Need Help with MRP Tunnel

[Firsick]

I have a MRP Tunnel with a Diamond 12 turn motor and a X432 Prop.
It dosent get on plain and it bearly moves in the water. Please give me
some advice on what to do to make this boat run? I dont race the boat
I just like to play.

[Fluid]

There are just too many reasons why the boat doesn't run right - I need more information to diagnose the problem. I used to run an MRP tunnel so I know a little about them.

1) How many cells, what type of cells, and how are you charging them?

2) What kind of speed controller are you running?

3) Have you lubricated the flex cable and the bearing in front of the prop?

4) Is the motor used, or new? Are the brushes and springs worn out?

5) How far in front of the transom does the boat balance with everything in it?

6) With the hull sitting flat on a table and the OB hanging off the table, where is the centerline of the prop - above, below or even with the top of the table?

7) Is the prop shaft angled up or down relative to the table top?

8) Does the prop spin very very fast but the boat still doesn't plane off?

With these answers I can give you better help.

[Firsick]

First thanks for your help.

1. 2 - 1500 Dyna Sport which equels 12 cells. I charge them with a
MRC Quick Charge 15 min. Charger.

2. Tekin Speed controler

3. Yes they are lubricated

4. New Motor and I would hope the Brushes and springs are new too.
I havent ran it but about 45 sec.

5. The boat is balanced at the turn fin or about 6 inches from the back of
the boat.

6. The Prop is below the Table but olny by about an inch.

7. The prop is angled up

8. When I run it out of the water for about 3 sec. you can feel wind like a
fan on high. But when I run it in the water it really dosent run right.

[Fluid]

Okay, several things to try. First, the 12-turn is too much for 12 cells, even the rather soft 1500s. If you run it again, add in about 3/16" of timing advance. That will reduce the damage, but it is still too much motor. A 16 to 19-turn would be much more appropriate with that much voltage.

Next, try an Octura x431 prop. This will load the motor less and flex a bit. You can use the x432 but don't run the boat for too long at a time without checking temperatures.

I'm not clear on how deep the prop is set, but the center line of the prop should be even with the tabletop to start. You can try raising (or lowering) it an 1/8" at a time, but start with it even with the table top. The OB should be angled up several degrees at the prop end.

I'm not familiar with that particular MRC charger, is it a timer only or a peak detector? If it is a timer only, you may not be getting a full charge into the packs. The packs should get warm when they reach full charge, if they do not then they are not fully charged and may not be putting out full power. If in doubt, trickle charge them overnight.

The next time you run the boat, even if it runs okay DON'T run it for more than one minute - use a stopwatch! Bring it in and check for heat in the motor, ESC and packs. If all is okay, then run it but not for more than two minutes total (if it will run this long). Watch the brushes for wear - with the motor hanging out there they can get wet, and when they do they wear down fast! Good luck and let us know how it goes.

[Firsick]

So this is what I did.

1. I took out 6 Cells and Im now running just 6 cells.

2. I removed the Octura x432 prop and replaced it with an Octura x430 prop.

Now it runs faster but it Cavitates. So I played with the trim first up then down then right in the middle and pretty much all over. Then I moved the motor up and down and played with that all over the place and moving the trim while doing this and no matter where I put the motor it still cavitates.

Any ideas???
Im lost. :confused:

[Fluid]

Okay, now with a more reasonable number of cells for the motor (good idea!) you can go to the larger prop. An x430 may be too small for a boat that size. The x432 is probably a good choice now, an x435 might be too big but you could try it if the x432 doesn't work. I know my old MRP tunnel ran with an x432 and 8 cells with a 15-turn motor.

Anyway, from here in Texas is it tough to call since I don't know how far up and down you moved the OB. I suspect that with the larger prop you'll solve the issue with the cavitation. You can move the CG back a 1/2" or so to plant the prop deeper in the water. Put the motor back so the centerline of the prop is even with the table top and angled up at the prop end a degree or two.

[Firsick]

Fluid
Thanks for your help. I will give it a shot and let you know the out come.
I can do all of this pretty quick because all I have to do is walk out my
back door and out on my dock to the water. You see I live on the lake of
the Ozarks. My wife and I own a bar and restaurant. So I will let you now
how all this works. I guess I can apply all of this knowledge that you have
giving me to the rest of my boats? I have 5 more to finish. I will get some
pictures up ASAP. Thanks again for all your help.

:) :) :)