Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: Pete25 on May 12, 2011, 08:38:32 am

Title: is my boat to heavy for motors ?
Post by: Pete25 on May 12, 2011, 08:38:32 am
ok this is a tricky one.. well for me anyway searched on Google so here goes im a newbie to all this so go easy on me if its a silly question  :P

i have my hull water tight (no prop shafts ) and im now wondering if i will have enough power to move the weight of the boat/batteries and so on.

i want to use 3 motors all with 50mm propellers

power will be 12v

the motors i want to use are

Johnson 600 size  3 - pole
12 volts
No Load speed is approx 20,000 rpm.
Dimensions: L65mm, D36mm, Shaft diameter 3.2mm Off load Current: 1.57A

im not looking for speeds of 1000mph  ok2 just a nice cruising speed will do me  :-)

i will weigh the hull later along with the batteries and post results here later today.
the hull is 6ft long

i have 3 led acid batteries and am i right in thinking if i use all 3 but wire them up Parallel  this will give me longer running time ?

hope someone can help  :-)




Title: Re: is my boat to heavy for motors ?
Post by: pugwash on May 12, 2011, 09:14:51 am
Pete Welcome to the forum.  I think you have this post the wrong way round - if you give the dimensions and
weight and type of ship then we can give you a better idea as to the propulsion system needed. i.e. is it a
slim destroyer type hull or a tug etc etc.
Also have you done a float test to see if the hull will support this weight of motors nd batteries


Geoff
Title: Re: is my boat to heavy for motors ?
Post by: tigertiger on May 12, 2011, 01:37:41 pm
In theory, even a small motor will move a big boat ...................eventually.

I would have thought the bigger issue will be getting enough headway to steer.
Are you fitting bow thrusters?
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 12, 2011, 02:06:30 pm
@ pugwash

my boat is a battleship style that is 6 ft long but a foot wide and just under a ft tall the boat is a flat bottomed design too

the hull on its own weighs 3 Kilo's

i have tested it in my pond in the garden and its very stable as it is without no ballast. this will be due to its flat bottomed design.
i put batteries  inside the hull were the batteries are going to be and the water level moved up no more than 5mm on the side of the hull
and 2 acid batteries i want to use Weight together a total of  4.5 Kilo's

so
2 batteries 4.5 Kilo's
Hull  3 Kilo's

as for motors they didn't make any extra Weight.. well nothing worth mentioning  

just for fun i added 3 house bricks and again the boat was very stable and  water level moved up another few mm i didn't want to push my look and add any more but i reckon i could add more if i wanted so hull can handle the more Weight than i want to put in it.

if you need more info let me no and ill find out thank you for your help so far  :)


@ tigertiger
i will be hopefully but i dint think i would really need them  but again what do i no im a newbie to all this and im learning as i go along ha
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 12, 2011, 02:08:34 pm
Hi Pete. I think three of the motors you mentioned combined with the 50mm props will easily be enough for a 6 foot boat although you may need some gearing to put less stress on the motors, give them more torque and allow better control at slower speeds. You Might want to think about using a mixer to control the motors as it can be a real handfull to control tree props at once.

Ali.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 12, 2011, 02:11:44 pm
Hi Pete. I think three of the motors you mentioned combined with the 50mm props will easily be enough for a 6 foot boat although you may need some gearing to put less stress on the motors, give them more torque and allow better control at slower speeds. We could do with more info on the boat itself so we can give you more comprehensive advice.

Ali.

more info above. posted the same time you asked :)
i will be water cooling the motors and will probably use gearing but for the minute i want to see what i can get away with  :P
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 12, 2011, 02:20:58 pm
Yeah thats fair enough, I did the same with my boat. Keep it simple while you get your head round it then add stuff later.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 12, 2011, 02:24:03 pm
Yeah thats fair enough, I did the same with my boat. Keep it simple while you get your head round it then add stuff later.
i dint think it would be this complicated at first now im starting to get headaches trying to figure things out  {-) hopefully ill get there in the end and will be able to help others like everyone els on here :)
Title: Re: is my boat to heavy for motors ?
Post by: John W E on May 12, 2011, 03:19:10 pm

