Print

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

[DJW]

Morning All


@Tony, I didn't know that the Aquaramas were sometimes rebuilt with diesels, part of the ownership would be the throbbing V8 sound I'd have thought..! But I think marine gearboxes are always reduction ratios aimed at slowing the shaft. To be honest I've not looked into that for the full sized boat.


@Derek, interesting points raised.  I'm not assuming any thrust bearings in the motors as far as my use is concerned.  Having said that I guess in their aero role the motors do have to take the full lifting force on their shafts so must have some capability...


The standard mount is the 'X' plate:





I intend to create a similar 'spreader' solution from aluminium plate, and incorporate water cooling channels.


My current thought is then to use some 7mm walled Aluminium channel (I use this in other work) with the motor mounted via 4 bobbins on one end, and the prop tube rigidly mounted at the other end (black pen in pic below).  And a solid coupling in between, the motors have a 6mm shaft, and I'd use 6mm prop shafts. The base of the channel then becomes the mounting surface to the hull.
The bobbin mounts will have 'cups' of either aluminium or nylon around them to reduce torque induced movement, so they just eliminate solid mounting to the hull, but don't allow the motors to move.  In this kind of arrangement:





I may look at not having a prop tube top bearing, just a seal...  Using the motor as the top bearing with a solid coupling, so they don't fight each other... (There's a thread on this in R&D section.)


This then gives two options for taking the thrust.


A suitably mounted / integrated P bracket, or the motor mount (left side in pic above) using a more conventional thrust bearing.


In terms of the potentially brutal power of these motors, I agree it could get catastrophic...  I'm planning to use the 80A Neuron ESCs from FrSky, these can be programmed to deliver super smooth acceleration, even if the users stick input is less than smooth. I'm using the 40A versions on my 1/10th and have arrived at very smooth low speed handling and acceleration.


The Translock system looks very elegant, more so than the usual collars with a grub screw, thanks for the link. I'll try to find some and report back.


Thanks for comments, and best regards to all.
David.

[tonyH]

Hi David,
I thought that was the case but this is one original.
Riva Aquarama Special #768This beautiful example of Aquarama Special is one of the last manufactured by Cantieri Riva, in 1992. The vessel was commissioned by one of Riva’s customers to be pre-owned as a support on a large yacht in Britain. The peculiarity that makes this model of motor vessel unique is the fact that freshly Riva provisioned it with 380 HP Diesel Hydro Force engines, later replaced with gasoline 350 HP Thermo Electron engines.Interesting fact: the fresh Diesel engines are available with the vessel. (Part of the sales blurb)
It would seem that the petrol ones were almost all direct drive, while with the diesels, the revs were upped by approx 2:1.

Are your engines mounted independently, or are you putting both on a single transverse mount to reduce the torque effect on the hull?


Tony
 

[DJW]

Hi Tony


That is interesting indeed.  I suppose the lower revving diesel, but with higher torque could handle the increased gearing and get back to 'normal' prop and shaft rpm.


I like the idea of making the motor mounts in one piece but it may become a bit difficult to machine in my small lathe / milling machine.  However I do think it would be useful to have an aluminium bridging plate / structure that can be removed.  I can then make up the components as smaller pieces using the bridging support to brace the two mounts together for installation / alignment, and then also to spread the forces from the motors.


Best regards
David.

[tonyH]

Hi Dave,
This is the way I fitted the motors in my Jackie S which is only 1/12 coming in at about 6lbs so built relatively lightly. The standard X mounts for the motors are fitted through a piece of 1.2mm roofing rubber straight onto a 1/4 inch ply frame as part of the structure. It's also reinforced with a spare bit of 1x1.  I cut the holes through the ply so I can get access directly onto the screws that hold the motor onto the mount. You've got so much spare displacement available at 1/5 that you could almost make yours out of mild steel!
Tony

[DJW]

Hi Tony


I've been thinking more about the single mount for the two motors and I think it can and should be done. Thanks for highlighting it at this stage..!


In other news I'm having some trouble getting the plans taken up from 1/10 to 1/5. I've tried a couple of local copy shops that can print to A0. But even folded once the 1/10 plans are 500mm x 700mm. So taking that up to twice the size exceeds A0.


My plan B is to set up a camera over the 1/10 plans, put a pencil grid say 100mm x 100mm over the plans. Then get the grids to 200mm x 200mm in Photoshop, print tiled output to A3 and tape em together...


But I'd be really happy to hear there's an easier way...


Regards to all.
David.

[DJW]

I think I have an alternative way to scale.

I use PhotoShop in the real world, so have tried using the Pen tool to trace an outline from a picture of the 1/10 plans.  The results look OK...

This is the outline of a part:




And this outline can then be pasted onto an A4 sized document:



And scaled:





Larger parts would have to go onto A3 and or be tiled on multiple sheets.  I quite like this approach for a couple of reasons:

1. Symmetric parts can just be mirrored, saving tracing time and ensuring symmetry.
2. Some mods will need to be made, around the motor bay for example, and also I like the modified chines on the 1/10 build, so I can edit the frames in PhotoShop.

