Trim tabs for Merry Fisher 795

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elsel

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I'm looking at options for getting trim tabs onto my 795. The local marina are keen on the Volvo interceptors but I have a few reservations. Access to transom is quite limited. Boat is moored year round. Does anyone have experience /advice with trim tabs for 795 or similar boats eg. 755, 695, 855?
 
I have a 695 and I am considering fitting tabs.. Mostly for levelling when people move around but also for more effectively pushing the bow down at slower planing speeds and in choppy conditions than using the outboard..

I am thinking either the bennett or lenco tabs and I am leaning towards lenco because access to the back of the transom is very limited and routing the electrical wires externally up the transom and then in trough a cable gland or something is far easier than trying to run hydraulic pipes around tight corners without kinking them.. I am not that keen on the interceptors on a small boat even though they have some very vocal supporters..
 
Thanks. I agree transom access is an issue on these style of boats. I note that Bennett have released electric tabs now as well. My reservations with Volvo relate to its invasiveness, quite a large hole in transom below waterline, and some reliability issues i see on forums. It's a neat concept though. What are your reservations on the interceptors?
 
elsel said:
What are your reservations on the interceptors?
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Biggest reservations are probably reliability as per the stories on the forum and cost.. I didn't know a large hole was needed below the waterline but that would probably put me off as well.. We had Bennett hydraulic tabs on our last boat and they worked great.. I guess the concept of a traditional tab appeals to me more because it's a simple concept just diverting flow, similar to an aileron on a plane wing..
 
I didn't know a large hole was needed below the waterline but that would probably put me off as well.. We had Bennett hydraulic tabs on our last boat and they worked great.. [/QUOTE said:
Yes 32mm hole at base of transom. Of course our guys have "never seen one leak" but if it does I guess the boat sinks. Haven't heard a bad word about Bennett and I'm also thinking about wire / hydraulics externally across transom then into boat from engine well. I guess hydraulic maybe more reliable for boat left in water but i'm tempted by the Electric for same reasons as you. Plus there's no obvious place for hydraulic pump without losing lazarette storage room. Lots to think about.... let me know what you decide, not many merry fishers around here!
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elsel said:
Yes 32mm hole at base of transom. Of course our guys have "never seen one leak" but if it does I guess the boat sinks. Haven't heard a bad word about Bennett and I'm also thinking about wire / hydraulics externally across transom then into boat from engine well. I guess hydraulic maybe more reliable for boat left in water but i'm tempted by the Electric for same reasons as you. Plus there's no obvious place for hydraulic pump without losing lazarette storage room. Lots to think about.... let me know what you decide, not many merry fishers around here!
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Sounds like you are on the same page as I am.. I also figured external routing of electric wires and then in through the well somewhere..

The Bennett hydraulic rams have a long history and strong following but I see on nearly all new boats that the Lenco tabs seem to be the standard fit item now so there are probably a lot out there and they seem to be working well.. I think the new Bennett electric rams are to try and get back in with manufacturers.. I guess only time will tell on the reliability.. On the Lenco tabs they have a standard mount and an edge mount models, the edge mount means less transom height needed and for me this looks like it will be needed so the ram top mount doesn't sit no or near the deck drain fittings..

Mine is on the maybe list for the winter, let me know how you get on and what you choose..
 
wipe_out said:
Sounds like you are on the same page as I am.. I also figured external routing of electric wires and then in through the well somewhere..

The Bennett hydraulic rams have a long history and strong following but I see on nearly all new boats that the Lenco tabs seem to be the standard fit item now so there are probably a lot out there and they seem to be working well.. I think the new Bennett electric rams are to try and get back in with manufacturers.. I guess only time will tell on the reliability.. On the Lenco tabs they have a standard mount and an edge mount models, the edge mount means less transom height needed and for me this looks like it will be needed so the ram top mount doesn't sit no or near the deck drain fittings..

Mine is on the maybe list for the winter, let me know how you get on and what you choose..
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Time has passed quickly but after a fair amount of deliberation I've gone for the new Bennett Bolt electric tabs, 12x12. I figure the transom access would be difficult for hydraulics and note that, as you have pointed out, the factory option tabs for the MF895 are electric (Lenco), same with Arvor/Quicksilver and other similar boats. So mine are due to go on next week.
Have you put anything on yet and if so what has been your experience? Would be interested to hear. Any issues with the transom shape or access??Elsel.jpg
 
elsel this e-mail to the firm that fitted my Volvo Penta interceptor blade trim tabs might be useful to you. It also shows the importance of getting references on the firm you want to use:

"I doubt you will have any recollection of this, but back in 2011 I approached you to fit Bennet style trim tabs, cost about £600, and service my outdrive and 3 litre Mercruiser inboard. You persuaded me to buy Volvo interceptors and against my better judgement, as the design seemed so naff, I agreed to buy them. After an extraordinary 6 month delay carrying out only part of the above work, I was presented with a bill about double the original budget. It was explained to me a couple of times that as my boat was only a leisure boat, you had to prioritise work on commercial vessels, as their owner’s livelihoods depended upon them being fixed quickly. At the end, the engine wasn’t serviced, I had to get another marine engineer to do that and I also had to pay another firm to come and fit the drive bellows as your engineer couldn’t, despite repeated attempts. All is this I took on the chin, including the loss of use of the boat for the summer, until 10 days after I received an invoice for the work I received a shirty message chasing me for settlement despite the extraordinary delay, cost over-run and the fact I was left with an unserviced engine.

