Trim Tabs

[New Boater]

Hi All,

Can anyone throw me some quick advice on trim tabs

I have quite an old system fitted I think. Two buttons on the helm (bow up/ bow down) no lights, no indicators, no beeps! Just two old plastic rocker switches

One trim tab has stopped working

The pumps and motors etc look mint

I want to update the system (especially the switch end)

Do I need to buy a complete system?

Can I just up-rate/update the switches and have indicators of some kind?

I have no idea where to start

Can anyone recommend a good supplier that I can bore to death with questions?

 

[jfm]

For indicators on hydraulic systems, there are broadly 2 types.

First type = much more common these days- has a sliding resistance sender in the ram, so you can't retrofit to existing rams and you would need new rams. These days the output can be N2K, though a gauge/LEDs on dash should be fine.

Alternative type uses a mechanical teleflex/morse cable. The outside end is attached outside to the trim cylinder, and inside end operates a mechanical indicator on the dash. Sounds heath Robinson but actually very good, and widely used on Italian boats in years gone by. I suppose you could attach the inside end of the teletex/morse cable to a rheostat to get an electrical output. This system can be retrofitted if you're good at making brackets and stuff.

If you can't diy this then you're better just buying a new system (while keeping your old actual flaps)

 

[Sticky Fingers]

Interesting to see this, was looking at my 25 year old hydraulic Bennett tabs last week, I also have the up/down switches with no indicators, and wondering the same question.

 

[PaulRainbow]

Interesting to see this, was looking at my 25 year old hydraulic Bennett tabs last week, I also have the up/down switches with no indicators, and wondering the same question.

My Bennett tabs (slightly older than yours) had indicators with a row of LEDs, a set on the flybridge and another at the lower helm, connected to an electrical box of tricks. The box of tricks went up in smoke and a replacement wasn't available. Can't remember if it was possible to fit a whole new setup, but i didn't like the look of the prices anyway. I fitted a Garmin GBT 10, circa £150, which converts the analogue signals to N2K and is displayed on my MFDs.

I'd expect your rams would have the wires as JFM describes above (first option), but double check. I'd also expect most modern MFDs to be able to deal with the data, but again, double check that yours will, if it's of interest.

 

[Sticky Fingers]

My Bennett tabs (slightly older than yours) had indicators with a row of LEDs, a set on the flybridge and another at the lower helm, connected to an electrical box of tricks. The box of tricks went up in smoke and a replacement wasn't available. Can't remember if it was possible to fit a whole new setup, but i didn't like the look of the prices anyway. I fitted a Garmin GBT 10, circa £150, which converts the analogue signals to N2K and is displayed on my MFDs.

I'd expect your rams would have the wires as JFM describes above (first option), but double check. I'd also expect most modern MFDs to be able to deal with the data, but again, double check that yours will, if it's of interest.

Ooh that’s interesting. Got recent Raymarine Axioms. About 5 years old, pretty sure they’d be ok as displays. No idea about the wires, this is the Bennett pump, any clues there?


Sorry to hijack thread. Hopefully illuminating!

 

[PaulRainbow]

Ooh that’s interesting. Got recent Raymarine Axioms. About 5 years old, pretty sure they’d be ok as displays. No idea about the wires, this is the Bennett pump, any clues there?


Sorry to hijack thread. Hopefully illuminating!

Looks the same pump as mine, but the wiring is part of the rams. Look where the rams are fixed to the transom and you should (hopefully) see a grey wire, like this;

 

[Sticky Fingers]

Rams look identical to that albeit covered in Antifoul Can’t see the wire in my photos but likely it’s there.

 

[PaulRainbow]

Rams look identical to that albeit covered in Antifoul Can’t see the wire in my photos but likely it’s there.

View attachment 190394

You can't see the wires from the outside, they come in through the centre of the mounting bracket.

 

[Sticky Fingers]

Ah right, OK. Don’t think I’ve got a pic that covers that. I’ll have a look next time I’m down, maybe next but one weekend.

 

[New Boater]

Ok done a little digging after I posted and it looks like the switch has died

I have an audible (mechanical) click on ip and down on the port switch and an audible click only on the up on the starboard switch

Not that bothered about the indicator lights as it is obvious what the boat is doing so does anyone know where I can get a simple set of rockers?

Thanks guys and girls

 

[PaulRainbow]

Ok done a little digging after I posted and it looks like the switch has died

I have an audible (mechanical) click on ip and down on the port switch and an audible click only on the up on the starboard switch

Not that bothered about the indicator lights as it is obvious what the boat is doing so does anyone know where I can get a simple set of rockers?

