AQUASUB

Oh by the way I have had no fuse blow outs,with the other subs mentioned it might be that water has intruded into the motor and has caused it to sieze up ,check them regularly as this sub has a not very good main shaft seal ,that was one of my first mods as metioned in other posts.


Dave

Skip Asay

"Well Skip without actualy owneing one of these great subs you are as usual venturing."

It's not necessary to own one of these boats to understand how an electric motor works.

"No Skip again you don;t see the point ,its not a mater of haveing to cool the thing its just a beter way or a good insurance to do so,keep the little bugger happy and cool,it keeps the air inside of the casing cool so that it won't expand ,it also increases the efeciency of the motor quite a bit as I myself found out in several experiments."

All unnecessary as long as you're using the right motor/reduction/prop combination. My Type 56" XXIII, which is now 30 years old,has had the same motor for all but the past 2 months and the original motor is still going strong. BTW, I bought that motor used. The only thing I've ever had to do is put a drop of oil on the bushings every couple of years. And it's NEVER gotten hot or even warm for that matter. I'll disagree with your claim of increased efficiency with water cooling unless you're getting the motor so hot it will boil water.

The reason I've replaced the motor is to prove that a little 385 size motor WILL drive the 2 3/4", steeply pitched 3 blade prop very well. And it only draws ONE AMP at full speed.

"My motors are are just as common as yours ,simple can 12 volt units ,but I gear them down to as you even said with yours ,to 3.5 or 2.5 to one depending on the prop and how fast I want her go."

Now this opens a can of worms (pun intended). I've seen the master Mabuchi catalog and let me tell you, there are literally HUNDREDS of 375/380/385/400 size motors. The number "3" tells the diameter of the can while the 75/80/85 number tells the length. But the windings inside are all over the place. To cut to the chase, I've seen 380 size motors which draw only 50 milliamps and turn less than 5000 RPM (unloaded,@12 volts) all the way up to a 35,000 RPM screamer that draws 3 1/2 amps UNLOADED and this was only at 7.2 volts. So to say that you're using a "can" motor tells me nothing.

"yet most of the surface high speed boats have it standard every time"

Let's stick to the application at hand. We're talking subs here, not high speed boats.

"So please think about it its prity much so a no brainer the wy that I have cooled my motors is super inexpensive,simple to make and lasts a long time."

I'll stand by my original statement - "If water cooling a sub's motor is necessary, you're doing something wrong."

"Also remember that why would marine engineers and manufacturers of boat engines go threw all that expense just to keep the engine cool why? Its makes them last longer by far."

Again, I'll say "Let's stick to the application at hand." We're talking about electric motors not internal combustion engines.

"Of course you may build a sub without cooling there is nothing wrong with that but just remember that alot of the batery power yor toting around is going to be lost in heat build up caused by a motor that is warm or getting hot,the hotter it gets the worse the loss of effeciency ,look it up its all there."

For the most part, the heat generated by an electric motor is caused by the amperage going through it. Keep the amperage down and guess what? You don't have to cool it.

Skip Asay

AQUASUB

Skip I am glad that you agree with me ,like i said you don't have to water cool  any thing its just good insurance.

It is always good to compare what has been an acsepted practice in the real world be it combustion engines or Nueclear Powered Subs so that the end product is of high quality and will last ,they do so do I.That is very relavent to the discution.

What Skip is advocating is an old school method that hay if it works it should not be improved.What he fails to see is the facts ,not created by me but simple laws of fysicks,no mater how small or large the motor is it is going to produce heat and in an inclosed space it will get worse.My system simply removes or transfers that heat to surrounding water.

I use standard 12 volt air cooled 12,500 rpm no load motors geared down 3.5 to 1 ,plenty of reserve power .

Dave SB-2.0  

Skip Asay

"like i said you don't have to water cool any thing its just good insurance."

That's a little different from what you've been saying, isn't it?

"It is always good to compare what has been an acsepted practice in the real world be it combustion engines or Nueclear Powered Subs so that the end product is of high quality and will last ,they do so do I.That is very relavent to the discution."

Let's stick to the subject, shall we? Internal combustion engines need water cooling.....electric motors don't unless they're forced to carry too much load. And that's just what I'm saying. If you feel the need for water cooling, then you're working the motor too hard. Heat is generated by the amount of current flowing through a motor. The higher the current, the higher the heat. So water cooling can help cure the symptom but not the problem. There's also the fact that a lot of current going through the motor is that much less left in the battery which means that much less time in the water. See what I mean? Cure the problem not the symptom.

