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HMT Resolve by PreservedKillick - Caldercraft/Jotika - RADIO -1:48 oceangoing salvage tug

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Haven't posted in here since the forum's previous incarnation, but starting a large new build, so here goes....


I've previously completed a static display HMAV Bounty in 1:64, and have the completed hull of a (huge!!) 1:64 Agamemnon on the shelf


Unexpected windfall and a hankering to have a go at R/C sidetracked me (again!) in the direction of this kit. I wanted something Naval (ish) and at a decent scale, as I like lots of detail. After a bit of research and "umming and ahhing", plumped for Caldercraft's "Resolve", which fits the above bill, and both my static builds are Jotika/Caldercraft jobs, so I know and trust them.


Excellent service from Cornwall MB, as ever on delivery of the box. Size was no surprise, as it has to have a single piece hull in there somewhere, which "aint going to be small" at this scale. Well packed, as ever - quantity of contents not too scary, as Agamemnon is considerably more complex. Spent a good week (of available time) checking the contents, especially the enormous number of castings - only found two small problems (one missing porthole, and a couple of brake drums that clearly are a different part), which I shall need to get onto CMB about - not bad really - I think packing that lot would drive me nuts !


Also invested in the "Tugboat Book", which has a review of a build of this kit by Brian Peach - I think I'm going to need all the help/clues I can get on this one !


Next spent a day or two researching and head scratching over power plant, R/C etc. - never done any R/C so all new to me (which is partly the point). Steam would be nice, but *way* too pricey (the windfall wasn't that big !), so electrickery it is. There is virtually *no* guidance in the manual on powerplant, coupling, props beyond "its designed for twin Decaperms and you can buy a complete add-on kit", however these motors seem to be outrageously expensive. My one-and-only-reference (Brian Peach) used 65mm props on his build - looks a bit big to me, so I opted for 50mm - learning in the process that the props on a twin screw rotate in opposite directions so have to be "handed"


Looked into brushed vs brushless motors - brushless, though generally lower cost, seem to be for the powerboat fraternity and revving much too fast to direct drive props on a tug. Useful chart on Raboesch site giving max RPM against prop size suggested 7000 max for 50 mm props. Either gearing down brushless, or using a geared motor would be options. Not comfortable with trying to construct some sort of reduction gearing, so eventually plumped for MFA Torpedo 800's, which whilst still not cheap, do come with mountings. These are 12V nominal


Batteries is a whole other issue - NiCd, NiMH,LiPO or good 'ol lead-acid ? Lead-acid for now as its low cost - will see how it goes


Decided budget would stretch to Electronic Speed Controls - twin Viper 15's. Whilst my trade is electronics, I'm not keen to spend too much spare time on it (spare time is for modelling !), so off-the-shelf it is. Briefly looked into controlling both motors from a single ESC, but there are a few horror stories out there, so I've gone for two.


Next problem - how to actually physically connect motors to propshafts (the shafts are the only bit of the drivetrain that actually come with the kit) - lots of things called "coupling inserts" available - took a while to realise these are meant to go into some kind of miniature universal joint (I told you I was new to this...) - apparently something as simple as a piece of suitable rubber tubing can also work, but I don't fancy it at 5000 RPM :-o


Finally a suitable RC system - a Futaba 3PRK with two proportional channels and a third on/off switch channel. I might want to upgrade to something with more channels if I get into controllable sound and lighting in the future, but this will do for now




Unfortunately I commiited the cardinal sin at this point of ordering all the above running gear (about £250 worth all told) from a supplier I had not previously used - Westbourne Model Centre. Sadly they failed to so much as acknowledge the order, and when I checked on the web, there are some quite adverse comments about them. After several days, and multiple unanswered emails, I eventually telephoned them, cancelled the order (which they'd apparently been sitting on due to the RCS being out of stock), and re-ordered the whole lot from CMB (who acknowledged immediately, as I would expect, and the whole lot is currently in transit via tracked UPS for delivery tomorrow).


Anyone else have trouble with Westbourne recently ? Wouldn't want to flame them based on one bad experience, but failing to even acknowledge an order is unique amongst suppliers in my experience, as is utterly ignoring emails. The moral is - if you haven't used a supplier before, place a *small* order first, and see what happens - guess I got blase about web ordering - never had this sort of problem before. Lesson learned.




