Hi

this hull looks nice but is a little bit complicated to you. It was only an example.
Try to find any deep - vee hull made from fibre glass.

The lenght about 650 -700 mm.

Then buy two 6v batteries and marine ESC with water cooling inside. Find any aluminium rudder you can get or similiar made from reinforced plastic. Get your remote control in local hobby shop: two channel fm system ( Futaba ). Buy two props: 39 mm and 42 mm diameter.

If bought, put your hull on the water. Put all you have to the hull. Try to put 700 on the middle, and two batteries on each side of inner space of the hull. Think where to put receiver and ESC. Try to find a place for rudder servo.

Now, wait a second and try to make a thin line with waterproof marker to mark water line on the back, above the expected place for making hole for the shaft tube.

Maybe this method is primitive, but that's the simplest way of planning your first speed boat. Remember - you are going to use piercing prop. I did it many times and I was succeded.

P.

Hi

an old rudder to be used in my new 700 motor project.

Speedmaster stuff is good. Octura good too.

You can find some all-in-one stuff like these if you wanted.
http://www.offshoreelectrics.com/products.php?cat=69

hey guys
quick question
whats the difference between the speed 700 8.4bb motor and the speed 700 12 bb motor?
is one faster than the other?
also, are tirn fins and trim tabs necisary for good handling and control?
thanks

12v motor is VERY slow for scale models, 8.4v is what you want.

Spin fins and tabs are needed for control

Ryan

ive decided to go with the 700 12volt motor, what should i use for batteries? would 2 EP4500 6 Cell batery packs work?

I'm confused. I just posted after you asked the question and told you, the 8.4v motor is what you want. What are you building a tugboat or fast electric?

Ryan

Hi there

few posts ago I presented the way how to plan your first boat.

But I forgot to add the most important information: learn as much as possible!

Some guy wrote that 12v 700 motor was too slow. Funny.

THIS IS MY FIRST RULE: EVERYTHING DEPENDS ON COMBINATION OF MOTOR, PROP, AND HULL.

These three 'parts' of each project describe the final efect. You can use 400 motor and reach 50 km per hour, using small 1000mAh battery. You can also buy huge 700 motor and power it with 14.4 v and as a final efect you get NOTHING because of wrong prop.

THE SECOND RULE IS: A PROP DIAMETER MUSTN'T BE BIGGER THAN ANKER ( ROTOR ) DIAMETER, if we talk about direct drive.

Few years ago I built Graupner Key West catamaran. It was powered by 700 motor and 9.6 battery. It was a bullet! When I added additional cell I was shocked! It was fast as a jet! Don't believe in all what people say.

So, if you have good deep vee hull and all equipment you need, it's time for building the boat. If you remember first part of my lesson, you shouldn't have any problem with your project. Drill a hole below the water line. The distance between a hole and water surface should be equal to the prop diameter. That means that if the boat doesn't run, the edges of prop touch the water surface.

That's all for today. Have nice time.

Peter

Some guy who has been there done that. First of all, that motor won't even wake up until 16 cells are used.

What about the absolute most important component of an RC FE boat, the cells? Something that controls everything and you fail to include that in your lecture. Not to mention the ESC, type of drive, and setup.

How can you possibly come to the conclusion of this? First of all a DC motor does not have a rotor, it is called an armature. The size of prop has very little to do with the Diameter of the armature. Depending on how many cells are used drastically changes the prop you may run. I have ran upwards of a 55mm prop with a 700 motor direct drive which is 10mm larger than the CAN of the motor.

Where have you ever heard of any one doing this on a surface drive hull? So if my hull is heavier my prop shaft will be higher up as the water level increases? This is the exact opposite of what you want considering when on plane you will have no prop in the water.

My boat may be lighter or heavier than yours, this should NOT play any difference in where the prop shaft transom hole is placed!

On my old 24� and 27� mono, the prop shaft holes center was placed about 1/8 to 3/16� above the bottom of the vee. On my 46� mono, the prop shaft hole is place a little higher than ¼� above the bottom of the vee.

The edge of the prop touches the surface? So if I increase the number of cells used, drop in prop diameter, the hole must be higher up on the transom. You are going to end up with a hull that will not plane!

Also, you will only have the radius of the prop above the prop shaft center line.

Ryan

Hi there

Ryan, thank you for your opinion. However I only wanted to present some of my opinions in this matter. We forgot also about many other parametres.

