graupner scimitar speed

[chris PoultonParticipant @chrispoulton72699]

hi all, totally new to electric boats and have an old but new (unused) graupner scimitar speed, with a gearbox and speed 600 motor. this boat has a straight shaft through a small skeg in the hull, so change will not be easy. can anyone point me in the right direction to get a good brushless motor, esc, prop and motor mount, preferably from one supplier? thank you.

[chris PoultonParticipant @chrispoulton72699]

want to go brushless

[ashley needhamParticipant @ashleyneedham69188]

Chris. Can I ask why you want to go brushless?? have you run the boat as it is yet?

Do you want to go REALLY fast, racing or just bomb about the pond.

Ashley

[chris PoultonParticipant @chrispoulton72699]

hi Ashley and thanks for replying. i have not tried it in brushed mode at all. brushless to me seems so much more efficient so a bit more speed, lower current, more run time on lipos, of which i have many as i fly rc planes.

[ashley needhamParticipant @ashleyneedham69188]

Chris. While brushless does indeed deliver these virtues, it will be a bit poke`n`hope as to fitting your boat with the best combination. It will probably be more expensive, and you will not have reverse either on most brushless ESC. Graupner designed the boat with best efficiency in mind, and although using existing technology, the speed600 is still a motor of choice in a lot of fast applications. Aircraft are a slightly different matter as weight also comes into play, which is not quite so critical in a boat, unless racing.

Not only that, but you will essentially have no idea as to the improvements you may or may not have made as there will be nothing to compare it with. the likelyhood is you will fit something considerably more powerfull and juicy than that fitted, the boat will be much faster than standard, but the run time is not likely to be much improved, if at all.

Just playing devils advocate really. I would simply purchase some Nimh batteries, a 25A ESC and have fun.

Ashley

[chris PoultonParticipant @chrispoulton72699]

I think you have a very good point there Ashley, and I will take your advice.

Cheers

Chris

[Srdjan BelgradeParticipant @srdjanbelgrade75162]

Hi Chris and Ashley,

I just created an account here to be able to reply to you. To sum up at the beginning, I did what you intended to do many happy faces as a result.

In details:

Platform: Graupner Scimitar Speed

Condition before upgrade: Speed 600 motor applied elsewhere and misplaced during the years. Original spur gear milled to pieces back in the day (propeller got caught in a floating garbage bag at full speed). The original gear ratio was 3:1. Otherwise the boat was in perfect condition.

Plan: The idea was to keep the possibility to run the original motor (actually it is now a Tamiya silver can 540 motor), so I ordered 2:1 gearbox, to increase the speed running on "standard" motor through gearbox. But I also wanted a direct drive option in order to be able to use any kind of motor.

Result: Still having a standard gear option available, but I think I will never use it again (maybe just for training my boy when he gets into RC boats). What I use is Astro Flight 40 Brushless motor running on 12 NiMH through Castle Creations Phoenix HV controller. (And yes, I do not have the reverse option, but so far I had no need to use it.)

The boat is quite heavier in this brushless configuration, but if you look up on the net, you will see that the engine is more than capable of pushing it along (1kW max power). Insane? I know Balancing the heavy motor so far in front and 12 NiMH batteries was a bit tricky, and I am still not sure if it is good at the moment. I think it would be the best to switch to lighter LiPo batteries. Also, I have not been able to test the max power due to not having the perfectly still stretch of water that is long enough to whip it around at high speed. Due to the powerful motor, the acceleration has to be gradual, as full throttle from standing leads to toppling over (back flip) of the boat.

All in all, it is a lot of fun to drive, incomparable to the standard setup.

In addition, to make the handling and performance more stable and controllable I am now designing the remotely adjustable trim pads. I am not sure if I will be successful but I absolutely have to try that. It would be great to see how to actively balance the weight of the equipment in the boat, and/or to control the ride height of the nose.

As soon as I have some images, if you are interested, I will post them.

Best regards!

Srdjan

[chris PoultonParticipant @chrispoulton72699]

hi everyone, i have finally gotten round to actually trying the boat on the water. i took Ashley's advice and kept the brushed motor setup. the only change is that i used 3-cell lipos instead of nicads, simply becaus i have lots of them. performance was quite satisfactory. not mind-blowing fast of course but decent, proving Ashley right.

what i did discover though is that even in a tiny chop, the boat is all over the place, and since we do nothave any suitable ponds here, i am rstricted to salt water in bays or mrinas, so i need a bigger boat with more deadrise and more freeboard. i also like the idea of sticking strictly to scale boats and the nicest i have seen so far is an aeromarine (i think) apache, which looks almost identical to the old 'cigarette' offshore boats. anyone else have any other ideas, or a nice hull/deck for sale?

cheers

chris

[ashley needhamParticipant @ashleyneedham69188]

Chris, there are loads of "offshore" hulls out there, mainly for pukka racing, and loads of stuff to detail them with (pilots heads and such). Try looking on offshore racing sites or use "racing boat" (or similar) on internet searches..

Ashley

[ashley needhamParticipant @ashleyneedham69188]

good selection here…..**LINK**

[Srdjan BelgradeParticipant @srdjanbelgrade75162]

Hi Guys,

Yes, the finest chop on the water surface is the enemy especially when off and then back on the throttle during the sharp corners… I even managed some submarining

Anyway, the gearing I ordered online arrived and I wanted to show you the boat with Tamiya Silver Can coupled through 1:2 gear ratio setup (approx. 8.000 rpm on the prop without the load, in the water, I guess this drops quite a bit, since Silver Can is not a very capable marine motor):

I hope for more calm winter days, so I can show you the brushless madness

[ERIC PILAVIANParticipant @ericpilavian90207]

Hi Chris Poulton

I hope you will find my message…

I just found an old box with a Scimitar speed from graupner but there is no more instruction to build it : would you please scan it for me and send it to me ? Or anyone for sure.

Sorry for my bad english and thank you for you help, I would like to make a big surprise to my little boy but there, I'm lost

Tks

Eric

[Empire ParkstoneParticipant @empireparkstone]

Hi toplink on this page

**LINK**

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