Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[dlancast]

Dear Folks,


Having just completed a static model of the "J" boat "Endeavour".  I have decided to attempt to convert a static model of a Tramp Steamer that I converted from a "Millford Star" model several years ago.  The original kit was of a Fish Trawler, using a fiberglass hull, she was designed for RC sailing.  I always had RC in the back of my mind someday, that I would want to convert this model for RC sailing.  I don't have a great deal of experience in RC, so will need some help in getting the right equipment installed.  I know little about wiring and batteries.  I guess, to start off with, I need to cut along the edges of the super structure in order to gain access to the inside of the hull.  I want to keep in mind that I will need to make a way to seal that structure, when it is placed back on the hull for sailing.  I'm thinking of also using magnets to hold it into place and make a rubber gasket to seal it.  As for ballast, size of motor, type and size of servos and battery.. I know nothing.  It has been recommended that I purchase a 2.4 GHz Channel hopping system by Spectrum, model DX5e that I should be able to get transmitter and receiver for under $100 US.  So, I guess, cutting is in order now.  I'll be updating as I go.  Tks for help, ahead of time.
Regards,  Dennis

[dlancast]

more.

[warspite]

Basically the access should allow the fitting of the battery and all the electronics, see 'Stans' threads and refits for excellent ideas, the sealing of the deck usually does not need the use of a rubber / foam gasket as a 'BUND' wall is only needed.


Bund walls are the sides of a box, with no top or bottom lids, the shape is just inside the super structure but the height is anything from half way up the inside of the superstructure to several millimetres ( parts of an inch ), enough that when water sloshes over the deck the bund way stops it from rising up between it and the inside of the superstructure, in effect it looks like the entrance to a hold where the superstructure is the lid, the seal is between the deck and the bund wall.


When you were building the carriers, the plastic parts sometimes had a raised lip that fitted inside a piece that had to locate in a particular location, a bund wall is the same thing, only deeper and surrounding the hole into the hull.


How are you planing to attach the rudder and its linkage, i.e. when you remove the rear superstructure is there sufficient space to get access to the rudder area?, from the picture it may be necessary to cut out the rear deck area for the purpose of putting the rudder linkage in if not already accounted for when you first built it

[dlancast]

Thankyou for the tips.  I hadn't considered the "lip" and "wall" method, makes perfect sense.   As for the rudder access, yes, the hull opening extends close to the aft deck  and I should have access, if memory serves me.  I remember that the kit did provide a proper stuffing box for the  screw and the rudder as well.  I'm hoping it will just be a matter of installing a rudder "horn" and linkage.  I will provide more pics as soon as I get the super structure off.  I've started cutting... I did such a good job gluing that its slow going.    Dennis

[dlancast]

Well, the super structure came off easier than I thought, with very little damage.  Pics show rudder post, stuffing box and hull access.  Getting ballast up towards the bow will be difficult.  Idea I have is to purchase lead fishing weights, coat with epoxy and slide them towards the bow and then down on keel to stern, trim to waterline in bathtub.  I am estimating 5lbs of lead should do it for ballast.  Open for suggestions at this point.  Tku, Dennis

[dlancast]

more.

[dlancast]

more.

[dlancast]

more.

[warspite]

Coating the lead fishing weights in resin and then putting them in place is usually not a good idea as they invariably get everywhere coated in resin before they get to the final resting place, may be better to think of a lead fishing weight bean bag arrangement, small bags to position / fit and then check if they move about in a violent storm situation, alternatively a plug of Rockwool loft insulation (glass fibre or more ethical versions are available) to pack out the bow over the bags of shot, also allows the bags to be removed in the future.


Looking at the prop shaft, it seems to be shortened somewhat, would a coupling have enough shaft to be able to connect, looks like it needs to be removed and replaced, pliers on the inside, spin the prop of as the shaft is drawn into the hull as getting it past the rudder looks tricky, unless when the prop is off it can pass the rudder when its at 90°.


Same may go for the rudder, it doesn't appear to have any post above the tube so it's not possible to attach the tiller horn, removing the rudder may mean cutting it out and replacing the whole thing and then remove the prop shaft and replace that

[JimG]

Looking at the prop shaft, it seems to be shortened somewhat, would a coupling have enough shaft to be able to connect, looks like it needs to be removed and replaced, pliers on the inside, spin the prop of as the shaft is drawn into the hull as getting it past the rudder looks tricky, unless when the prop is off it can pass the rudder when its at 90°.

