Miss Geico 17 brushless conversion / planer board / trim tab on rudder set up?
So I picked up a few MG17's for summer time pool racing, as well as brushless set-ups for each. I've been digging through the forums on here, as well as just about every YT video I could find on it. There is one video in particular, posted by Waggers79 a few years back, that shows very nice performance from this little hull. Here's the link:
I'd like to replicate that. He did it by counteracting the direct drive angle using a (planer board?) trim tab on or near the rudder. I'm looking for info available on parts to use, pics of what's entailed, and/or how to go about fabricating it.
Here's a quote taken from his video comments on what he did: "Next part is very important; the pitch of the drive shaft was designed to put the prop at a particular angle for the cat to plane out on the water with the stock motor. With the power increase the boat will nose dive and flip...The best solution I found was on another video on here....fit a trim tab to the bottom of the rudder (easier than it sounds) thus driving water pressure from the prop down onto it which will drive the nose up and allow her to plane out...."
Any personal experience you guys have with this would be very helpful, thanks! -Mark
PM member H&YRACING. He had one at a pool event in Indy this year and it ran great in smooth water. Perhaps he can send you some pictures of his. It was totally custom and rebuilt with scaled down hardware like you would use on a traditional FE cat hull. New stuffing tube with a bend, strut, offset rudder, and a brushless motor. There were no trim tabs on that boat and it certainly wasn't nose diving.
I would cut the straight shaft housing off the bottom of the hull, fill it in, and consider using this strut/rudder with an appropriately installed and curved stuffing tube: https://www.offshoreelectrics.com/pr...prod=ose-80972. That particular unit has a limited strut height adjustment and may or may not work with your hull. I put one on my 16" scratch-built cat (not yet completed) and had to modify the transom to get the prop in the right location. Another alternative would be to use the Octura strudder assembly. Here's a photo of the Octura unit on a 17" brushless cat I had a decade or so ago. It was an order of magnitude faster than the one in the video you provided, but due to other design factors, it didn't corner very well at the speeds it could obtain.
PM member H&YRACING. He had one at a pool event in Indy this year and it ran great in smooth water.
Thanks fweasel,
I was delighted by the performance of such a small hull. As you said its setup like a full size hull. Most of the hardware is hand made. Simple but strong.
Points of interest:
1. The Plastic strut was removed carefully using a sharp knife and gently persuading it out.
2. motor mounted further back to allow more room and better balance.
3. Servo mount is mounted in right sponson. This frees space and makes great alignment with rudder.
4. Inner plastic lip around lid opening is trimmed extra close to create room for sliding batteries and ESC in position.
5. All old mounting holes (10) were plugged with plastic white plugs and glued in place. This included moving the water cooling exit to port side.
6. The entire drive line is the same as a larger one. Brass stuffing tube, .096 flex cable & drive dog.
7. Rudder is stainless steel with water pick up attached to back. Homemade steering arm from aluminum.
8. Bottom sanded flat (blueprinted). The bottom picture showing the white areas where the green was sanded.
If I was better I'd attach the the video of it running in the pool this past January. It's over powered with a 3600 kv motor and 3S battery. On its first run I was surprised how stable it was in the turns. I'm not sure how fast it is, but I wouldn't shy away from any challenge. Looking forward for someone to run it in our "mini" class this year.
Miss Geico 17 brushless conversion / planer board / trim tab on rudder set up?
Lots of great info, thanks guys, much appreciated.
I’m pretty limited on what I can tackle right now due to being overseas for work and not having access to certain tools and parts.
I’m trying to focus for starters on improvements I can make to get these boats decently operational on 2 or 3s here at the pool without getting in over my head on modifications.
If I can get the right parts though, I guess I might take a stab at the driveline.
With regards to the flex cable, are they available in a pre cut size that works well for this hull or do they have to be custom fitted?
With regards to the flex cable, are they available in a pre cut size that works well for this hull or do they have to be custom fitted?
