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[Allen A]

A (final ?) update on both boats then ..


The No 1 boat is repaired in as much as I was able to join the coupler together again and I managed to straighten the prop shaft to where it is about 99% true (you can learn a lot watching 'The Repair Shop') ..     and it ran very well on a test late afternoon today, I will of course still get a new prop shaft and coupler though .. !!


The No 2 boat was running well as said in an earlier post, albeit with a tendency to drift to port, a nice turn of speed (not as fast as the No 1 boat) and it responded OK to rudder commands, however in as much as the original boats had three engines, props etc all turning the same way, I have taken off the 40mm contra props, reversed the stbd engine polarity again and re fitted the standard 35mm props with both turning anti clockwise,  it runs well on the stand but has yet to be tested on water, all in all though I don't expect any problems.


Going back to page one of this I have, Im pleased to say, come along way with the No 1 boat and what it was like originally to get to what it is today and learnt a lot in doing so thanks to help and advice here from those that gave it ... I bought the No 2 boat as a slightly started kit with a view to completing it and applying what I had learnt from the No 1 boat, ultimately to sell that one ...  however given the state of the No 1 boat and all I have put into it plus its performance capabilities, Im probably going to keep it and sell the No 2 boat ... but not before I can get some stills and videos of a two boat patrol  on the water, which I think .. Im hoping .. will look good ??


I will add pics as and when .. and perhaps if .. I manage to do that !

[Allen A]

Hello again all


I have not as yet had the opportunity to sail both boats in what I would see as a safe and controlled area, a canal as I've said before, not being an ideal place, witness a couple of scares I have had in doing so.


I'm wondering to about waterproofing them both in as much as they ship a very little bit of water through the area where the superstructure meets the deck, anyone have any tips there please ..  Also in as much as I have now built two of these, but both being rescue refurbish tasks in as much as both had been started to a degree when I got them, I am considering trying to buy an unopened/complete kit to build having leant a lot from these two.

[Backerther]

Hi Allen A,
So nice to see you back on here again.
In my waterproof methods for this PT-boat, I did it in the process of assembling the model, using magnets and
and rubber as in the pics below. And I could have fundamentally good result, not to say perfect.

[Allen A]

That looks neat .... I have done something similar in as much as adding a lining to the edges of the deck, but then I stuck some fabric down with double sided tape and then treat it all with a waterproofing liquid .. time will tell ..?


Taking the No 1 boat to a club near me tomorrow as a quest so will see how it handles on a proper boating area, the No 2 boat is undergoing a minor refit in as much as I wasn't happy with the way the motors were mounted so am rejigging it all at present, as I will ultimately want to sell that one would like to be as neat as possible.

[Allen A]

This is my attempt at waterproofing, Ive extended the deck edges with plastic card, put a layer of double sided down with a fabric layer on top of that, then used a waterproofing medium on the fabric and topped it off with a thin layer of grease ... ok a little messy to look at like this, but with the superstructure mounted its not visible and hopefully will do the job ??


NB; .. by way of explanation, the old motor is for ballast and seems to work well, however I am thinking of swapping the battery and old motor around as the battery can be fiddly to place in position where it is.

[Allen A]

With reference to my comment above about making another model of this, but from an unopened unbuilt kit .. ( perhaps this should be in wanted ? ) .. a thought crosses my mind and forgive me if it has been broached in the past ..


Given that the Linderg variant is quite basic detail wise but an excellent motor platform and that Italeri are excellent for detail but not easy to convert to RC, would it be possible I wonder to combine the two ie; use the hull deck and cabins etc from the Lindberg but then all the finer detail items from the Italeri when and where (and if) they would fit, the difference in scale at that size would not cause that much of a problem maybe ?


Wondering on more experienced folks thoughts on it all, given the prices of the kits too it could prove to be costly, but maybe worth it ??    


nb; ... note to mods a 'thinking' emoji could be useful ... 

[Backerther]

The pics below are the latest waterproof measures in my Pt-109 which is perfect against water ingress from the deck.
I applied a thin coat of bath cork around the edge of hull deck and fixed the detachable deck with 4 screws to get an ultimate
effect for fast continuous run on the water for about 7 minutes. And I did it successfully except a drop of water possibly
from the stern tube...



1; bath cork applied and screws to get an ultimate effect
2/3; A drop of water can be seen only here after the high speed run....
4; Sufficient care for an overheat of motors must be taken if run fast continuously....
  I know many Rc boaters who have burnt the motors on the water leaving their boats afloat on the water.
  In most cases, they did not take special measures to cool the motors and/or ESCs.... "oh,a'cchi-chi" too hot to touch !!
Even I did it once in the past in my Jupiter P-550 powered by Mabuchi 540...


