Trim tab problem / troubleshooting help please.

tmh

Lieutenant Junior Grade
Joined
Aug 16, 2006
Messages
1,136
Hi. My 1988 Cruisers 33' express has helm-controlled trim tabs - sorry, I do not know the brand. One works fine, the other does not move. I have a few questions on troubleshooting this problem.

1. First, can someone explain the operation of trim tabs? In my bilge area is the box that contains the tranny fluid and what seems to be the two helm controlled motors. Two leads come off that (hydraulic hoses I presume), one to each trim tab. This somehow tells the hydraulic control cylinder on the tabs which way to go. How is it that there is only one resevoir for fluid then? What controls which tab responds?

2. Operation. I know how tabs work - tab down, bow comes down. What I am wondering is are my helm controls upside down and backwards (need 90 deg. rotation)? Sitting at the helm facing forward, the tab rocker switch on the port side controls the starboard tab. If I push the port switch up, the tab goes down, push the port switch at the bottom (down) and the starboard tab goes up. Is that correct? The markings are faded, if ever there so it doesn't tell me anything.

3. When I push the starboard switch either direction, I hear the motor do something, but nothing happens to the port tab (or the starboard for that matter). I can move the tab my hand against the cylinder so I know it's not "frozen". So this is where I need a plan to troubleshoot it. We added tranny fluid to make sure it's full.

Any help on these three questions? Thanks.
 

tmh

Lieutenant Junior Grade
Joined
Aug 16, 2006
Messages
1,136
Re: Trim tab problem / troubleshooting help please.

Well, I just read a bunch more "stuff" from Bennett (I assume my tabs are Bennett). Now I THINK my tab controls are correct. Pushing the top of the rocker switch is "bow down" so if I want the port bow down, I push the port switch "up" (bow down) which moves the STARBOARD tab down, hence pushing the port bow down as desired. I guess this becomes "normal" once used once or twice, but it sure is confusing if not marked!

I also saw the Bennett troubleshooting guide which I will follow next time I am on the boat. I'm guessing I have a bad electrical connection - hope I can find it.
 

JoLin

Vice Admiral
Joined
Aug 18, 2007
Messages
5,146
Re: Trim tab problem / troubleshooting help please.

Well, I just read a bunch more "stuff" from Bennett (I assume my tabs are Bennett). Now I THINK my tab controls are correct. Pushing the top of the rocker switch is "bow down" so if I want the port bow down, I push the port switch "up" (bow down) which moves the STARBOARD tab down, hence pushing the port bow down as desired. I guess this becomes "normal" once used once or twice, but it sure is confusing if not marked!

I also saw the Bennett troubleshooting guide which I will follow next time I am on the boat. I'm guessing I have a bad electrical connection - hope I can find it.

Yeah, you got it right. They're hooked up so you can instinctively control the attitude of the boat rather than having to analyze the effect of moving which tab in which direction.
 
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