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Old May 24, 2014, 10:11 AM
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Build Log
Robbe najade (rebuilding a basket case)

Having (quite possibly very foolishly) sold my other Najade last week I picked up a Najade off Ebay this weekend. Unfortunately when it turned up it was in a lot worse condition than the pictures suggested. The previous owner has extended the rear but made a very poor job of it. Filler all over the place and very poor attempt at glass fibre. For some inexplicable reason the previous owner replaced the twin rudder arrangement with a single one which was mounted by cutting away the mounts and replacing it with a piece of styrene literally stuck on with a lump filler. I remounted the motor and added a brushless FSD 3674 watercooled motor. Unfortunately when I tested it it leaked like a sieve and handled very poorly. Also the water cooling didn't work at all.

I've pulled off the rear deck extension so I can rebuild properly and sanded the whole thing down. I've also removed the rudder "mount" ready to reinstate the original configuration.











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Old May 24, 2014, 10:17 AM
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Been putting in a bit of work today on this, I've installs the new rudders, added a brace across them (the structure that is in the original kit was cut away by the previous owner). I've also added a new water pickup pipe and exit. Ive properly attched the trim tabs too. Finally I've been trying to tidy up the finish, sand down the rough bits on the back etc..







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Old May 24, 2014, 10:18 AM
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Been working hard on the najade today, hopefully she'll be ready for preliminary sea trials on Sunday.
First order of business was adding the panels on the back quarter of the superstructure. I've been using super glue and acceleration spray. This lets you use superglue as really tough filler. Much better for gap filling that messing about with miliput. The gaps between the panels and superstructure have been filled and sanded flat:





The next part was a much bigger job that it looks. I needed to replace the original scratched glass with a fresh set that had came with the boat. Unfortunately when I tried removing it it was completely stuck to the bottom of the removable top. I had to cut away some of the plastic at the bottom and take the glass away in one piece. Then I had to rebuild the top using plasticard as the previous owner had made a hash of cutting it out and had cut to much away so the glass didn't fit properly. This was further complicated by the fact I had to make it fit perfectly as I couldn't add any filer when the glass had been fitted.





Finally I blended the wing bit onto the superstructure using the superglue filler technique and then sanded using 240 grit paper so it's now super smooth!



Tomorrow I'll be cutting out the portholes and installing the crazy expensive ones I bought from Germany!
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Old May 24, 2014, 05:00 PM
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Cheers horses! Been beavering away to get her ready for some sea trials tomorrow. I've installed the surrounds for the new portholes (the plexiglass and Chrome bits will be added after the hulls painted). I've also added a skylight. Next order of business was sealing the hole on the rear platform. I used a thick piece of styrene sanded down for the deck. Then filed the gaps with super glue and miliput where the gap was too big. The last thing was to put in battey retainers and connect the water cooling. Unfortunately whilst testing the water cooling system for leaks I found out the was a rather a large one in the cooling jacket of the brushless motor. I think thisusy have been one source of the leaking (and explains why the water cooling wasn't working). I was able to reseal and it's all good.









Test fitting glass inserts:





Rear deck:



The gap:



Sealed



Test fitting the decking:





Not quite the basket case I started with!

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Old May 25, 2014, 04:05 PM
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Tough crowd here eh?!
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Old May 26, 2014, 03:30 AM
Taking care of the pond.
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United States, CA, Sanger
Joined Apr 2004
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Looking good.
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Old May 26, 2014, 08:22 AM
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Looks 100 percent better already.
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Old May 26, 2014, 12:58 PM
Sometimes I am the weapon
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South Korea, Gyeonggi-do, Ansan-si
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Not a tough crowd but quite slow at times. Also be aware that we Yanks are celebrating Memorial Day weekend. Big holiday but a bit somber.

Anyway you're off to a great start resurrecting this wreck. I don't think many would have the dedication or patience for something in so rough a condition so I salute you sir.
I think this hull needs twin props as per my original assumption when you said it originally had twin rudders. It just seems fitting for a yacht like this but it already has that channel in the hull for a single prop I see.

The wood floor looks great. Are you going to add more scale details like a wheel, throttle quadrant, gauges et cetera to the flying bridge? What scale is this?
Keep us posted.
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Old May 26, 2014, 04:52 PM
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Quote:
Originally Posted by Harquebus View Post
Not a tough crowd but quite slow at times. Also be aware that we Yanks are celebrating Memorial Day weekend. Big holiday but a bit somber.