It looks like there is a collet at the inner end of the shaft to hold it in place and stopping it from sliding back. When the collet is removed there should be enough shaft to allow the coupling to be fitted.
Jim

[dlancast]

thanks so much for the help gentlemen.  Yes, I'd thought about the bag idea, but not the insulation.   I think that getting that ballast installed first is what I need to tackle, so today, I'll do the first float in the bath and see if 5 lbs is gonna trim her out to lines.  I'm thinking the radio gear won't weigh that much, but the batteries will have to be considered.  Yes, I can release the collet collar on the inside end of my prop shaft and gain enough shaft to connect to motor.  Its a bit of a slow go trying to find the proper radio gear, batts. connectors, etc.  There is so much to pick from on the internet, hard to decide what is best.  I am concentrating on the motor for starters and found a build on one of the forums of the Millford Star and was able to get this ID.... MonoPerm Motor PEED 500E, or 550.  Does that seem about right?  Tks again, Dennis

[dlancast]

Update: purchased all of my radio gear, motor, servo, etc.  Bench tested gear... everything works.  I did a float test in my bathtub with 5lbs of lead and found a few leaks around stuffing boxes, so been dealing with that using epoxy to fill-in.  Had to order linkage for motor coupling and rudder horn.  Working on how I want to place everything.  Slow progress.  Dennis

[warspite]

sorry for not keeping up with this, after removing the collet, was there an end bush to keep the shaft centralized.

[dlancast]

I had to remove the bushing I had on there to gain enough shaft to attach my coupling.  The coupling should act as a bushing to keep the shaft centered, etc.   Tks for asking.  Dennis

[SailorGreg]

I had to remove the bushing I had on there to gain enough shaft to attach my coupling.  The coupling should act as a bushing to keep the shaft centered, etc.   Tks for asking.  Dennis

Dennis, if you are saying that you had to remove the fixed bushing from the tube as well as the collet, and are now relying on the coupling to hold the full length of the prop shaft central in the tube, I fear you are heading for problems, mainly to do with a wobbling shaft. Assuming you are not going for a completely rigid one, couplings all have some play in them and this play will transfer to the end of the shaft.  You will probably experience vibration and noise at various throttle settings.   If you need to remove the bushing to get the coupling to fit, I would seriously consider buying a longer shaft.  And even if it's a rigid coupling, you are then relying on the motor bearings to maintain a central position for the shaft, also not a good idea in my view.  Of course, you might already have it all set up with no problem at all, in which case you can ignore my forecasts of doom!
Happy building
Greg

[dlancast]

I hear you sir,..... the tube or stuffing box is still in place, the prop has its own bearing, which presses up against the tube outside the boat and secured by a nut.  Inside the boat, I have removed the bushing that was slipped onto the shaft, the shaft is not long enough to secure a coupling, so I removed the bushing and will use the coupling end that is slipped onto the shaft and secured with a set screw.  I can then bring the nut closer in to "lightly" snug the prop "bearing face" to the tube to help provide a seal.  The stuffing box is packed with vasiline.  The coupling will be a swivel type.  This model will be slow, so no high turning issues.  If I have to, I will replace the shaft with a longer shaft, but for now, I don't think that will be needed.  Hope I am explaining myself.  I'll provide pictures as soon as I get the coupling in the mail and can set things up for you folks to see proper.  Tks for the input.  Dennis

[dlancast]

Ok, I finally got my coupling.  I discovered that I do have enough room for the bushing to go back onto the shaft.  I did a test install to see how things look and I can get a good coupling between motor and shaft.  I knew ahead of time that the motor is a bit large in diameter and will cause a slight mis-alignment, motor to shaft.  That is why I decided to use a swivel coupling.  With the motor resting on the keel, there is a slight angle.  I will use wood side mounts to pin the motor in and also use a metal strap over the top to secure the motor.  Since the motor will be slow turning, I am hoping that the mis-alignment will work with the swivel coupling.  Won't know until I secure the motor and test it under power.  If not, I will be forced to buy a small diameter motor to achieve straight alignment, as the stuffing tube is now perminantly secured to the keel.  I'll attach some pics for you.  Dennis

[dlancast]

more.

[dlancast]

Motor is now firmly strapped in.  Next is to epoxy the battery box in.  Dennis

[RST]

You should test it the old fashioned way and put a dry cell or two and find the sweet spot. Just enough for the motor to turn. That finds good alignment in my experience. A single universal joint is not much forgiving on misalignment.

