Smoking gun...or leaking tabs

[dsiekman]

Had the boat pulled for the season on Saturday. I went back down yesterday to take a look at a few things. The slime has now dried on the outdrive - the hose wouldn't reach - and a few things became very obvious.

Dried slime is a great indicator of a leaking petroleum based product! Unfortunately, my port drive and both trim tabs were showing dark areas. The tabs are showing leaks around where the piston goes into the cylinder. I'm hoping this is just a simple seal replacement.

I also noticed just how small the tabs look compared to the boat. They can't be much more than 8" wide and maybe 12" long...on a 29' boat! The odd thing here is that they are OE.

I will try to take some pictures and get them up tonight. Has anyone rebuilt their tab actuators? Can't imagine it is too hard, but what about cost?

 

[Tabman]

Re: Smoking gun...or leaking tabs

dsiekman,

Do you know what brand your Trim Tabs are? If they are Bennett, we can send you the parts and instructions how to change the O-rings in the actuators at no cost. What you my want to do first is put both Trim Tabs in the full down position and leave them there overnight. If they stay down then there is no leak and no reason to replace the O-rings, if one or both retract overnight then there is a leak and they can be rebuilt. The bottom portion of the cylinder body on Bennett Trim Tabs is open and often water drips out for quite a while after hauling the boat out and that may be what you are seeing. But again, if they do have a leak and are Bennett Trim Tabs I can help.

OEM Trim Tabs are often undresized, at least when compared to what we recommend. Depending on the size you have and the space on the transom it is usually quite easy and not too expensive to upgrade to larger Trim Tabs. The larger Trim Tabs will be much more efficient and will create less drag since they will produce the same or more lift while deflected less than the smaller ones.

Once you post a photo I'd be delighted to recommend replacements if you are interested.

 

[Robbabob]

Re: Smoking gun...or leaking tabs

dsiekman,

Do you know what brand your Trim Tabs are? If they are Bennett, we can send you the parts and instructions how to change the O-rings in the actuators at no cost. What you my want to do first is put both Trim Tabs in the full down position and leave them there overnight. If they stay down then there is no leak and no reason to replace the O-rings, if one or both retract overnight then there is a leak and they can be rebuilt. The bottom portion of the cylinder body on Bennett Trim Tabs is open and often water drips out for quite a while after hauling the boat out and that may be what you are seeing. But again, if they do have a leak and are Bennett Trim Tabs I can help.

OEM Trim Tabs are often undresized, at least when compared to what we recommend. Depending on the size you have and the space on the transom it is usually quite easy and not too expensive to upgrade to larger Trim Tabs. The larger Trim Tabs will be much more efficient and will create less drag since they will produce the same or more lift while deflected less than the smaller ones.

Once you post a photo I'd be delighted to recommend replacements if you are interested.

When I grow up to a boat that needs trim tabs, I know which brand they'll be!

 

[dsiekman]

Re: Smoking gun...or leaking tabs

dsiekman,

Do you know what brand your Trim Tabs are?

OEM Trim Tabs are often undresized, at least when compared to what we recommend. Depending on the size you have and the space on the transom it is usually quite easy and not too expensive to upgrade to larger Trim Tabs. The larger Trim Tabs will be much more efficient and will create less drag since they will produce the same or more lift while deflected less than the smaller ones.

Once you post a photo I'd be delighted to recommend replacements if you are interested.

They are Bennett Tabs. I did the "leave down" test this summer and they seemed to hold, but I will test again now that she's out of the water and easier to see. I rubbed a little on my fingers and over the smell of the dried slime - pretty nasty - I believe I detected the smell of petroleum based something. ATF, power steering, oil, ??? I will test that again too in a few days as any water should have drained out, but oil based fluids should keep the slime looking dark and wet.

The area is pretty tight, so I'm not sure if there is space. If so, I would be interested in the upgrade. I am also considering the NMEA 2000 tab position senders for my Garmin 4208. I'd like to be able to monitor them and that seems like the cheapest option. I have also considered the automatic tab control, but we'll have to see if Santa can fit that one in.

I will try to get some pics tonight if daylight savings time cooperates. Thanks, Tabman!

 

[dsiekman]

Re: Smoking gun...or leaking tabs

When I grow up to a boat that needs trim tabs, I know which brand they'll be!

Yeah, no kidding, huh? It is nice to know that some companies still stand behind their products!

 

[Tabman]

Re: Smoking gun...or leaking tabs

They are Bennett Tabs. I did the "leave down" test this summer and they seemed to hold, but I will test again now that she's out of the water and easier to see. I rubbed a little on my fingers and over the smell of the dried slime - pretty nasty - I believe I detected the smell of petroleum based something. ATF, power steering, oil, ??? I will test that again too in a few days as any water should have drained out, but oil based fluids should keep the slime looking dark and wet.