Bit laborious, but it can work I think.  Anyone tried this approach, if so how did it work out..?

Best regards to all.
David.

[Mark T]

Hi David this is one epic build that you are on 


Making plans larger is not an easy task and I think that your approach maybe the best way.  I have tried to upscale and even just copy large plans at the printers and it never seems to come out exactly to scale.  They always seem to stretch a bit going through either the scanner or printer and this has caused me many problems on my current build.


Good luck mate I'm sure its going to be beautiful 

[ChrisF]

Hi David

I use a similar approach to producing my drawings albeit at 1:12. I use Microsoft Visio and trace PDF's of the drawings, either obtained as PDF's or scanned, and then modify them to suit my needs. Once traced I can print out at any scale I like and as you say join A3 prints together. To ensure accuracy  I enclose parts in rectangles so that I can align them. For producing frames/bulkheads I draw half, mirror them and join together. I use Lightroom for my photography but not Photoshop so can't really comment on it's suitability.

CAD would be a better program but it takes some learning. I bought TurboCAD but have only scratched the surface with learning it. Visio isn't the best program for drawing but I used to use it at work so can get good results from it.

Chris

[DJW]

Morning Both


Thanks for the comments and encouragement. I like the idea of using rectangles on the tiled prints to get good alignment. I've used Photoshop for years. But never the pen tool. That seems to unlock very smooth curves, and given the start and end point of the curve its possible to manipulate the curve to fit what's being traced.


I'm thinking that although it's laborious, it doesn't all need to be done at once. So initially keel and frames, then as required. And then if mods are needed on the way they can be incorporated.


An epic build...  We'll see. Its going to be a challenge for sure. I'm still finishing the 1/10 build and plan / hope to have it ready to run for spring 22, hoping to take it to a few open days and meet up in the real world..!


So now its a case of scoping out how best to approach a 1/5, start to fabricate and acquire some of the core parts that the hull will need to accommodate, I'm thinking the drive train. Then build them so I have them on hand to start the hull.


Best regards
David.

[ChrisF]

David

That's also the approach I take. Rather than draw everything up at once I draw up enough to start building, as you say keel and frames first and then draw up the other parts as I go along.

Whilst I enjoy the drawing it can get a bit laborious especially if you want to get building! It also has the benefit that you can take actual measurements of what you have built so far, in my case for fitting the superstructure.

Certainly is going to be an epic build!

Chris

[DJW]

Afternoon All


Continuing to acquire parts and researching hardware to be used.  I've been very impressed with the TCS Micropumps, very efficient, I have the M200 version in my 1/10 build.  I was looking at a suitable version for the 1/5th and found a brand new still in its box M400S on eBay at £35.00, a bit better than the eye watering £90.00 rrp...  Its a 34g brushless pump that circulates up to 2.6 litres / min through 6mm dia connectors, runs up to 12v, consumes just over 7w and interestingly its speed can be controlled with a PWM signal.  I doubt it'll just hook up to a receiver, but via an arduino it will allow increased circulation based on ESC or motor temps, rpm or whatever.








https://micropumps.co.uk/TCSM400range.htm


I have some 9mm id brass for the prop tubes and have been looking at this material to create some bearings for the P Brackets and maybe where the prop tubes exits the hull.


https://www.igus.co.uk/product/539?artNr=SFRX-1000


Its machinable, so could create conventional and flanged bearings plus thrust washers at whatever size an length required. This time I'd be on a mission not to use ball race bearings in the drivetrain.


Best regards to all.
David.

[Mark T]

One of the best things about building big - is you can put whatever you want inside it.  That pump looks very well made.

[DJW]

Afternoon All


Main focus is trying to get my 1/10 Aquarama build finished, but also giving thought to the 1/5th...


I've found that I can play with 3D printed parts to iterate towards a suitable mount for the motors and shafts. (3D printer, new toy for Christmas...)


So useful to be able to test a part, then improve it, get all the dimensions correct before committing to aluminium, here's the first result, a couple of parts to hold the motor using M6 bobbin mounts:














The threads protruding from the bobbin mounts will have another plate attached, the two plates will have channels machined out to make up a water cooled plate once fabricated in aluminium.


And playing with a printed fan blade too...





Best regards to all
David.

[Thor]

Nice work!
I do the same with 3D printed parts on my Riva build!Dual motor mount prototype:

[Mark T]

Lads - Wow I think those motors would happily pump a large central heating system let alone a boat. Keep the updates coming 

[DJW]

@Thor. That's a beautiful mount and gearbox. Really looks the part. Will you run with the printed version or build in aluminium..?  Looks substantial enough to go with the printed version. Those inrunners look pretty fast. Are you gearing down..?  You'll get a really low shaft angle with that design, really nice. I'll be making the 1/5 mount as a single unit too. Really helps with alignment and rigidity I think. Hope you set up a full build log. Looking great from what I see.


@ Mark....  yes... quite a bit of power to deal with and all being well tame...

[DJW]

Evening All


Printer has been busy this week with an update to the motor mounts, I think these are getting close to whats required in terms of design.