[dlancast]

Well sir, you are most correct on the alignment issue.  I do not have good alignment.  I did a test runup and the rpms for the motor is too high, so I just pulsed the trigger on the transmitter to get the motor to spin.  Lots of vibration and "noise"... I know its not good and aside from tearing everything out, including the stuffing box to be able to insert a longer shaft and maybe get another coupling installed.. I dunno.  I think less rpm on the motor will help... I think there is a motor rpm control on my transmitter....    I am certainly out of my element with this project.  Or... a different coupling design.  A spring or rubber in the middle of the coupling??  Dennis

[roycv]

Hi Ian, yes the old ways as RST mentions do work fine.  If the motor is running too fast the battery voltage is too high.  Not sure how you are fixed in these things but the propellor looks rather fine pitch I would go for a coarser pitch and slow revving. 

I have a small 32 inc coaster and I can watch the the prop turn over.
Another test is when you turn the motor shaft by hand you can feel the 'cogging' there will be twice as many sitting points as there are poles on the motor.  When the drive train is connected can you feel this same cogging from the prop as you turn it?
 
It may be you have too much grease in the prop tube if not.  I use a really free flowing but waterproof mix of 1 part vaseline / grease to 1 part WD40 / to 1 part ordinary lubricating oil.  Mix up and poke it in.Try to get the above sorted before trying anything else.

You may well have bolted your motor down but it only needs a small amount of holding in place.  I hold my motors in place with bathroom sealant, which is still bouncy when dry, this absorbs vibration as well.
Is the u/j screwed in place on the prop shaft?  This will have been lock-nutted as well but this can slightly distort the alignment.   I place a small washer between the u/j and the locking nut, and tighten up gently, if there is still vibration loosen the nuts and turn the prop shaft 180 degrees holding u/j in place and try again.
The motor shaft from what you have said does not line up with the prop shaft, the bigger the angle of the motor to prop shaft the worse it can potentially get. 

On another thread you can read that as the angle of a u/j increases so does the uneven rotation increase of the prop shaft.  Yes I know it looks continuous and it is connected to a motor in continuous rotation but the u/j transmits a rotation that in radians per sec is uneven and so there is noise/vibration.
regards
Roy

[John W E]

hi there, I am trying to put a link on here to a build which is very similar to the one that you are trying to achieve.   It was done by another lost soul from this form DickyD and as everyone on this forum remembers Dicky - he was one hell of a builder and one hell of a character - and, I am pleased to say I met him face to face.


Anyhoo - the link I have put on here, is, as I say is from Dicky's build.


The other thing is - a while ago I built a model the Duburg - and it is roughly around 46 of your American inches long - and it is powered by an MFA 500 low drain motor and its driving I think about a 50 mm 4 blade prop - direct drive on 6 volt.  It gives it roughly a scale speed - The other alternative which I have used in the past is a belt drive system with 2 pulleys - this enables you to align your motors up if you havent got much space.


john
Coastal Tramp Steamer (modelboatmayhem.co.uk)

SS Moray Firth (modelboatmayhem.co.uk)

[warspite]

Dennis, in regards to the prop tube, i noticed in the recent photo's that there is the bush with the grub screws, then there is a fine line about 2-3 mm after it on the prop tube, is this the prop tube end cap - that ensures the prop shaft remains central i.e. a bearing retaining the grease etc.?


it may be wise to obtain another coupling and connect the two with a small length of equal diameter rod and shift the motor back along the red wood motor packing, it would reduce the angle of misalignment, and as said earlier, one coupling is always problematic, but two in series may alleviate the issue, if you have a metal lathe you could turn a solid coupling that is long enough to lift the fouling edge off the keel (or if you know someone who can also put the grub screws in as well).


Also the back two screws that are holding the can down will force the rear down exaggerating the misalignment, you may need to pack the back to reduce the pressure, maybe even move the strap forward to get the clamping force on to the front edge of the can.

[chas]

Hi Dennis, the misalignment in the motor drive isn't tricky to overcome, and whatever coupling you end up with, an imperfect drive will always niggle at you. You've had some great suggestions already, it boils down to re siteing the motor, with an alternative coupling like a pulley/ belt, or moving the motor further away from the shaft untill they align. Using a coupling something like this.
https://www.cornwallmodelboats.co.uk/acatalog/couplings.html


     
Or you could change the prop shaft for a longer one that would fit in the same tube and bearings, that would raise the height of the driven end, making alignment easyer


Another simple way is to use a smaller diameter motor, is my memory correct that the model is about 900 mm long? If it is, you can use a 385 motor, designed for 6 to 15 volts. They have plenty of power, I use them in several models so it would be an easy, cheap cure.
 I hope that helps a bit.
Charles