Trim tab settings for double set

[mrproc1]

Hey Ya'll....
I just got my second set of tabs as you can tell from new paint pics. I was wondering should I set the outter tabs a little bit more down so once the boat starts to chine walk at speed it won't roll so much with the outter set more down??? Just a thought, what's the rule of thumb.
Someone smarter than me should make adjustable tabs from the TX and make millons!!!!

[dag-nabit]

Trim tab settings really are specific to each individual set up, so there isn't really a rule of thumb that applies to all boats.

Technically the function of the trim tabs is not to stabilize the boat, but rather to adjust the attitude of the hull by either lifting the stern and pushing the bow down, or allowing the stern to ride lower and let the bow ride higher. A well trimmed boat should run pretty stable, so indirectly the trim tabs can affect stability.

Your strut alignment, battery weight and position, and the placement of other components all affect the center of gravity of the boat and how it will ride with everything at "neutral" settings.

As an example, the Aquacraft SV27 comes from factory with battery trays that don't allow for changing the battery position forward or aft, and the motor, ESC and Rx are all factory positioned to distribute the weight to provide a decent center of gravity. With the strut angle set at neutral, running a pair of 2S 5000mah batteries my SV27 tends to ride a bit high on the bow making it prone to blow over at high speed. I can adjust the attitude of the boat to lift the stern and lower the bow a couple ways. 1. adjust the strut angle slightly negative (down), or, 2. adjust the trim tabs slightly negative (down) to do the same thing, raise the stern and force the bow down.

I left the strut at neutral and after a bit of trial and error found the correct setting for the trim tabs to provide a stable, fast ride.

Note: If you adjust your trim tabs too far negative you can "kick" the stern up when you hit a wave which will cause the boat to "nose in" and torpedo under the surface.

The Spartan is a bit of a challenge to dial in for a couple reasons. The first being the large battery trays that allow for almost infinite combinations of battery placement, and obviously the larger and heavier the battery, the more sensitive the set up will be to changes in battery position.

IMO finding the battery position that provides the best balance between stability and speed is the first step in dialing in this boat. Batteries too far forward and the hull runs wet, which helps increase stability, but sacrifices speed and can increase the risk of nosing in. Batteries too far aft and the hull runs drier, which helps increase speed, but reduces stability and can increase the risk of blow over at high speed.

Once the best battery position is found the ride can be fine tuned using strut angle and/or trim tab adjustments.

The second, and likely most significant challenge to achieving a stable fast ride with the Spartan is the very deep vee of the hull. When the Spartan rises up on plane the steep rise of the vee is kind of like trying to stabilize a triangle resting on it's pointy end.

To date I'm not aware of anyone who has solved the chine walk on the Spartan to the point they can claim a 100% stable ride. Myself, after much trial and error have managed to get a reasonably stable ride at high speed, but hit a bit of a wave and my Spartan will get loose real easy and throw itself into a death wobble.

To summarize: IMO and experience battery position will provide the most significant results when tuning the ride on the Spartan, once you have determined the best battery position, fine tune the ride with minor adjustments to the trim tabs and strut angle.

Kevin

PS as a side note I'm experimenting with running one of my Spartans with no trim tabs or turn fins installed. It has been a crazy summer and I haven't had a chance to run the boats much and have only managed one run with the "bare ass" Spartan. The initial run would suggest that running without the trim tabs did not make the boat any less stable, it seemed to be about the same as before, but it will take several runs in various water conditions, and trying different battery positions, before I can draw any conclusions on the effectiveness of the trim tabs.

[mrproc1]

Thanks Kevin, I was hoping you 'chine' in. I also was thinking about taking the tabs and turn fins, just to see what she'll do..As far as battery placement. I run mins all the what foward, with the stir at neutral, and just a little of negative of the tabs seems to but the boat right on the surface at speed. So I will have to play around with placement of batts and strut angle, with good notes.
Thanks for all the info, I'll have to read it couple times for it all to soak in. Keep me updated on the no tabs and turn fins

[dag-nabit]

Your welcome, and have fun experimenting.
Kevin

[Heaving Earth]

Think of it like this, you're trying to balance a triangle on 1 point. It's gonna rock back and forth. Adjusting the inner tabs will be more effective than adjusting the outers. Which tabs are closer to the water at speed? The inners

[mrproc1]

FML!!!!! Took he boat out a little bit ago, and one of the wires from ESC to the battery's blew off!!!!