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[DJW]

Afternoon All

Realised it was a while since last update, so here's some progress.

I've now started to bond the various pieces once they were tweaked and persuaded to fit.  I'm finding that accuracy is very hard to maintain when scaling up, tolerances of transferring plans to wood, cutting that wood, is not the same as telling a laser cutter / CNC to cut another set of frames / parts...  Some parts I'm having to sand to fit, some I'm actually building up a mm or so.

So the bow is now pretty much in one structural piece:



The boat itself remains in two parts.

At the stern, the stringers that run either side of the shafts are now bonded to the transom and the two frames near the stern:





The space between the stringers has been made solid between the transom and the last frame, I've then routed out slots to take the P Brackets, also for the two exhaust stubs, and then built up and drilled for the rudder tubes.  This is now a very rigid section and the running hardware should be kept well aligned.









Also been busy getting the transom elements to all fit nicely, I'll post once that's all sorted and bonded.

The stringers are deeper than the frames so I can trim them in place to match the line of the hull.

I'm pondering the keel joint at the moment, I think some additional stiffening / strengthening is called for...  On the 1/10 version its just a 3mm ply plate each side of the joint, then it relies on the planking for strength. I can do that and will with 6mm ply plates, but think I need the additional stiffening.  The bow is almost a cage of ply parts, so rigidity is build in, and the stringers have made the stern part of the hull similarly rigid...  I'm thinking a pair of mid hull stringers that lace into the bow and stern sections, we'll see.

That's it for now on the 1/5th.

Have had the 1/10th Aquarama out on the water a few times this year, this was in the sunshine at the excellent MBM Wicksteed event:



Huge thanks to everyone involved in organising a great weekend..!

Very best regards to all.
David.

[DJW]

Afternoon All


I now have the two halves of the boat joined.  Next to the 1/10th for comparison, LOA 172cm.





And starting to look at the motor mounts, the base 6mm ply panels are in and will now be reinforced to the keel and frames.  I need to lift the motor mounts from the panels slightly to accommodate the rubber mounts and to increase the prop shaft angle slightly.  So I'm 3D printing some wedges that will sit between the aluminium mounts and the ply plates.  I hoping the shaft angle will end up around 9 or 10 degrees...  I managed 7 degrees on the 1/10, but that used a gearbox to keep the shafts as low as possible at the motor end.  This process will also give me the mount points for the P Brackets.








Best regards to all.
David.

[derekwarner]

Following on DavidThats impressively large  ......funny how scaling can confuse the mind  .....


Without me attempting to confuse myself, could you confirm what the all-up weight of the 1/5 Scale boat


Derek

[T888]

Hi David,




Your Build is impressive 

[DJW]

Thanks Chaps..!

@Derek.  As I understand it, the scale weight is the full sized boat weight / the cube of the scale factor.  So in this case the full sized Aquarama is about 4,000kg, and the scale factor is 5 (as its a 1/5 model), so its 4000 / (5x5x5) which is 4000 / 125...  Which is 32.  So the 1/5 Aquarama should be around 32kg.

I'm sure there a few 'buts' in there, one of them being the longitudinal centre of gravity, which I think should be a tad aft of the centre of the waterline length.  Get this wrong and the boat won't behave right on the water.  So I'll be aiming to build lighter overall and especially at the bow, I think under 25kg is a reasonable target, then leave some room for ballasting to get fore/after and port/stbd balance about right. There's a related point that's beyond me to understand properly, and that's how buoyancy / displacement will affect things.  I've modified the hull shape a shade as I did on the 1/10 to give a bit more lift at the bow.  But I think this reduces the displacement at the bow, so the 1/10th sits a bit bow down for my taste when at rest, but does lift nicely when under way...

Short answer, I'll be building light so I can adjust when the time comes.

Best regards
David.

[DJW]

Meant to add.  What you see in the pic above is 5.5kg, everything is mainly 6mm birch ply.  Each motor on its mount with prop tube is 1.0kg.  The LiPos are also just under 1kg each, I'm thinking add 2 or 4 depending on whether they help with ballasting.

[ChrisF]

Hi David

The Fairey Huntsman 31 can suffer from a bow down attitude at rest due to the bow being streamlined and its narrow vee shape which doesn't provide much buoyancy. Sterns are a different matter if they are wider and are flat bottomed or a shallower vee than the bow.

My Huntress with stern-drive is heavy at the rear (I haven't checked where the balance point is) and yet sits bang on the waterline, the hull being so bouyant. Away from the bow planing hulls seem to be very toletant of weight distribution so as you say building the bow light is the key as less buoyancy is provided in that area.

Chris

[DJW]

Afternoon All

Back on the case with the 1/5 build.

