Yes, from a handling point of view pretty sure that hawing the propeller under the hull is good. All the hull behind the propeller acts like a trim plane stabilizing the trim of the hull. Probably number one priority.
There are some drawbacks also i guess. Efficiency of propellers are usually said to be better when located more at the stern or even behind. It can also be located higher than under the bottom, that again reduce the tendency of lifting the bow. The vertical up and down movement is often the smallest just by the transom, that’s good for the propeller. But over all, for this application, hawing it under the hull is probably a very good compromise, also from a safety point of view best place.
Anyway the whole idea of the tow boat is great, soon we will see someone water skiing behind:)
So cool Valhalla!
Are you still using the same (2) 6s 2200ah lipo batteries in a plastic bag? Are you switching from a potted motor to a mast clamp setup or is that just a prototype?
Thanks for helping beginners!
So I ditched the whole heavy duty plastic bag idea. Was not heavy duty at all. I feel very confident with the batteries in the apache case. So the motor is still the 65161 120Kv from Flipsky. It is on a printed mast clamp attached to a chopped Axis Mast. I had an extra Axis mast due to a seized bolt.
So I finally got some time to data log. The equipment used is as follows: Axis 1010 Front Wing, 75 cm 19mm Mast, 340 Rear Wing, Ultra Short Fuse. Today was mainly to get data for the Flying Rodeo Prop and another Prop I made. Unfortunately I wasn’t able to use the prop I made bc I screwed up the diameter for the shaft. I’ll have to drill it out a bit and rebalance.
I omitted the Temperatures bc I don’t really think most of you found that parameter useful. Also I’m not too confident on the accuracy of the velocity readings but it can’t be too far off.
Also a video of the v2 running as requested. Still some speed left as the large front wing is still holding me back a bit.
Also a demonstration of waterstarting the tow boogie.
1, Start on the belly
2, Give some decent speed
3, Be sure throttle finger is steady, and place back foot on rear pad
4, Push Front foot in between hands
5, Stay low and slowly increase throttle to build speed
6, You should feel more steady and now you can finally apply rear foot pressure
Big tip is on the belly stage be easy on the trigger and build to a steady speed neither accelerating or decelerating as this reduces jerking of the handle.
A file to my mast Clamp for the Axis 19mm Mast. I have another Nose Cone but want to see if it makes a difference with efficiency. Parts needed are listed. For the Hub only print if your Prop hub is less than 54mm. I have a 2mm gap between front and back but I’m sure if you really wanted too you can fill it in. I myself don’t see any negatives having it.
Thanks so much! I was hoping you would share the file. Just happen to have my Axis beginners mast I do’t use anymore. Your videos are great. Towing into swells on a tiny summer day is a dream you have inspired me to achieve.
Do you have a recommendation for a battery charger? Thanks for the link to the batteries. Been trying to find them for a while. Was about to order from Alibaba but Amazon will be faster.
I like your reports of efficiency cruising at only 25 Amps with the rodeo prop. I’m keen to build a boogie, but I’m concerned about the safety of the open propellor. Have anyone tried a duct / kort nozzle on the ocean rodeo prop, and tested the efficiency change? It seems the kort/rice nozzles can be efficient up to about 10 knots, which seems plenty of speed for a tow boogie.
Haven’t tried a nozzle or duct yet. I would like to. Maybe that’ll be the answer to the torque roll. Also I added a charger to the list.
So today I tested the Manta Foils Efoil Prop. It looks to have more pitch compared to the FR 6" and definitely more surface area. The material is super interesting. It feels like a super rigid metal and has a slight ping when you tap a screwdriver against it. The hub diameter is 40 mm vs 53.6mm for the FR 6". With my current spacer between motor and prop I definitely lost some efficiency so keep that in mind.
So I really like its performance for the Tow Boogie. It has far less slip than the FR probably due to the increased surface area. There is quite a bit more turbulence coming from the prop than the FR. Not a bad thing but its something to note on the Boogie. There is quite a bit of speed this thing is capable of but I’m limited by the space provided and my nerves.
Most of my posts about props have been about efficiency but after enjoying the tow boogie for so long I’ve come to realize it isn’t always about how many watts I use. This prop is real fun in flat water because of that “grip” it has on the water. Next test would be in rougher water with the boogie bouncing around.
I’ve also redesigned the motor mount to better handle the harsh conditions in open water conditions. Apparently the Boogie dropping 3-4 feet straight down from a set can cause cracks to from in the mount. So what I did this time was cut a piece of the trailing edge off to offer more area for the rear of the mount to rest on. I also filled it a bit with silicone to offer a bit of dampening. I’ve also reduced the size to hopefully make it more aerodynamic and use less material for printing. Also where can I save .step files? I think that makes it easier for people to edit and cut out their own profiles or should I stick with .stl files?
No modifications. But the spacer between motor and prop will have to be modified for the smaller diameter hub. I wouldn’t say I prefer it yet as I treat changing props like changing wings on a foil. It’s great fun and has good speed but a noticeable decrease in run time. With towing that isn’t really an issue since you wait in between sets anyway. I’ll report back once I’ve had more time with it.
I’d be keen for a powerful foiling rodeo fin for towing, can I test one?
Valhalla, regarding the vesc graphs for the FR prop with 20 motor amps vs the Manta prop at 35 motor amps - was the speed a lot higher with the Manta, shown in VESC as manta 45km/hr vs FR 30km/hr? I wonder how the Manta would go for current usage when going slower.
Yeah don’t focus on the speed too much. For some reason the speeds are not accurate at all. I should start using my watch for those measurements. So what I do is try to get to the lowest stall speed of the wing and hover as much as I can without stalling.
All testing is done with a 40L FFB 4’5” board, Axis 70cm 19mm mast, 1010 front wing, 340 tail, ultrashort fuse.
I admit it’s not the most ideal way of testing but it’s just glimpse I feel of what each prop does well.
Also tried out the Manta prop in surf for the first time today. It did phenomenal. Great grip even in white water, good pull to get me out of wired sections, and I felt it breached less often than the FR. I think the last comment can be omitted bc I haven’t the slightest why it would be that way. The only downside is that large efficiency gap compared to the FR. I was also using my Armstrong 1250 wing with 232 tail today. Got a quick session before work so I was heavier on the trigger but did notice more prominent voltage sag when I glanced down at the trigger. Overall great session. I would really like better efficiency but it is the Trade off for certain performance increases.
