Joysway Razor 37 inch bare hull mono assembly

[sciesielka]

Prop testing done - Ready to play!

I completed prop testing and have ordered an Octura x447, sharpened and balanced already since I've never done that myself. This boat with this setup runs right around 40mph (64kph). I think it's running a little wet, but I didn't change anything as I wanted to get all of my data and speeds with the same setup. Besides, assuming I can dial it in better, the numbers and temps should look better too!
Now that I have access to a lake where I can run full speed for more than a few seconds, this should be a lot more fun. Plus, the lake gets bigger waves when it gets windy (no motor boats allowed on this lake) so I can play with stinger and trim tab setups to optimize what I have.

Here are all of the detailed prop testing results from multiple days starting in mid-March 2021 through early-April 2021, minus temperatures:
I_Razor Sea Trials prop tests all combined.jpg

I'll post additional videos this month!

And while this boat's not a real fast FE, for the places I can run it and since I'm not racing it, this will be perfect ... until, or if, I feel the need for more speed and then it should be a pretty simple platform to upgrade!

[sciesielka]

Help needed, is it running wet?

I spent a lot of time testing to get the right prop for the Invincible Razor custom build and now that I'm running it for fun, I'm noticing more that it probably needs further setup work.

Here is the video over 2 days running it with the same setup, just different water conditions. I have not adjusted the stinger yet and I can shift the batteries back to get the CoG to about 26% compared to the 28% it's running at during these clips. Should I add positive angle to the stinger to get the bow higher? Or is this running well enough for just playing around at the lake and not racing?

As mentioned in the earlier posts, it's two 3-cell LiPos for 6S total, a Leopard 4082 1250kv motor, 150A ESC and a sharpened and balanced Octura x447 prop.
Motor and ESC temps stay under 90F and the batteries were just over 100F both days.

Thanks in advance for any advice! I added a link to the video but also embedded it here, so one should work.

[Panchothedog]

From watching your latest video it does look a little bit wet for smooth water situations. Three things will loosen it up and potentially allow it to run faster. Put the batteries farther back, raise the stinger angel, OR raise the angle of the cavation plates. From photo # 4 in post # 6 I really can't see them that well but from what I can see they look like they could be low.
They should not be flush with the bottom of the hull, but be about 1/16"
above the bottom. If not they can cause a lot of drag, but with trail and
error adjusting they can control the ride attitude of the hull as much as
either of the other two methods. It also looks like you run in some pretty choppy waters, and for that you are probably right where you want to be.
Loose trimmed out fast settings are for smooth water and no or very light wind. Run that way in rough water or windy conditions and you will be
up side down fast and often. NO FUN.

[Peter A]

Definitely drag issues at the transom. As Pancho said raise the height of the trim tabs 1-2mm, and get rid of that extra water pickup. That alone will cause the boat to run wet. The single pickup from the rudder is sufficient cooling. Run through the esc first, through the motor and out. You will then find your cog at 28% to be loose, and will want to be able to adjust it to up to 35% for rough water running. The boat is light in the nose which can be seen when it bounces off small waves, it is just the tabs and pick up drag making it run wet.

[sciesielka]

Definitely drag issues at the transom. As Pancho said raise the height of the trim tabs 1-2mm, and get rid of that extra water pickup.

I originally had the trim tabs set approximately 1 to 1.5mm up from the bottom of the hull and parallel, so zero degrees angle. Based on your guys' recommendations, I made some changes. First, I was going to just remove the trim tabs but chickened out. Instead, I slotted the holes in the trim tab plates so I could really get them raised. For the one run I got in this weekend, I had them parallel to the bottom but they are 3 to 4mm up from the bottom (I assume that's a pretty good indication I may not even need them, correct?). I also raised the extra water pickup (haven't removed it ... yet). I kept the stinger at zero degrees angle and the same height from the last run and kept the CoG at about 28% again. One change at a time right!

With the trim tab change and the water pickup adjustment, it ran drier and overall handled better. I was also happily surprised to see that I gained 4mph [6.5kph]

When I get more time, I will also play with the battery placement and stinger angle to see what else this boat has in it!

Thank you for the advice!

[sciesielka]

Seeking additional setup opinions

I think my CoG needs to be moved and I'm hoping for some advice. I have been running my Joysway Invincible Razor quite a bit this summer so far and need some advice. I have seen my boat go airborne a few too many times, even when it's not that windy. With my batteries full forward in the battery trays, my CoG is 28/29%. I'm thinking I need to make new battery trays to get the CoG further forward, maybe 32% (which on this hull is moving the CoG an inch closer to the bow).
My question is, to get the best overall performance from the boat, a fun/sport boat, not a racer, should I move the CoG or angle the trim tabs more and/or angle the stinger down?
My thought all along was that I would only angle the stinger and/or trim tabs down when the water gets rough. To keep the thing from going airborne, I move the CoG. Is that correct?
Thank you in advance for the help!

[boatsrnew2me]

boat is running well in the video i watched (first one) you should be able to get higher top speeds though .1250 kv is not alot .your going to need a big prop . i spin a x447 or a cnc x448 on my pursuit with a 1600kv motor on 6s and i get speeds just above 60mph .comes in with motor under 120 degrees ,esc too
nice build .i dont boat much anymore but i enjoyed your video .carry on

ps- yes your boat is running too wet .you need to get the hull up out the water more .try raising the stinger more .