Volvo QL vs Bennett trim tabs

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Volvo QL vs Bennett trim tabs

Postby Dug » Jan 12th, '09, 08:44

Hi all,

I have been thinking of adding tabs to Alchemy. I know the Bennetts are excellent, and have watched rave reviews for quite some time.

Volvo Penta came out with a different approach called the QL tab fairly recently however, and I like that it doesn't stick out off the transome like an airplane wing.

Has anyone got any experience with these, and knowledge of how they are holding up in the real world?

What are the thoughts on these? Thanks!!!

Dug
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Postby CaptPatrick » Jan 12th, '09, 09:01

Gerry Santiago has them on "Zero Cavity" and I think Bruce installed a pair last year... From everything that I've seen, read and heard, it'll be the way I go on any future installs. The QL450, (17.71" x ~3.5"x ~2"), would be the ones for the B28 or B31. Whole lot easier installation, less mechanicals, no hydraulics, and mfg claims quicker action.

Br,

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Postby Bruce » Jan 12th, '09, 09:08

I'd use the Volvo over the Bennett. You don't have to deal with wing flaps hanging off the transon anymore.

BUT they must be installed correctly to work. The transom on many boats has a curve. You must make a piece that fits behind the tab to makeup for the curve, otherwise the plastic housing will crack and the mechanism will bind and not work.
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Postby CaptPatrick » Jan 12th, '09, 09:36

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Postby In Memory of Vicroy » Jan 12th, '09, 09:49

My experience with Volvo engineering (say "over engineering") and use of plastic teaches to avoid the stuff.....looks good on paper but in the real world does not hold up. But you guys know my views on B31s & tabs. anyway.

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Postby Carl » Jan 12th, '09, 11:32

UV, normally your right on, but in this case I have to say Volvo kept the design super simple with those QL tabs. As far as plastic, Bennet uses plasitc for the hydraulic Rams so no advantage there either.

I was against tabs for years on my 31, but last year putting on a pair really made a big difference, especailly at the lower cruising speeds. Picks the butt up so she stays on plane at lower speeds and added a couple knots to most cruising speeds with same burn and rpm.

Its also nice to be able to tweak the trim instead of having to ask some people to move over, only to have everyone then move to the other side. I'm not saying my wifes family does this...but then again I'm not saying they don't either.

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Postby Dug » Jan 12th, '09, 12:23

Excellent point about the fairing block.

I am thinking Starboard... though I know that 5200 doesn't adhere to that.

Hmmm....

Maybe apply the sealant, mount it all up, and then do a final tighten after cure?

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Postby tunawish » Jan 12th, '09, 12:58

Dug,
Looking at same thing for B20,

25bertram.com site has more info on the Volvo system, I thought you were a member there???

I am skeptical of the QL system due to what I have heard of them needing to be wiped down to prevent growth from affecting operation and past experience with electric type.

I've put in Bennet and Boat leveler over the years with no problems other than a bit more difficult to install.

The last restoration I used electric Lenco, were a snap to install but didn't last two years.

Does anyone know if Volvo internals are all plastic or stainless gears?
Thats what let go on the Lenco..

Ray
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Postby Raybo Marine NY » Jan 12th, '09, 13:07

Dug wrote:Excellent point about the fairing block.

I am thinking Starboard... though I know that 5200 doesn't adhere to that.

Hmmm....

Maybe apply the sealant, mount it all up, and then do a final tighten after cure?

Dug


mahogony, teak, or even bob's favorite azak would be a much better choice for shim material.
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Postby CaptPatrick » Jan 12th, '09, 13:13

Dug,

Forget the starboard... Here what you do:

Decide the location where the tab is to be mounted. Mask it off with blue tape. Over the blue tape, mask with a larger piece of plain paper. Mask the whole tab tightly with two layers of Saran Wrap, (or similar plastic food wrap). Mix up thickened epoxy to the consistency of peanut butter.

Gob onto the back of the tab enough of the epoxy to more than fill the space. Press the tab against the hull, tape it onto the hull as necessary, and clean up the excess squeeze out. Let it cure out in place.

Once cured, remove from the hull, separate from the tab, and sand down as necessary the profile of the epoxy wedge. Install the wedge to hull using screws and 5200. The tab will no have a flat spot to be installed on.

Do the same thing for the other side...

The double masking is necessary since the epoxy will tend to stick to the immediate surface masking that it's contacting. Don't use waxed paper on the hull masking 'cause you can't tape to it. Although you could use the Saran Wrap if wanted.

Br,

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Postby CMP » Jan 12th, '09, 14:18

Patrick, that's one helluva lot easier than what I went thru to install mine on the B25.

Dug, the QL's are fantastic. I first put them on the B20 and they worked great. I need to remove and re-install them on the B25 as the way I installed them was not perfect. I will use Patrick's idea and do it right this time. The system is easy to use, simple to understand and works great. Call Arjen Steegstra or Aaron Myerson at Power Products in Wakefield, MA 781.246.1810 to get them ordered...

