports&pleasureboats section, or the "Pimped Microcosm" in the steam section, in that facebook group.

Bert

[1967Brutus]

Well...

For a very first time sailing, not bad at all... Not perfect, I noticed that the completely different load and torque range in which the engine is now running has quite an effect on the carburetor settings. And since the fuel consumption has also visibly decreased (I think I have now sailed for a good hour with 150 ml, that was around 200 ml before) things are now EVEN more critical than they already were...
The engine stalled quite often on the water this session, and that is not nice of course, but that on-board starter is fantastic. I guess, with some finetuning, that will slowly get better.

What I expected turned out to be true: I have lost a lot of pulling power, but I do not know exactly how much yet, because my unster jumps on hold after a few seconds, and I spend too much time letting the boat rest fall into the wire. I really need some help with that. But from what I could see, it dropped from 1,9 kilo in the direct drive version, to about 1, maybe 1,1 kilo in this set-up.

I made a "towing resistance", just an almost filled (so still just floating) jerrycan.


That actually went quite well... Towing and filming at the same time is quite difficult, so just a short vid:

https://www.youtube.com/watch?v=KO_pu-FzcXs

Of course, the improved functioning of the propeller pitch control was also filmed, and this is also a cinematographic disaster of a film, but anyway:

https://www.youtube.com/watch?v=n34LlAlYJj0

The swift and unambiguous response of the boat is a HUGE improvement, propwalk indeed is virtually completely gone when the boat is stopped in the water, and this makes handling the boat when there is a towing line out behind it, a LOT easier and safer.

At the end of the ride, the drive belt of the water pump snapped (lucky, because I can see THAT on the telemetry, I still have to figure something out for the lub oil pump), so to be on the safe side, I replaced both.
This set has been on, if I remember correctly, since just before the engine was tinkered with in Woutertje, the hour counter is now at 6 hours, so I think I'll replace them every 2 hours to be on the safe side. Then I still have stock for at least 70 hours of operation.

I think the gearbox reaches about 60 degrees, about "hot to the fingertips, but no pull-back reflex".

[Martin (Admin)]

 

    So I fired up the trusty old Ferm piece of crap masquerading as a lathe    

 
 
                 

[Martin (Admin)]

  Not sure if you've already posted Brutus... how is the exhaust routed?

[1967Brutus]

  Not sure if you've already posted Brutus... how is the exhaust routed?

I think I posted that, but can't remember for sure.

In any case, I routed the exhaust through the actual funnel. For that, I took off the funnel from the accomodation, worked out the innards so I could fit an aluminium tube all the way up.

At the engine manifold, I hooked up an old expansion muffler from a .12 class IC RC car model, which "more or less" fitted relatively conveniently.



The muffler is connected to the funnel-tube by about 20 cm (8") thin walled very flexible Silicone tubing.



It is a bit of a fuss to pop that tubing on the muffler, but once done, it usually does not have to come off again for a while.

So when the boat is sailing, it emits a nice blue plume of exhaust gas from the authentic place.
https://www.youtube.com/watch?v=_6-f_VWYC54
It is remarkable how positive people respond to that: "Oh, look, it even has smoke coming out"... Most people do not realize that that is not just smoke but actual exhaust gas from an actual engine... Funny, that...

[1967Brutus]

Me and my smug self...

Tested the boat yesterday because of a meeting today.
No problems yesterday, but today went through 6 or 7 water pump drive belts, none lasted longer than 2 or 3 minutes, but no apparent reason for the faillure.

Finally the last run, the pump turned out to be stuck, so I was of course pretty "xxxxx".

Initially feared pump bearings were shot, but it turned out I obviously failed to clean out all the metal debris from modifying the cooling system.
Had to open the pump to remove a few splinters, and flush out the entire system.

Tested the boat in the bathtub for 15 minutes, seems OK.

[1967Brutus]

Finally the last run, the pump turned out to be stuck, so I was of course pretty "xxxxx".

Oops... Apparently I used language that was off limits.

My sincere apologies to the users and mods, I really was not out to offend anyone.

[1967Brutus]

Since I hurt my back yesterday putting the boat in the water, I did not feel going back to the RC meeting today.
So I did a little maintenance (refreshed oil, regreased prop, adjusted valve clearances, nothing too fancy) and cleaned the "engine room" a bit.

Sump oil probably has been in the engine for about 5 runhours, and was black, but did not look "dirty" if you get what I mean. Pretty sure, the new charge can hold maybe 10 hours.