I've started to line up and secure the motor mounts, P brackets and rudders. Still work in progress, cutting shafts to correct length, trimming here and there to get the fit correct.





The motors have to be able to be taken out and reinstalled installed when the mounts remain attached to the thrust bearings / shafts, so the coupling on the motor end can be slid up the motors drive shaft to give clearance, then secured back in place to mesh with the shaft.  Flats have been ground on the motors and prop shafts wherever you see grub screws on the couplings and thrust collar.  This lets the motors be lifted straight out of the mounts after removing the 4 bolts going into the rubber mounts.





P brackets are held on two 4mm bolts (then filled with epoxy when lined up), just the rear bolts initially to allow alignment.







Motor mounts are secured to the hull with 4 x M6 SS bolts each.



And before I get the epoxy out on the prop tubes / mounts and rudders, I've decided to use some 2mm ply for the aft 50% of the bottom of the hull.  The Aquarama hull is flat enough in that area to get away with it I think, then I'll carry on the forward section with 2mm lime planks.  I'm just wanting to get the cut outs done for the prop tubes, P brackets and rudders. Rough cuts at this stage.  I'm thinking to then install the rudder tubes, then the ply hull panels, then final alignment and fixing of the P brackets, prop tubes and motor mounts.  Plus a bit more reinforcement below the motor mounts before the ply panels go on, they will take the thrust, so ideally they need to be stopped from parting company with the rest of the hull...

Best regards to all.
David.

[T888]

Hi David,




How are you planning on maintenance access to the motors, coupling etc

[DJW]

Hi David


Taking the motor out of and installing it back into a mount is quite easy. The coupling on the motor shaft has two grub screws that once loosened allow the coupling to be retracted so it's no longer meshed with the prop shaft end of the coupling. Like this:





Then four bolts taken out of the bobbin mounts and the motor lifts out.


If the mount has to come out for some reason, the flange joining the prop shaft to the thrust housing has to be split, so four allen key bolts removed. Then the flange is on same axis as the bolts that hold down the motor mounts. So the motor mount lifts out while still attached to the thrust bearing housing. Of course that's after the prop shaft has been eased out backwards.


Bit involved,  but workable I think.


Best regards
David.

[DJW]

A couple of pictures of the thrust bearings in the thrust housing. This one takes the forward thrust and passes it to the motor mount.





And fully in place.





Then other side of the mount, the thrust bearing for astern.














Also cut the exhaust stubs from 25mm od brass tube. Started to think about marking out and cutting the flanges.








Good to be making some progress again.


Best regards to all.
David.

[DJW]

Evening All


Decided to carry on developing some if the internal hardware while access is easier.





The rudder servos are mounted on a 3D printed carrier that clamps to and through the keel, this version moves the servos further aft. There are now panels in the floor of the battery area and L shaped panels that retain the electronics boxes.





I'm thinking to mount the vibration unit on the frame ahead of the rudder servos, in the middle above with the motor sticking out forward. A 3D printed mount coming this week for this unit. . Then the vapour unit will hopefully fit between the vibration unit and the rudder servos. Port electronics box in place in the above pic.


And a better pic of the rudder linkages. 3mm steel rods, threaded into ball joint ends and aluminium servo and rudder arms.





I'm hoping that the two servos will allow for some interesting tweaking of rudder response when it comes to FrSky programming.


Best regards to all.
David.

[ChrisF]

Just caught up with your build  David. Absolutely fantastic as usual! You're certainly taking model boat building to a whole new level.

Chris

[DJW]

Hi Chris


Happy New Year to you..!


Thanks for that...  Seems like I'm going off at a few tangents at the moment, but hopefully making progress.


The Vibration unit has had some attention:














And here it is all together:








And this is where it mounts:





Also working on some of the cabin panels:





And have another new Proxxon toy...





I think there's a load of sanding heading my way, so I thought I needed a bit of help.


Still playing with the vapour generator...  This is the latest top coming off the printer:





Also been using the printer to create some conduits for the cables that will need to go in:





And finally for now...  I saw this.





And I'm thinking 'boat trolly'.  Apparently it's customised from a Scania Vabis bus from the 60s / 70s...  Maybe I found my next project.  At least for the 1/10th.  I'll need a bigger car if I try for the 1/5th...  Maybe a trailer.


Anyway, that's it for now.
Best regards
David.

[DJW]

OK...  This post should see if anyone's awake...   


I've been giving thought to the finish of the 1/5th.  It's a shade premature maybe as the hull isn't planked yet.  There are however a couple of side panels in the cabin that need varnishing before they get installed.  So I think it's time to evaluate how to proceed, and do some testing.


