Trim tabs

[Capt Matt]

Buy the Lennco's, Faster response and they do last. Way easier install too.
But buy the simple switch system without the control/brain box.
Just bought a new set of 12X12's for my 69 rebuild. Could never run another boat without tabs
Take it from a fishing guide that uses my tabs almost everyday. 11 years one actuator replaced
Any Hydraulic pump in salt water is going to get salt damage.  Same pump system on my powerpole and I have replaced it twice in 5 years. The pump costs way more than a actuator.

The rule of thumb for trim tabs is
If the boat is stored in the water use the bennetts
If its stored out of the water use lennco's

Just my 2 cents
Capt Matt

[saltfly]

Capt. Matt you are the second guide I’ve heard from. First one on here. My friend and guide Kevin Joeshans up here on the Chesapeake. Has Lenco’s. They came on his 20 foot Jones brothers. He has been using them almost every day, for 5 years with no problems. So there are a few who are in the lenco camp. Thanks for the response.

[Blue Agave]

I second Capt. Matt.  I have lencos on my boat and have replace one actuator in 10 and a half years and Lenco replaced it at no charge.  The electric tabs are much more responsive and there is no pump to be concerned about.  I'd also go with the simple switch without the led indicators.

[saltfly]

It looks as if there are a few people that have had success with lenco’s. I am wondering. It seems when lenco’s have a problem, its with the seal. That the actuator rod slides against  when it is in motion. This is a curiosity for me. Since this is not a new technology. And I’m sure both companies have taken apart each others units. Their both sliding seals and if particles build up on the rod. It should be happening for both the Bennett’s and the lenco’s. So both seals would be subject to the same type of damage. So I wonder why lenco has this problem but no one has it with Bennett’s? Which would cause a leak. Now both actuator are subject to expansion and contraction, do to thermal cycling in all their matl. Which could indicate that one is using more thermally comparable matl’s. in their product. Now that would be of interest to me. Since I’m in the mid Atlantic, which means hot summers and cold winters. I’m starting to think that its not the particulates on the rod that is the problem, but could be thermal related. When contraction accurse. The rod gets smaller in dia. And the seal gets smaller but the hole in the seal gets larger. Since it’s the matl that shrinks, not the hole. Since the hole is nothing. What this would mean, that its water in the actuator from thermal cycling not particulates. Now with that said. Maybe tabman can answer this. Does bennett allow hydraulic fluid to get on the rod to lubricate it? That would keep down wear on the seal, which would also maybe keep marine related particulate from building up. If that is the case. All people with lenco’s would have to do is wax their actuator rods once in a while. The wax would keep down wear as well as particle build up. Now is this making sense to anyone? Or am I just over analyzing again.

[Tabman]

Actually there is no seal where the piston shaft enters the cylinder body on a Bennett actuator.  The seal is made on the piston face itself.  Water is allowed to enter the bottom of the cylinder when it retracts.  Since there is no seal where the shaft exits the cylinder body it does not matter if anything grows on the shaft itself. This also allows the entire length of the shaft to be painted with antifouling paint if desired.

On a electromechanical system there must be seals where the shaft enters the cylinder body, and consequently they are prone to damage from growth on the shaft.  The shaft of a Lenco actuator must not be painted as that will compromise the seals as well.   On company, LectroTab has placed their seals above the range of motion of the shaft to prevent damage, but this prevents them from making shorter actuators (helpful in mounting them on small boats).  Also they have patented the idea, preventing others from copying it.

Another issue that a hydraulic actuator does not have to contend with is the creation of negative air pressure when the piston is extended.  On an electromechanical actuator the volume inside the cylinder body increases when the shaft extends, lowering the air pressure inside. When the pressure is lowered all of the seals have to resist an increased pressure on the outside that wants to draw water into the cylinder body.

LectoTab has incorporated a "breathing tube" in their design that is built into the electrical cable and allows air to be drawn in as it extends.  However the locatin of the breathing tube can draw moist air into the cylinder, hastening corrosion.  Again LectroTab has patented this idea.

Lastly on Bennett actuators it is easy to replace the O-rings on the piston face if they should ever develop a leak. It's about a 15 minute job. Just the other day I sent o-rings to a boater with a 36 year old system and it is once again working fine!

Sorry for the long post, but I'm pretty nerdy about this stuff.  I have taken apart many actuators that have failed (ours and our competitors) in order to understand why they fail.

Of course I work for Bennett so I am a bit biased  

Tom
Bennett Marine

[saltfly]

ah that explains it. At least for me. I've never had a reason to look at tabs before. That is till now. no seal  at the rod and housing would make since. If the seal is between the actuators pisston and the housing. Lenco's would have to have one their. With them you can't have water of any kind getting in to the actuator. But I do see the problem. You have to have a pressure relief tube as you said. And that tube would take in air as well as push air out. The would allow moisture from the air (humidity) to enter the actuator. Ok now I see why they fail. Thanks tom. Thats the problem when your from an engineering back round. You have just got to know how somthing works. That's why when we get something. We have just got to take it apart to see how it works.