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  Disturbing Lenco Trim Tab Cautionary Tale

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Author Topic:   Disturbing Lenco Trim Tab Cautionary Tale
Morocco posted 09-03-2003 03:33 AM ET (US)   Profile for Morocco   Send Email to Morocco  
As some of you know, in April I decided to put trim tabs on my '87 25 Revenge WT. After some research, I chose Lenco Tabs mostly because I didn't want to deal with the slighty more complicated hydraulic system on the Bennett tabs, and most of the folks that I talked with seemed happy with them.

They were installed easily and worked perfectly -- until Sunday, when the controller box (a cigarette pack sized junction that 'gathers' the wires that run from the tabs and sends a wire to the 'double rocker' switch on the control panel) exploded and caught fire.

Yes, exploded and caught fire.

We had just pulled the hook and had come up on plane, running the twin Johnson 150s at an easy 3400 RPM when a BANG about the size of an M-80 went off under the helm, followed by lots of white smoke seeping up around the throttles, gauges and out of the small cabinet just below the wheel. When a noise is loud enough to startle me over the sound of those 150s (they are really pretty loud) it is a good sized noise. We quickly shut everything down, I grabbed one of the fire extinguishers and went down into the cuddy, pulling the snap-on cover open a little to peer into the 'electrical space' behind it -- where a 4 or 5 inch flame flared and then extingished itself just as I was about to squeeze the trigger.

With everything turned off and the hatches and portlights open to vent the smoke, I was able to get in there with a flashlight -- the plastic cover of the box had blown a quarter sized piece of plastic across the space, leaving a now melted hole in the box, which is mounted alone to the inside wall of the starboard inner hull -- there is literally not another wire or object that could come in contact with it, and it was as dry as a bone. I did a quick inspection -- everything looked good in there and not even the 20 AMP inline fuse to the box had blown. We started the engines then brought the house batteries on line and everything worked, so we went home (because one of the tabs was in the 'half down' postition, we had to go a bit more slowly, but we were basically trimmed for cruise anyway.)

Here is the cautionary part: I talked to Lenco today, and they weren't a bit surprised -- this was a 'known condition.' While they were nice, and of course offered to send me a 'new and re-engineered' control box for free (after requiring my credit card for the 'core'!) -- I was a little pissed off to find out that they knew that 'some of these resistors are sensitive and won't handle a voltage 'excursion' on SOME boats.' I guess a number of them have either melted or 'popped' and their take on it seemed to be that instead of recalling or pulling all the suspect control boxes, they would just wait and let the 'ones that were bad declare themselves.' They also told me that 'no way' could the box catch fire, that it was 'potted' and 'self-extinguishing.' But I will tell you that although that did turn out to be the case, there was a visible flame on my boat, at least for a couple of seconds.

I was sort of speechless. I still can't quite process that but I guess if they had told me up front, I wouldn't have bought Lencos. Actually, I'm sure of that.

Again, they were very nice, and until this happened I was recommending them all over the dock, but the tech guy told me that though the 'new' box was re-engineered and improved, there might be a lot of 'old' boxes out there (remember, mine was only installed in April) so if you have Lenco tabs, now you know. I'll still run them, but I can't say that I trust them.

A fire on a boat is never a good thing, and we were lucky that there were no children to scare and that nothing else burned. I just can't believe that the people at Lenco would let people go to sea, knowing about this 'minor' problem.

Anyway, no lawsuits, no injuries -- just a little caution for everyone to file away if you run these.

adaps4 posted 09-03-2003 08:30 AM ET (US)     Profile for adaps4  Send Email to adaps4     
Thanks for the info.

The actual cause of the explosion you heard was probably directly related to the "potting" that they used. I work with surge suppression in commercial and industrial facilities, and some of the cheaper manufacturers will pot their products. This is a cheaper way to contain the heat and protect the connections. The pop was probably caused by the lack of air in the enclosure used. Also, UL will rate these potted items safe when the enclosure used will contain any fire that could occur. Not the safest way to do things, but it is very common. They will smoke like hell, and make a mess, but I wouldn't worry about your boat burning. This is normal operation.