hi there Pete25
 
In the 60s and 70s the RAF had the English electric jet fighter.  Its party trick was to hurtle along the runway and then go supersonic as it took off -  I think your model may do the same  {-) {-) O0 with them motors and 50 mm diameter props spinning at 20,000 rpm  ,may just be a tad too fast, the motors will be drawing about 20 amps each plus they will get very hot, you should maybe be looking for motors that spin at approximately 11,000 rpm

aye
john
 
Title: Re: is my boat to heavy for motors ?
Post by: unbuiltnautilus on May 12, 2011, 03:47:15 pm
Hi, the Johnson motors are fine for fast hulls but I would avoid running 3 in a displacement, scale hull. Two, via reduction gearboxes on 6 volts should be more than enough for your model. I would suggest if you go the way of the reduction gearbox, you consider 2.5:1 or even 3:1 reductions. A better motor choice would be three Graupner 500E or similar, I would still peg back your voltage to 6 volts though.
Title: Re: is my boat to heavy for motors ?
Post by: tonyH on May 12, 2011, 04:01:15 pm
Just adding a minor spanner, if the draft is between 3 & 4 inches, the displacement could easily be up to 30kg. How would that effect the choices already mentioned?

Tony
Title: Re: is my boat to heavy for motors ?
Post by: boatmadman on May 12, 2011, 04:15:54 pm
And another spanner coming in!

That boat is going to be heavy and awkward to handle between garage - car - water and back.

You might want to think about putting in some free flooding ballast so you dont have to carry as much weight about.

Ian
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 12, 2011, 04:42:00 pm
I'll give you an example. It may help, it may not.
My boat is 4'8'' long by 8'' wide and is about 15Kg. It has twin 50mm props which have quite steep blade angles so they bite the water a lot. I opted for 540size motors with 11:1 gearboxes because I felt I needed torque rather than speed. The props spin quite slowly without the motors stalling. When at scale speed the motors are at around 50% power which means I can wind them up if I need to get out of trouble. Each motor runs off a 20amp speed controller powered by a single 12V battery. Apart from the props and the battery I would just uprate the different components eg I think the speed controllers would need to be 30amps minimum, the gearboxes can be 6:1 if you like. The more suggestions you get, the bigger the picture you will get. The rest is up to you.

Kind regards Ali.   
Title: Re: is my boat to heavy for motors ?
Post by: tonyH on May 12, 2011, 08:39:54 pm
Hi Pete, it sounds as if you've got a real beast there :-))

Can I suggest that you need to get a better idea of what the motors have to push first. The reason for this is that in your first post you mention that 3kg dropped the hull by about 5mm. That would mean that if the depth under the waterline is 2 inches then the all-up-weight would be over 30kg but if it's 3 inches then well over 45kg etc. You could find out in the pond by just adding weight to bring it down to the level you want.

As Ian said, you could be getting into quite a heavy ship to move, whether on or off the water.

Any chance that you could post a pic or two so that, maybe, we could help more.

Cheers

Tony
Title: Re: is my boat to heavy for motors ?
Post by: john s 2 on May 12, 2011, 09:18:54 pm
As regards Motor size. If there are a bit on the big size and overpowered, does it matter? I always thought
that the pupose of an Esc was to vary speed. Some esc's can be range set. Mtronics for instance. This is
assuming your finger doesnt work well enough.Fit what youve got and enjoy. John.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 12, 2011, 10:16:15 pm
thank you to everyone that has posted i really do appreciate it  ;)

if i stick with one lead battery 12v  to keep weight down would this run 3 12v motors for a good run time ? that's why i was going to use 3 batteries in parallel

also my pond is 3 ft deep if this alters any of my results :)

i don't have any pictures as they were not good quality However i have a video of the hull here

http://youtu.be/Ee9wJpThPQ4
Title: Re: is my boat to heavy for motors ?
Post by: john s 2 on May 12, 2011, 10:41:52 pm
Its difficult to be precise about run time as there are so many variables. Certainly with three 12v 7amp hr
batteries youd have a long time say 2 to 3 hrs? Id fit one to start allowing for more if run time not sufficient.
Please remember that Gel Cells do not like to be run flat. It will shorten their life. John.   
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 12, 2011, 11:28:26 pm
That hull looks familiar. Maybe someone on the forum has used one of these.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 12:23:29 pm
i have posted he video of my hull on this forum in other sections. i got the design from looking at real full size battleships  :-)

will this battery be ok to use with my motors ? and could i use 2 of them in parallel if i wanted.