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Whilst waiting for running gear to turn up, started preliminary build


Built the cradle, drilled the hull for propshafts and rudder tube, washed the hull to remove release agent - all OK

The hull is a *big* lump:





Now the slightly alien concept of assembling deck camber beams *outside* the hull, then fitting the whole lot in one go....





Not helped by the fact that two of the beams are mis-numbered - fortunately it's fairly obvious the top of each beam should be level with the top of the longitudinal stringers, and they're all different heights, so correct numbering can be deduced. The numbers in the photo are the correct order based on the CNC sheet numbers 




The instructions also refer to the mid-section bulkheads as having different part numbers (373,374), whereas on the CNC sheet there are two 374's and no 373 (that I can find) 


I begin to get the impression that there are a *lot* or minor errors in the documentation, that will keep me on my toes....

Edited by preservedkillick
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Camber beam assembly duly glued and stuck to bench (hopefully not permanently - eek!), including mid-deck bulkheads. Upper longtitudinals still to be sanded to match camber 




Oh joy, more bugs in instructions "remove from CNC fore sub deck (362)". OK 362 is listed as (and clearly is) a bulkhead fascia. Perhaps they mean 392 - that looks sort of foredeck-ish - nope that doesn't fit (I think that's the screen-printed overlay for part of the foredeck). Think they mean "461 Foredeck", 


I don't think the guy who wrote the instructions ever met the one who listed and numbered the parts (or at least, they didn't communicate well)




In course of the above confusion, noted that 392 has a nasty blemish - I think its a flaw in the plywood - doesn't look like a scratch. Have to see if I can get CMB/Jotika to replace this, as it will be pretty obvious in the end result. Of course this was never a problem on my previous builds, that both had individual deck planks - some madmen even do individual trenails (at 1/64th !) - drawback of screenprint I suppose.







Edited by preservedkillick
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- and here's all the running gear (thanks CMB)

The eagle-eyed may spot one small issue - one of the props is 50mm, the other 55mm! - almost certainly my mistake - I was a bit punch drunk by the time I'd researched this lot, and then had to order it all twice from different suppliers. No doubt CMB will swap one of them out for me.....




Motor coupling something like this... The inserts seem to be quite a loose fit in the UJ - one hopes the nylon/plastic splines are up to the job (the UJs/inserts are Raboesch, as is the prop)




The motor blurb flogs an add-on belt-drive reduction to reduce RPM by 2 suitable for "large props on tugs" - think I'll see how direct drive goes, given that I'm using ESCs  (the running total bill is quite high enough, thankyou!)

Edited by preservedkillick
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Onwards and sternwards......


Rudder and propshaft supports fitted. Bit of a decoy in the instructions recommending "from the plan, measure and mark the positons of the A-Frames". In fact there's a slot under the forward end of the rudder skeg into which the lower end of the A-frames is clearly intended to fit (with a minor amount of persuasion), and once you also have the propshaft tubes fitted and got them parallel to the keel, then the position of the top end of the A-frames (and the plates) is pretty much fixed. I'm using the R/C, rather than scale rudder.


Forgotten how tedious full-cure epoxy is (I've been on the Dark Side for a bit aka plastic modelling, where nothing takes more than an hour to go off), but boy is it strong ! 





Edited by preservedkillick
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With propshafts in place, a fairly obvious problem becomes apparent - the inboard end of the shafts is so close to the hull that its over 20mm below the lowest possible height of the motor shaft, assuming that the motors are mounted horizontally - even if I mount the motors direct to the hull


Plan A is to tip the motor up at an angle, and use the UJ to connect to the (essentially) horizontal shaft. No idea if the UJ is capable of operating with this much misalignment (don't have a protractor, but it looks >30 degrees). Having dislodged one of the propshaft supports from the hull whilst playing about with this, decided to build an out-of-the-boat test rig. Tried building a sloping mount for the motor/mount assembly, then realised it would be easier to remove the mount and (with some difficulty) bend it to the desired angle, Also got hold of a slightly longer propshaft (11" rather than the supplied 9"), which gains a bit more space under the UJ


Test rig also used to check out the RC gear - all seems to work with no great drama - only got 1 ESC/motor connected thus far. Need some inline fuses for the ESCs




Running the test rig up, the shaft makes a bit of a racket - needs more support at motor end methinks. UJ doesn't seem to be objecting, though of course, there's little or no load - certainly the drive gets transferred "around the bend".