Looking forward to your sailing report on here at your nearest club.?!!!

[Backerther]

You seem to be interested in static scale realism for this MTB which is, needless to say, OK for your style of enjoyment.
But I rather would like to put more stress on scale realism of movement on the water simply because it is a kind of RC powered
boat. In this sense, excessively detailed decorations are not necessarily required for my RC scale boat that is EXPECTED to run
like a counterpart of 1/1 on the water. In this viewpoint, even a semi-scale RC boat will do for me in the EXTREME case.
In other words, PTB not too slow while a scale cruiser boat and a large warship be graceful or magnificent in their sailing on the water..


PicNo,1 is my semi-scale 1m(40 inch) class Jupiter F-99 powered by and converted to a brushless motor, aged close to 45 years old
lady still in service as a senior flagship.    She is still graceful in her run...

[Allen A]

You seem to be interested in static scale realism for this MTB which is, needless to say, OK for your style of enjoyment.


Hi, actually no, you have apparently misunderstood my explanations and descriptions ... it is true I do like detail but also when and where as here there is movement involved then I like the movement to be realistic too and both boats sail very well, the No 1 boat being quite fast, probably too fast for a scale speed, the No 2 boat being perhaps a little more 'sedate' but still produces a nice bow wave and wake and with the bow riding high at speed on both boats.
The No 1 boat has a crew of 14 and I have used my imagination to try and place them all in work like positions, I have added a few extras here and there, flak matts for example, oil drums and depth charges, also as said before it has lights fitted at the bow, in the cabins, the searchlight works and the mast light too is operational, it is important I feel to not only have any moving model move realistically, but look realistic too.


A couple of pictures attached of the No2 boat on the canal recently, sorry for lack of quality but they are still grabs from a video program

[Backerther]

Thank you for sharing your pics with us of decent scenes sailing at moderate speed realistically by the waves and wakes.!
I wish I could see the video that might clearly and vividly appeal your boats sailing realistically.!!
You had better have put the video itself on here since it is a power boat and moving scene.....    Next time, I could expect..?

A static scene of RC boat/ship on the water is generally not so interesting, appealing and impressive for me simply because
it is the very RC boat....
Scale realism of the scale model boat is good if represented by the sailing scene/performance IF she is ON THE WATER in a sense.
Needless to say, static scene is also enjoyable, happy and interesting to see on the water from the viewpoint of scale realism.


Pic; The RCed static model on the water ..?   no working /movable parts except screw props, AA gun mounts and rudder..!!
But its Ok since I rarely stare at her nor play with the AA gun mounts in the room except getting her out for sailing at speed on the water once she has been complete in my case. 

[Allen A]

Not sure if this will go but a short clip from a standing start 


OK so I cant seem to attach a short Mpeg it seems .. not sure how to get a video to view then .. sorry

[Allen A]

Hmmm ....  I could be on the point of a large problem with the No 1 boat, it runs well as I say but I have noticed the motor gets hot .. and I mean HOT ..??    .... pic attached of it in situ, it was sold to me for the boat but think it is more suited to fast cars, especially as it was from Model Sport in Otley whose speciality cars and trucks etc seem to be ... thought I would mention here first though to see if it rang a bell and could be something else ??

[Colin Bishop]

If it is running hot then it is overloaded in some way. Too big a propeller or maybe binding in  the shaft tube. If the shaft isn't binding then try smaller props to get the system balanced. A motor won't get hot when under no load unless you are putting a massive over voltage through it.

Colin

[Allen A]

Hi Colin ... thanks .. still something of a novice at all this but have learnt a few things and have checked the motor to make sure no wires crossed or touching, also prop shaft runs freely with a little fore and aft play and battery is well within the capabilities of the motor .. 11.7 Lipo .. given the capabilities of the motor from my limited knowledge I cant see where it is under pressure as such as the boat fairly rockets along at full power, a little frighteningly so given my limited skills, the prop is a three bladed brass one about 30mm diameter


I have noticed though something of a 'rattle' from the motor itself when running medium speed on a stand so may go back to shop with it for their opinion, could be there is a fault there, a 'Friday night or Monday morning' one ... hopefully it is something as simple as that .. its a 540 and a little large and whereas it is square laterally it is very slightly low inline wise horizontally with the prop shaft because of the top deck/cabin fittings on these boats limiting my raising it more inline, wondering if they make a 450 or something like that which in being smaller in size I would assume would allow me to raise the motor a little more level ??