12V 7.5 Ah sealed lead-acid batteries
7.5Ah (7,500mAh) measured at standard 20 hour rate.

do i add each amp of a motor
Johnson 600 size  3 - pole
12 volts
No Load speed is approx 20,000 rpm.
Off load Current: 1.57A

as i want to use 3 motors all three is a total of  4.47 amps
so do i find a 12v battery round 4 to 5 amps ? ummm

Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 13, 2011, 12:41:43 pm
My boat has run for 5 hours on a single 12V 7A Lead Acid battery using the MFA919D motors I Mentioned earlier. I also have a spare but never needed it. From my experience this type of battery should be fine as I wouldn't think your motors will be running at full tilt all the time. Make sure you get the right speed controllers that can handle the motor current.

Ali.     
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 01:55:49 pm
thank you for that :) i have a car battery charger here. (never used) and was wondering if it would be ok to use to charge one 12V 4.5Ah Lead-Acid Battery
the charger says  12v  2.7A  DC 4 AMP  Would it be ok to charge this battery with this ?
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 13, 2011, 02:37:57 pm
I think you can use it but beware. It depends on the output. If it is 2.7Ah a 4.5Ah battery would need less than 2 hour to charge. if it is 4Ah it would need about an hour. I think that how it works. My mains charger dose 700mah so it takes 10 hours to charge a flat 7amp battery.
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 13, 2011, 02:45:09 pm
I prefer to slow charge batteries rather than ramming juice down their necks.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 03:09:29 pm
ow.. well the charger has a fully charged led indicator on it so ill just try it and keep an eye on it..  :-)
again just want to thank everyone for your help and comments :) i will keep you posted on this website as the build goes on.
i should receive most parts in a weeks time then i can get a start on building drive shafts and installing motors and so on. thanks again
Title: Re: is my boat to heavy for motors ?
Post by: John W E on May 13, 2011, 03:20:35 pm
Hi ya Pete25

A couple of questions first:

1.  On your battery charger, is there a switch which states GelCell charge/auto charge for car batteries?    If not, and it is just purely a car battery charger, it may do some damage to your gelcells charging it with this

2.  When you are quoting your amperage on motors, as 1.5 free running - this is the actual amperage that the motor will draw when running with no propeller or anything else connected to the motor - it is free running.  Once we connect a propeller shaft and propeller to the motor, this creates resistance to the motor and then causes the amperage to climb up - so you will note if you connect an amp meter between the battery and the motor whilst you have the propeller/propeller shaft connected you will see the amperage go up towards 1.75 amperage or thereabouts.    Now you stick the propeller into the water causing more resistance to the motor and you will the amperage climb up even further, possibly towards the 10 and 15 amps per hour, depending upon the size of propeller fitted.    With the motor now drawing between 10 and 15 amps, the life span of your battery or running time will decrease drastically.

As a quick rule of thumb, divide the running amps of motor under load by the amp per hour of the battery.     

That will give you an approximate run time on the water.

Last but not least, looking at the video of this hull - are you going to put bulkheads/stiffening inside to support the skin structure.   If not, you will find this will become very flimsy.

aye
john
Title: Re: is my boat to heavy for motors ?
Post by: Colin Bishop on May 13, 2011, 03:38:32 pm
Quote
As a quick rule of thumb, divide the running amps of motor under load by the amp per hour of the battery.     

Not struictly applicable to lead acid cells as they don't like being discharged below 50% of their nominal capacity. Nor do they like being fast charged either if you want a useful life out of them.

Colin
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 03:53:12 pm
it states on the website i got the battery from this

The maximum charge current is 25% of the battery capacity (e.g. 2Ah battery = 0.5A maximum charge current).
SLA batteries should be charged regularly to ensure that they do not deeply discharge.
Battery Technology:   Sealed Lead Acid (Rechargeable)
Capacity Range:   4000.0mAh - 4600.0mAh
Voltage:   12.00V

the battery i want to charge is    
Ultramax NP4.5-12, 12V 4.5Ah Lead-Acid Battery

my charger i want to use says on it
12v lead acid batteries only
minimum capacity .20 Ah
input 240v ~50Hz 55W
output 12v 2.7A DC 4Amps


@Bluebird  my hull will be strengthened just waiting on the materiel :)
Title: Re: is my boat to heavy for motors ?
Post by: John W E on May 13, 2011, 04:43:34 pm
hi here Pete

The battery charger you are using will do the job;

I have included a couple of pics of the Destroyer - HMS Daring - she is just a tad short of 5' - she is 1:72 scale.