"What Skip is advocating is an old school method that hay if it works it should not be improved.What he fails to see is the facts ,not created by me but simple laws of fysicks,no mater how small or large the motor is it is going to produce heat and in an inclosed space it will get worse.My system simply removes or transfers that heat to surrounding water."

Do your homework, match the motor/prop/reduction and no water cooling is necessary. Period.

Skip Asay

AQUASUB

Let's stick to the subject, shall we? Internal combustion engines need water cooling.....electric motors don't unless they're forced to carry too much load. And that's just what I'm saying. If you feel the need for water cooling, then you're working the motor too hard. Heat is generated by the amount of current flowing through a motor. The higher the current, the higher the heat. So water cooling can help cure the symptom but not the problem. There's also the fact that a lot of current going through the motor is that much less left in the battery which means that much less time in the water. See what I mean? Cure the problem not the symptom.

"What Skip is advocating is an old school method that hay if it works it should not be improved.What he fails to see is the facts ,not created by me but simple laws of fysicks,no mater how small or large the motor is it is going to produce heat and in an inclosed space it will get worse.My system simply removes or transfers that heat to surrounding water."

Do your homework, match the motor/prop/reduction and no water cooling is necessary. Period.

Skip Asay

Skip you still don't see my point and yet you have finaly agreed to the fact that a motor will generate heat that we agree upon right.
However you still feel that I over tax my motors by not matching the props exetra,you could not be more mistaken.They are perfectly matched or how else could I get 2.5 to 3 hours of continuese use out of a single charge as is the case in my larger subs DO YOU ,and a whoppinig 90 minutes out of the SB-2.0 when without the mods it would barely do 30 minutes,by the way its the same exact motor just geared down and water cooled.The guys at TT did not bother to do that because it cost more and would hurt the bottom line since there main goal was to produce a better pool toy,not seeing the true potential of this great sub.

Your sympton is simlply being old school and not wanting to change old edeas,and then put new ideas down we have all seen that symtom before,well there is another way to skin a cat and it works just fine period.

I have done more homewark than than anyone could imagine on RC sub propultion and I like them to run a long long time with nice cool motors,cooler than just throwing them in there and hopping they will stay cool ,they won't even if they had no prop,now do you see my point,I hope the rest of you do,it helps to keep a cool motor even cooler not because it is a necesity or even required but is simply good insurance to keep them happy cool.
I will post a detailed    how to install water cooling on your sub later.


The idea of having another batery to back up the fail safe is a good one but that would intail complex separation of the main circuit board.The SB-1 has a built in voltage sensor that automaticly surfaces the sub when power is low at a factory set level and it works every time.
Remember to check that stern shaft seal for leaks it will and flood the motor then seize it up and cause the fuse to blow.


Dave  SB-2.0 

Skip Asay

"They are perfectly matched or how else could I get 2.5 to 3 hours of continuese use out of a single charge as is the case in my larger subs DO YOU"

Based on what you've written before, if you're only getting 2 1/2 to 3 hours out of a SIXTEEN AMP HOUR battery, boy are you doing something wrong.

"and a whoppinig 90 minutes out of the SB-2.0"

That's all with a 4 amp hour battery? My Type XXIII lasts OVER FOUR HOURS on a 4 1/2 amp hour battery.

"I have done more homewark than than anyone could imagine on RC sub propultion"

Sadly, I have to say I don't believe that statement based on what you've written.

Skip Asay

AQUASUB

Based on what you've written before, if you're only getting 2 1/2 to 3 hours out of a SIXTEEN AMP HOUR battery, boy are you doing something wrong


Again you take my statements way out of the facts,the sub that has the big 16amp hour batery uses a drill motor and trany and turns a huge  3.5 inch heavy pitch prop ,you know the Alfa 5ft that is now on its way to Canada .She would run for 2.5 hours at mid power !And run the air compressor as well as the asorted hydraulics,so you fail to mention that in your statement,there is an awfull more amount of power being used for the ascesories than just the main drive.
Your subs on the other hand don't even aproach the power levels mine do,no hydraulics,you use I believe gas to blow the tanks and mechanical or neumatic  means to move the masts,thats fine but hydraulics is way cooler even sounds like the real thing and cost a fraction of what a mechanical system would while being super reliable and simple.

It would be nice if you could see it and operate it before you cretique it ,that is the gentlemans way to express ones opions but I gues you did not get that class.


Dave SB-2.0

AQUASUB

PS do your homwork

Skip Asay

"Again you take my statements way out of the facts,the sub that has the big 16amp hour batery uses a drill motor and trany and turns a huge 3.5 inch heavy pitch prop ,you know the Alfa 5ft that is now on its way to Canada .She would run for 2.5 hours at mid power !"