[Backerther]

If you should think that the motor is well-aligned and screw shaft is also smoothly rotated by hand, the rest is water-cooled
to cope with the over-heat. A motor is generally apt to get warm/hot when in rotation dependent upon the loads / speed against which an adequate measure has to be taken to cool/keep the motor temperature within a certain level.
The faster the boat, more the cooling is required not to get it blown up by the heat as I have predicted and warned previously in
my post dated July 13.
Especially RC scale boat is normally sealed completely against water ingress which is not good for motor cooling unlike other
RC cars and RC planes which are normally open to the air.

I have adopted the water -cooled system for all my FAST scale boat as a common sense, whenever she is "destined" to run faster continuously on the water. Slow moving FAST boat is not so interesting to see on the water from its nature/characteristic
just like a racing car running so slow on the course and vice versa for an old but fast classic cars,.... though interesting in another meaning???


The pic is my PT-109 ejecting powerfully the cooling water from the freeboard continuously for seven minutes this time
keeping the motors within a certain level of temperature.


The video is the best to show how a moving RC model ship actually, vividly, clearly and exactly behaves on the water, which 
is impossible to represent real movements by still/momentary images, needless to say...


Lindberg 1/32 PT109 sailing test resulted in success in the third trial run. (youtube.com)
.....continuous sailing at speed with no problem by the water-cooling.
 

[Colin Bishop]

Unless you are building and running racing boats where you need every last ounce of power from the motor, watercooling should not be necessary. Motors may a get a a bit warm to the touch but no more than that. If they get really hot then something is wrong and watercooling is only treating the symptoms rather than the cause.

Looking back over the thread there is a suggestion that the tube has been filled with grease. If so, this may be the root of the problem. It is tempting to do this to provide a watertight seal but not necessary as the washer on the end of the shaft will prevent all but a few drops entering. Only the bearings at the end of the tube need a touch of grease and the aft one is effectively water lubricated anyway.

At slow speeds a grease filled tube feels very smooth but one the revs increase you get viscous drag which greatly increased resistance and thus current consumption. You don't even need to be going very fast either. I had this issue with my 48 inch fishery cruiser and removing the grease from the tubes cut current consumption by 60% or so t just moderate speed.

Glynn Guest explained this very well in his recent Model Boats article on Drivelines. I don't think he will mind if I quote the relevant section below.

Colin

*******************
Some modellers insist in filling
the propeller tube with grease.
This might be an advantage if
you have a leaky propeller tube
and the thick grease would
hinder the inward flow of water.
The problem with grease is its
viscosity, in other words its
‘stiffness’ and resistance to
letting things flow around it. A
good illustration of this effect is
to take a knife blade and move it
edge first through a low viscosity
fluid such as water and you will
hardly feel any resistance. Now
try it through something more
viscous like treacle or jam, even
with the sharpest of blades you
will feel noticeable resistance.
The same thing happens inside
the propeller tube as the rotating
shaft struggles against this
viscous drag.
In my less experienced youth,
I built a model based on an early
torpedo boat. It was outfitted
with a motor and battery pack
typical of fast electric racing
craft and similar performance
was expected. In fact it
wallowed around the pond in a
disappointing fashion and
displayed a short battery life and
very hot motor. I had of course
followed the accepted wisdom
of filling the propeller tube with
grease. Removing the grease
and replacing it with oil resulted
in the model storming across the
water in a much more realistic
manner, a cooler motor and
longer powered run. Since then
it’s been a ‘no-brainer’ for me to
avoid grease filled tubes and
only use oil.

[Circlip]

Allen, you need to tell Colin about the discussion with Stan and me last Sunday re the non straight line alignment of the prop shaft and the motor IN SIDE ELEVATION. Looks OK from above but the side view explains why you managed to shatter the Hewco when bunging it into reverse and also why the motor runs hot.


 Regards  Ian.

[Colin Bishop]

Allen, you need to tell Colin about the discussion with Stan and me last Sunday re the non straight line alignment of the prop shaft and the motor IN SIDE ELEVATION. Looks OK from above but the side view explains why you managed to shatter the Hewco when bunging it into reverse and also why the motor runs hot.

Yes, I don't imagine that would have helped! Glynn's comments about grease are still very valid though as I can confirm myself. By stuffing the tube with grease you are effectively creating a torque converter.

Glynn's original 2012 Drivelines article in 2012 can be seen on the Model Boats website although all the diagrams are at the end following its conversion from the old Model Boats site.

https://www.modelboats.co.uk/1270/drivelines/

Colin

[Backerther]

I have been enjoying to sail very much many RC fast boats up to today as seen in the typical video above, all of which were water-cooled and filled with grease in the stern tubes. No problems including motor blown off by the overheat could took place at all after the fast sailings on the water. A motor is normally easy to get warm or hot even if well-aligned or adjusted if it should run
 continuously fast for a certain time on the water.