I'm not sure yet whether the two mounts will be fabricated in Aluminium as one unit, or use a temporary or permanent 'bridge' to join the mounts.  Aim is to ensure alignment during installation, then to provide a rigid structure during use, each motor is 2.2hp...  Issue will be machining in a single piece, it will be quite large for my lathe / mill.  Distance between shafts is around 170mm.





Plan is to have the left side of the mount (above) take the shaft thrust and transfer it to the motor mount using a couple of thrust bearings.  Double thickness mount plate is size mockup of cooling plate.


The last pic shows the Aluminium channel that I plan to use once the final design is arrived at:





In other news, 2 x 80A FrSky ESCs plus an FrSky 8 channel Rx arrive next week.  Props have been ordered from Prop Shop, 2 x 3033 3 blade units (76.2mm diameter x 83.8mm pitch) and 2 x 600mm x 5mm shafts, but I suspect they're a few weeks away.  That prop size is available in a 5 blade config too, so I'm thinking if I need more bite I can move up to the 5 blade units without changing the diameter.


Various other seals and drivetrain parts due in too.  I'm looking at SLEC for the wood, once I have the list together I think a trip to collect will be in order.  Been upgrading my Proxxon bandsaw by fitting a fence, had to make one, why doesn't anyone sell one to fit..?


Best regards to all.
David.

[DJW]

Afternoon All


Bit of a pause on the 1/10 build waiting for some materials, so some 1/5 progress.


Taken delivery of the two FrSky 80A ESCs, the level of control is exceptional, and the telemetry...





And have been working on the designs for the motor mounts and thrust bearings, so just in plastic for the time being:





And state of play at the moment:





Acquiring the materials to translate the mounts to aluminium, also the prop tube in brass.


And started to look at the build slip, it needs to be about 1.7m in length and is made from 40mm extrusion.  3D printed brackets for supporting the keel, and a sweep up of support for the bow, should give a good firm and accurate basis to build from. I'm hoping that using the extrusion will allow supports to be added / moved for the frames as they go in.





And for some perspective, the 1/10 build alongside...








Just waiting for the wife to realise what 1/5 scale actually means...


Best regards to all.
David.

[derekwarner]

Evening David....."just in plastic for the time being" ........

Just wondering, with the strength of engineering plastics of today, are there any studies that confirm 'thermally deposited - printed structures' of aluminium are of superior strength to the engineering plastics?

I ask this, as from a design perspective, most if not all areas of critical stress can be eliminated or compensated by the design, so by the printing process irrespective of the medium being printed?

The printed plastic motor mounts you show appear to be extremely robust. ...or am I missing something?

Derek

[DJW]

Hi Derek


An interesting thought. I've not considered the printed parts as the final hardware. Just a way to get the design right. The printed parts could have fillets added to give more rigidity, and the infill increased, these versions are not solid. This could well make them viable as mounts. There is the issue of heat from the motor. Aluminium will conduct that heat away. Plastic will not.
I think for this build with 1600w motors I would not be brave enough to trust the Plastic versions. I do have a rebuild of a robbe fireboat on the to do list, this will be a perfect test for 3d printed parts, including mounts.


I've only been playing with the 3d printer for a month or so. Very impressed so far.


Best regards
David.

[PRG]

Hi David,


A question you might be able to answer.  I have just been out with the boat and lost a propeller, high water and clipped it on the jetty!  Partly my fault as originally I fitted 30mm brass props then tried a 35mm in plastic to see if it would fit.  A close shave but yes, anyway having lost the prop this afternoon I need to replace with 35mm brass. Where and what do you recommend?


Thanks for any advice Paul.


Love the 3D printing.

[DJW]

Hi Paul


Ouch...  Sorry to hear about the loss of the prop...


I'm using props and shafts from


https://www.prop-shop.co.uk/


These are cast props, nicely balanced.
 
On my 1/10 I have a set of 'Standard Scale' 1415 bronze props. That's diameter x pitch in inches, so the 1415 props are around 35.6mm diameter.  I have pushed this to 1517 units to get a bit more bite as the motors were not loading up on the 1415s, but I'm running 370w brushless motors.


On the subject of props... It just so happens that the new props and 600mm x 5mm shafts for my 1/5 arrived this morning, and they're beautiful..!


These are new 'Standard Scale' units from Simon at the Prop Shop at 70mm diameter, so around 2.75 inches with a 3 inch pitch.





And for scale, a standard servo:





Best regards
David.

[PRG]

Thankyou for the advice, nice looking new props!

[Mark T]

Hi David - any chance you could point me in the right direction for those 40mm aluminium extrusions?  I've been seeing quite a few builders using this stuff and I have an idea regarding a building rig for it.  Cheers Mark

[DJW]

Evening Mark


I use HepcoMotion for the extrusions and fittings. 


https://www.hepcomotion.com/product/aluminium-profile-construction-system/mcs-aluminium-profiles/


I needed their extrusions and bearings for a commercial photography project a couple of years ago and had some spare for modelling. It's precise and rigid. They will cut it to size if required too, otherwise it needs a serious mitre saw to get an accurate cut.


Best regards
David.