I'm not living in US, that's why I used names usually being not used in US like rotor. There is a case ( stator ) and rotor. I never run with prop bigger than the case, but there is no problem with doing this. Many of my friends never use bigger props than the case, that means that the rule is not only mine. Usually we have three main parametres: hull - it's shape, motor, and prop. Making the right combination of these three is not easy. Many books were written about it. As an engineer and electrician I can write also my book about it. We can make good boat using many methods: CAD project, including complicated electric calculating. The point is, that the easiest way for making first speed boat is to understanding basic ideas how to do it. If you are to start your boating, you can choose your own way. I remember very well when ten years ago I built my first boat. I was given a hull ( deep vee ) and I didn't know anything how to do it. My father showed me many interesting things. After two years I was able to build a speed boat without calculator or PC, using balsa wood from fruit wodden box found in the local fruit shop's backyard. Now I use sometimes CAD and spend many hours with my friends talking about characteristics of electric motors. But it came to me after years of making boats. I prefer to show practical way of making boats. You right when you say that batteries are important. I say ALL IS IMPORTANT! But in the begining of any process we don't know much. Probably our young boater doesn't know much ( with all respect to You Speed King ). He asks about many things: rudder, fins, props. We won't make him next expert without explaining all he needs, but let's do it step by step.

I do hope you understand what I mean. In addition I will say, that making professional speed boat means taking into consideration all aspects of running and all parameters, even those forgotten. That's why this job is a great fun and I like it as hell!

By the way: I talked about Graupner 700 Turbo electric motor ( Europe ).

Respect to you Ryan.

Peter

"I'm confused. I just posted after you asked the question and told you, the 8.4v motor is what you want. What are you building a tugboat or fast electric?"

srry about that Ryan, im not trying to ignore you. I made a quick uneducated decision (before i saw your post about the motors) about the motor thinking that 12v would be faster than
the 8.4v. I gues not. if the 8.4v motor is better ill check it out. does that motor still runn on 12 cells?

from my understanding, the prop shaft should come out of the transom right in the bottom of the v so that half of the prop will be in the water when running. am i wrong? what is the best way to determine where to put the prop shaft? ill put up some specs of the boat later and a list of hard ware etc that i plan on using to see if im looking at the right stuff.

thanks
Morgan

Hi there

I see that you still talk all the time about cells.

Adding cells is not a solution for making boat faster. Each motor is designed to be used with it's voltage.
Making voltage higher means changing everything.

Usually standard or selected 8.4 v 500, 600 class motor is not ready for being powered using 12 v. It will be damaged in short time. All information about motor voltage should be given in it's manual. Moreover, each serious firm put into motor box it's characteristics.

An european, german Speed 700 Turbo with 5 piece armature ( 5 piece rotor ) uses 9.6 - 12 v and is specially designed for Mono class electric speed boats. When you want to use 14.4 then you have to add water cooling. The time of performance is about 3 minutes.

That's all from me about that. I hope your project will be ok, speed king. Your previous version with 700 was right. Your choice.

When boat is running only falf of prop should work in the water. So, how to determine where to put the prop shaft when is not running, during assembly, to get such effect? I know how to do it, does Ryan too? Any theoretical opinions? Maybe some mathematics?

Regards
Peter

Hi there

in addition pictures of Mono sped boat by Graupner.

carefully designed speed boat without water cooling.

"Your previous version with 700 was right. Your choice."
so does that mean that i should be using the 12v motor?

is there an advantage to running an outboard? easier set-up etc?
would it be any cheaper than an inboard?
as i am still in the design process(somewhat designing the boat around the motor and hardware) i can scale the hull to any size and make any necisary modifications

thanks

Morgan

In FE boats you will find over 95% of the hulls in here have water cooled motors. The 8.4v motor on 12 cells will run you very close to 30mph if not over. I would highly recommend water cooling the can and brushes. This is standard practice in FE boating.

The rated voltage on the motors are industrial ratings specifying the voltage in which provides the best life and performance. The lower this voltage rating is, the higher the KV. A lot of these motors are not made specific to R/C and used in several industrial applications.

I have ran several 700 8.4v motors on 12 up to 14 cells for years. They run a long time on this voltage. Key point is, it isn’t voltage that burns up motors, it is current. This is controlled solely by the prop or load placed on a motor.

Graupner 700 8.4v motor has a kv of 1750 and will spin up to a loaded 20 000RPM on 12 cells. This is a pretty common setup for LSH and LSO racing.

It’s not that difficult at all, many boats are setup so that the prop shaft exits the very bottom of the vee. This makes it very consistent from boat to boat no matter how heavy or large the prop is. A reference point must never be something that can vary with weight or prop size.

