Ron S

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Hello,
I picked up this kit a few years ago while on a trip to the Netherlands. It is of the THOR, which was evidently built as a Coast Guard vessel for Italy. The model is powered by 2 small waterjets. I started building the kit about 1 year ago, then it was shelved for some other pressing projects. I decided this boat will be finished ASAP for a New Years resolution. [8D] I figure if I post a partial build thread on it, I will have no excuse for not finishing it!

Ron S

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Since I have a coast guard model already, I decided I was going to hack this one up a bit, and make it into some sort of coastal interdiction craft. Whatever that is! [8D] Either way, it is an excuse to try some unusual camo, and stick some machine gun mounts on it. It is no longer scale, but more of the lines of fiction scale. This is a partial build thread, so as you can see the hull upper/lower halves have been joined, and the deck installed. I even have the little winch/rubber boat thingy painted. This afternoon, we had some nice weather, so I started on the camo. I wanted to do a simple camo scheme, something similar to what they would use on some of the modern North European vessels.

Ron S

My Feedback: (2)

After having gotten the majority of the paint on the superstructure, I am now adding the little door handles, ladders, light housings, and eventually the overhead radar mast thingy to the superstructure. Some other items below are shown, soon to be installed. The model hull is currently empty - I've installed the waterjet passages, and thats it. I'll post more pics of that area when I dig into it.

My intent isn't to make it any sort of superfast speed boat - I'm not sure how all the plastic pieces will hold up. So I've picked up a pair of Speed 600BBs to run the waterjets. I also would like to keep the model lightweight, so I've just ordered some 7.4v 2400mAh LiPos to power the model. We'll see how it works... I also picked up a set of relatively lightweight LEDs to run the various running lights. Its supposed to run on 3.6 to 5 volts. 5 v seems pretty bright... I also replaced the decal obround portholes on the forward hull with some round portholes, from Hobby Lobby. I figure then I can put a red LED inside the hull, as if the crew are inside reading various maps, and planning an attack. Or, maybe just watching TV.

Ron S

My Feedback: (2)

I was having some difficulty find little sailor guys in the correct scale, so I just picked up some 1/35 scale guys n' guns to stick on the model. I think I'll add a couple 50 caliber gun mounts on the front deck, and perhaps one on the aft deck. This weekend the weather is supposed to be a bit colder, which means an excellent time to start building the gun hardware! [8D]

I should also say, the model has some simple shaped stanchion-rails that need to be soldered together. This part went much easier than I thought it would be. I just cleaned the brass parts, added a light amount of flux, and silver soldered each part with a light solder coat. Put the parts together, heat'em up, and bang your done! The hardest part was making sure the parts are rigged properly with clamps, etc, before adding the final heat. So don't be scared of silver soldering brass if you've never tried it. I remember seeing threads of folks making cooling volumes for their electric motors - I'm not ready to try that yet.

pompebled

Would you like a tutorial and pics?

Just let me know!

Regards, Jan.

Ron S

My Feedback: (2)

Thanks Jan, thats a very nice, clean job. [8D] My last boat, I used nothing but air cooling on the motor, and they do get quite hot to the touch, but they are seeming to survive, after 2-3 years of once-a-month use... This time around, I'll try the brass tube method - this can only be better, if only slightly. I will consider the fancy water jacket idea on my next project, pending how this goes.

I guess I also need to figure out where to take in the water for the motor cooling tubes... I figured at first to perhaps add 2 flush inlets on the bottom of the boat (to keep the bottom clear of any "appendages" sticking into the path of water), but an alternative would be to put an "inlet tube" just aft or perhaps into the water nozzle itself. I think that would produce much better flow through the tubes, but might produce a slight thrust loss. I'm not sure what method is most commonly used... ?

I now have 50 cal guns and a 30 cal gun assembled, and painted. I've also made some gun mounts out of some Plastruct and G-10 glass, and have attached them to the fwd and aft portion of the superstructure. And now the radar mast is attached. I think the superstructure is ready now for it's last coat of base color, to cover the mast, gun mounts, rails, etc.

Ron S

My Feedback: (2)

I've decided to take a break from the external fiddly bits on the deck, and start working below the deck. I'll probably make some sort of lite-ply tray or deck to hold the LiPos, speed control, etc. The motors bolt directly to the waterjet passage, which has been installed.

A question for people that have used waterjets before - I have simple, short Aluminum couplers to go from the motor shaft, directly to the propshaft. Is this okay from a vibration standpoint? Should I use some sort of rubber isolated coupler instead? The AL coupler does a diameter stepup, from the .125" dia motor shaft to the .157" dia prop shaft. If one is available, (an isolated coupler) would have to be very short. I guess I could always replace it later down the road if needed...