BW23 posted 09-03-2003 09:14 AM ET (US)     Profile for BW23  Send Email to BW23     
That is amazing. I would make sure Lenco sends you a completely new wiring harness and send them the bill for the repairs.

A letter to Boat US would also be in order.

Regards,

Dave

kingfish posted 09-03-2003 09:33 AM ET (US)     Profile for kingfish  Send Email to kingfish     
Morocco-

Do you have the rocker switch with integral tab position indicators, or just the simple rocker switch without indicators?

Reason I ask is, I have the simple non-indicator switch on my Lencos (been running without a hiccup for three years), I installed them myself, and I don't recall a "controller box". I don't recall anything between the rocker switches and the trim tabs except electric cable.

fno posted 09-03-2003 11:32 AM ET (US)     Profile for fno  Send Email to fno     
An otherwise uneventful day of fishing made that much more exciting by the folks at Lenco. It's fairly common for the service guys to tell you what he did. They see only the problems day in day out. adaps is right about the potting, lots of smoke and it's usually a capacitor that blows up if there is one in there. If your that convinced that the Lencos are crap, install Bennets and wait for the pump motor to burn up. That will be a little harder to put out once it lights up the gas fumes in the bilge. Be glad the box and it's smoke and fire was on your instrument panel.
13_Dauntless posted 09-03-2003 01:45 PM ET (US)     Profile for 13_Dauntless  Send Email to 13_Dauntless     
fno,

I monitor this forum as a Whaler owner, but since I work for Bennett Marine, I always read threads about trim tabs with great interest. As an employee of Bennett, I hope that this post isn't misconstrued as spamming, but I would like to comment on your post above.

Bennett Hydraulic Power Units are designed to be installed in any compartment in the boat. Becasue of this, they are ignition protected, so there should never be any risk of the pump igniting gas fumes. Independent laboratories have certified that the Bennett V351 HPU meets the Ignition Test Requirements of ISO 8846 for non-sealed devices, ABYC requirements stated in E-8, the SAE requirements stated in J-1171, and the USCG requirements stated in Title 33 CFR 183.410 (Ignition Protection, Induced Explosion Test).

Christian Redditt
Bennett Marine

adaps4 posted 09-03-2003 05:04 PM ET (US)     Profile for adaps4  Send Email to adaps4     
Morocco-
The reason for the fire was probably the opening of the cover- giving it oxygen. If you had not opened it, I do not think there would have been anything more than smoke. It sounds like whatever protection the unit had, did it's job. I know that it is scary, but that is what it is supposed to do. Possibly a larger control unit is available, or maybe a non-potted aftermarket product with thermal fusing. This type of fusing would prevent the item from ever getting above a certain temp. It breaks at certain temps, thus disabling the device. Good luck.
Morocco posted 09-03-2003 05:39 PM ET (US)     Profile for Morocco  Send Email to Morocco     
Kingfish -- I have the same 'non-indicator' switch. On the back is a plastic four pin connector that accepts the wire from the control box.

fno -- I don't think the Lencos are crap, they were flawless up until this event. As for Bennets, I have no experience with them at all -- although I am happy that this box was about as far away from any gasoline as you can get on my boat. It sounds like Bennet at least has addressed the problem of fire safety.

adaps -- that area is covered by a vinyl cover that is held with 6 snaps, it is far from air-tight and the flame was visible just peering in as corner was lifted.


While it is generally advisable to NOT open a hot closed door in your home or any other place on land (where there may be another escape)when the escape route is a 2 mile swim in 59 degree water, I'm going to take my shot at any small fire, in the first 30 seconds when I might still have a chance of putting it out. If you have a fire at sea, and you're waiting around for 'safety devices' to kick in, you should be doing it as far away on the boat as possible, and getting ready to abandon her -- because at that point, you're just a passenger on a scary ride.

where2 posted 09-04-2003 10:06 PM ET (US)     Profile for where2  Send Email to where2     
The electronics geek in me has to ask: Were you operating the tab switch when the pop occured, or was this without touching the tab switch?

If it was without touching the tab switch, the question in my mind is: What part of the circuitry is drawing current sufficient to overload a "resistor" when you are not operating the device?