I found that if the prop shaft exits the boat a little higher such as 1/8� clearance for 22-30� mono’s from the bottom of the vee to the bottom of the prop shaft, much better handling and performance are expected.

I’m not to fond of the Graupner hulls. Weak performance and low quality hardware. A boat without water cooling is typically found in the scale section of RCU not in FE.

Ryan

I'm a huge fan of OB racing. The problem is there are not enough quality setups(OB) on the market. Graupner makes a couple, but they are very limited and perform poorly.

Outboards tend to be easier to setup, can be cheaper but suffer from performance.

What is your goal for this project. What is your expected top speed? How much money can you budget to hit these speeds?

Ryan

Peterpella I don't know how mutch experience you have, but ryan just kicked your ass quite hard. Please be patient to learn that way something more. I have almost zero experience with brushed motors but my opinion was = ryan.
Besides why your boats shaft exits hull so high? when it will go on plane your prop will push air...

Hi there

Graupner in europe means quality. For over 20 years Ive been using graupner parts and ALWAYS they were TOP QUALITY. Where did you get yours parts from? China? Probably some graupner's subcontractors produce them in China, or in any cheap country. **** happens.

All motor I used in the past ( brush ) were made by Graupner or Robbe or Multiplex. Each of one was selected, however, all of them were produced by MABUSHI. Only the sticker was from the firms mentioned above. I destroyed dozens of them during tests in my workshop because I believed they would run on 12 cells. But they werent.

All above shows that we had different experiences in the past. Nothing wrong, I think. I usually hadn't been running Speed brush motor on higher voltage. Each magnet overheated loses its power, or lemme tell you this in that way, that magnets change their characteristics. So we have to cool them down to the safe temperature.

However we all know that. So, let's go forward and help speed - king. I suggest him to start with 700 type motor, add cooling system.

You Ryan show him where to buy all these things. Speed king has got two batteries already. Why not to use them?

Peter

Hi

i don't think that anyone kicked my ass.

If yoy don't have any knowledge about brush motors try to ask instead saying stupid opinions.

This forums is not only for people who wants to add to their boats as many cells as it possible. Or mount the biggest prop they have.
I also use my brain and try to get some interesting in books, or use some mathematics.

I used to share my opinions even there are people who don't like it. After almost 10 years of boating I can have my own opinions.

Peter

So you just ruined dozens of motors on "land" testing them while they have no cooling? some inrunners heat up at no load so strong that you can not hold, but put a cooling jacket and water does its job. All boats that are a bit extremely fast must use cooling, or use some new nasa tech
sorry for butt

As far as Graupner goes, they don't even use a stinger or strut on their hulls. I also don't see trim tabs. There appears to be only one turn fin if I am seeing correctly. A solid straight shaft is used with a solid coupler. Plastic Flexible Rudder.

I'll show him where there are plenty places to purchase quality harware. We simply have not got that far.

Higher Voltage does not increase heat, it is current that controls heat. If there is too much heat you are drawing too many amps.

By The Way, I missed the post where you attached photo's of your prop shaft exiting. If you decide to use a 39mm prop, good luck with achieving any type of speed. That is far too high as only 1/3 of the prop will be in the water. I'd suggest patching the hole and re-mounting it as per my previous recommendations.

Ryan

to fiend: during 10 years lot of my friends destroyed many speed motors. don't think we were so stupid to test them without cooling.

to ryan:when I was younger Graupner had wide range of any equipment. during few last years they reduce their offer as much as possible but why? in addition, you also try to learn something: heat is being generated by current, or call it 'amps' running in aramature and believe me IT CHANGES MAGNET CHARACTERISTICS. I have degree in electricity, so will you be so kind and take it under consideration, will you?

Graupner is not the same. This firm changed a lot. I don't like it.

Beside, got question to you. Did you see that Mini Rio by Aquacraft? Is it possible to buy it with remote except this 75 Mhz?

Thanks

Graupner was much more popular at the entry level of R/C boating 5-10 years ago. Since then they just can't keep up to companies like Aquacraft. Dealers like Hobby-Lobby slowly started dropping there products years ago as they weren't selling. I believe they only carry the systems Cat now.

Heat weakens the permanent magnet of any motor. Once this happens the motor will run excessively hot as efficiency has greatly deteriorated. Using Neodymium magnets will lessen the chance of this. Unfortunately most of Graupner motors use Ferrite magents.

I also don't understand why you keep listing your experience and credentials. I could do that just as easy, would it make me that much further ahead?

Ryan

Piranhia is waiting for the first run on Sunday........

Have nice weekend gyus.

Pics are to be sent on Sunday also.

Peter

Peter, how about some video?

Ryan