Trim tabs not making a difference

[bigdogg1]

Have a 24' with Bennett tabs. On dry land, they have been checked to fully go up and down as required but on water, there is absolutely no difference when I try to trim the boat level.

I am wondering if they are not holding pressure perhaps when under speed? I will try them later today to see if they hold their positions but wondered if anyone else has had this issue?

 

[noluck]

no, mine are very effective. what are the boat specs?

 

[bones]

When on dry land, fully extended maybe you can push up on them?

 

[ryanb]

Maybe air in the hydraulic lines? They will move under no load (ie at a standstill or out of the water), but water pressure would push them back up underway.

 

[bigdogg1]

no, mine are very effective. what are the boat specs?

24' Harbercraft. 200 main, 9/9 kicker, pilot house. Boat lists to kicker side. Gas tank straight down the middle under the back end (7' long, 2' wide).

 

[ryanb]

The list is probably from prop torque, assuming your kicker is on your port side.

 

[ziggy]

I had mine working backwards. The mechanic hooked them up and guess didn't realize that the port switch controls the starboard trim tab. Made for some interesting times when I first got the boat lol!

 

[bigdogg1]

The list is probably from prop torque, assuming your kicker is on your port side.

Makes sense from a physics point of view. I don't know prop specs off the top of my head. I will try t osee if the tabs hold under pressure before playing around with prop changes.

 

[ryanb]

Makes sense from a physics point of view. I don't know prop specs off the top of my head. I will try t osee if the tabs hold under pressure before playing around with prop changes.

No way to get rid of prop torque with a single. You can balance with your weight distribution, but then you'll be listing the other way at rest.

 

[noluck]

No way to get rid of prop torque with a single. You can balance with your weight distribution, but then you'll be listing the other way at rest.

prop torque or torque steering has no affect on the boat listing, it has a affect on the boat steering as it comes out of the water, and wants to rip the wheel out of your hand.

listing is purely load, and tabs working correctly will counterbalance this. those are big tabs and will more than do the job once working right. if you need a hand p/m me

 

[Hookin'up]

maybe the tabs are too small. look on the bennett site and see if they are correct for your boat size

 

[bigdogg1]

Thanks all! When done, both the port and starboard held against pressure. However, I am going to start step-by-step and simple. Just read through the manual and am hoping that by simply adding ATF that they will extend down more. I will post the results and thanks again. Noluck, I will send off a p/m if unsuccessful.

 

[noluck]

roger

 

[GLG]

Bennett tabs has a trouble shooting website here is a link.
https://bennetttrimtabs.com/tech-help/

could this be your problem?

 

[ryanb]

prop torque or torque steering has no affect on the boat listing, it has a affect on the boat steering as it comes out of the water, and wants to rip the wheel out of your hand.

listing is purely load, and tabs working correctly will counterbalance this. those are big tabs and will more than do the job once working right. if you need a hand p/m me

It absolutely does make a boat list. How much will be a function of deadrise, beam, bottom design etc. Imagine your prop is in concrete instead of water, what's going to happen to the boat? It's going to want to spin around the axis of the prop.

Do you have a duoprop on your boat? If so I can see why you might not be familiar with the concept.

While I don't have Bennett tabs on my boat, my electric tabs, which are smaller than Bennetts work great for trimming out my 24' aluminum that is probably very similar to yours.

 

[profisher]

Being hooked up backwards would be a good guess. Next time try raising the tabs and see if the bow goes down. If they are already in the level position and the wires are reversed it will do nothing as they are trying to go up instead of down.

 

[baddogg]

It absolutely does make a boat list. How much will be a function of deadrise, beam, bottom design etc. Imagine your prop is in concrete instead of water, what's going to happen to the boat? It's going to want to spin around the axis of the prop.

Do you have a duoprop on your boat? If so I can see why you might not be familiar with the concept.

While I don't have Bennett tabs on my boat, my electric tabs, which are smaller than Bennetts work great for trimming out my 24' aluminum that is probably very similar to yours.

ryanb
Which type of trim tab do you have? I am still looking to purchase something. Thanks

 

[trophywife]

tabs not far enough apart? or too far? are they pushing down on clean water?

 

[bigdogg1]

Keeping my fingers crossed . I went through all the variations of switching to confirm that the wiring was correct and that the slave cylinders were moving in the right directions. Both sides worked as expected. I checked the reservoir tank and still had fluid in it even after both tabs were extended. After McGyvering a fill hose out of funnels, tubing, and a cake decorating adapter because the entire unit had been installed just inches below a permanent fish hold, I added about another inch or so of fluid. Bennett's site suggested 2" when fully retracted. After adding beyond this, I gained another inch out of the cylinder so I hope this helps. If not, I will have to check the size although they are similar to what I have had on other boats of this size and design. They also seem to be placed in a spot to maximize their impact on water flow under the hull.

Hope this works out and will post a fishing report from French Creek if the winds settle as forecast by BWDave. Thanks again for all of the suggestions.

 

[ryanb]

ryanb
Which type of trim tab do you have? I am still looking to purchase something. Thanks

They are Lectrotab brand. Only trouble I have had with them are the port side tab is a bit sticky and sometimes needs to be rocked back and forth to get it moving. Can't figure out why, and hasn't gotten worse so I live with it.