Home built cat and leopard 5692

[mm123521]

Hello All:
About 9 years ago, I was into gas boating (zenoah's), and have been inactive sence then. Now, I have discovered FE. This home built hull will be my first electric boat.

Back then, I built 6 or 7 hulls, mostly plywood over foam, cats.

Took one of my hulls and cut the center out to yield 2 nice, 41 inch, sponsons.
Now building a narrow, 7 inch wide center to glue between the sponsons.
I got a aromarine sprint cat 44 inch hull with an 8 inch center. I figure there will be less lift on a 7 inch wide center, and I'll get more speed before it blows off.

Got the 7 inch wide center built, with a Leopard 5692 motor all mounted up and water cooled.
Have a 12S 5000MaH battery, and a Castle ICE 160 HV controler (I will water cool the controller). Motor is 730 KV, so I'll get about 32000 RPM.
The hull is incomplete, but it looks like it will have a RTR weight of 11 pounds.

Looking for 60 to 70 MPH. I think theres plenty of power. I think speed will be limited by the hull blowing off the water.

I have fooled around with the CG and can get from 34% to 45 % by adjusting the battery position.

Pictures to follow.

Mark

[mm123521]

http://i192.photobucket.com/albums/z65/mm123521/HPIM1031.jpg

http://i192.photobucket.com/albums/z65/mm123521/HPIM1032.jpg

http://i192.photobucket.com/albums/z65/mm123521/HPIM1030.jpg

http://i192.photobucket.com/albums/z65/mm123521/HPIM1034.jpg

http://i192.photobucket.com/albums/z65/mm123521/HPIM1035.jpg

http://i192.photobucket.com/albums/z65/mm123521/HPIM1029.jpg

The pink stuff is insulating foam, the wood is mostly 1/16 inch plywood.
Check out the motor hatch. About 25 4-40 flat head screws and a 3/16 inch neoprine foam gasket will keep the motor compartment dry. Will build similar hatches for the rear compartments.

Mark

[tiqueman]

Weclome to the forums. Cant wait to see the pics! Search around on the cat builds. Especially Bonewars Martrimo build. Some cool ideas for keeping the hull planted.

HA, you posted pics while I was typing. Nice!!!!!!

[Ub Hauled]

Interesting that you placed the motor so far forward, are the batteries going to make a difference in the CG if moved? Where is the CG without the batteries in it?
One thing I notices is that the motor compartment is very tight, this may or may not increase the temps on the motor if you push it a bit harder (bigger wheel)... just a thought to keep in mind.
nice build though, keep pix coming on the progress

[mm123521]

Ub:

Yes the motor is way forward, but CG can be at 34% , if I move the batteries to the rear. CG with no batteries makes no difference, cause you cant run the boat with no batteries. I put the motor way forward, so I could adjust the CG to about 40% if I need to, to keep it from blowing off. I wonder if it will still handle if the CG is at 40 % ?? I dont know, its been a while sence I designed any hulls.

Your right! There will be NO air cooling of the motor. It is in a very small, air tight compartment. I built a water cooling jacket for the motor. I hope thats enough?

This boat is designed to be 100% watertight, using closely spaced screws and gaskets on the hatches. Also everything is built strong enough to survive 15 G decelerations when it blows off and crashes.

I will work on rudder mounting tonight.

Mark

[Ub Hauled]

lol
I was asking about the CG with out cells in case you need it to be less then 34% like you said it yourself, you have been out of the market for some time and the hull may like the rear CG since the tunnel is narrow... I could be wrong, just a thought.
Welll... my take on cooling is, there is no such thing as too much cooling when it comes to electric motors being pushed hard... again, your cooling jacket may be more then enough.

Keep on trucking man, I wanna see the outcome

[mm123521]

Ub Hauled:

I hear what you are saying about the COG.
As the build advances, I tested the COG again and I can get it back to 30%.
That is with one set of batteries (12s1p). The COG will get better if I use 2 sets of batteries (12s2p).
The boat may hit the water next weekend.
It looks like it will come in at under 12 pounds with one set of batteries.
Drive line has nice gentle bends and is smooth. Using a 1/4 inch flex cable.
Working on cooling the ESC (CC ICE 160).
I got an X452 prop (from an old nitro boat) as a starter prop. It should get me into the 50's MPH???



Mark

[Gerwin Brommer]

Any pics of the sponsons ?
100% flat, no steps ?

[mm123521]

Yep -- no steps.
It ran good that way when they were gas powered.
I was going for simple construction.
I built 3 gas powered boats this way and it didnt seem to be a disadvantage.
The construction is: thin (1/32 inch and 1/16 inch) ply wood over foam. The steps are a lot of extra work.
Maybe the light weight construction compensates for the lack of steps??

Also there are no strakes to keep the water from rising along the inside of the sponsoons.

I'll bet it still goes fast!!

The foam is built in flotation.

Mark

[Gerwin Brommer]

My only concern is the narrow surfaces of the sponsons surfaces, that actualy touch the water when the boat is at speed.
Combined with the high tunnel and low weight of the electro-setup.
It might wanna go fly easily on the straights, and drift like h*ll in turns ?????

[mm123521]

Gerwin:

You may be right, but, I'am gonna find out in just a few weeks!
If it doesnt work out, I'll just buy a hull and transfer the drive components to the purchased hull. I like to build from scratch, so I chose this path first, over just purchasing a hull.
The tunnel on this boat is 1 inch narrower than a 44inch Aeromarine sprint cat and about the same height, so I think it will stay on the water better than the sprint cat. But it is hard to predict the aerodynamics of a prototype hull.

Mark

[MOSQUITO6717]

How does Leopard5692 work on your hull? , I am planning to put one on my Sprint cat 42" soon.

[mm123521]

OK , I got the boat in the water!
I was worried the small prop would cavatate and not "hook up".
But, It sure hooked up!!!
Huge acceleration! and full speed on the streight away. No signs of a "blow over" and it was a very windy day.

Sorry, but I was alone, so no pictures or videos.

X452 prop and 32000 rpms (12S and 730 kv) should equal 65 MPH????

I only made 3 full speed passes (about 75 yards long).
Then I brought it in to look at the cooling water flow.
When I put it back out, I punched it from a standing start and it leaped out of the water and flipped over!! It was on the water 20 minutes, up side down, so i took it home to check for damage. It got a small amount of water inside from a seam that was leaking. I was so anxious to get it on the water , that I skipped the leak test.

Batteries were at 24.3 volts, after the run. Running two 6S packs 5000 MAH. This means that I didnt use much power from the batteries?

Ok, on the streight away, it was bouncing up and down, every 40 feet or so.
It was not running flat and steady. What would cause this? COG too far forward at 34%??
I know my rudder is way too long - it extends 3.75 inches below the sponsoons.
Could this be the cause? The steering was very sensitive when running full speed.
I am using a Futaba 6EX, a joy stick radio - that wasnt helping the situation and Iam not used to steering at high speed.
Next time, I will have the rudder trimmed to a reasonable length and the rudder adjusted to limited travel.

MOSQUITO6717: Plenty of power with 12S and a Leopard 5692 !!! No cooling problems, but the water is Ice cold in Illinois, in november.

Mark

[FighterCat57]

Keep the long rudder. It will help turning the cat.

Try moving COG back to 28%.

Cool boat. =)

[mm123521]

Fighter cat:

Ub Hauled might have been right about the COG too far forward.
I have a light boat (12 pounds full up - ready to run), so I can add weight to the rear (UGH! ) and try it again. Thats the problem with building your own hull, you have to guess at a lot of things.

Mark