This is the running gear set up in her - she has 2 x Graupner 500 motors - rated at 7.2 volts and running at 17,600 rpm.  She draws 9 amps at the most efficient.

There are 2 x 30mm props on the model and with these props the motors draw roughly about 4-5 amps under load.   The speed controllers are ACTion P80s and they are rated at 20 amps each - a bit of overkill - but - hey it does the job.

Also there is a mixer involved in it which mixes the speed of the props and motors with the movement of the rudders.    I run the model on 2 x NiCad packs of 7.2 volts  - 3300 m/a .   This gives me ample time on the water.

aye
john

Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 05:50:56 pm
thankyou :) loving the pics ! i like how the motors are fixed in. i might use that design in mine if its cool to pinch that design ? :P cheaper than the steel brackets thats for sure .

well iv just ordered 2 12V 4.5Ah Lead-Acid Batteries not sure if you receive them fully charged or not but i will try my charger when they need charging on it :)

at looking at your pics i can see now why everyone is saying i have too much power  {-) but just because iv got all that power dont mean i have to use it all aa cheers everyone for your help :)
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 13, 2011, 07:47:57 pm
thankyou :) loving the pics ! i like how the motors are fixed in. i might use that design in mine if its cool to pinch that design ? :P cheaper than the steel brackets thats for sure .

well iv just ordered 2 12V 4.5Ah Lead-Acid Batteries not sure if you receive them fully charged or not but i will try my charger when they need charging on it :)

at looking at your pics i can see now why everyone is saying i have too much power  {-) but just because iv got all that power dont mean i have to use it all aa cheers everyone for your help :)

will i need to use 3 speed controllers then as i have 3 motors for propulsion ? i will be using a servo for a rudder
Title: Re: is my boat to heavy for motors ?
Post by: Stavros on May 13, 2011, 08:52:40 pm
The batts will have a partial charge in them so charging will be a advisable


stav
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 01:20:38 am
Hello again Pete. Yes you will need 3 speed controllers and you would need to use 3 separate channels on your transmitter. Once you go past two props it gets hard to control everything at the same time. With a three prop boat I would suggest a mixer which reduces the channels needed and will help the boat turn by slowing down or even reversing the prop on the inside of turn. A mixer was suggested for my boat but I turned it down as it isn't really necessary, now however I am thinking of getting one so I can free up some channels to use for something els and I won't need two pairs of hands. :}

Yours Ali.    
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 14, 2011, 02:05:59 am
Hello again Pete. Yes you will need 3 speed controllers and you would need to use 3 separate channels on your transmitter. Once you go past two props it gets hard to control everything at the same time. With a three prop boat I would suggest a mixer which reduces the channels needed and will help the boat turn by slowing down or even reversing the prop on the inside of turn. A mixer was suggested for my boat but I turned it down as it isn't really necessary, now however I am thinking of getting one so I can free up some channels to use for something els and I won't need two pairs of hands. :}

Yours Ali.    

that sounds complicated to do is there a way i can use one speed controller to begin with then later use a mixer and 3 speed controllers ? the pond i will be using this boat in is my local boating lake which is very big..
cant i just get say like one 60amp speed controller and rig all 3 motors up to the positive and negative (daisy chain the motors to the speed controller)

i need to try and keep cost's down iv spent a scary 100 at the minute and iv only got 3 motors.parts to make 3 drive shafts/parts for water cooling motors/3 50mm propellers/ 12v acid battery and nearly finished hull (needs waterproofing)

