Rudder Water Pickup - How to get more water flow?

[LuckY07]

I have a stock PB Voracity 36 and I keep reading about people who've "drilled out the cooling pick-up on the rear rudder."

I came across this post on a blackjack 24 thread, but it wasn't clear to me what exactly they are modding on the rudder.

Is this mod to enlarge the existing hole on the rudder?
Or are you supposed to drill a hole through the rudder so that water enters from both sides?

Attached is the pic I'm referring to.

[LuckY07]

Another post says to file one side of the rudder (leading edge) on an angle until you hit the water pickup. I'm wondering if this would help
on my voracity. I ordered a new Kinetic rudder for it and haven't installed it yet, I would imagine I can file that down like this describes?

File the starboard side of the rudder blade until the water PU oval meets the leading edge of the blade.

Your not really making the rudder overall thinner, you are just removing material at an angle.

do you understand?

The oval becomes elongated.

Grim

[runzwithsizorz]

As an experiment I used a drumel to drill a hole on the opposite side, and slightly higher than the original, (careful not to drill all the way through). I then used a grinding wheel to shape the slit, and
reamed the exit of the rudder slightly. *In theory* this would increase volume, and/or velocity, perhaps maintain flow when turning. This was a long time ago, and at that time I had no way of checking temps.
Since then I have used dual pickups, and on one boat FOUR.

[LuckY07]

As an experiment I used a drumel to drill a hole on the opposite side, and slightly higher than the original, (careful not to drill all the way through). I then used a grinding wheel to shape the slit, and
reamed the exit of the rudder slightly. *In theory* this would increase volume, and/or velocity, perhaps maintain flow when turning. This was a long time ago, and at that time I had no way of checking temps.
Since then I have used dual pickups, and on one boat FOUR.

Thanks for the reply, but what about just filing one side of the rudder like grim says?

Is that still an acceptable method of getting more water flow through the rudder intake? (by making the hole bigger/oval)

[runzwithsizorz]

Thanks for the reply, but what about just filing one side of the rudder like grim says?

Is that still an acceptable method of getting more water flow through the rudder intake? (by making the hole bigger/oval)

Can you link to the article?

[martin]

Make the oval larger & also file the oval channel closer to the leading edge of the rudder. Using larger 4mm bore silicon water tubes in the boat also helps, make sure the larger bore silicon tube is a good fit on the various brass nipples or put a zip tie on each nipple to make sure the tubes don't blow off with water pressure.

[LuckY07]

Can you link to the article?

I found Grim's post here >

http://forums.offshoreelectrics.com/...-on-the-Rudder

[LuckY07]

Make the oval larger & also file the oval channel closer to the leading edge of the rudder. Using larger 4mm bore silicon water tubes in the boat also helps, make sure the larger bore silicon tube is a good fit on the various brass nipples or put a zip tie on each nipple to make sure the tubes don't blow off with water pressure.

I thought by filing the rudder leading edge (which naturally makes the hole oval) would increase the hole size enough.

Do you recommend to also make the hole size bigger using a file?

I still haven't bought a set of files.. can I just buy any old flat file from home depot to use for this and S&B a prop?

Thanks.

[Mxkid261]

That inlet almost looks drilled out a little already. Not familiar with the voracity rudder but it looks like it has a pretty large opening already

[runzwithsizorz]

Yo OP, without the proper tools I would advise you do nothing, (sorry), well maybe adding a second water pickup, which does not require a lot of knowledge, or tools. What makes you think
you NEED to do this? How are you currently measuring temps? What is getting hot, ESC, motor, both? BTW, the water should enter the bottom of the motor jacket not the top.

[LuckY07]

Yo OP, without the proper tools I would advise you do nothing, (sorry), well maybe adding a second water pickup, which does not require a lot of knowledge, or tools. What makes you think
you NEED to do this? How are you currently measuring temps? What is getting hot, ESC, motor, both? BTW, the water should enter the bottom of the motor jacket not the top.

I like to modify things, so this is just for fun. I also want to learn what mods others are doing as I have read to enlarge the pickup
hole in several threads as a good mod to get a little more cooling.

After taking my Voracity out on it's maiden a few days ago on 6s Dynamite LiPos I brought it in and used my $20 Duratrax flashpoint to measure the motor/esc/batteries.
I was running it 50% throttle for about 10-13 minutes and my temps were:
~ 110F on the ESC
~ 105F on the motor
~ 95F on the battery

I assume I want my temps to just be under ~ 150F?

As for tools, I was planning on buying them. I wanted to know if I needed a special file grit or if the standard stuff they have at the
big box stores is fine. I bought an Octura m645 (close to stock Voracity) prop and will need to sharpen it as I also bought a GrimRacer
precision prop balancer.

[Fluid]

A separate water pickup for both ESC and motor is usually a waste of time. Run a single pickup to the ESC first, the water removes only a small amount of heat from it, then route to the moror and out. Most here just have no real understanding of the thermodynamics of water....

Sure you can use two if you're a gluton for punishment, but my carefully controlled testing shows no repeatable advantage. You need "adequate" flow, but how much that is deeps ends on your cooling system. Most folks could not perform a scientific test if their life depended on it.

.

[fweasel]

specific heat baby...

[martin]

Running an esc at partial throttle is hard on the esc, run more full throttle but for less time than 10-13 minutes.

[LuckY07]

Running an esc at partial throttle is hard on the esc, run more full throttle but for less time than 10-13 minutes.

How do my temps look? What am I trying to stay under tempwise?

I thought with full throttle I should only run a couple passes and then go back to less throttle to let the motor/esc cool?

Do you suggest I run for like 7-9 minutes and do several 75%+ passes mixed with half throttle?

I'm new to this hobby so excuse the stupid questions :)