Speedmaster .21 setup

[MikeP]

I seem to be having trouble getting my CG set on a SM .21 with a MAC motor.

I would like to get it at 8.5". The only way I can get it close is to mount the fuel tanks in the sides of the hull and slide the motor back 2" from where the instructions indicate. This motor position is as far back as I can get it with out the flex hex going under the radio box. Doesn't seem right.

Also how much does your average .21 mono weigh?

Mike

 

[Joe_Knesek]

Mike, on my 2004 model Speedmaster, I have the motor mounted 12 inches from the inside of the transom. I get a Tank made from Mike Z that is tall but only about 2.5 inches long. This keeps the fuel close to the CG. I mount it 15 inches from the transom. I use 2 micro and 1 regular servo and a AAA pack. The box is mounted 1/2 inch from the transom. This set up is fast and stable but a little light by the end of the run.

I also have a 2004 model set up @ 13 inches for rough water. It's slower but finishes all the time. My 2005 model is set @ 12.5.

 

[MikeP]

Thanks for the measurements Joe, here is a pic of my hull maybe you can see somthing I am missing. The motor is a 11" from the transom this puts the CG at 8.5". I have been checking the CG with everything in place.

 

[MikeP]

Another shot

 

[Ron Olson]

You need to angle the motor downwards for thre cable to run properly through the hull. I have mine set up with the motor further forward also with the fuel tank up under the deck. It's tight but fits. No trim tabs or turn fin and it handles well.

 

[Pennywizz6]

I envy your boat mike, its awesome!

Phil h34r:

 

[Joe_Knesek]

Then engine seems too far back to me. You have the same trim tab set up I'm running.

 

[izitbrokeyet?]

I have my speedmaster set up at 12".......8.5" is way too loose

That motor should have the carb throat just behind the drop-off in the deck channel.

I also run mine without tabs.......runs well without

 

[Preston_Hall]

Mike,

Did you measure the CG with the shaft and pipe mounted? Was the tank empty?

 

[MikeP]

I finished the boat Saturday night getting ready to run it Sunday. It was ready to run with a empty tank. Motor is mounted at 12" from transom. The carb intake is just inside the top deck.

I don't see how you can set a MAC motor at 12" have no trim tabs and have your CG where it should be according to the directions.

If 8.5 is to light 9.0 should be good. I would think 9.5 is going to be slow.

Thanks very much for the input.

Mike

 

[Joe_Knesek]

Mike, I'd run it like you have it. If it's too tight, move the tanks to the side to adjust the CG. It's going to look like a dog by itself but with other boats running, it will free up well.

 

[tracerbob]

Hey guys, still working on my boat. Engines mounted right on 12" form the transom. Threw all my radio gear in it this weekend and it balanced at 8-1/2" minus the tank. Haven't had much time to work on it as my day job has kept my busy with overtime. As you can see, I've mounted everything as low as possible and now I'm having to rethink the radio box as the stock one won't clear the pipe. <_< That green piece of foam is a mock up of a new radio box. it's going to be a pain in the butt to get everthing to fit.

 

[tracerbob]

Here'a shot from the side.

 

[tracerbob]

I also had my machinist buddy at work chuck up the stinger on his lathe and cut it back to 2-1/2" total length. He also moved the stepped down section back a 1/2" to clean up around the prop. I hope once I mount the tank, it will still balance out

 

[Joe_Knesek]

it's going to be a pain in the butt to get everthing to fit.

Instead of making a new box, just cut a section out of the stock box and glass it back together. That's what I've been doing and I stress tested it last week @ the Nats and it does not leak.

 

[MikeP]

Thanks for the help guys.

Here is a new question, do you have any drain holes for water that might get picked up during a run?

Mike

 

[izitbrokeyet?]

the strut hole is oversized to allow for adjustment and get the water out. When it stops, it sinks down until the flotation keeps it up.

 

[MikeP]

Hmmm, if you run the stinger it covers the oversize hole.

Mike

 

[ClayGlover]

that thing's a lot pertier than my seaducer

looks good mike

 

[Ron Olson]

I don't have an oversized hole for the cable, I set mine up according to the instructions. My rudder linkage hole is a bit big so I just tip it up and out it comes.