HK Smash Shark P1

[785boats]

Where is the balance point on the boat with the setup you have shown in post #8? It should be at about 28-30% of the length of the boat, forward of the transom, not including the overhang.
The battery looks too far forward to me. I think we ran that type of boat with the battery close to the motor & the ESC beside the motor on the left.
That m442 should get that boat up on the plane if the cog is right.

[mcmoise]

Im having the same issue with my hk outerlimit.

[Old School]

The balance point is at approximately 35%. The battery is in the location as set by HK. I will relocate the ESC and bring the battery aft. I believe the TFL detongued prop that I used has not enough blade area to get the boat moving.

[Doby]

Why didn't you mount the trim tabs flush with the bottom of the hull?

[Old School]

With the ESC to the left side aft and the battery moved aft to the motor, it shifted the C of G approximately 1.25 inches aft making it still around 33%.

As regards the trimtabs, sitting them flush would have positioned them under the stinger shaft location on the transom placing them always in the water.

[Doby]

Ummmm..your hull will be keeping them out of the water.

[iop65]

Trimtabs should be about 1-2mm above the bottom
But i doubt he will need the with the cg so far forward

[Old School]

I have not been able to test yet, however, a search on Google returned a result whereby if in initial setup the throttle reversing switch on the transmitter is in the "REV" position and the motor is set to turn in the correct rotation relative to the prop then full throttle application on the transmitter will only see approximately 50% throttle at the ESC. On my transmitter the writing is so small that 20/20 vision is needed to see the switch position. My transmitter had the switch in the "REV" position. I have corrected the situation with the switch in the normal position, set throttle range on the ESC and motor rotation normal.

To sum up, apart from correcting the situation above, I have shifted the C of G slightly aft (1.25") , lowered the stinger to lowest possible position, fitted a rotating bushing (to minimise friction in the drive) and fitted a 440/3 prop. I know shifting the C of G did not get the boat on plane so hoping that any of the other corrections will help when I finally get to test the boat.

[Old School]

I finally was able to test the boat after doing the above modifications. The boat now has a very good turn of speed however, under power the hull porpoises. When power is applied the hull accelerates hard but then with speed increase it becomes decidedly unstable with the bow rising and falling. The hull completely leaves the water as the bow rises and then the boat settles back into the water and repeats the process (stinger strut was adjusted in a neutral position).

Unfortunately, I was unable to retest the boat after moving the battery forward approximately an inch (almost to original stock position) and adjusting the stinger strut with a negative adjustment to hopefully keep the bow down under acceleration. The hull seemed fine under right hand turns but seemed to chinewalk slightly on left turns. As the boat passed over ripples in the water from previous passes it did seem to induce a little chine walking but otherwise not evident.

After ten minutes runtime (4s 5000 mah 45C) only the additional factory caps on the ESC were warm. The motor, battery and ESC were all almost cold.

[rol243]

sounds like the trimming is nearly there. its good if you can leave the prop set parallel with zero neg or positive and just correct the trim via battery placement. good run time too, check voltage per cell to make sure all is safe.

[Old School]

Each cell read 3.5 volts after the run (ran until LVC). I was amazed at the change in performance. Previously it could only raise the bow and push through the water like a displacement hull. Now it flies, not as quick as my son's cat but a joy to watch.

I have a Grim Racer 44 1.5 2-blade to try, but as my son starts next Monday with the Queensland Ambulance Service as a paramedic, today was the last day we both could be on the water. I may have to join a club??????????