How do trim tabs work?

[Blackmanba]

G'day mates. I'm new here. I have just finished restoring my ten year old 50inc Mono with Hansen Zenoah Indy G23. It is set for racing but never used for that purpose and was sitting in my garage for years. It has trim tabs and turn fin on right side.It has sub surface prop settings.My first run showed that it still had same speed and controllability it used to but it run very flat. I adjusted prop and trim tab angle so that end of them pointing bit more upwards to get on plane. As result, it gained better acceleration and heaps more top speed. Not flat anymore,:D,however it didn't turn well and ended heavy span broken rudder linkage.I fixed it by now but I don't know what to do about it. :o Is this help if I flatten tab angle a bit? Thank you for your help.

[Ron Olson]

The trim tabs aren't the problem then, it's the turn fin not being installed correctly or not being large enough.
Can you post a picture of the transom so that we can take a look? We might find something else that may be the problem.
If the boat is running too loose on the water and you're trying to turn it running wide open, there may not be enough of the hull in the water to dig into when turning causing it to slide.

[Blackmanba]

Thank you. I will try to upload a photo as i hve no digital camera. The turn fin is Prather Stainless large turn fin for Gas Mono. It turned too violently, I mean like snapping.

[Blackmanba]

Here is the photo. Sorry for poor quality it was taken useing Mobile Phone Camera.

Mmm.. I cannot insert my photo in enhanced mode... I will try again.
I tried to post it many times but your program keeps tellimg me that my picture has error although it is fine within my PC. :confused:

Oh well, if trim tabs are OK then may be my rudder servos through rate was too much therefor it turned the boat too quick? If so, I will adjust my Futaba 3VCS's ST-EXP to mild and ST-Speed for delay. Should I also use program mixing to back off throttle a bit from full potision as radder moves? Thank you.

[Ron Olson]

Try going with wider turns to see what happens if where you run has the room. Trying to read what you first posted, I'm not sure if you typed that it is spinning out in the turns. If so, the center of gravity may be too far forward lifting the rear out of the water causing a spin.

[Blackmanba]

Thank you Ron. Sorry my poor English as it is my second language. The boat turns OK if it takes time and big radius curve but it was so sensible to my stick movement. It turned like snapping a pencil as I start pushing the stick to right. I hope you can understand me this time.

[Blackmanba]

I hope this time I can post the photo.

[Blackmanba]

Another one

[Blackmanba]

Other side

[Ron Olson]

You just may have too much steering throw or trying to turn it too tightly. Hard turns with too much steering can spin the boat out. You only need 15-20 degrees of steering throw in each direction from center.

[Blackmanba]

Hi from down under, thank you for providing me the solutions with great infos. I was always wondering how much of st-angle would be appropriate but never found it. I will reset my throw rate to much that angle. :) So, what do trim tabs do? RCBM was always only my source of knowlege and now I have just found that it was getting better. :D

[Blackmanba]

HI Ron, I finally had chance to run my boat with new settings according to your info today. I have to thank you. I had my best run ever. I took it to big river and I was in a modern alminum boat with 30 hp ooutboard. The RC boat jumped wake beautifully stably and easily passed our real boat which was going at full throttle. I did'nt need to back off at all to turn eather way (of course right hand turn was better though). With huge rooster tail, it kept going. Now I cannot go back to my usual lagoon. It's too small for it. :)