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Author Topic: What have we here?  (Read 10518 times)

XV Pilot

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What have we here?
« on: July 05, 2012, 08:54:06 PM »

Hello All!

While not new to RC, I am very much a beginner to the RC boat scene, so please bear with me.

After hearing that I was considering buying a model boat, my brother-in-law kindly gave me one he had knocking about in his shed. He in turn had been given it by a friend, who bought it at a yard sale, so we don't actually know what sort of boat it is or where it came from. The hull shares a lot of styling cues with the Graupner B-24 Nimbus, and shares the same overall dimensions. However the gubbins inside are very much toy grade. My plans at this point involve fitting hobby-grade gear and giving it a decent paintjob, then running it at a nearby RC boat club, either racing it or just running it for fun.

I will no doubt have many questions as the project progresses, but here are a few for starters:

Can anyone recommend me a rudder assembly? The boat has been fitted with two motors and props, but has no visible means of steering. I guess it used to steer tank-style using differential thrust?

I'd also like to find out if this boat fits into any particular racing class, and if so, what would be required to make it race-legal?

I have a Spektrum SR200 receiver and a waterproof high-torque Futaba servo available for the project but I would appreciate some recommendations as to speed controller. At first I am planning to keep the stock pair of 380-size motors which I will run in parallel. However, as I may race it at some point, I'd like an ESC that can handle whatever race-legal powerplants y'all recommend.

I have heard different views as to the need to extend the standard Spektrum RX antenna for marine use. What is the consensus here on the forum?

Finally, are there any general recommendations regarding colour schemes? I know in the RC glider world, it is better to have a light colour on top and a darker one underneath to aid visibility at altitude. Is there any similar convention for boat colour schemes for visibility on water in high-glare conditions?

Thanks!






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Stavros

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Re: What have we here?
« Reply #1 on: July 05, 2012, 09:25:22 PM »

Right it is baisically one of these

http://www.ebay.co.uk/itm/28-Double-Horse-7000-Wing-Speed-Remote-Radio-Control-RC-Fast-Speed-Boat-EP-RTR-/261022035088?pt=UK_ToysGames_RadioControlled_JN&hash=item3cc6202c90

Personally I wouldnt bother as it will cost a packet to do so BUT if you want to go ahead I suggest you need the following

1x 2 channel transmitter
1x reciever
1x Action P94 combined speed controller mixer
1x Stick Pack
1x Action bec 5v

With this gear you wont need rudders as the P94 will allow you to steer the boat via the transmitter


Dave

Dave
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XV Pilot

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Re: What have we here?
« Reply #2 on: July 05, 2012, 09:50:03 PM »

Yep, that looks like the same hull moulding.

I already have a suitable transmitter (DX3C), receiver (SR200), plenty of 7.2V stick packs and a few spare BECs, so if I go that route all I'd need is the ESC/mixer thingie. However I am not sure if steering by differential thrust is all that good from a performance point of view - after all, you turn by slowing or stopping one of your motors. Surely I would be able to hold more speed through the turns if I could keep both motors going full-throttle and turn using a conventional rudder. What are the forum's views on that?
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Stavros

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Re: What have we here?
« Reply #3 on: July 05, 2012, 10:10:33 PM »

Best thing you can do with it is to get rid of both motors and put a single brushless in it with a rudder and then it will fly thas what I did with mine,BUT I was lucky as I had a trashed boat and simply transferred all the goodies


Dave
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Martin [Admin]

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Re: What have we here?
« Reply #4 on: July 05, 2012, 10:30:41 PM »


I have two of these hulls, I think they are have quite a good hydrodynamic shape.
 They are of quite a hard plastic so a bit brittle, try to reinforce the bow tip inside with a big blob of hot glue, silicon, epoxy etc.

 Here a couple of pictures of mine when it was in progress..... now on hold before completing Mk I  <:(

Mk I    - Fast as possible with fitted motors... and more batteries, until they burnt out!
Mk II   - Single Speed700BB motor with Graupner Strudder Mk III
Mk III  - Above with Brushless various motors
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XV Pilot

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Re: What have we here?
« Reply #5 on: July 05, 2012, 10:39:56 PM »

Sounds like a plan. I'm thinking of filling the front of the hull with expanding foam, with will give reinforcement and emergency buoyancy in one go. Think this will work?

Short-term I think I'll stay with two motors, simply because they are there already. But long-term a single brushless would be on the cards I think. I'm already going that route with my RC cars. I don't have a trashed boat to nick gear out of, but if I trash this one, I can always transfer the gear into another, so it still makes sense to get decent gear.

Any ideas on racing class, class rules, etc?