That's over SIX AMPS current draw! It's no wonder that you've resorted to water cooling. Too much load on the motor.

"And run the air compressor as well as the asorted hydraulics,so you fail to mention that in your statement,there is an awfull more amount of power being used for the ascesories than just the main drive."

I'm quite sure that the intermittent use of the air compressor and hydraulic pump will not pull the battery down all that much.

"Your subs on the other hand don't even aproach the power levels mine do,no hydraulics,you use I believe gas to blow the tanks and mechanical or neumatic means to move the masts,thats fine but hydraulics is way cooler even sounds like the real thing and cost a fraction of what a mechanical system would while being super reliable and simple."

You are the one who should do his homework. The XXIII has hydraulic periscope and snorkel and uses a pump for the ballast.

"It would be nice if you could see it and operate it before you cretique it ,that is the gentlemans way to express ones opions but I gues you did not get that class."

I've noticed that every time you're confronted with reality, you resort to attack mode. Why is that?

Skip Asay

AQUASUB

Sorry ,I am not at all in attack mode nor syndrome mode ,if anyone is cobative its always you ,no mater who strokes you the wrong way you are Johny on the spot with your out dated antics in which your way is the only way,hay get a life and get used to the fact there is other ways to build a sub,may I say  similar to the way the big boys do it.
Thats where the real homework that is worth a darn is.

Dave

Skip Asay

I've never been able to reason with an unreasonable person.

Skip Asay

AQUASUB

Thats because you don't  reason with a sledge hamer but with cunstructive mutuel respect for all involved.

Dave Amu Sub Yard

Graupner Shark
Galathe 1.0
Sb-2.0
SC SH Akula II
Robbe U-32
Akm U-31
Alfa 5ft
Robbe TypeXXI  X 2

And  so on.....

nick_75au

On a 3 1/2" prop that's quite reasonable, what RPM is it turning, and what volts, Drill motors can handle 30 amps for short periods in a drill and easily sustain 10-15 for a full charge.

Ive got a 4 inch prop in a boat that draws 5 amps on 24 volts at 2500 RPM, a Motor and gearbox set up for same RPM and run it on 12 volts it draws 10 amps no matter what motor I use.

My SB-1 runs fine on a 55 mm prop cu8t down to fit inside the shroud and no other changes, I did replace the ESC because the stock ESC did not like 12 volts and the BEC kept cutting out.

Nick

Skip Asay

"Ive got a 4 inch prop in a boat that draws 5 amps on 24 volts at 2500 RPM, a Motor and gearbox set up for same RPM and run it on 12 volts it draws 10 amps no matter what motor I use."

How many blades on the prop? Is it safe to assume that 2500 RPM figure is out of the water? What is your overall gear ratio? Have you tried any other ratios? What motor are you using?

Are you tired of all these questions yet?

Skip Asay

nick_75au

Its 2500 RPM in the water actually its not much more out of the water, Its Direct Drive, 4 blades, A Raboesch type 1, the motor is a Johnson WPS 5.2water pump motor designed for 24 volts, its rated current in its original application is 5 amps

WPS 5.2
Pressure Flow Amp. draw
12V 24V
3.9 A 1.6 A
4.9 A 2.1 A
6 A 2.5 A
7.1 A 3.1 A
8 A 3.6 A
9.2 A 4.1 A
10.3 A 4.7 A
11.2 A 5.1 A
Fuse required 15A 8A

Data from Johnson website listing current draw at various (pressures removed as not relevant to discussion)

Nick

Skip Asay

nick_75au -

There are some holes in your description but I won't take you to task. I will say, though, that there's no way I would feel comfortable pulling 10 amps on anything other than either a race boat or a 20 footer (with me in it!). I've seen trolling motors turning 8 " props that didn't draw that much.

Skip Asay

AQUASUB

What Nick is saying is perfectly correct ,its Skip trying as usual to say that it is not,my motors and drives are very similar.
A ball bearing 3.5 to one gearbox maid by Master Airscrew and a stsndard 12 vdc can motor RS or HS 550 and 2.5 3 bladed moderate pitch prop does the trick ,very simple inexpensive and lasts a very long time especialy water cooled for sub use natuaraly.Even on a boat it would run very well.
I have tried hundreds of diferent motors and the good old standard Johnson or Mabuchi has never let me down I garrantee it!
The pics show the gear case and the complete unit,this one is the special Aquadrive one I call it ,there is a gear pump on the other end of the motor that has an extended shaft that just so happens to be the right size for the pump!
Most of my subs use a pump that is driven from the main shaft in a sealed continues loop of 2 coils and a mixture of water and any freez to lube the pump and prevent corrotion.
Dave

AQUASUB

The last gear case is the one used in the SB-2.0 from MPJ

Dave

Skip Asay

I can only repeat - If you have the need to water cool a motor in an R/C sub, you're doing something wrong.