I have no idea if this is a normal sort of arrangement, or if it will ultimately be reliable (how long will the UJ last, am I putting undue stress on motor shaft etc. etc......


Not sure how to fix motors to hull if I go with this arrangement - the mounting needs to be utterly low profile to avoid making the alignment even worse. Fibreglassing the motor mounts direct to the hull seems to be a possibility

Edited by preservedkillick
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Hmm, really, REALLY don't like that angle....

Plan B is to use an additional short intermediate propshaft and another UJ. This largely solves the angle issue - the only drawback is that it pushes the motors forward of the access hatch, though since they'll be face mounted to the mounting plate, it should still be possible to remove them if necessary - the ESCs, fuses, receiver etc will all still be under the hatch and accessible (need to think about where the battery is going - certain to be a C of G issue !)


The supplied 9" propshaft is *very* close to the hull inboard, but with the shallower angle in the UJ, should be possible to avoid longer shafts

Looking at Mr Peach's build, looks like the output shaft of his geared Decaperms is pretty low down and he clearly has them tipped up a little, with a bit of an angle in the UJ, so he doesn't have the same problems I do




The piece of dowel is (obviously) a mockup for the intermediate shaft

Edited by preservedkillick
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Moving forwards at a reasonable pace at last....

Running gear layout largely resolved (arf) - nothing glued yet - real soon though.

I'll need to make the midships deck removable somehow I think, if only for battery access, which makes hiding the motors under there a non-problem.

Currently mounting battery fore/aft to avoid having to cut the longtitudinal stringers - that might not be a problem once the deck support is all glued in place - mounting battery athwartships is preferable from a C of G aspect I think - this beast is going to be *heavy*.

Assuming the RC receiver will mount on the servo tray - need to check a 400mm or so Y cable to the ESCs (assumed near the motors) will work OK

Deck supports fitted, apart from around the stern.

This is fun - oh wait - that's the point !



Edited by preservedkillick
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Motor base painted both sides and installed

SImple retainer for battery added - will be transverse as shown  - stringers above will be removed

Aft propshaft tubes resined into the hull where they pass through - neat trick picked up elsewhere - prop the hull up so the tetrahedral recess is the lowest point, then just fill it with fibreglass resin. Inboard end of same shafts fibreglassed to inside of hull (hidden under servo tray). Wonder why they make the hardener that garish (blood) red colour ?

SImple supports added for forward propshafts - tubes are epoxied into these.

All four propshaft tubes stuffed with grease (well, Vaseline)

Deck camber beam framework firmly epoxied onto the hull - aft subdeck fits OK - need to cut the stern end off to allow access to rudder post

Rudder tube and servo arm installed - servo arm was a nasty loose fit onto rudder post, requiring some skullduggery to avoid bonding tube and post together....

Will probably remove the remaining two cutouts in the servo tray (provided to allow controlling optional steam plant throttles) to provide access to the couplings beneath

Next job is to finalise and install the wiring - decided to mount the ESCs on the inside of the hull adjacent to the motors, using a simple wooden block mount and double-sided pads + tie wraps to secure


Edited by preservedkillick
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  • 2 weeks later...

Much progress on electrics (with a bit of on-the-fly redesign). Decided to use panel-mount fuseholders and add LEDs as an indication that power is applied to each ESC/motor. Everything wired up tidily (IMHO) and fired up both motors together for first time (I even remembered to disconnect one of the ESC Batt Elimination Circuits, so they don't fight each other). Couplings make quite a racket - need to look at some damping methinks. Also added battery charging sockets to the servo tray (connected only when there's no power applied to ESCs/motors) - although I need to make the midship section removable, I'd like to avoid removing it anymore than necessary, and certainly not just to charge the battery. Rudder servo works OK - need to add the linkage. Almost time to dunk the whole thing in the test tank (aka bath) to make sure it doesn't leak (the boat, not the bath) before proceeding. Noticed that (perhaps not surprisingly), a fair bit of the grease in the propshaft tubes gets "wound out" by the driveshaft during running - not sure if that's normal, or how to prevent it, other than keep putting more in.





