Broad Ambition - The Model

[Ray]

It would be interesting if you have time to do a short video of everything working Grendel, I still marvel at your modelling skills! 👍

[grendel]

Ray, while you were posting, i was busy creating such a video, seen here

 

[Ray]

Fantastic! Thanks Grendel, that's exactly what I was hoping to see. Great job! 

[grendel]

Just a few teaser pictures really, as it was so windy at beccles sea trials were postponed, it was still plenty rough enough at deep dyke this morning but I wetted model #2's bottom all the same, she performed admirably, but I only got a few pictures on my tablet, the rest are on the camera as are the videos, so will be uploaded when I get home.

[Ray]

Looking good! 👍

[Polly]

It is looking very good! For some reason, Peter wouldn't let me step on BA II when going aboard Jayne 2, I cannot think why not.

[grendel]

well as it transpired, performance was quite good, but the battery was near exhausted, this was because I pklugged it in on the sunday morning to show off the sound unit to Rbin, and forgot to unplug it, this meant that both the sound unit and speed controller were sitting on standby for the best part of 36 hours before I ran my sea trials, as the sound board in operation can draw 1.8A its surprising I had any battery left at all, still the sea trials were a success.

herewith we have the rest of the photos (the videos will have to wait until I upload them to youtube)

I particularly like the one above, showing a nice bubble at the forefoot and some wake and wash.

Yes I did try racing a day boat, and very nearly kept up with it too.

[Ray]

She looks great! I particularly liked this shot 

[grendel]

she can turn in little more than her own length too.

[Ray]

Such a shame the original doesn't have a bow thruster! 😁😁😁

Only kidding Griff 👍

[grendel]

 

[Ray]

How cool is that! 👍

[grendel]

its not easy controlling the model and pointing a camera.

[Ray]

I can imagine! I guess there's no room for a cam on board, although it would be a great viewpoint!

[grendel]

to be fair i could put one on board, i just didnt think about it.

[Ray]

Probably for the best, you've put so much work into authentication it could detract from that and after all the best view is watching her cruise!

[grendel]

Well when i was testing the model i thought the prop shaft was a bit stiff, so today in a problem solving state of mind the propulsion system was stripped down, thoroughly cleaned in an ultrasonic cleaner and tested, i did notice some points of wear on the prop shaft, these were situated at the bearing surfaces at the ends of the prop shaft itself, nothing major, but very slight scuff marks, these were sanded off with a fine wet and dry paper.

following this the prop shaft was re-installed and it was during this i noticed the shaft wasnt cleanly entering into the shaft support, it was only by a mere fraction, but the support is glued into the hull, so a large punch was used to push the support further through by the fraction that was needed, and the part reglued into position after testing. 

every other component (the model car cv joint) was then re-examined and tested to try and find where it was being tight or noisy, strangely with so much metal contact points in the cv assembly, when run independently, it was whisper quiet, all the noise is being generated in the prop shaft itself, and support. i think the noise is mainly where it is being amplified by the hull out of the water, once its in the water and boxed in by the roof and cockpit decking it should quiet down somewhat. 

[grendel]

here is the drive line, complete with rc car cv  joint, the angle of this is adjustable. also shown is the prop shaft support, this had to be moved down approximately 0.5mm or less to  get perfect alignment

[Ray]

0.5mm! Moving something by that small an amount must present problems in itself. Have you had a chance to see if she is running quieter with your adjustments?

[grendel]

she is a little quieter, but i need to put her in the water to really see.

[ZimbiIV]

If that's a brass top support bar it will oscillate counter to the shaft rotation, change it for a steel one.

Then you will find out if any mis-alignment of the shaft is tightening up rotation, the mount will shudder1

paul

[grendel]

the bar is only stopping the cv mount pivoting, it cant rotate in the direction of twist. i have done another test, measuring the current draw, previously it had been around 0.7A flat out, remeasuring has brought this down to 0.4A current draw, for me this means a source of drag on the motor has been reduced. the current in the water will be higher as the prop will be moving water against resistance, but i do hope to see an improvement in performance. a current draw of double, ie 1A, would give a run time of about 5 hours before the battery dropped to 50% charge.

[ZimbiIV]

Brass is not strong enough to prevent any form of movement it needs at least 3 contact points to try and stop movements.

Any trace of vibration will not be dampened by brass.

Fixing that joint will show where any tightness is.

paul

 

[grendel]

well having an hour or two to spare i took the model to the local boating pool, the noise does lessen when the boat is in the water, i took 2 videos, one on shore and one on the boat, and if any more proof was needed that the noise is generated through the boat, then the on board camera is the proof, with the noise beint transmitted to the camera through the mount. i also found that a flat is required on the motor shaft as by the end it had worked loose and was slipping. one more thing i noticed was that at full power i was getting the motor cutting out momentarily, i'm not sure what is causing this at the moment, but i will track it down, its not the speed control overloaded as thats a 30 amp one, i might try a different one if it continues. just to compare.

[grendel]

you will probably want to turn the sound down on the first one as the noise is resonating through the camera mount