All history now, except I feel I need to warn you off selling these Volvo units, if they are still being manufactured. They never really seemed to work but I went on believing the tell-tale LEDs that they were operating in part until a week or so ago the boat started heeling alarmingly and I thought for a moment I was taking on water. Pulling the boat out of the water, I found both units inoperable despite what the dashboard tell tales said, one extended right down beyond its maximum position, hence the dangerous and unstable handling of the boat, and the other fully retracted and jammed.

An engineer took the units off and I was very irritated to see that only the starboard unit was bolted through the transom. I had spotted your engineer astonishingly using self-tapping screws to attach these interceptors to the glass fibre transom! The blades clearly take the force of dragging a 3.5 tonne boat through water at 25-30 kts and screws could easily rip out of the stern leaving a large 32mm dia hole below the water line, quickly sinking the boat. However my trust in your engineer was misplaced, as once my back was turned he didn’t bother using bolts on the port unit but just self tappers, something I never noticed until we removed the units last week. Just as well this port unit never really worked or extended its blades.

Splitting the units to examine them soon revealed why they were a waste of £1,156.50. The electric motor was a rusty mess and the interior of the blade mechanism was full of marine life. Entirely predictable; if you put a flexible plastic body next to a 135hp outdrive flexing the transom, it is bound to let in water.

More worrying for me are the gel coat stress cracks leading from the numerous below water line holes your engineer drilled in my boat. I now have a glass fibre expert booked to come to see the hull to see how the holes can be reliably plugged and the stress cracks rectified. Again I am missing summer use of the boat.

I was worried to see one firm on line still seems to sell these things, I really think you should warn Volvo Penta that they are a dangerous and damaging waste of money."
 
ChrisinCornwall said:
elsel this e-mail to the firm that fitted my Volvo Penta interceptor blade trim tabs might be useful to you. It also shows the importance of getting references on the firm you want to use:

"I doubt you will have any recollection of this, but back in 2011 I approached you to fit Bennet style trim tabs, cost about £600, and service my outdrive and 3 litre Mercruiser inboard. You persuaded me to buy Volvo interceptors and against my better judgement, as the design seemed so naff, I agreed to buy them. After an extraordinary 6 month delay carrying out only part of the above work, I was presented with a bill about double the original budget. It was explained to me a couple of times that as my boat was only a leisure boat, you had to prioritise work on commercial vessels, as their owner’s livelihoods depended upon them being fixed quickly. At the end, the engine wasn’t serviced, I had to get another marine engineer to do that and I also had to pay another firm to come and fit the drive bellows as your engineer couldn’t, despite repeated attempts. All is this I took on the chin, including the loss of use of the boat for the summer, until 10 days after I received an invoice for the work I received a shirty message chasing me for settlement despite the extraordinary delay, cost over-run and the fact I was left with an unserviced engine.

All history now, except I feel I need to warn you off selling these Volvo units, if they are still being manufactured. They never really seemed to work but I went on believing the tell-tale LEDs that they were operating in part until a week or so ago the boat started heeling alarmingly and I thought for a moment I was taking on water. Pulling the boat out of the water, I found both units inoperable despite what the dashboard tell tales said, one extended right down beyond its maximum position, hence the dangerous and unstable handling of the boat, and the other fully retracted and jammed.

An engineer took the units off and I was very irritated to see that only the starboard unit was bolted through the transom. I had spotted your engineer astonishingly using self-tapping screws to attach these interceptors to the glass fibre transom! The blades clearly take the force of dragging a 3.5 tonne boat through water at 25-30 kts and screws could easily rip out of the stern leaving a large 32mm dia hole below the water line, quickly sinking the boat. However my trust in your engineer was misplaced, as once my back was turned he didn’t bother using bolts on the port unit but just self tappers, something I never noticed until we removed the units last week. Just as well this port unit never really worked or extended its blades.

Splitting the units to examine them soon revealed why they were a waste of £1,156.50. The electric motor was a rusty mess and the interior of the blade mechanism was full of marine life. Entirely predictable; if you put a flexible plastic body next to a 135hp outdrive flexing the transom, it is bound to let in water.

More worrying for me are the gel coat stress cracks leading from the numerous below water line holes your engineer drilled in my boat. I now have a glass fibre expert booked to come to see the hull to see how the holes can be reliably plugged and the stress cracks rectified. Again I am missing summer use of the boat.

I was worried to see one firm on line still seems to sell these things, I really think you should warn Volvo Penta that they are a dangerous and damaging waste of money."
Click to expand...
Wow pretty damming report, I would be rageing...but some useful info there to take in...unfortunately at your expence.
 
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