Re: Cheaper alternative to Bennett trim tab switch?
I appreciate the help. I don't know how old it is, the boat is a '73 cruisers Mackinac and they don't look to be factory installed but it's possible.
I was originally looking at using a couple of 5-pin relays with a normally closed pin to interrupt power to the opposite direction's power wire. Then using some (on)-off-(on) rockers. Could do it for free (power window switch and leftover relays) and an hour or so of work.
Option 2 is I think I could accomplish almost the same thing with some (on)-on-(on) rockers and loose the relays.
Option 3 and what I'll most likely go with is to use a micro controller, probably an Arduino. I should need 4-relays, 2 of them with a normally closed contact just for the motor's safety in case of a software bug, 4 transistors to drive the relays, and some other small componentry. I can use a waterproof membrane keypad to control the tabs.
The next step would be to add a 3 axis accelerometer to feed the controller boat attitude data. It could filter the data and actuate the trim tabs accordingly.
The next next step would be to bring in NMEA data from a GPS antenna to give speed and reference a table to get to a better trim tab position sooner based on a table and to use the derivative^2 of instantaneous position to "level" out the accelerometer's reading.
It would be easy to scroll ride angle data and GPS info across an LCD screen.
I think for any auto trimming work I would have to figure out a way to get some kind of position feedback from the tabs to avoid over extension/retracting which seems tough given the environment these things operate in.
Aside from the position feedback from the cylinders, I think I could put this together with new components and the accelerometer and maybe a GPS antenna for less than the cost of the "correct" switch in a few evenings. I could use the same controller in the future to hold a heading for the kicker motor too.
I've done more complicated projects like this at work and at home and I'm not too afraid of over complicating a non-critical item like this, I think it will be worth the little bit of extra work.