"Seeing is believing" and "Example is better than precept" are my favorite proverbs.
Take my Jupiter F-99 for instance. She has been in service for nearly 45 years up to today with no troubles filled with regular maintenance of grease and water cooled system.

[Colin Bishop]

I'm not saying it won't work, only that it isn't working efficiently. All that heat is energy from your battery which instead of being used to drive the boat, is simply warming up the lake! It's like riding a pushbike up a hill in low gear, you can do it but its a heck of a lot more effort than using a high gear.

Colin

[Backerther]

It' worth challenging to water-cooled system if you do not have any ideas to come up in your brain.
I have ever experienced 3 years before to blow a motor off in my Jupiter P-550( 20 inch long) completely due to tremendously hot heat. And I challenged to water-cooled system for a better solution and I did it completely as seen below.
1;I made a water jacket
2;I also set it around a brand-new Mabuchi 540 motor.
3;set it in the hull securely
4;a water pic-up is set this position in my case where is OK, if possible, ideal if within a prop rotation diameter scope
 "Example is better than precept"even in this position as in the next pic.
5;water drain is confirmed !!and the boat could succeed in fast continuous sailing with no anxiety of possible over-heat threat.


Before that, refrain from all the mis-alignments and secure smooth rotation of the screw shaft.


Wishing you a success. !!!

[Allen A]

Gentlemen .. thank you and all points taken I assure you .. to whit .. I have just spent a couple of hours dismantling and cleaning, de-greasing my prop shaft as I had indeed greased it in the belief it would help ... pics attached of it all as it came out of the boat and of the cleaning materials ... please don't have nightmares 


I haver also managed to raise the motor a little more than is showing in the picture below, it is just clearing the underneath of the upper deck structure now and as for the nearness possibly contributing to the (over)heating of the motor time will tell.


Pics also attached of the prop itself for 'inspection' ..    .. would be interested to hear any comments,  pro or con please gents.


Ian, nice to meet you last Sunday, wont be there this week but will be on the 28th with both boats up and running for shakedown runs and hopefully photo and video opportunities ..

[Circlip]

Looking better Allen but the link from Colin re G G's driveline article should be noted. 'Motor Mounting' paragraph two, last sentence. Max efficiency can only be achieved by correct alignment. Problem with that motor and layout as you realise is that water cooling coil would be a problem to fit due to deckhouse clearance, or lack of it. Another check re water ingress, try sealing, purely as a test, the joint lines on the deck with electrical insulation tape. As we stated last week, water is probably getting in through  the deck line rather than up the shaft.


  Regards  Ian.

[Backerther]

The motor shaft and screw prop shaft have to be in-line as much as possible as seen in the Pic No1 which I think is nearly perfect.
And I confirmed ACTUALLY with a small battery the smooth rotation of screw shaft by tachometer and my experienced ears? if it should be calm, natural and smooth sound.
1; This is so called in-line.
2/3;I used 1.3V battery to check how fast/smooth RPM will be by this voltage...faster the better for smoothness
   after grease up
4;The result was 1900RPM for port and 2000RPM Stb side. And so natural sound of normal rotation for my ears.
    540 class motors+1.3V +1900RPM+natural sound are equal to OK for me.
 (Allen, try this test, if possible, to know how your prop shaft will be just for your reference after present  modification.)

I judged the above as sufficiently OK for smooth rotation of 540 class motors by which enough speed could be done as seen
in the video posted yesterday.    Example is better and persuasive than theory/precept..??!!!

[derekwarner]

Kiyo......as you say, music to our ears is a surprisingly accurate way to determine motor speed comparison 


These relatively low-cost DC motors have by the manufacturing design, have a confirmed preferred direction of rotation [alignment of carbon brushes over the commutator etc]


It is also necessary to understand having a port & stdb motors with opposing direction of prop rotation, dictates the EMF created in each motor is opposite


This is the reason you see the differing speeds ....20,000 to 19,000 RPM etc


A proof of this is the 12v DC motor vehicle windscreen motor.........these have a single ball bearing in the endcap of the motor shell......when the motor is excited by electricity, in the preferred direction of rotation, the EMF forces the rotor shaft onto the ball end the endcap to act as a thrust ball, and minimising friction


If the polarity of this motor is reversed, connection to the voltage creates the EMF that pulls the rotor shaft off the ball......and the motor effectively hunts [longititudional float of the rotor during use]


A tachometer will also confirm a small % variance of output shaft speed 


Derek