I have a pair of Traxxas XL-1s to use for speed controllers. I am debating whether to cut the speed controller switches out altogether - reason, is because usually after a model run, the first thing I do (after pulling the boat out of the water) is to turn the model off, and disconnect/remove the batteries. The switches seem unnecessary. Plus, less wires in the model. Hmm...

Probably then, inbetween the motors and speeed controllers, I might place the 2 steering servos for pull-pull to the waterjet nozzles. Or, I could steer one nozzle, and attach an arm from nozzle one, attached to nozzle two so they both steer identically. Hmm...

And now, I'm thinking I could probably do pull-pull to each nozzle from the same single servo. I may give that idea a go. I can see how operating each throttle individually might be nice, but I don't see an advantage in having independent steering of nozzles.

pompebled

Hi Ron,

If you check on other jet builds, the water intake usually sits on top of the jet, behind the rotor, so it benefits from the pressure being build up.
Powerloss is minimal.

If you want the coils to be effective, take off the motorstickers, and slide on the coils (with a tight fit) on the can with some heat conductive paste, cover the coils with a piece of shrinkwrap to cover the paste (it's nasty stuff) and press the coils onto the can.

Adding brushcooling is always possible afterwards, should the motors get too hot.

If the couplers run true, I'd use those rather than flexible ones (if they exist soo short...), just make sure the shafts are properly alligned.

Regards, Jan.

Ron S

My Feedback: (2)

Oww! I just got timed out on RCU while adding an update... [:@] Either way, I've taken your good advice and removed the motor labels, for better heat transfer to the cooling tubes. I've soldered the leads in place, and they're ready to install in the boat. I've also made a removable radio tray to hold the electrical goodies.

pompebled

Looking good Ron!

Your coils around the cans are rather short, there's room for 6 or 7 winds, but, if the motors stay cool enough, there's no reason to upgrade the cooling.

Should things get too hot, add brushtab cooling first, as that's more effective than adding more coils (of which you'll need 3 ft per motor).

Regards, Jan.

Ron S

My Feedback: (2)

I agree the cooling coils are a bit fewer than I've seen in some posts - it should help some though. I can measure the temps after a run after we get it running in the water. I did apply the heatsink compound to improve the heat transfer. I checked some other threads in the electric boat racing forum, and was surprised to see a large thread on waterjet powered models - well over 90 pages, and very informative. Tonite, I spent some time installing the motors. The waterjets had to be grinded on a bit to accept the Graupner 600 motors, but they fit now. Looking over the Kehrer jet drive website, it seems the jet drives were made for a bit larger of a motor. Oh well, we are where we are - I wasn't planning on racing the model anyway. Radio tray is also installed.

Ron S

My Feedback: (2)

I applied 1.5 volts to each of the motors, and the RH side appears to run very smoothly - the LH side has a slight amount of vibration. I may have to go back to the motor mounting, and wiggle it around a bit, to see if it can be smoothened out some. Probably after the motor and bearings get broken in a bit, that may help some. Seeing where the heat sinks are for the speed controllers, I think I will perforate the forward portion of the aft deck - which is immediately behind the superstructure aft wall. This will provide a spot for the warmed air to escape. It should be partially hidden too, since it will be in the shade of the upper bridge of the superstructure.

Which makes me think I might want to consider more exit holes in the model, probably aft. Hmm...

I am considering seeing if I can program my radio so that one stick will normally control the steer, and perhaps the second stick I can use to operate the throttles like a tank - that is, LH throttle signal will increase, while the RH throttle will decrease. That way, making a coordinated turn might be improved. Its atleast worth an experiment, and I could easily remove the program if it is deemed useless. [8D]

The previously mentioned jet drive thread also has some ideas on where to take the input water from, so addressing the cooling water path will probably be next.

Except I'll have to wait a couple days... Tomorrow, it appears we'll be having nice weather, so it's time to test fly a model plane I finished a month ago.

pompebled

Hi Ron,

As the kit has been discontinued for some time now, my memory of what goodies were inside have faded somewhat, your remark of running two 600 motors made me google:
http://www.rc-modellbau-schiffe.de/w...&threadid=3198

Never mind the German language, the pics clearly show two 700 motors for the Thor Jets, running on 12 cells NiMH each.

I fear the performance with the 600 motors will be disappointing at best, most likely they will glow briefly under load and die, as the load of the Kehrer jets is too much for them, watercooling them to the max, with a full can- and brushtab cooling will not help, I'm affraid.
I'd make arrangements to allow the change to 700 motors, should the 600 motor set-up fail

The original was designed by Franco Harrauer, Italy, as a yacht, later adapted to be a coast guard vessel.