Edited by preservedkillick
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Thinking about doing something clever with the lighting (both Nav lights and lights within closed areas e.g. bridge). Thinking about some sort of "zoning" with individual control of each group of lights to allow e.g. separate on/off/flashing, and separate dimming. I fancy using some sort of microcontroller to do all this, which will also easily cope with decoding the pulsewidth-modulated output from the RC receiver to provide remote control

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She passed the bath test (just about fits !). No sign of leakage. More than enough thrust and in the right direction (given contra-rotating Left/Right-handed props, I wouldn't have been surprised if she'd taken off astern or spun round in circles). C of G looks somewhat aft, but all that white metal will add a fair bit, so I'll wait until later before trimming ballast. Not enough space to assess effectiveness of rudder, though it wiggles convincingly under RC. Noise from couplings is still to be honest horrendous, but I have no idea how much noise they should make, and I do have 4 of the blighters - no sign of distress anywhere, even under load (full speed in water got a bit messy though)


Servo tray secured with bolts into captive nuts so there's some (limited) possibility of demounting it and getting at the wiring behind it if necessary


Aft subdeck installed, with stern section separate as suggested in the instructions, so top of rudder post can be accessed (I'm paranoid as this is my first shot at this stuff)


Camber beams added to mid deck. Photo shows screen-printed forward decks loosely in place in preparation for marking out breakwater and cutting down bulwarks. I'm considering planking all the decks properly as having built a static display kit with discrete planking, I don't like the screen prints. Using tanganyka I estimate this should cost no more than about £20 (plus an awful lot of labour, but I'm up for that)


Got a basic microcontroller development kit on order for the lighting controller - this comes with a suitable small board containing the micro, plus a prototyping area that should be big enough to add the extra bits I need - basically just a few transistors to sink the LED currents. The board will run off +5V, so can use the ESC BEC output that is currently idle. Need to make sure the electronics/software side doesn't take over from the modelling..... Probably put the Lighting Controller in the midship section rather than near the servo tray, as that's where most of the lights will be





Edited by preservedkillick
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Filled and (almost) sanded gaps around the sub-decks - have to remember these edges will be visible, as the planking doesn't go right up to the bulwarks like it does on period ships. Sanded the inside face of the bulwarks a bit to reduce the obvious fibreglass look (no gelcoat on this side of course). Nervous that the ply capping rails are a bit flimsy/vulnerable - think I'll put a small timber support rail around the top inside edge of the bulwarks to provide more support (I'm not above violating authenticity for the sake of practicality !)


Next need to add 60+ metal hull fittings, including cutting holes for most of them. Will cut holes for portholes (not mandatory) to allow interior light out - this will also mean drilling through the internal longitudinal stringers.




(the watertight doors are waiting to go on the transverse bulkheads, not the hull, obviously...)



Tanga strip for decking arrived (blitzing service from CMB as usual) - gone with 3 * 0.5mm for the main decks and 4mm * 0.5, cut in two lengthwise for the cladding bits. The grain on this batch is beautiful (it does vary considerably, as I found on my static builds) and will look *soooo* much better than the screen prints. Dithered for a while on whether to use 1mm thick planks and plank onto the subdeck, using the screenprints only as a template, because I haven't used 0.5mm before, and don;t know if it will leave enough thickness for finishing (scraping). In the end (admittedly partly because CMB didn't have any 3  * 1), opted for 0.5mm, which I'll plank directly onto the screenprint, then fix the whole assembly to the subdeck. Time will tell if 0.5mm planks are thick enough - have to be gentle with scraper...)


Development board for lighting also arrived - should be just the job from the look of it. The red part is only there during development. I also have a couple of blank copies of the board so I can build one up without some of the extraneous bits (red LEDs etc), which are only there to demonstrate what the board can do "out of the box"



Edited by preservedkillick
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Hi PreservedKillick.

