Need help please
 

Hi guys I need some help with my craft. This is my first boat so it is a BIG learning curve for me. I have a few questions, hope someone can help

A: What should I pack the drive shafts with? oil grease?

B: I have a couple of motors they are 380's, do I need bigger motors? or gear reductions? or both?

It is about 6 feet long and has 2 X 50mm 3 blade props. I am not looking for speed, more of a scale speed. Will they work.
Any help and advice would be greatly appreciated

http://i147.photobucket.com/albums/r...k/PB082211.jpg

RE: Need help please
 

Depends on the prop size, but dual 380s would probably be best geared down 3:1 or so. Otherwise, you may bog them down too much and overheat....just my opinion....

RE: Need help please
 

...just my opinion....

Your opinion is correct. Without gearing, those motors are future landfill. I would use gearing with what ever motor you decide upon.

Let's get some more comments on this one. Someone out there has done this before.

Are 380s too small for a boat that is six feet long, with 2" (50mm is about 2") props? Probably.

I have always hedged my bet on more power. Wind and strong currents can push a boat around. You may want to go with a pair of 12v 550s (such as the MACK 5045) as a minimum.

For gearing, you can look at Harbor Models and Lloyalhanna Dockyard for ideas. They also have some motor / gear combos that will work well. You may even want to call them for a recommendation.

Simple brass gears can be bought from Dumas in a variety of ratios. Electrify makes a gear set for sailplanes that bolts directly to the face of a 550 sized motor with a 2.5:1 ratio.

Sounds like the hull might accommodate a fairly large battery (sealed lead acid) so supplying amps is probably not a constraint. I really believe that 75% of the success of this project will be found in the gears. Once you have a good gear set (3:1 sounds about right), just about any good motor will run efficiently. But 380 is just intuitively too small.

RE: Need help please
 

rcshipyard I like it. What's she for ?? Looks like a work horse Nice Job

RE: Need help please
 

A rule of thumb indicates that prop diameter should not be greater than motor diameter without gearing.
Its a big boat, so big motors and gearing is the way to go. A 380 with a big prop is a recipe for rapid disappointment. As suggested, 550s or 545s plus gearing should suffice. Lots of people have good results using automotive motors - fans, window winders etc, sourced from scrapyards. Big enough to do the job, speed and torque good, modest current drain, lots of poles and generally built like brick outhouses.
Pulleys and belts are usually quieter than gears.

RE: Need help please
 

First I agree with what has been said. Having a smaller 18" pusher work tug, they have high superstructures so catch a LOT of wind. Going sideways or backward at full throttle is no fun. The brass Dumas gears sets are VERY noisey...nylon-belts/pulleys is better. There are some good Graupner or Pittman servo motors that might work. You might also look at the Dumas-Pittman (#2004) 5000 RPM motors for straight drives and adjust the props accordingly and they are quiet.

Dave...RCTUGGER

RE: Need help please
 

You WILL DEFINATELY need 1 or more keels to prevent the wind from taking complete control. 2 keels would also protect the props & rudders on setdowns.

Once you get the SIDEWAYS drift down to what you will accept, then the main motor size will be much smaller.
What is the weight with no battery or motors ?
Is the bow curve really that far back as the picture looks like ?

I dance to a different tune all the time. ;)

RE: Need help please
 

Thanks for the input. I have a couple of unused Tamiya stock motors and a couple of 2.5/1 reduction boxes, and found 2 matching ESC's will give them a try and work from that. The idea about auto elec motors sounds like a good way to go for 12 volt.

I am building this as a landing craft for my RC 1/16 tanks. i have no idea how much it weighs yet so on the weekend i will get some side on photos and find out how heavy it is

Thanks again for all of your help

RE: Need help please
 

Here ya go, a few snaps from the side and a couple of the props.

http://i147.photobucket.com/albums/r...k/PB162215.jpg

http://i147.photobucket.com/albums/r...k/PB162220.jpg

http://i147.photobucket.com/albums/r...k/PB162217.jpg

http://i147.photobucket.com/albums/r...k/PB162218.jpg

http://i147.photobucket.com/albums/r...k/PB162222.jpg

RE: Need help please
 

Looks ready to swim.

Did you hide the ramp cables?
If you need to add a keel or keels. Use clear plastic. Did the real ones have keel.
What is the classificationof her? LC............
I found a close one. LCT MK-6 ?