Thanks guys and girls

I have a set of Bennett switches, i swapped mine out for a custom panel. PM me if interested.

 

[stelican]

Ok done a little digging after I posted and it looks like the switch has died

I have an audible (mechanical) click on ip and down on the port switch and an audible click only on the up on the starboard switch

Not that bothered about the indicator lights as it is obvious what the boat is doing so does anyone know where I can get a simple set of rockers?

Thanks guys and girls

Thank God for the simplistic move! Any Bennet dealer should be able to supply.

 

[MapisM]

Alternative type uses a mechanical teleflex/morse cable. The outside end is attached outside to the trim cylinder, and inside end operates a mechanical indicator on the dash.
Sounds heath Robinson but actually very good, and widely used on Italian boats in years gone by.
I suppose you could attach the inside end of the teletex/morse cable to a rheostat to get an electrical output.

I'm a big fan of mechanical indicators.
I had them on a Fountain, OEM fitted with Mercury Racing K-planes tabs and integral morse cable directly connected to dash linear gauges.
Razor accurate, and very reliable. That's stuff worth considering only on 50+ kts boats, though.

The indicators that more than likely you've seen on Italian boats of years gone by is what BCS (later taken over by Twin Disc) mated with their full trim tab system.
That's what I've got on on the current boat, and is also based on a morse cable like the K-planes, but a very short one, just long enough to enter the stern and reach a small internal box. Which I never bothered checking in detail, but I guess it's essentially a rheostat as per your assumption. And from that box, there's an electrical wiring to the dashboard gauges.
Which may sound even more Heath Robinson-esque than a morse cable controlling directly the dash indicators, but also this hybrid (for lack of better wording) system is very accurate and reliable.
With the added bonus of avoiding long morse cables and allowing multiple gauges - typically, lower helm+flybridge, a problem that doesn't exist on speedboats.

 

[snowbird30ds]

The old "rocket" joystick died on my old bennetts tabs and I replaced with a pair of Momentary on-off-on dpdt rocker switches for a princely sum of a tenner, about another tenner got me a custom engraved surround to cover the existing holes and all works well.
The indicator sensors can be added to bennett rams by replacing the top hinge, I have an old "trimdicator" display on my boat seperate to the switches.

 

[jfm]

For switches you should just buy Carling Contura in whatever series (1 to 5 iirc) matches the other switches on your dashboard.

 

[Refueler]

I'm still trying to identify my system so I can think about tab Indicators .... that's after I fix the tiny leak on one ...

I noticed a 'rainbow' on the water when operating the port tab just before lift out .....

 

[MapisM]

Momentary on-off-on dpdt rocker switches

From an ergonomic viewpoint, I sort of like your lever switches better than the original ones.
But in your boots, I would have taken the opportunity to install them as logic suggests, i.e. up/down to raise/lower the tabs respectively.
I know that Bennett follows the twisted logic of what tabs do to the bow and (for reasons only known to them!) they reverse it, so you must press the button down to raise the bow and VV.
But other than sticking to what is possibly an acquired habit, it's much more straightforward to press a lever or button down to lower the tabs, and VV.
In fact, also the Contura switches that jfm mentioned, which are labelled with arrows raising/lowering the bow, are meant to raise the tabs by pressing them up, and lowering by pressing down.

 

[snowbird30ds]

It's cheap enough for another facia if I fancy a change and a quick shuffle of the terminals but I'm used to it now.

 

[PaulRainbow]

From an ergonomic viewpoint, I sort of like your lever switches better than the original ones.
But in your boots, I would have taken the opportunity to install them as logic suggests, i.e. up/down to raise/lower the tabs respectively.
I know that Bennett follows the twisted logic of what tabs do to the bow and (for reasons only known to them!) they reverse it, so you must press the button down to raise the bow and VV.
But other than sticking to what is possibly an acquired habit, it's much more straightforward to press a lever or button down to lower the tabs, and VV.
In fact, also the Contura switches that jfm mentioned, which are labelled with arrows raising/lowering the bow, are meant to raise the tabs by pressing them up, and lowering by pressing down.

That's how i did mine, using the Carling switches suggested by JFM

 

[MapisM]

That's how i did mine, using the Carling switches suggested by JFM

Interesting to see that some Carling switches show the up/down arrows astern.
The ones I had in mind when I said "labelled with arrows raising/lowering the bow" are the following.
But at the end of the day, it's totally irrelevant because by lowering the tabs you also lower the bow, and VV.
It's only at Bennett that they think it's more intuitive to use an up/down switch the other way round!