First off,I had an outragous experience with Westbourne.I ordered nearly £1500 worth of stuff including Robbe F14 Navy radio and all the expansion modules/ decoders,I was billed for everything straight away,but took me nearly 3months for everything to arrive and numerous telephone calls,never again!!!

Next,and more bad news I am afraid.Your UJs are noisy because they are only designed to counteract misalignment to fractions of a degree.It is normal practice to align the shaft and motor with a piece of brass tubing,ensure as near perfect alignment as is achievable and then replace with a UJ to reduce vibration and correct any miniscule misalignment.I can understand the installation issues you experienced,but the only way to overcome the problem would be to either raise the front of the shaft,changing the angle of the propshaft,or use an offset gearbox or pulley/belt setup.Decaperms have an offset output shaft,allowing the motor centreline to be higher than the propshaft.

You have two options,either leave as is and expect drivetrain failures on a regular basis,or correct the issue before you go much further.I only wish I had seen your posts earlier,but unfortunately I haven't had much time of late to spend on here..

I am truly sorry to give you this news,I can only feel for you as potentially it does mean quite a bit of re-engineering.

The third option,but would advise against it,is to use two flexydrive shafts designed for IC powerboats,however these are designed for use with high power engines and will kill the charge in your battery very rapidly.


Kind Regards



Edited by NMBROOK
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Hi Nigel - thanks for the response (there *is* other life here!)

1. Westbourne - can't imagine they'll be in business much longer. The guy there actually said to me "oh, we don't do email really"  quite how they expect to deal with web orders without, I have no idea. They also seem to think taking weeks to process an order (with no attempt at communication) is somehow acceptable, when the competition is turning orders around is < 3 days. If it helps, a recorded delivery letter seemed to get their attention, but it'll be a very cold day in h**l before I even look at their website again.

2. Couplings. Hmmmm. Taking into account (a) I'd have to tear a fair bit apart to do anything (B) I'm not sure what else I can do without different motors, added gearboxes etc. etc © I'm not sure how many "miles" I'll actually put on this beast actually on the water, then I'm inclined to live with it, even if I have to mend the drivetrain occasionally Seems a bit of a flaw in the design that the shafts are near enough resting on the hull where they come in, making it almost impossible to align with any kind of drive. The Decaperms are a frankly ludicrous price - probably in hindsight, I would have been better with smaller, geared motors. There is a belt drive available for the Torpedo's but (a) it's at least £40/side (B) looks like the output shaft is still a fair way from the edge- it's real aim is RPM reduction/torque imcrease. What's likely to fail ? the couplings or the motor bearings ? The motor is clearly out of a drill, so I would have thought pretty robust

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Hi again preservedkillick,

Looking again at the pics,I trying to think of a way to keep potential maintainance to a minimum.The couplings will fail earlier than normal but in the swing of things they are fairly inexpensive and are better kept as a 'week link',The application of some grease will help a little.You may encounter some improvement by installing a brace at the very inboard end of the propshafts.You motors should be ok as from memory the 800s are ballraced as standard.The only area other than the couplings is the inboard bearing on the propshaft.You can buy shafts that are ballraced on the inboard side but I don't think you can retrofit these bearings to your shaft as the outer tube diameter is larger.So I would go with simply bracing the inboard end of the shafts.It is possible to replace the plain bearing in the shaft without removing the outer shaft at a later date.One last point,the best test is to get it on the water as soon as and see how everything behaves.I doubt with water resistance you will run anywhere near 5000 RPM that you can in a dry test.You may find anything more than 1/3 throttle is just silly anyway,otherwise you would have built a Perkasa :D

Hope this helps a little


Kind Regards



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  • 4 years later...

Hi preservedKillick

As a newcomer to this site I was really grateful for your musings about HMT Resolve. Thanks.  Does the correspondence finish here? How was the RC issue resolved finally and was it worth installing?  I am new to RC and thought that at least it would work as a static model (having previously worked on HMS Snake from Caldercraft). I therefore find it odd that they omit propellers of any kind; for the price even a cast version would be fine! They have not replied to my e mail (of course). I too have been stung by Westbourne - amazing that they remain in business as it was 4 years since your experience. Thanks. Strech.

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