From what I've seen on twin jet set-ups, reducing the output on the inside motor in a turn will need a lot of tweeking, as too much will start to act as a break and cause 'interesting' handling issues (=heart stopping maneuvres, not as you'd intended...).

Only at low speed, the reducing might work, it's better to have the mixing option on the reverse functions though, which allows for very sensitive low speed maneuvering.

Regards, Jan.

Ron S

My Feedback: (2)

Uh-oh, that doesn't sound very good! [:@] Unfortunately the kit did not come with motors, nor did they come with instructions on what to use. I've used the same type motors on a similar sized model (actually a bit heavier, non waterjet) with good results. If this is not enough, I should be able to pull the 600s out and replace with 700s. And if I have to do this, I have another boat kit (well, 2 actually ) waiting in the "wings", where a pair of 600s would be fine.

"glow briefly under load and die..." That sounds soo negative!...

I can make out some of the German language, but can't see the pics. I don't think I'd be able to properly register to see the pics, but thanks for the link anyway!

pompebled

Actually it looks rather nice; you'll see the ring of fire on the commutor gradually get bigger and brighter, to the point where there are no brushes left, or the segments of the commutor have arched-welded away, whatever comes first..., it can be a matter of seconds, depending on the ampdraw.

I've seen a clip of it on you-tube but I can't find it anymore, sorry.
If you want to see it for yourself, you'll have to install a minicam on the maidenrun. (protect the lens, things will tend to fly off)

Two 9,6V 700 Neodym motors (with can- and brushtabs cooling) on 12 cells each, would be the 'weapon of choice'.

Regards, Jan.

Ron S

My Feedback: (2)

That will then require the unfortunate replacement of pretty much all the running gear - motors, speed controls, and batteries. Which I'm not unwilling to do, but since I have all this stuff installed, I'd rather proceed for now. If it creates a floating fireball, it will atleast make our next model boat outing interesting. I also mostly fly turbine powered jet models, so I always have a fire extinguisher in the car.

I also have a fuse installed inline with the motor, so if the amps start getting high, it should take the fuse out way before the fireball emerges. But, the fireball has me intrigued - perhaps I should get some larger fuses...

I did perforate the fwd aft deck with some cooling holes right above the speed controls, in case heat is an issue inside. I threw some more paint on the superstructure, and installed some of the nozzle hardware outside the transom. I also installed some brass tubing on the nozzles, per the Kehrer website. (Water pickups for the motor cooling tubes). Hopefully my hobby shop now has my receiver crystal in stock, so I can soon install the receiver.

Our next boat float is Feb 21, so I guess I'll shoot for having the boat ready to run (or ready to glow) by then. The next few days, I'll be tied up with other projects, so I might not be able to do much on the boat till then.

Jan, are there any good hobby shops in/near Sneek? This particular model was bought in Sneek, at a shop where the first floor is for toys, and the second floor is all modelling related stuff... I had stayed in Lemmer for a few months (about 3 years ago, or so), and during the weekends, I usually tried to hit the roads looking for hobby shops.

pompebled

Hi Ron,

That store is still in business, in fact it's the only one selling model stuff in a 50 km radius.

I thinks I've seen your Thor on the shelve there, as it was the only jet driven boat they've had for years...

I frequent the store regulary to get my supplies, but the choice is limited, I haven't been able to buy the motor I wanted as long as I shop there..., fortunaly there's always the internet, but I like to be able to handle the items I buy.

I don't think, your motors will die in a blaze, as they won't be able to rev high and create that ring of fire on the commutor; most likely it will be the windings that will give up due to overheating.

Fuses, what fuses? Bridge those with big solid brass bars!

I'm really curiuos how the 600 motors will hold up.

Regards, Jan.

Ron S

My Feedback: (2)

I'm back from my trip, and now it's back to the boat. [8D] I've final installed the steering nozzles, and have attached Kevlar lines to them to route to the steering servo. I've punched some holes in the transom, and have installed bulkhead passthrus, to run the waterlines for cooling. Next will probably be to get the radio on over the weekend, and make sure the steering will work properly. Along with the throttles. I've also gotten back to putting little bits and pieces on the superstructure.

Since I want to run the boat next weekend (if the weather is okay), I may use that for the "sea trials" run, and perhaps some items won't be complete - like the figures, lights, etc. We'll see. I need to be working on another project over the next couple of weeks, which will be taking half of my available time.

pompebled

Nice work Ron!

I'm curious how the steering will work, using Kevlar strings, I've only seen nozzle steering with solid bars or bowden cables (airplane style).

I can't see it clearly in the pictures, but it seems you just have two capacitors on each motor instead of the usual three?

Fingers crossed for the maiden!

Regards, Jan.