Unfortunately there are not and yes the brass stuffing tube and shaft have to be custom fitted. I'd say converting the drive line over would have the single biggest impact.
Miss Geico 17 brushless conversion / planer board / trim tab on rudder set up?
Originally Posted by H&YRACING
Unfortunately there are not and yes the brass stuffing tube and shaft have to be custom fitted. I'd say converting the drive line over would have the single biggest impact.
Rgr, thanks. I will see what I can do with the stock driveline and new electronics, and go from there. Maybe in the interim I can figure out Waggers79’s rudder/trim tab mod, use that while abroad, and then make the switch to a flex cable when back home.
The aluminum parts on the boat as seen in the pictures are very nice. If you don’t have those skills a GP1 strut and rudder system would get you very close, but those will be plastic....... you could even use the wire drive from the GP1 too and the collet. Again it won’t be to the same standard, but it will be a major improvement over the stock boat. That brushed system is a bit of a turd.
Sorry to interject Mike. I know that thing is a rocket, just a few ideas, if tools are limited.
The aluminum parts on the boat as seen in the pictures are very nice. If you don’t have those skills a GP1 strut and rudder system would get you very close, but those will be plastic....... you could even use the wire drive from the GP1 too and the collet. Again it won’t be to the same standard, but it will be a major improvement over the stock boat. That brushed system is a bit of a turd.
Sorry to interject Mike. I know that thing is a rocket, just a few ideas, if tools are limited.
Thanks for the idea. That seems promising. I'm gonna order one set of the GP-1 drive line components for starters and see how it goes. I messaged AQ CS to get the specs on the wire drive and stuffing tube. Waiting to see how intact Hobbico CS is these days with all that is going on.
I also ordered some small stainless trim tabs to attempt the YT Waggers79 rudder/board mod. We'll see how that goes. Mail takes roughly a month to get here, so this might take awhile.
Sounds like the tab on the rudder is more like a hydrofoil
Yep, pretty much
Quick update: The first boat just arrived in the mail yesterday along with a bunch of upgrades. I got a box from OSE today with all the Leopard motors and cooling jackets. On top of that, I just found the YT video that was referenced in the initial quote, about attaching a trim tab to the rudder. It looks pretty straightforward. Will post up pics and the specs on the upgrades as progress is made. Still waiting on new couplers, batteries, and some other goodies which is gonna take a few more weeks.
Hi there, I would like to duplicate this setup. Could you please tell me how high(low?) you have the center of the propellor from the hull? Also, what diameter and pitch prop are you using. I am going to use a 2800 kv 4 pole inrunner(2850) and experiment with 2 and 3s batteries. Also, when you sanded the hull did you just try to make the bottom flat or was it a little nose high? I am newish to boats. I plan on using the blackjack 24 propshaft setup.
It's taken awhile...like a year but I finally got back to this and got it finished! Decided to scrap the trim tab plan and go for the flex shaft conversion. Many thanks to Dr. Jet, H&YRacing, and Trigger, for their input. All were beneficial in helping me decide how to move forward on this.
Getting the stock strut out took some effort. When holding the hull at a certain angle in the light, you can tell where the strut was fused into the bottom of the hull. Next step was to use a blade and trace the outline of that fusion as best as possible, and then to deepen the cuts to where the strut could be coaxed out. I debated using a Dremel cutting wheel but in the end decided on my trusty Emerson instead which I felt like would be more time consuming but offer a greater amount of control. Took about thirty minutes to get the stock strut out and another 30 minutes to clean up the edges and sand off the rough spots.
Next step was to start prepping for paint. I ended up using both the Dremel and pieces of a disposable nail file for that. There will be no confusing which MG17 is mine at the pool!
My priorities of work were to paint, then do the AQ strut install. I was limited on colors, but ended up going with a metallic orange Tamiya paint followed by a semi gloss clear coat, also from Tamiya. Pretty happy with the color contrasts between the orange and Geico green!