On the 1/10th I used a couple of thinned Z-Poxy finishing resin coats to seal, then thinned International Original Yacht Varnish to build up.  With all the sanding in the middle. Then buffing and polishing...  The finish was OK, but not the glass effect I'd been hoping and trying for.


So, Z-Poxy seems elusive to find and it has an amber tint, so I've narrowed down to Hempel 599, 'a two part epoxy with low viscosity and good penetration', its £20 for 750ml so I have some to see how it performs.  In the tin it has the consistency of water.  So plan it to use a brush to apply it, and I'll report back.


Then, the varnish.  I don't think I gave the Le Tonk a fair evaluation last time, so I want to try again, and compare it to Epifanes High Gloss.  Both have a formidable reputation, I'm going to try harder to manage the temperature and humidity, I suspect this was an issue in earlier attempts with the Le Tonk.


And I intend to thin and spray the varnish.  At least test spraying...


This will mean a load of coats to build up thickness, so I can see some sort of spray booth when the time comes for the main hull.





Anyway, that's my thoughts.  Any comments on any of the above gratefully received. 


Best regards to all.
David.

[SailorGreg]

Not wishing to teach granny to suck eggs, but this is worth a look for anyone wondering how the professionals get that glass-like finish -
How To Apply Epifanes Clear Varnish
Greg

[DJW]

Hi Greg


Not at all and thanks for sharing that link. That guy Dan Lee certainly know his stuff, its good of him to share his skills, inspiring. I have seen some of his videos on YouTube, he's been building a 1/4 scale of his 'Temptress' design. Very skilled man...
Very best regards
David.

[DJW]

Evening All


I've made some progress with the hull. The motor mounts are now fixed as are the rudder tubes.


Also been working on a water inlet fitting, similar to the full set Aquarama fitting. This is the real fitting:





I started with creating three brass pieces, the strainer, the plate and the threaded tube. The tube is a drilled out and machined 10mm brass bolt. Bar for the strainer is 20mm stock and plate is 2mm, plate...





Milled the bar to give it a taper, then created a cavity:





Then a small abrasive disc held in the lathe chuck to cut the slots:





Ended up with these parts:





Fitting like this:





And when silver soldered and shaped:











I don't honestly know whether the full sized Aquarama has an inlet per engine, I suspect it does, but I only need one. This will go to one pump then split into two circuits.


Best regards to all.
David.

[Capt Podge]

...been working on a water inlet fitting


 This will go to one pump then split into two circuits.

Best regards to all.
David.

That's a good idea and great work in creating the fitting.


Cheers,
Ray.

[ChrisF]

You're on the wrong forum David! Only joking, superb work as always.

Chris

[DJW]

Evening All


@Chris, well one of the challenges of building at 1/5th scale is there is very little available off the shelf, so it all has to be fabricated. And as you know, I enjoy that..! I can get away with a few short cuts and interpretation on the more functional fittings as they're pretty much hidden, the challenge will ramp up with the classic Riva fittings...


The Hull is coming along. I've used 2mm ply for the aft section of the planing surface of the hull.








Also decided to reinforce the chines. I was going to use 10mm Square spruce, but decided to laminate several lime planks to get the shape I need. So the result is 10mm x 6mm shaped to fit. I used titebond 3, and clamped the laminate to the hull before the glue fully grabbed to get the shape. Pleased with the result.





Hard to show the compound curves, might be easier once fitted to the boat...





Next task is to cut out the frames and inset the chine rail. Nice to see the lines of the Aquarama starting to show themselves...


Best regards to all.
David.

[ChrisF]

Crikey, with it standing on end you can appreciate how big it is! How much do you think it's going to weigh?

Even with the diversions, which you were obviously going to have to do at some point, you're making good progress.

Chris

[DJW]

Hi Chris


Calculations say it can weigh 32Kg...  I'd hope for closer to 25. I'll see if I can get all the hardware into the hull and get it on the scales...


Best regards
David.

[DJW]

Evening All


Made some progress this weekend on the stern of the Aquarama. I'm using 2mm birch ply for the lower transom area, then 10mm x 2mm bass planks. Some shaping of the frames using the new Proxxon belt sander, then placing a single plank to butt the ply to as the starting point.





Using Titebond 3 and brass pins to secure. Clamps where necessary while curing. I use a 0.8mm drill to guide the pins and prevent splitting.










The ply needs trimming to the hull line once glue has cured. Same with the planks once they're all in place. The planks you see above have gone on without shaping, the remainder will need some shaping to avoid gaps.


Always good to see the Aquarama shapes and curves coming out...!


Best regards to all
David.

[Martin (Admin)]

Wonderful !

NB: Any particular reason for using Titebond 3  as opposed to other wood glues? ?