Ron S

My Feedback: (2)

You are correct - these motors have caps already soldered in place, in the same locations you show the 10nF caps. If there is a 3rd, perhaps it is under the motor aft endcap... I'm using similar motors on another boat, and I've had no known interference issues. For my previous boat, I did go ahead and install a base-loaded short antenna, that was aligned vertically. On this boat, I currently have the antenna running fwd, then coming back. For now... I may go ahead later and install a whip antenna after the first run on the water.

After I wrote my last update, I decided to start on the lights, for the heck of it. I have simplified the lighting such that all the lights are on the superstructure (L/R running light, and aft searchlight that will light up the aft deck, and a single red LED that will light the cabin and fwd portholes. I also need to start installing the superstructure windows. I will keep the aftmost portholes and the 2 door portholes open to help with cooling. They aren't that large, but I can always pop additional holes later.

At some point, I'd like to add a bow light and perhaps a light near the transom. I would think those might be required in the (full scale) boating world. I'm not familiar with boating "rules of the road". [sm=pirate.gif]

Ron S

My Feedback: (2)

Here is a pic of the underside of the superstructure. The LED leads will be soldered to a connector / extension, that will allow hooking up to a separate battery pack on the tray inside the hull. After the windows are installed, I'll add a fwd "dashboard" inside, just below the forward windows, just to reduce the amount you can see inside. I may add a couple partial figures at a later time, but I most likely will not make up internal detail.

I had to raise up the steering servo, because the Kevlar lines were a bit too close to the motors. I'd prefer they not melt while I'm running. Of course, if I notice at some point I have no steering, that should indicate I should slow down to let the motors cool - an indication the motors are having a meltdown!

I use Kevlar pull-pull on rudders of some of my smaller airplane models - it's what I have laying around. I gave them a pull test - way more than what the model will see. It should work, as long as the rotation arm distances and angles of the waterjet nozzles are duplicated on the servo wheel. In this case, approx .45" distance from the pivot point, and about 60 degrees off of the centerline.

pompebled

Hi Ron,

You're right, some motors come with the two 10 nF caps installed at the factory, if yours have them too; you could omit the external caps and only add the 47 nF between the connetor tabs and have the suppression as shown in the schematic.
But, if it works, don't change a thing!

Kevlar has a fairly high melting point, if they should melt during a run, there's definately something on fire under deck....

Cooling through open doors or windows is rather overrated, hot air builds up and needs to be forced out mechanically, having a small computerfan blowing air (preferably from outside the hull) over the ESC's and motors will be more effective than leaving a door open.

Regards, Jan.

Ron S

My Feedback: (2)

Actually, at our local electronics store, I did see they carry some small cooling fans, probably designed for cooling computer CPUs. I just noted that fact. I'm not sure what voltage they run on. Next time I'm there, I'll check - not sure if they run off of CPU voltage or not. If I have to go that route, I'll have to build some sort of "vent exit". That wouldn't be too difficult.

I was playing around with the ESCs this afternoon, and noticed when I switched one battery/ESC off, and left the other side to run, both motors would run...[:'(] Thats not good, because I think that means the motor (that shouldn't be running) current is being dumped thru the receiver! So I disconnected a ESC positive terminal off one of the Futaba connectors going to the receiver - this way, the ESC is only getting the white signal wire current. This also means only one battery is supplying the BEC circuit to run the receiver. On the good side though, if I like, I should now be able to control each motor individually.

pompebled

Hi Ron,

As you've connected two ESC's with BEC to the receiver, pulling one of the red leads from one ESC to the receiver is the correct way to wire it.

You'll not notice the fact just one BEC is powering the receiver and servo's in normal running, as the motors will draw the bulk of the current, depleting the batteries.

The computer fans are available in a number of Voltages, so you should be able to pick one that's suitable for your powersource.

Regards, Jan.

Ron S

My Feedback: (2)

I tried taking some pics of the lighting, but I didn't spend too much time with the camera. I'm sure it can be done - I've seen nicer lit boat pics in this forum. Anyway, here's a pic. I think I'm going to at minimum add another red light in the enclosed cabin area.

I also planned on adding some sort of "SEAL" team boarding net thingy on the Port side, that will overhang from the boat side. Not being able to find what I thought was a suitable net size, I decided to "glue together" my own. I tried 2 superglue viscosities, along with a "canopy glue" type, and had the best result with the canopy glue. It isn't really meant for hanging in the water while running - just to make the aft deck more busy. Here's the net being assembled - tomorrow I trim the excess ends and hang in place. [8D]

The model also came with a gray rubber type bumper strip to slide onto the boat outboard edges. Unfortunately it is a difficult fit. I found where I can order the same size black neoprene tubing, so if the supplied gray stuff doesn't work, I can go to the neoprene. The neoprene should be the same size as the blue glow-fuel tubing shown in place.