The area is pretty tight, so I'm not sure if there is space. If so, I would be interested in the upgrade. I am also considering the NMEA 2000 tab position senders for my Garmin 4208. I'd like to be able to monitor them and that seems like the cheapest option. I have also considered the automatic tab control, but we'll have to see if Santa can fit that one in.

I will try to get some pics tonight if daylight savings time cooperates. Thanks, Tabman!

DSiekman,

Well I hope Santa is good to you

I'll keep an eye out for the picture and see what you might be able to do about larger Trim Tabs.

The NMEA option is pretty cool and if the 4280 has the software to read Trim Tab position it is a really economical and easy way to do it .

 

[dsiekman]

Re: Smoking gun...or leaking tabs

Okay, a couple of pics...

 

[dsiekman]

Re: Smoking gun...or leaking tabs

One other interesting side note...

When I was operating the tabs, the stbd side switch did not want to engage. Contacts maybe? When it did and I would let off, one of my cockpit lights would briefly flash on. Grounding issue maybe? It was only the one light and it has an LED bulb. If not LED there probably would not have been enough voltage to get anything visible out of an incandescent. Looks like I have my work cut out for me this winter.

 

[insanity]

Re: Smoking gun...or leaking tabs

That is some fantastic customer support. I have some smart tabs, and they are a lot larger for a smaller boat at 18?.

 

[Tabman]

Re: Smoking gun...or leaking tabs

Okay, a couple of pics...

Thanks for posting the pictures. They brought back some memories for me, I helped Cobalt with those Trim Tabs quite a few years ago, took the measurements off one of their boats and did the drawings for them.

Unfortunately due to the hull design with the extension of the hull past the transom there is really no way to install larger Trim Tabs because if we go any wider there is a risk of disturbing the water flow to the propeller and the overhangs prevent the space towards the chines from being utilized.

 

[Tabman]

Re: Smoking gun...or leaking tabs

One other interesting side note...

When I was operating the tabs, the stbd side switch did not want to engage. Contacts maybe? When it did and I would let off, one of my cockpit lights would briefly flash on. Grounding issue maybe? It was only the one light and it has an LED bulb. If not LED there probably would not have been enough voltage to get anything visible out of an incandescent. Looks like I have my work cut out for me this winter.

Let's try cleaning the back of the switch and if that does not work, try step three in the troubleshooting below and let me know the results.

Tom McGow
Bennett Marine

Fluid: Automatic Transmission Fluid (ATF) any type. Hydraulic Power Unit is self bleeding, running the Trim Tabs up and down 3-4 times will purge air from the system.

Fuse: 12 volt system use 20 amp in-line fuse on positive. (24v & 32v use proportionately smaller)

Red=Port Valve
Green= Starboard Valve
Blue=Motor Forward (pump pressure)
Yellow= Motor Reverse (pump retract)
Black on HPU=Ground
Orange on Helm=Control Positive

Troubleshooting

1.If one side is not operating reverse hydraulic lines on the front of the Hydraulic Power Unit to determine if the malfunction is in HPU or actuator / hydraulic lines. If after reversing the lines symptom shifts to the other side the malfunction may exist in HPU. If the symptom remains on the same side, malfunction may exist with the actuator / hydraulic lines

2. Is the unit receiving a solid 12 volts? Low voltage will some times cause the solenoids to not open preventing the tabs from moving even though the pump motor is running.

3. Conduct the following test:

Remove the wires from the helm control and touch together as follows:

Operation=Reaction
Orange (+), blue, red=Port trim tab down
Orange (+), blue, green=Starboard trim tab down
Orange (+), blue, red, green=Both trim tabs down
Orange (+), yellow, red=Port trim tab up
Orange (+), yellow, green=Starboard trim tab up
Orange (+), yellow, red, green=Both trim tabs up

If the trim tabs function correctly for each wire grouping then the switch is at fault. Also note that any loose or missing screws on the back of the switch (whether a wire is connected there or not) can cause the pump to malfunction.

This test may also be done right at the pump by substituting a "hot lead" for orange. There is usually a connector to the wire harness within a foot or so of the pump. You want to check this connection for corrosion. You may wish to cut the connector off on the pump side and try the test on bare wires.

4. If you suspect corrosion on the wire connector near the pump, cut it out, test as above and reconnect using butt splices.