Rich

RE: Need help please
 

Come to a bit of a standstill (waiting parts) don't you hate that? :-\
Grabbed some stuff and loaded up the LCU/s to fill in a bit of time :'(

http://i147.photobucket.com/albums/r...k/PB192234.jpg

http://i147.photobucket.com/albums/r...k/PB192238.jpg

RE: Need help please
 

At 6 ft long your 380 will not have the power this model needs I would sagest at lest 600's you could run 700 or 800 motors I would gear them at 2-3:1. Yes Pack the stern tubs I use auto wheel bearing grease, water proof, High presser, stays where you put it, last forever. If you would like to see some of my 103 boats go to www.jsgill.net.net

RE: Need help please
 

. Got it built and fitted out, still needs to get wet. Off to the river with the video camera first chance I get. But for now here are some snaps.

http://i147.photobucket.com/albums/r...k/PC072244.jpg

http://i147.photobucket.com/albums/r...k/PC072245.jpg

http://i147.photobucket.com/albums/r...k/PC072261.jpg

http://i147.photobucket.com/albums/r...k/PC072262.jpg

http://i147.photobucket.com/albums/r...k/PC072255.jpg

http://i147.photobucket.com/albums/r...k/PC072260.jpg

http://i147.photobucket.com/albums/r...k/PC072257.jpg

http://i147.photobucket.com/albums/r...k/PC072253.jpg

http://i147.photobucket.com/albums/r...k/PC072252.jpg

http://i147.photobucket.com/albums/r...PB192234-1.jpgOk

RE: Need help please
 

Just posted a video of the Landing Craft,sorry but only on dry land :-\ Can't wait for the week end

http://www.youtube.com/watch?v=egt1iD7x_Qo

RE: Need help please
 

Looking good OZ.
Nice rusty weathering on the weld seams.

Rich

RE: Need help please
 

Back again. Took the LCU down to the river today for its first run.:)

Tried it without any tanks first just in case it didn't do what it was supposed to do, All went well;)

Loaded 2 RC tanks on board and set off again, but then in the middle of the river it stopped running, then the wind got stronger and it found its way to the tidal flow.[X(]

PANICE[:@]:([:'(]

But lucky for me the wind blew it to the edge of the river and I was able to rescue it without any damage to the Craft but a lot to my pride.[:-]

The props and rudders got jammed with weeds. Did a quick Video[&o]

http://www.youtube.com/watch?v=T-KJ4ShtgwU

RE: Need help please
 

SALTWATER CROCS !!!!



:D

RE: Need help please
 

What a fantastic build, nice work

Looks like the Onkaparinga, definitly no crocs, swam across it once in the middle of winter to retrieve my IOM after suffering the same fate, Brrrr

Nick

RE: Need help please
 

Ok, went down to the river today with my landing craft, a couple of tanks and my M16.[&:]

After battling with the weeds, strong current, and high winds I had a great time and everything went well. Except for the flat battery in the M16.[:@]
The Landing Craft runs very well, too well, it is too fast on full throttle. [X(]

Any way a picture is worth a thousand words so here is a VIDEO.[8D]

Click on the link below.[:-]
http://www.youtube.com/watch?v=UHgErYUvns8

RE: Need help please
 

Cool vid.

RE: Need help please
 

Only thing I saw that you might want to address is the ramp speed. If I remember correctly, the ramp on the smaller landing craft just free fell to unload, so if you have a way to increase the speed...........................
Otherwise, looked really good

RE: Need help please
 

A great video Oztruck. Lots of action and animation.

Suggestions
Perhaps slightly less pitch on the prop blades may slow it down a bit.
A flag may add to the realism.

Reilly4

RE: Need help please
 

We used something similar when the army was building the runway on lord Howe Island. Today is Australia day so I will see if I can get some small Australian flags to go with the LCU, M113, Centurion Tank and Mk 3 Land Rover and get some Vietnam type video. Thanks all for the help.

RE: Need help please
 

Moved on from the 40's to the late 60's. Hope you like it


http://www.youtube.com/watch?v=wuuw3S2w-Jo

RE: Need help please
 

I like the air brake release, and the back up alarm...

Are you using the Tamiya truck/tractor sound chip?
Other than those two points, It sounds great.
The speed of the ramp is excellent also.

Great build and performance. :)

RE: Need help please
 

Yeah it is the older Tamiya sound for there trucks not the MFU. Thanks for the encouragement.