Skip Asay

nick_75au

My apologies, it was 1800 RPM out of the water and 1500 in the water, its been a while since I ran the boat, Is that the hole you were looking for? I would like to know

Your kidding about the 10 amps aren't you, we have the smallest Minn Kota trolling motor and it draws 44 amps at full throttle, obviously less at part throttle.

The motor I have is the 24 volt version, the 12 volt version has the higher amp draw, in fact its around double for the same power output which is basic Ohms Law.

Nick

Skydrol

My Feedback: (1)

Well this is an interesting debate. How about taking a specific motor/gear reduction / prop combination from skip asay, and run that. messure the battery run time and temperature. Then see if there is any advantage with cooling.

I see both points, I think.

From what I have understould, Aquasub simply believes that cooling is a good practice. From what I have read, he does not say that cooling is required. But that any cooling is benificial even if not actualy needed.

Skip asay says that if things are matched properly, no cooling is needed. and if it is not needed, then why do it?

This is down to numbers.

Skydrol

My Feedback: (1)

I am going to check into the battery backup system.

Yes the original fail safe looks for low voltage, water, pressure. But if for some bizzare reason the a problem is eccountered that causes the fuse to blow, non of that works at all. Then you are going swimming.

I have not looked deeply into the components of this boat, I will though.
It could be complicated, and maybe it might not be so. Perhaps I could install a relay that is held open as long as normal battery circuit is complete. if for some reason that circuit is suddenly broken. the relay relaxes and provides the path for the smaller emergency battery to the same overall system. That way you could manualy surface. Or It could switch and say short the water sensor, simulating water on board, and causing the roll pump to purge the ballast. Or short the pressure sensor. Doesn't need to be a big battery.

Its all for fun anyway.

Skip Asay

"Your kidding about the 10 amps aren't you"

No. Actually, I'm not. I honestly can't tell you the manufacturer but about 15 years ago I was involved with a project that required 2 trolling motors to drive a small barge. In the testing phase, I ran one of these motors up (in the water) with an amp meter attached and read just about 10 amps at somewhat less than full speed (full speed was too messy!). What I left out was that I had cut the props down from 8" diameter to 6".

Skip Asay

Skip Asay

"its Skip trying as usual to say that it is not"

Perhaps you could tell me just where you saw me say that? I've looked and I've asked others to look as well and they all come back with the same question - what is he talking about?

Skip Asay

AQUASUB

Yes I have done just that in a series of in water tests on my U-32 , on the SCR in one test the cooling sytem was disconnected ,the telemetry read out started to go up above 120 depgrees in 8 minutes! The other test with the cooling system connected as nor mal and the readout read 98 degrees and running at a fast pace in the tank.
I use a wireless telemitry system we would all benifit from that does not lie or is byiesed in any way.
The responce I got from Skip was ,"the prop is not turning "there fore its not valid ,man if one could see those blades turning at high speed ,in slow motion then that would be nice the prop is by the way a 3.5 inch 6 bladed simitar scale prop of brass.This is turned by a Makita ball bearing and trany water cooled by a shaft driven pump as i have discribed.

I made those videos that show the readouts in real time they are self evident that water cooling is a very good idea.Now for this particilar model that is very large a unique powerplant had to be made since I like high performance without harming the drive.On a smaller less demanding model small motors and props one can get away with no water cooling but still there going to get warm.

By the way skip those trolling motors you discribed and used are water cooled and if you where to contact the manufacturer they would tell you that they must be used in water as desighned.

Also Skip by the time you get the sub out of the water and opened all the way to the motors they have already cooled down guite a bit ,there fore your bassis for stating the true state or temp of the motors is baseless and not scientific or realistic without on board telemitry.I sugest that you get the telemitry system install it which is a piece of cake even a cave man can do it and show us what temps your motors are runing with your set up.
I have proof that cooling with water works as it has for many years ,can you prove me wrong without telemitry,not likely and is only considered as hearsy not scientific by any means.
Telemitry system used is the Seagull by Eagle Tree Systems please view there web site ,absolutly the best!
Just for fun.

Dave