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Postby wmachovina » Jan 12th, '09, 15:29

Dug-- Iput the Qls on Seachele,basically doing as Capt Pat described creating a flat surface with epoxy and cabosil. worked great except for what I got in my hair, and let cure nicely thankyou-- The tabs work great are not in the way at all. They have little effect on the bowdown,not that theres much there but lateral trim running in a headsea with a crosswind is the whole rationale. Bill
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Postby John F. » Jan 12th, '09, 18:37

Carl--

Did you put the volvo tabs or other tabs on your boat? I was wonderign how much stern lift you'd get out of the volvo design vs. a more conventional tab, and how much stern lift you get out of a conventional tab anyway. Less fuel sounds good.

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Non objective comment

Postby keysdisease » Jan 13th, '09, 09:56

Gentlemen,

Please note that I was once the Special Markets Manager for Bennett and that I have no direct experience with QL Volvo Interupters, except from a competitors point of view. So that's where I'm coming from.

Tab vs no tab:

No boat "needs" tabs. They will float and move without them. All boats are designed to run best on an even keel within a certain bow up attitude. Any good tab system or interupter will help maintain this optimum "comfort" or "efficient" attitude (if sized correctly)

Either system will allow the vessel to run more efficiently, especially when used with speed info (gps) and fuel flow info. As noted a push of a button vs asking someone to move. Also, loading changes. Fuel is used, ice melts, tons of fish come aboard, beverages are consumed. Wave and wind create a dynamic environment and a vessels ability to adapt to maintain an efficient attitude typically results in a more comfortable and efficient ride.

Interupters:

Been around a long time, military uses them. Proven concept. Works on different principle than tabs.

Science:

The Science between the two systems (tabs vs interupters) calls out that tabs work better at slow speeds. Interupters need more speed in order to start working. if the goal is to plane comfortably at slower sppeds to stretch fuel Tabs should work better.

They both create lift at the transom, although through different science.

Installation:

Interupters from QL should be easier to install because there is no pump to install. A Bennett pump is smaller than a 6 pack of tallboys.
Both systems need fairing blocks (for a B31) and both need dash switches and wires run from transom to dash.

Reliability and longevity:

Bennets have a 5 yr warranty. There is one moving part on the transom and the electrical component (pump) is mounted inside the boat. Most problems with a Bennett system can be fixed without hauling the boat. There are Bennett systems on the water that have been in service continually for 20+ years in salt water that are still operational.

QL Interupters are electrically actuated at the transom. Their long term reliability is still being tested. Like Lenco electric trim tabs, they count on seals to keep electric components dry.

Marine growth does not affect Bennett systems, the planes can be painted with antifouling per paint company guidelines for underwater metal and the actuator can be painted without any special priming.

Interupters do have the advantage that there is nothing sticking out the back of the vessel. Instead there are "planes' that stick down vertically from the transom. For some this may be an important factor.

Just a few comments from someone that was pretty close to the subject, hardly objective but then, I told you that.

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Postby Dug » Jan 13th, '09, 10:06

Steve,

Thanks for the info!

I am actually looking to keep bow down a smidge in a head sea. I know, I can slow down, and often do.

I have less of a problem with side to side weight distribution.

Once again, I am glad I asked the question, and don't have any prejudice against Bennetts. In fact I know they are time tested and very well backed particularly given the consistent testimonials here on the board to them being backed even out of warranty!

Thanks again!

Dug
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Postby Carl » Jan 13th, '09, 11:01

John F.

I was all set to put on the Ql's, the flush against the stern had me won over. But then I did a job for a marine distributor and he offered a clean swap for the Bennetts. I went that route.

In the just on plane to 18knot range the tabs really lift the stern up and give a faster cruise or you can ease the throttles back a tad for better economy. Basically I'll pick up about 2 knots, or I can cut back and reduce burn by maybe 2-4 gph depending on conditions or some combination of the two.

Bringing the bow down a hair is also really nice in a head sea...

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Postby John F. » Jan 13th, '09, 13:23

Steve and Carl-

Thanks for the info. Picking up 2-4 gph is nice.

John
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Postby Rawleigh » Jan 14th, '09, 09:20

I have a set of 25+ year old Bennetts on my B31. They have been bulletproof! Nothing else on the boat (except the hull) has lasted as well. Most of my fishing is on the Chesapeake Bay. I have had no problem with cut off lines with them. I know that they are there and work the lines around them with no problem. Like all underwater metal, they do have a problem with bottom paint. Proper prep and two layers of the proper primers will cure that problem. We put them on so that we could run from the lower station in bad/cold weather. I don't use them often, but when I need them they work every time!! I am skeptical of sealing electrical actuators underwater. I am sure that in the short haul it will work fine and look great, but these are boats most of use have for the long haul.
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Postby In Memory of Vicroy » Jan 14th, '09, 11:53

I had Bennetts on the B25 that I needed bad with the Vulva duo prop diesels. It also needed the Doel Fins too.

The Bennett stuff was pretty straight forward and I busted an auctuator by accident and they replaced it out of warranty knowing it was not a product failure but an accident. Good folks.

UV
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Postby ed c. » Jan 19th, '09, 23:03

I put Bennett trim tabs on 2 years ago. 12x30 inches. Easy as pie . Works great. Good Luck
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Postby ZeroCavity » Jan 20th, '09, 10:22

Doug, I'm very happy with the Volvo QL tabs. No problems so far and they perform great.
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Postby ed c. » Jan 21st, '09, 22:26

Dug, for a shim on the Bennetts I used PVC board, cut down from 3/4" thickness. This stuff is great, not cheap, but it will last forever.
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