And any suggestions regarding a suitable rudder assembly and where to get it? I like what you've done with the inboard rudder, but I have also seen some rather nifty spring-loaded external rudder assemblies that I think might work, and would be easier to fit. Views anyone?
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martno1fan

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Re: What have we here?
« Reply #6 on: July 05, 2012, 11:26:35 PM »

Not to be rude but the best thing you could do with that plastic hull is throw it in the bin and buy a nice fibreglass hull,put decent quality gear in and you will be happy whereas you will never be happy with that boat.
Mart
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Stavros

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Re: What have we here?
« Reply #7 on: July 05, 2012, 11:36:42 PM »

Expanding foam will absorb water dont do it,if you want to add foam get some f the closed cell variaty as for racing classes dont think there are ny for this boat and tbh it will be a waste of time go out and enjoy it


Dave
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XV Pilot

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Re: What have we here?
« Reply #8 on: July 06, 2012, 12:08:41 AM »

Thanks for the tip about the foam. I thought that squirty foam naturally formed closed cells. I'll hunt down some of the closed foam variety. In a way it is a bit of a relief that there seems to be no racing class for this boat - if there was, I'd feel duty-bound to make it race-legal, but as it is, I can just build it, run it and have fun.

And yes, I know it isn't the best quality hull, but it was free, so I am not going to throw it out. If/when it breaks, I might replace it with a fiberglass one, or I might go back to Plan A and buy myself a Plura-hulled Robbe Katja. We'll see when the time comes.
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XV Pilot

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Re: What have we here?
« Reply #9 on: July 06, 2012, 12:47:30 PM »

So back to the questions:

Rudder size: I have found quite a selection of externally-mounted spring-loaded rudders on the CornwallModelBoats, but I don't know what size to go for. Any suggestions?

Rubber boot thingie: I am sure you are all familiar with the rubber bellows thing that many modellers use to prevent water from entering the hull through the rudder pushrod hole(s). Could someone tell me what they are called and where to buy them please?

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essex2visuvesi

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Re: What have we here?
« Reply #10 on: July 06, 2012, 12:54:33 PM »

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XV Pilot

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Re: What have we here?
« Reply #11 on: July 06, 2012, 03:00:30 PM »

Thanks for that!

I've considered sticking with the differential thrust steering using the Action P94 mixer/ESC, and was quite tempted to go that route due to simplicity. However I have decided to go with a conventional rudder on cost grounds. It doesn't make sense to me to spend almost 80 quid on the P94 as opposed to just over 30 quid for a basic conventional marine ESC plus the gubbins required to install a rudder, especially on a hull that I have been told isn't worth using.

So, my shopping list consists of the following:

Threaded Rod (2)   
Ball Couplings (2)   
Rubber Bellows (2)   
2332 Rudder Assembly 60x40mm   
Mtroniks Viper Marine 15

Anyone think I'm on the right track?
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craig dickson

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Re: What have we here?
« Reply #12 on: July 06, 2012, 09:15:06 PM »

Thanks for the tip about the foam. I thought that squirty foam naturally formed closed cells. I'll hunt down some of the closed foam variety.

Just on the foam issue for boat buoyancy, personally I recommend the two part liquid marine grade mix. It is much easier to apply and when enclosed in a section designed for the mix it leaves a neat job. And it sets exothermically throughout the foamed area unlike the spray can stuff that relies upon moisture.

I bought my two part foam from here:

http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__2_Part_Polyurethane_Foam_Liquid_415.html

This photo shows it in the bow and front side sections of my new build:



Craig
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XV Pilot

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Re: What have we here?
« Reply #13 on: July 06, 2012, 11:26:18 PM »

Thanks for the link. That looks like just the stuff I need.

On another note, I discovered something that all you nautical fundis probably knew already, namely that this is a pretty accurate 1/10 scale model of a real V24 powerboat. With the addition of mirrors, exhausts, wiper blades and a rail along the foredeck(?), and the removal of the external radio switch and antenna, I am confident that I can make this into a passable scale model. There is even space under the cowl to build a scale cockpit, which I might do at some point once I have the hull and running gear sorted.

This is excellent news for me, as my original reason for getting into model boats was that I wanted something to tow on a trailer behind my 1/10 scale Tamiya CC01 Pajero, and I thought a functional scale boat would be cool. So this is no longer a racing boat project. It is now a scale representation of a racing boat project!  :D
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essex2visuvesi

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Re: What have we here?
« Reply #14 on: July 07, 2012, 12:27:14 PM »

Funny how addictive this hobby becomes

I picked up a couple of cheapy NQD boats for the kids 3 years ago, now have at least half a dozen boats on the go
one day ill finish one of them lol
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XV Pilot

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Re: What have we here?
« Reply #15 on: July 15, 2012, 08:47:08 PM »

While trying to make my mind up about the internal gubbins for this project, I have been playing around with some ideas for the colour scheme. As is my usual practice when doing this, I started out by doing a quick line drawing of the craft in MS Paint:



Then, using the Area Fill function, I was able to play around with different colour ideas. I knew I wanted quite a bit of red on it, in order to match the red of the 1/10 Pajero that will be towing it on a trailer, and I knew I wanted a white canopy with dark tinted windows,so I filled in the colours appropriately:




However this looked a bit plain, so I looked again at the Pajero with its red bodywork and silver/grey bumpers and wheel arches, and added some silver to the equation. I also tried a white vertical stabiliser:




I liked the red and silver, but I wasn't totally happy with the white, so I tried extending the white area all the way to the stern, and adding some white in front of the windscreen. This was too much white, so I changed the vertical stabiliser back to red:




I rather liked this colour layout, but after looking at the model I decided that I didn't fancy my chances of being able to pull off a neat job of masking the dividing line between the red batwings and the white engine cover, as this area follows a compound curve. So I set this area back to red. However I did like the idea of a bit more white, so I decided to add a white line from the bottom of the windscreen to the bow:



I'm thinking this will be my final colour scheme.