if there is no way out and i need to have 3 speed controllers what amp controllers do i need and how do i wire them up ? {-) i cant find any instructions on Google :((
and when i use 3 speed controllers how do i use them on my reciver . thumb stick up and down to control all 3 speed controllers? sorry if this is a nube silly question
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 02:27:44 am
Don't rush into anything. It is best to take your time, get the right stuff when you can afford it. You can connect all the motors together but you may find that your boat doesn't want to turn. Plus a big speed controller like a 60 amp one is very expensive and can be a bit un-sensitive.
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 02:37:01 am
It may sound a bit preachy but it took me two years and about 900 to build my boat. I may have had some beginners luck with some things but I never rushed and tried to get the right stuff first time. It will cost you even more if you have to replace parts.
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 14, 2011, 03:08:26 am
It may sound a bit preachy but it took me two years and about 900 to build my boat. I may have had some beginners luck with some things but I never rushed and tried to get the right stuff first time. It will cost you even more if you have to replace parts.

you have a point there.. ok ill go the 3 speed controllers then :) then its done properly . iv just found a video on how to wire them up to one channel on the receiver which is what i want for the minute .

im unsure which esc's i need would 20amp esc be ok with my 12v Johnson 600 motors Off load Current: 1.57A

Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 03:13:33 am
I would probably go with 25s or even 30s. 
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 03:18:24 am
You will be amazed how much difference it makes when your motors are trying to turn the props in the water.   
Title: Re: is my boat to heavy for motors ?
Post by: derekwarner on May 14, 2011, 03:19:55 am
Pete25....I understand your $ costs constraints  <:(....but it appears you did not plan & do your $ sums prior to the build  >>:-(...hence your current $$$$$ quandry

I also understand & agree with the comments from wartsilaone....so is there a compromise?  ;D

1. you could consider running the two outboard motors only...the middle motor could be installed with the prop...but not connected electrically
2. you could consider fitting oversize rudders [two or three] depending on the vessel original design

From here you could consider two ESC + use two channels on your TX...which wil get you into the water & running....sometime down the track when $ funds were available an ACTion mixer could be considered between the two outboard motors only

Not sure on the best search method here, but I have read about 3 engined model vessels [PT style vessels?] where the center engine is only used for high speed work & running without any form of ESC....this facility could be simply switched by servo to micro switch & controlled by another TX single switch function.....

A few things to consider  :-)) .....clearly all is not lost    :-X ....Derek
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 03:28:01 am
I agree with Derek. You could have the middle prop running free for now as the other two motors should be enough to push the boat along. Twin rudders would definitely help.
Title: Re: is my boat to heavy for motors ?
Post by: Netleyned on May 14, 2011, 07:13:06 am
Pete, Is this the Boating Lake?
If so, Come down and see us on
Wednesday or Sunday Afternoons
or Tues/Thurs evenings.
Plenty of experts and not so experts
willing to help.

Ned

(my much modified Victoria in a nice breeze)
Title: Re: is my boat to heavy for motors ?
Post by: John W E on May 14, 2011, 09:42:20 am
hi ya Pete25

I wonder if it would be adviseable for you to temporary 'shelve' shis project.  You may wish to take on a project such as one of Glynn Guest's builds which you will find a lot of his plans have a lot of articles which appear in Model Boats magazine.   Doing it this way - everything you require is set outfor you - i.e. motor/speed controller/props & soforth - a simple plan of this sort is a bit like learning to drive - although you dont like the car you are learning to drive in - it may not be your choice it teaches you the basics.

So once you have learned the basics = you can go back to your choice of model with a lot more confidence and understanding of this modelling field.

aye
john
Title: Re: is my boat to heavy for motors ?
Post by: Shipmate60 on May 14, 2011, 11:26:18 am
Pete,
It might be worth taking Bluebirds advice for a while to consider ALL the options which are:

All 3 motors on 1 Speed Controller.
This can be done very cheaply with an old fashioned mechanical car controller which will take horrendous current safely.
Or a large capacity Electronic Speed Controller.

Only power the 2 outboard motors.
Can be powered as above or with 2 Speed Controllers.
This has the advantage of only using 2 vertical sticks on your transmitter so easy to control.

As above but with the third motor switched by a high powered microswitch switched from another channel on your transmitter.
2 outboard motors powered by 1 ESC using 1 channel and the third using another ESC from another channel on transmitter.

Another option, but not a good one is to use an ESC on the centre motor and switch the outboard motors.

