TFL Small Bolt Hydro

[Richard_K]

I am new to RC Boats and am considering purchasing a TFL Smal Bolt Hydro. The recommended battery is 2200 mah. I am wondering what C rating it needs to be. The recommendation is 2S or 3S.

Also can anyone give an approximate run time to expect say from a 2S 2200 battery.

Thanks

Richard

[eric_laermans]

It all depends... for a large part on the prop you use, but also on further finetuning measures you take. I think average continuous currents will stay underneath 20A and peaks will also be limited.

C-rating: 20C is okay, 30C might last a little longer. Never deeply discharge (keep 30% reserve), never store fully charged.

[Dashunde]

Mine just arrived Friday and I am beginning to mess with it.. very nicely made little boat indeed.

Run time? Will totally depend on your throttle finger, the prop you install, and how much native drag is in the over-size cable drive line.
I'll be looking at a wire drive set-up for this awesome little boat if I can get it to run really well otherwise.

You may want to go with 3s 2200 (fits no problem) and a Octura 432 prop.

Keep in mind, plowing through the water slowly with a hydro (or any boat) will not really yield longer run times.
Get it up on plane where it is much more efficient, and keep it there. You'll also get better water flow through the esc/motor, which in turn will run a little cooler.

[eric_laermans]

For this boat the 1.5mm wire-drive I normally use, would be perfect (http://www.drpsychoteam.de/). I can assure you, I built the aforementioned wiredrive in many mini-hydros and they have accepted a lot of abuse over the years never letting me down. Reason: it is made with small tolerances (i.e. high precision).

PS I have no financial interest, but have been in the position of seeking a good wiredrive myself on the internet and it is very hard to find. What I like about drpsychoteam also is that they deliver it as a complete 'package' including a coupler between 1.5mm wire and (any size) motor-axle.

[Dr. Jet]

I ordered the Small Bolt because it looked like a well-designed product made from quality materials. As a highly experienced Fast Electric model boater, I did not view this boat as “Ready to Run”, but rather as a complete “kit” that would need some refinements, modifications, and “dialing in” before putting it on the water. Upon opening the box, I was pleased to see that my expectations of quality were substantiated. This is a VERY NICE product.

Before putting it in the water, the first thing I did was add a carbon fiber doubler to the inside back of the right sponson. Hydroplanes, by their very nature are designed to turn in only one direction, so I plan to install a turn fin on the right sponson to allow it to corner at full speed in a right turn. Next, I installed some foam floatation pieces in the sponsons and along the non-trips in the hull sides. It’s like a life vest for your boat. If you hit something and knock a hole in the hull, the foam will prevent it from sinking. Don’t ask me how I know this!

The next step was to pull out the flex shaft. I removed the strut and discovered some REALLY THICK grease on the stub shaft that was ostensibly there to keep water out of the drive shaft. While this works, the thick grease is a lot of drag on the rotating parts. I cleaned the heavy grease off and replaced it with a thin layer of some light marine grease. I pulled out the flex drive shaft and put a bit of silver solder on the motor end of the shaft to keep it from unraveling. I lubricated the flex shaft and re-installed it. Next, I put some electrical shrink tube on the brass flex shaft housing tube and over the nose of the strut. This helps reduce the possibility of water getting into the hull through the driveshaft without the additional drag of the heavy grease. I adjusted the angle and height of the strut so that the bottom of the strut was even with the bottom of the sponsons, and such that the strut was about 2 degrees down. Actual water testing may require the strut depth and angle being tweaked for maximum performance. The videos I’ve seen of this boat running seem to have the stern too low in the water. I may need to mill the slot in the strut a bit to get the prop a little deeper.

I’ve seen a lot of complaints about the servo, so I carefully checked the rudder linkage for signs of interference with the transom or the water-tight boot.

Finally, I installed a balanced, sharpened, polished, and de-tongued Oxtura X632 prop. This may be a bit too much prop for this motor/hull/3S lipo combination I plan to run, so I will have to keep a close eye on motor temperatures for the first few runs. If things are too hot, or I feel I’m not getting full RPM out of the motor, I have a raw X632 that I may cut town to 30mm when I prep it.

My only complaint: The bottoms of the sponsons are not flat, they do not have sharp edges, and there is no deadrise. While the boat will run just fine as-is, properly detailed ride surfaces will loosen the boat up a whole lot which will give a big improvement in speed. While I would normally use epoxy and micro balloons to re-shape the ride surfaces, I have some 1/2mm carbon fiber sheet that I will use to create glue-on ride plates. That will ensure a flat ride surface and make it easy to put in about 4 degrees of deadrise.

All in all, this is a good boat for the casual hobbyist and a great modification platform for the serious enthusiast.

[Dr. Jet]

I had some issues on the first few runs of this boat, and I initially blamed it on the "big" prop. I went down on prop sizes to no avail. I finally realized that (Number One) the throttle control was reversed and I was running on the reduced "reverse" throttle setting. The second (Number Two) problem I discovered was the "hooked" turnfin I was using was causing the boat to roll in a most unusual manner (see: https://www.ebay.com/itm/TFL-Aluminu...EAAOSwZVlXmrZN). The small hook on the bottom of the fin would either flip the boat to the left or dig the right sponson in if it wasn't PERFECTLY aligned. I opted to make a new fin with no "hook". That should solve that issue.

Regarding not getting full power in "forward": When setting up the boat on the bench, I selected the setting that gave "forward" rotation of the prop when I pulled back on the trigger. WRONG!! I was getting the proper rotation, but I was in the reduced power "reverse" mode. I swapped two of the motor wires to the ESC and reversed the "servo reversing" setting on my transmitter. That fixed the issue, but by that time I had installed a cut-down X427 on the boat, so as it pretty quick by then, it was nowhere near it's full potential. By then, I was out of batteries, so further testing will have to wait until the next outing.

Stay tuned for further impressions and modifications.


UPDATE: The new turnfin did not solve the flipping problem. Run this little guy with no turnfin and call it good!