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XV Pilot

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Re: What have we here?
« Reply #16 on: July 15, 2012, 11:39:13 PM »

Here is the full-size inspiration:



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Stavros

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Re: What have we here?
« Reply #17 on: July 15, 2012, 11:44:40 PM »

That will look awsome painted up



Dave
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Martin [Admin]

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Re: What have we here?
« Reply #18 on: July 16, 2012, 11:08:30 AM »

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XV Pilot

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Re: What have we here?
« Reply #19 on: July 17, 2012, 09:23:57 PM »

Did a bit more work on the boat:



I removed the wire antenna and external switch, and filled the holes they left in the deck moulding since I will be running an internal antenna and switch in order to preserve the scale appearance. I also altered the profile of the vertical stabiliser a bit to make it better match the tips of the batwings.
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XV Pilot

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Re: What have we here?
« Reply #20 on: July 19, 2012, 08:55:28 PM »

No more progress on the boat as yet, but this evening I ordered the ESC, rudder assembly and paint, as well as a set of wing mirrors and wiper blades to make the cabin look a bit more detailed. Should be some visible progress soon!
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XV Pilot

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Re: What have we here?
« Reply #21 on: July 23, 2012, 04:54:12 PM »

Some visible progress:





While waiting for CMB to despatch the rudder and linkage gubbins I ordered last week, I made a start with the paint, which arrived within two days of ordering from Modelsport.  :-))

I don't want to start putting final colour on the hull until I have the gubbins finalised, as that is just asking for the new paint to be dinged and scratched. However the canopy can sit safely on the shelf while I fit out the hull, so I decided to paint that. After wet-flatting it and giving it a coat of Halfords plastic primer, I hit it with some Tamiya Racing White and Gloss Black. I am quite pleased with the result.

Now to wait for CMB to send the rest of the bits I need to get this model on the water. How long do they take generally?

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XV Pilot

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Re: What have we here?
« Reply #22 on: July 28, 2012, 03:52:36 AM »

With the delivery of my parts from CMB, the last few days have seen some significant progress on the technical side of things. Gone are the toy-grade gubbins - the inside of the hull now looks far more hobby-grade now that it contains a Spektrum RX, Mtroniks waterproof ESC and Futaba waterproof servo:





Still to come are a pair of Graupner Speed 400 motors to replace the dodgy Mabuchis, and I am still thinking about the best way to waterproof the RX. I could put it in a balloon as I do on my scalers, or I could plasti-dip the PCB. Having it sitting where it is will be fine for initial testing though.

I now also have a means of steering the thing! After looking at many, many rudder options, in the end I went for a basic folding unit from Graupner. I haven't found any conclusive answers regarding how far it should be from the transom or how far it should protrude below the hull, so I will have to try it and see.



Bathtub trials show it to be floating level with no leaks, CoG is at roughly 30% from the transom, even the stock motors develop enough thrust to rapidly empty the bathwater all over the floor, so I think we're ready for river trials tomorrow! If all goes well, all the gubbins will come out again, and I'll start prepping the hull for paint. I also need to start thinking more seriously about my trailer design.

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XV Pilot

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Re: What have we here?
« Reply #23 on: July 28, 2012, 12:18:29 PM »

Well, river trials were inconclusive. The boat certainly has some go to it, but steering is a bit of a hit-and-miss affair due to the rudder not repositioning itself as advertised.

The boat handles just fine if the rudder is in its fully-down position. However the river isn't exactly free of flotsam, and each time I encountered any, the rudder would fold back as it is supposed to. However it wouldn't return to its normal position afterwards.

CMB advertise it as having a spring to return it to its normal position, but I have a feeling this only exists in their imagination. At first I thought something might be jamming on my rudder, but after disassembly, I can find no spring, or any evidence of where one may be fitted. It looks like the rudder is designed to be held in place by friction from its clamp, and if it folds back, it has to be repositioned manually.

I must say I am very disappointed with CMB. Can anyone recommend a model boat shop with a bit more honesty and accuracy in their online advertisements, and that can actually be bothered to reply to emails?
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Martin [Admin]

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Re: What have we here?
« Reply #24 on: July 28, 2012, 01:11:38 PM »

What Amp Mtroniks is that? 12A?..... that might be a bit low.....

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