Put the boat through its paces one more time, for 30 minutes, most of it at full power, with occasional manouvering, mainly to fine tune the temperature control.
Since I now have variable RPM (and thus coolant flowrate rising and falling with RPM) this "following flowrate" apparently greatly assists in keeping water temperature constant. I draw that conclusion because I most definitely see controlling action of the bypass valve, and the temperature very positively follows the setpoint if I change that in the TX programming, but there is very little action based on "load": If the RPM goes up, the controlvalve more or less remains in the same position, and the temperature by and large remains constant. Which makes sense, I guess, since a higher flowrate at the same temperature also results in a greater heat transfer, apparently keeping pace with the also increased heat production.

The funny thing is: if the engine has stabilized at idle/prop neutral, and then full ahead is ordered, due to the immediate rise in flowrate, while the engine block is not yet "heat saturated", the temperature initially DROPS a bit, and vice versa, when the engine has stabilized at full ahead, and neutral is ordered, the heat-saturated block and now reduced flow cause the temperature to rise, ever so slightly.

I got that on (rather boring) video.

https://www.youtube.com/watch?v=HkTEqgTl8Bk

Also, due to the control system, the engine heats up much quicker, previously it took about 4~5 minutes for the temperature to stabilize (not very stable, I usually saw about 5~10 degrees C variation, depending on load and speed through water), but now it stabilizes in about 1~1,5 minute, and variation is 1, maybe 2 degrees.

I still want to try and install an oil temperature sensor, because of how I connected the coolant-bypass to end between oil cooler and liner-cooling.

After the moral dip of yesterday, now pretty happy about how the installation is functioning.

[1967Brutus]

Where last weekend (Saturday) was a total off day, today was the local club-evening, and Woutertje functioned flawless, for a full two runs of each approx 50 minutes, with a bunkerstop inbetween. The fuel tank was nowhere near empty at the first stop, but better safe than sorry. I think the tank allows about 90 minutes of runtime.
EDIT: Checking the "bunkerstation" it turns out I went through approx 250 ml of "bunkers"...

Bought myself a cheap inflatable dhingy, and duh, what do you think....

https://www.youtube.com/watch?v=VW7p_9WWX_8

[1967Brutus]

And a next step has been made:
A long time ago I made a "kinda-sorta" oil cooler for the Cison, basically the reasoning was "if it helps none, it also won't hurt none".

I still had a free temperature telemetry port, so a few minutes fidgetting with the sensor, a piece of brass tubing and opening the oil line after the pump, and presto, an oil temperature measurement.

Of course, this needed to be tested, because I wanted to know what kind of oil temperature we are running, and of course I also wanted to know if this oil cooler thingy actually does anything... (yup, ANY excuse to play in the bathtub... :p).

Tested for little bit over 15 minutes. Water temperature rose pretty quickly, in about 2 minutes that was above 70 deg C and stabilizing.
Oil temperature came up a LOT slower, took about 10 minutes to stabilize, and it ended around 56~57 deg C.
Now the interesting thing was that oil temperature followed load, but SLOWLY... At full ahead it crept to 57, at zero pitch, it VERY slowly dropped to 56. I repeated this 2 or 3 times to make sure, and it was repeatable.
The latter means that the oil cooler is ACTUALLY functioning, because the topside of the engine never dropped below 75 degrees, and that drop in temperature needs to come from somewhere.

55~60 degrees is a mighty fine temperature, loads of headroom, the oils I am using can easily handle 100 deg C or higher, but below 60 is very nice.
Only thing is, it is not hot enough for the oil to evaporate water or fuel, so it means regular oil changes to get rid of accumulated pollutants. But that is no biggie, it's only 25 ml per charge.

I'm a happy chappy again...

[1967Brutus]

And today another clubmeet (different club, different pond), so also another near 2 hrs of runtime (counter now at 10 hr 50 min, meaning the gearbox and temperature control now both have about 5 hrs of operational time).

This time 2 x 15 minutes of "people transport" (towing myself around the pond), and I did not see the engine above 75 (short hiccups of 76) and oil temperature never went above 58 deg C. With free running boat, those temperatures were even a bit lower.

I am absolutely happy... My towing skills also improved, I managed to tow without a single jerk in the towline. Takes quite a bit of focus and pretty quick thinking, but I managed. Could also be beginners luck...

[1967Brutus]

The newer design looks to be more secure. I probabbly bought the Rivabo vp prop around 40 years ago to replace the reversing gear setup I had originally made for the tug. This worked ok but with straight cut steel gears it was noisy and gave a loud clunk every time iit changed from forwards to reverse or back, there was also no proper neutral position so the boat couldn't be stopped.
Jim

Just as an aside note, I recently, actually just yesterday, learned that "Rivabo" actually WAS Raboesch, one of their trading names (probably a different derivate of the name of the company founder). Which made me think about your description of having the pitch yoke screwed on the shaft... I can only think of the need for a shaft/hub design suitable for both directions of rotation as a reason why they would change that design.