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Old Oct 22, 2012, 10:26 PM
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I would look at the Graupner carbon filled props these are strong props that will hold up to your application .Anything from 29mm t0 42mm in 4 mm shaft size . Because I've never built a boat of this size I would be a bit Conservative . Try a 34mm or 36mm size prop . Run for one min come in and ck. the temps .if it's cool then you can go bigger .Best thing about these Graupner carbon filled props is they are relatively cheap and you don't have to sharpen and balance them . I'm sure you can find them some where near you , if not go to www.offshoreelectrics.com
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Old Oct 25, 2012, 01:05 PM
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not much to report, still in the sanding and waiting for stuff phase. current weight minus the motor, receiver and servo is 414g so it looks like i've blown my 500g target but seeing as i've no idea what constitutes a particularly lightweight boat i'm not that fussed!

hopefully I'll have a bit of time to glue it together this weekend
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Old Oct 27, 2012, 11:27 AM
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well this was always going to be a tight squeeze! there isn't going to be much room to play around with the CG once I start gluing motor mounts etc. what are people thoughts on the balance point for a small tunnel hull like this? I read something about 35% however is that from the front or the back? should i be aiming for bow heavy, stern heavy or somewhere in the middle? maybe its impossible to work out until the thing is in the water?!
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Old Oct 27, 2012, 11:43 AM
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30% measured from rear of transom , not the sponsons is a good starting point . The bottom of the strut about a quarter inch or an 1/8 inch up from bottom of the rear of sponson . Should be a good starting point . And have some fun .
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Old Oct 27, 2012, 08:18 PM
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If you mount the receiver up on a shelf at the transom I bet you could slip the battery under it and further rearward if you needed to.
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Old Oct 28, 2012, 06:12 AM
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thanks for all the information guys, i'm trying to take it all on board (excuse the pun )

Already having modified so many bits and trying to work out how to squeeze RC into a boat clearly not designed for it i'm thinking I should have gone the whole hog and designed the boat from scratch as well (which might have been even more nuts for a first time build!) or built from a plan (probably more sensible) ah well looking at the weather outside in England I have 6 more months of dark, cold and wet weather to design and build some more of these boats!

anyway back to the boat at hand I've glued all the main bits together now and made a crappy stand, i'll get some more pictures up later when the latest coat of varnish has dried.
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Old Oct 28, 2012, 11:08 AM
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sanding and more sanding. trying to get the bottom of the sponsons really flat and keep the edge sharp. i've also added another layer of balsa under the main hull to keep everything smooth. it'll be a shame to start drilling holes for all the hardware
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Old Oct 30, 2012, 07:44 PM
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still waiting for parts to turn up, slight tinge of regret when i noticed on the hobby king email it said allow 45 days for delivery hopefully it won't be that bad.

i'm painting now and with this colour scheme i really should run it on Lake Coniston, its not that far away and I'm thinking get there at dawn, freezing cold, glassy water, pay my respects to Donald Cambell. oh i'm getting all misty eyed now!!
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Old Oct 31, 2012, 06:54 PM
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still no sign of the motor, been amusing myself with silly paint schemes. are there any good guides online about how to fit a flexi-shaft? is there a trick to bending the brass tube in only one axis? i've not come across any info on this dark art?!
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Old Oct 31, 2012, 07:26 PM
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Tim,

If you simply “have at it” and make only one slight curve it will always be in a single axis. Barring that to anneal or soften the brass heat it up cherry red with a torch or gas stove… I added a video below. I have never found the need to anneal it and simply worked slowly but surely, in the sizes/diameters we are dealing with it’s pretty easy to do.


Annealing Brass (6 min 10 sec)
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Old Nov 01, 2012, 09:19 AM
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balsa

Your best bet is to get 3/16" brass tubing, get 2 pieces, one for spare. You can anneal with torch or bend by hand with CARE. Now use .130 cable and no liner for stuffing tube. When hand bending, wear gloves, to save your hands from injury. Take your time bending and check each time so you don't get kinks. When you get correct lenght and fit nicely into strut. cover join with heat shrink so no leaks occurr. Now if you want liner in stuffing tube, use 7/32 brass tubing and you'll have to sand liner alittle to make it fit but also makes a snug fit and won't move on brass. Now here's a tip given to me by Erney Lazenby of U.K.; sand flex cable except at the coupler and where cable goes into cable shaft. Reason is friction is cut down especially where liner is not used and less heat occurrs.
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Old Nov 03, 2012, 05:12 PM
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modifications to the original design continue, had to make something to put the rudder further back. i've also made a bit of mess of the rudder with the dremel trying to open up the water cooling slot, ah well. still no sign of the motor either
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Old Nov 04, 2012, 07:18 AM
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You can eliminate bracket you made for the rudder . All you need for this size boat is a L bracket and two bolts . Move the L bracket to the RH edge of the tub drill two holes ,On second thought it looks to be to much trouble with that bracket . But it,s just a thought .
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Old Nov 09, 2012, 07:02 PM
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got the motor at last so i've finalised the insides, made a battery holder, drilled and fitted the shaft, cut the flexi shaft, added some extra supports, drilled some pointless holes and covered everything in epoxy. everything is ready to screw in, just waiting on some XT60 connectors and its ready to float. its going to fun finding out what happens, i think the battery is a little on the large side!
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Old Nov 10, 2012, 06:59 AM
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looks like your about ready to have some FUN .Good luck with it . It's a good looking boat .
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