For me the best option but the most expensive is to use an ACTion P94 plus a condor ESC which will give you a mixing facility on the outer motors and throttle control on the centre motor.

I can only recommend you get the motors tested as SOME Johnsons pull high current on 12 volts but are fine on 6 volts.

Another consideration is the wiring from the battery to the ESC(s) as this will have to be able to take the full current of all 3 motors plus some reserve.

For 3 motors on 12 volts I do not think you have anywhere near the battery power so keep the model on the water for any length of time.

You really do need to have the motors tested to be able to tailor the Electronice to them.

Where abouts are you, it would help if you filled in your location.

The motors you have look to be quite high current motors with 1.57 Amps off load.
For 50mm props you wont need any more than about 5000 rpm so she will be grossly overpowered and looks like power hungry.

Bob
Title: Re: is my boat to heavy for motors ?
Post by: wartsilaone on May 14, 2011, 11:28:14 am
Hi pete. I know as a beginner you don't want to hear some of this and I don't doubt at all your intelligence and ability to make a great model. We are just trying to prevent you making the mistakes we have made and save you the countless pounds we have spent changing things. If you really feel you can do this project don't let anyone put you off. A friend of mine suggested I try something easier when I started my ship but that just strengthened my resolve to do it. Whatever you choose to do we will be here to help. There is no such thing as a silly question if you don't know the answer.

Yours Ali.


  
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 14, 2011, 02:52:42 pm
thanks again for everyone's help i really do appreciate it.. this is not my area of electronics . i build and modify pc's but my nolage stops at motors and speed controllers if you haven't guessed by now  {-)

i has seen mechanical speed controllers for round 15 but iv heard about arcing and reliability issues with then not to mention the heat. there so easy to set-up and i would probably go that route but the issues are putting me off.
not only that but i couldn't find a 12v model with hight amp capable.

does anyone no were i can get a old fashioned mechanical car controller from in the uk ? i could give it a go i suppose

i am defiantly going to use 2 rudders (large) for this boat im even considering bow thrusters as i have the tool and ability to make some of my own  :-)


@ netleyned

yes thats the boating lake in cleethorpes would it be ok if i pop down Sunday ? its bit late now to run down there. what time tomorrow would be good to turn up ?
Title: Re: is my boat to heavy for motors ?
Post by: Shipmate60 on May 14, 2011, 08:13:51 pm
Pete,
Here are some videos of my 10 foot Cruiser hull on the water with an ACTion mixer.
The hull and batteries are heavier than your proposed all up weight.
BUT she is running 50mm props (3) at less than half your proposed rpm.
As Bluebird has said she will fly.

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture031.mp4?o=4

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture030.mp4?o=5

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture029.mp4?o=6

Bob
Title: Re: is my boat to heavy for motors ?
Post by: RaaArtyGunner on May 14, 2011, 09:49:42 pm
Pete, Is this the Boating Lake?
If so, Come down and see us on
Wednesday or Sunday Afternoons
or Tues/Thurs evenings.
Plenty of experts and not so experts
willing to help.

Ned

(my much modified Victoria in a nice breeze)
Ned,
How did you achieve such a fantastic water display from the Fireboat, looks great
 :-)) :-)) :-)) %) %) %)
Title: Re: is my boat to heavy for motors ?
Post by: Pete25 on May 14, 2011, 10:07:36 pm
Pete,
Here are some videos of my 10 foot Cruiser hull on the water with an ACTion mixer.
The hull and batteries are heavier than your proposed all up weight.
BUT she is running 50mm props (3) at less than half your proposed rpm.
As Bluebird has said she will fly.

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture031.mp4?o=4

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture030.mp4?o=5

http://media.photobucket.com/video/prinz%20eugen/shipmate600/Picture029.mp4?o=6

Bob

wow that cuts though the water so nicely  and is really fast ! do you have any pictures of the motor section ? that is a nice hull design did you scratch build that ? i don't think i could ever build a hull that nice  {-)
Title: Re: is my boat to heavy for motors ?
Post by: Shipmate60 on May 14, 2011, 10:26:35 pm
She is a plank on frame hull built well over 20 yrs ago (not by me)

The pic shows the initial installation before the P94 was produced.
She was 1 of the first to have it fitted and tested.

Bob