5. Check to see if there is a relay in line on the wiring harness near the hydraulic power unit. If there is it is an Interrupter Relay (IR1000). It prevents the system fuse from blowing if you try to actuate one trim tab up and the other down at the same time. After you test as outlined above, try removing the relay from the wiring harness and retest the unit. If it works the IR1000 will need to be replaced.

Note Bennett no longer uses the Interrupter Relay, the control switches automatically lock out preventing the fuse from blowing, but your boat is old enough to possibly have one installed

 

[dsiekman]

Re: Smoking gun...or leaking tabs

Tom,

Thanks for the help. I will give the electrical test a shot this weekend when I have a little daylight to work with.

Nice to know who to blame for the tabs being so small! Just kidding. I'm sure that if two companies like Bennett and Cobalt got together than the product is top notch.

 

[Tabman]

Re: Smoking gun...or leaking tabs

It's funny, I have helped a lot of boat builders with Trim Tabs over the years but I really remember that one due to the tight space on the transom. I was at a boat show when Cobalt asked us to look at the boat and the way it was displayed I had to crawl under the boat on my back to take the measurements.

Let me know what you find when you get a chance to do the tests.

 

[dsiekman]

Re: Smoking gun...or leaking tabs

Okay, I went down and checked this morning and the tabs are still down. Good sign but it still doesn't explain where the fluid went as I topped it off twice this summer.

I hope to test the wiring this weekend.

 

[Tabman]

Re: Smoking gun...or leaking tabs

Okay, I went down and checked this morning and the tabs are still down. Good sign but it still doesn't explain where the fluid went as I topped it off twice this summer.

I hope to test the wiring this weekend.

OK, so far so good. Not sure either where you list fluid, you can try keeping them down longer but I doubt they will move if they stayed down that long already.

I'll stand by to hear what you find after doing the wiring test.

 

[dsiekman]

Re: Smoking gun...or leaking tabs

Okay, so I did the wiring test this afternoon. Everything worked. In the process of removing the switch, however, I think I found at least part of the problem. The screws in the positive "bus bar" on the backside of the switch were loose. In fact, one was missing. The screw holding the power feed was still tight, but there was some corrosion between the bar and the screw terminals under the bar. While I had the switch unhooked, I brought it home to take it apart. The contacts appear to be dirty and/or burned. Not sure if that is normal or not. I have attached a couple pics. Can I clean them or should I replace the switch?

Thanks

 

[Tabman]

Re: Smoking gun...or leaking tabs

Okay, so I did the wiring test this afternoon. Everything worked. In the process of removing the switch, however, I think I found at least part of the problem. The screws in the positive "bus bar" on the backside of the switch were loose. In fact, one was missing. The screw holding the power feed was still tight, but there was some corrosion between the bar and the screw terminals under the bar. While I had the switch unhooked, I brought it home to take it apart. The contacts appear to be dirty and/or burned. Not sure if that is normal or not. I have attached a couple pics. Can I clean them or should I replace the switch?

Thanks

I think the problem was the missing and loose screws. They all have to be in place and tight, a missing or loose screw would cause one Trim Tab not to work properly.

The "burning" you see is normal, remember when distributors had "points"? You can clean them if you like.

I would wager that if you clean the positive bar and make sure that all four screws are in place and tight the system will work.

 

[dsiekman]

Re: Smoking gun...or leaking tabs

Thanks, Tom!

 

[JBF 1962]

Re: Smoking gun...or leaking tabs

slightly off topic, but you mentioned that the tabs, if they leak will retract (rise?) My question, Tom, is should they be in that position when storing the boat for the winter or does it matter? This is my first boat with trim tabs (Bennett of course ^^) as well as being my first without the hydrofoil, which everyone keeps telling me i need >.<
Thanks
John

 

[Tabman]

Re: Smoking gun...or leaking tabs

slightly off topic, but you mentioned that the tabs, if they leak will retract (rise?) My question, Tom, is should they be in that position when storing the boat for the winter or does it matter? This is my first boat with trim tabs (Bennett of course ^^) as well as being my first without the hydrofoil, which everyone keeps telling me i need >.<
Thanks
John

John,

Although it really doesn't matter I think it is best to have then in the fully up position.

Regarding the hydrofoil, if the boat has properly sized Trim Tabs there is no reason to have a hydrofoil. In fact the hydrofoil will only add drag if the boat has the right Trim Tabs.

Also, since the hydrofoil is attached to the outdrive its lift (and drag) will vary depending on where the the power trim has the drive positioned. Trim Tabs let you control the boat's attitude allowing you to use the outdrive's power trim to get the best thrust (rpm) from the propeller.

I hope this helps.