Anyway you're off to a great start resurrecting this wreck. I don't think many would have the dedication or patience for something in so rough a condition so I salute you sir.
I think this hull needs twin props as per my original assumption when you said it originally had twin rudders. It just seems fitting for a yacht like this but it already has that channel in the hull for a single prop I see.

The wood floor looks great. Are you going to add more scale details like a wheel, throttle quadrant, gauges et cetera to the flying bridge? What scale is this?
Keep us posted.
Cheers folks! I only discovered after watching a video of a sunseeker manhatten 48 (which this is based on) that the real ones have two props. I think counter rotating props would help this boat had it not the tunnel going on at the back for one prop.

I got her out on the water yesterday, sadly I had to run her with the top off as my magnets haven't arrived yet. First impressions are that she runs fairly well, trim tabs arent really needed and seem detrimental to turns. However compared to the najade I sold I think the previous owner has added too much forward ballast. She sits more nose down and it looks like she needs more speed to get on the plane (although not by much). I also think I need to drop the water pickup as she requires a reasonable speed to get much coming through the system.

Regards finishing shes getting the full works, led lighting, properly chromed rails and some decent detail on the fly bridge with the original semi scale kit lacked.

Shes aparently 1/15 ish scale. About 960mm long!
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Old May 27, 2014, 11:57 AM
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Originally Posted by TomHugill View Post
I also think I need to drop the water pickup as she requires a reasonable speed to get much coming through the system.
Hi Tom,

Nice work on the restauration, my complements!

Regarding the cooling system, if the exit is somewhere above the waterline, the waterpressure has to overcome the height first before the flow gets going.

If you make the outlet under water, slanted backwards, the suction will keep the flow going once the system is filled with water (after a short burst of throttle) even when you're crawling along.

If you need more speed, replace the brass prop with one from the Graupner 2318.xx series, much more efficient.
Start small ( 2318.36K), as the two pole brushless you've mounted isn't exactly a torque monster and bogging it down with too much prop will cause it to draw high current which may result in overheating.

See to a continuous cooling flow before testing more efficient props.

Regards, Jan.
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Old May 27, 2014, 02:38 PM
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Hey Jan, thanks for the kind words. I'm going to drop the pickup slightly further into the propwash as I think its too high. Also moving the outlet sounds like it could be a good move. To be honest the motor and esc were not really overheating in my tests but I like to be safe.

Regarding speed with the motor/prop combo I'm hitting the limits of the hull and torque will pull her to one side at about 75-80% throttle. I do have trim tabs installed but these seemed detrimental.
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Old May 27, 2014, 04:48 PM
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Sneek, Netherlands.
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Hi Tom,

What size prop are you using?
The motor is the 28 mm FSD, right? Or is it the 36 mm version?
Which Kv and which Voltage?

If you're experiencing proptorque, you may need to increase the Voltage and decrease the propsize to keep the boat manageable.

If that fails, FSR style wedges, under the hull will assist counteracting the torque issues, but if you need to take that kind of measures, you're already running way past scale speed...

Regards, Jan.
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Old May 28, 2014, 04:49 AM
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Hey jan, it's the 3674 2075kv motor. Seems to have plenty of grunt!! It does a good 20mph before falling over so I'm happy with that. I'd rather keep the hull original that stick fins and what not over it to squeeze more speed out! After all it's a scale glider rather than a fast electric!!

Saying that I do have some 35mm props I could experiment with! Nothing lost if it doesn't work. Again thanks for the advice Jan!
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Old May 28, 2014, 04:56 PM
Boaters are nice people.
Sneek, Netherlands.
Joined May 2004
5,120 Posts
Hi Tom,

The FSD 3674 2070Kv is a smooth can motor witout the glued on watercooler:
http://www.fsd-motor.com/product/sho...?lang=en&id=95
With 1500W it's also a tad (more) overkill (than the 1100W of the shorter can motor)...

The watercooler motors are 3660 2726Kv:
http://www.sdshobby.com/fsd-3660-kv2...ng-p-4115.html
The higher Kv and the brass prop most certainly are an issue regarding proptorque.
Do you run on 2S, or 3S?

Regards, Jan.
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Old May 28, 2014, 05:04 PM
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Great job on the rehab of this boat!
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