Morocco posted 09-05-2003 12:16 AM ET (US)     Profile for Morocco  Send Email to Morocco     
Where --

Yes, I was adjusting the port side -- I have a 40 gal 'garbage can' bait tank on the starboard -- usually after getting the boat up and stable on plane, the last thing I'll do is trim out the starboard 'down' lean by bumping the switch a little. Since we were in a following sea, both tabs were fully retracted for the maybe 30 secs that it took to get the boat stable, engines trimmed out, etc. I think the thing popped on the second or third 'bump.'

Dick posted 09-05-2003 09:55 PM ET (US)     Profile for Dick  Send Email to Dick     
I have worn many different hats in the marine industry for more years than I like to admit.

As far as Bennett tabs are concerned the only pump problems I have ever encountered were caused by high water in the bilge submerging the pump. This certinly is not Bennetts fault. I also have found that Bennett has one of the best customer service divisions in the industry.

My experience with Lenco is limited to replacing actuator brackets that seemed to break quite often and were done at the customers expence.

Dick

kingfish posted 09-07-2003 11:33 PM ET (US)     Profile for kingfish  Send Email to kingfish     
Well I couldn't stand it any longer and went out and looked in my console today to confirm or deny that my memory served me correctly in recalling that there was nothing between my switches and my trim tabs except cable when I installed my Lencos.

And there was nothing. No "control box" of any sort. So I am very curious now as to what this control box is, and under what circumstances one is included with a new set of Lencos and why. I can't see what the reason for such an animal would be. The cables get routed forward to the proximity of the switch which has pig tails coming out of it color coded to match the wires in the cables and pigtails with in line fuses that go to power and ground. End of story.

What model and size were these Lecos?

kingfish posted 09-07-2003 11:34 PM ET (US)     Profile for kingfish  Send Email to kingfish     
And I'm interested in the Lencos, too...
Morocco posted 09-08-2003 02:12 AM ET (US)     Profile for Morocco  Send Email to Morocco     
Kingfish,

Curious. Check this schematic from Lenco's website -- this is what I have:

http://www.lencomarine.com/TrimTabs/ttstdswitch.html

They are the standard 'TT-12x12' tabs:

http://www.lencomarine.com/TrimTabs/sizefit.html

I'm not sure what the control box does, the instructions don't say, nor does the website. I'll give them a call tomorrow.

M

kingfish posted 09-08-2003 10:11 AM ET (US)     Profile for kingfish  Send Email to kingfish     
Thanks-

That is dramatically different from my setup - it looks like they have changed their design since I purchased mine in order to develop water proof connections at the switch. My switch is open at the back, so from inside the console you can look directly at the back of the switch and see the soldered and screwed connections - six wire connections behind each switch, I think. Something conductive touching more than one of the "right" connections at the same time could probably be a problem, but that's no different than about a hundred other such connections and terminals inside my console. I go to pretty great lenghts to assure everything remains dry in there...

kf

Bigshot posted 09-11-2003 03:19 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I have owned Bennett tabs and like them. They do have their drawbacks and maintenence issues but are very good quality. I want to put tabs on my 20' Hydra-sports and with the VRO tank, raw water washdown pump, 2 batteries, battery switch, fuel seperator, etc, I have NO room for a pump. I will now wait a few months to make sure I get the newer Lenco setup. I also like the way Lenco resetes automatically instead of an expensive option like Bennett.
kingfish posted 09-11-2003 04:06 PM ET (US)     Profile for kingfish  Send Email to kingfish     
Bigshot-

Just to make sure we're on the same page - I may not have written my last post so it sounded like it, but I *prefer* the old setup, especially if the new one has this propensity for the control box to blow up. I figure I am able to seal the switch to the face of the console adequately to avoid water intrusion, and the whole sytem (without the control box and sealed switch) is extremely simple - none of my other switches are waterproof either, except to the extent I make them that way. Mine have operated flawlessly and I expect them to continue to do so.

Lencos stay where you leave them (which again is fine with me; no fade, etc.); they don't automatically retract without the purchase of optional equipment.

kf

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