Next up was getting the stuffing tube bent, cut to size, and epoxied into place. To get the angle right, I mounted the motor and then kept testing and making small adjustments to the bends until everything lined up cleanly. This being the first time i've done this, i'm kinda cautiously optimistic that the bends are appropriate. I tried to make them as minimal as possible. I used the Dremel sanding tool to fine tune the fit of the strut components. For the strut guide tube piece, I used the Dremel as a drill press to open up the bore a bit to fit the stuffing tube. It worked, but heated the plastic up pretty quick. I didn't have a drill bit that was an exact match to the stuffing tube, but had one that was close. Kept at it until the stuffing tube fit snugly into place.
At this point I was still waiting on the coupler and CNC prop to arrive, but with everything looking good I started the reassembly. The Dremel got a lot more use along the way. I had to grind out sections of the tray inside the hull to properly allow the motor cooling jacket to fit as well as the battery. I just took my time with it, as I really didn't want to end up damage or crack the actual hull floor plate area or walls.
Last but not least, I installed the coupler and cut and soldered the flex cable. Getting the teflon tube over that little rigid section in front of the drive dog was kind of a bitch. I used a screwdriver with a slightly larger diameter that the inside of the teflon tube to stretch the tube a bit and had better success. I ended up using the Dremel to trim down the stuffing tube inside the hull, as well as to clean up the rear edge of the strut, gaining just a couple more mm for that perfectly fitted cable. To be fair, until this little ripper sees the pool for the first time I won't know if the fitment and tuning is on point. Hoping for the best! ...with any luck i'll be in the 30-40 mph range. All in all this was a super fun, first time boat build project. There were some small obstacles along the way but things just really worked themselves out. At least so far! Thanks again for your guys help and advice. Final build pics below, ...minus the Rx. That is due to reasons outside my control. When I get back to California in October, i'll drop that in, head to the water, and get on the throttle!
That strut looks very low with the bracket on the bottom like that, you might want to put the bracket on the back like H&YRACING's so you can get it up higher.
If you moved the rudder over to the right, you could have a straight pushrod which would be much stiffer than the curved one you have in it now.
That strut looks very low with the bracket on the bottom like that, you might want to put the bracket on the back like H&YRACING's so you can get it up higher.
If you moved the rudder over to the right, you could have a straight pushrod which would be much stiffer than the curved one you have in it now.
Yes I may adjust the guide piece in the strut. With minimal work, I should be able to raise or lower it in the upper strut mount about a quarter inch either up or down. It also may partially be the angle of the photos which make it look lower. I tried to get the stuffing tube pretty much level with the bottom of the hull after comparing it to the mfr website pictures.
Miss Geico 17 brushless conversion / planer board / trim tab on rudder set up?
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Originally Posted by Davey80
Thanks for the idea. That seems promising. I'm gonna order one set of the GP-1 drive line components for starters and see how it goes. I messaged AQ CS to get the specs on the wire drive and stuffing tube. Waiting to see how intact Hobbico CS is these days with all that is going on.
but I finally got back to this and got it finished! Decided to scrap the trim tab plan and go for the flex shaft conversion. Many thanks to Dr. Jet, H&YRacing, and Trigger, for their input. All were beneficial in helping me decide how to move forward on this.
I used a screwdriver with a slightly larger diameter that the inside of the teflon tube to stretch the tube a bit and had better success. I ended up using the Dremel to trim down the stuffing tube inside the hull, as well as to clean up the rear edge of the strut, gaining just a couple more mm for that perfectly fitted cable. To be fair, until this little ripper sees the pool for the first time I won't know if the fitment and tuning is on point. Hoping for the best! ...with any luck i'll be in the 30-40 mph range. All in all this was a super fun, first time boat build project. There were some small obstacles along the way but things just really worked themselves out. At least so far! 
Thanks again for your guys help and advice. Final build pics below, ...minus the Rx. That is due to reasons outside my control. When I get back to California in October, i'll drop that in, head to the water, and get on the throttle! 
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