Trim Tabs - Bertram 28

[HilaryS]

I have a 28 and have been considering adding Trim Tabs. I'm looking for insight regarding size, make, and model. From what I've read so far it seems that the default size on charts for a given length of boat isn't always the correct option due to other variables.

[Charlie J]

well I am a firm believer that the 31 does not need trim tabs
I am sure someone with a 28 will chime in, if there needed or not

[Tooeez]

I bought my 28 FBC in 1987, and installed Bennett tabs in 1989 and have no regrets and no problems with the units in all that time. Mine are about 12" long and 9" wide (I don't want to go out in the snow to get the actual measurements). Bertram had a 28 at the NY boat show that year, and I took the size and placement of the tabs off that boat.
The tabs work great to correct the lean when you get a couple of people sitting at the dinette. I also use them to push the bow down when running into a short, steep chop. Lately, when I have a heavy load on the boat I have started to put them down while at idle speed before putting the boat on plane. Seems to give some extra lift--I then back them off when at cruising speed.

[wmachovina]

Had a 28 for 12 years and my 31 for 6, 28 needed them and need I say Bob? Negatory on the 31. Now that I have a 38, it's like I have said, a blown up 28 and the tabs help quite a bit. Napier hull not a wide body.

[Yannis]

That's why she burns 2.5 lit per mile with 460-480 horses. Plus you can live standing in her. I have tabs too. Big difference. I'll tell you brand and type once I go down.


Went down today; they are Bennetts.

[RAWicklund]

I couldn't live without them on my 28. I have diesels, so more stern weight. They are Bennetts also ...hydraulic control. I have a few friends that have the Lenco elec. actuated tabs, but it seems I've heard of more issues with the Lencos....even though I have them on my bay boat and never had a problem.

As to your original question on size.... Not sure but I may be able to check tomorrow or Wed. .... Mine is a 94 model and the tabs came from the factory.

Ray

[Skipper Dick]

I have Bennett tabs on my 28. They are 14x9. I can trim for speed and fuel consumption using my Navman fuel flow. I can't imagine running the boat with out them.

[HilaryS]

I want to thank everyone for their feedback. I plan to install Trim Tabs during my next bottom Job. The sizes help a lot as well, I have seen charts that denote everything from a 12x9 to a 36x9 for 28 foot boats. Its nice to be able to hear what other 28 owners are using and are happy with.

[Tooeez]

Hilary, if I had to install them again I might put on slightly larger tabs: more surface area means less down angle for the same effect. The 9 inch width is OK, but 14 or 16 inches long might give more lift with less drag.

[RAWicklund]

I was down the bayou at the boat today..... My tabs are 18"x9" installed by factory.(94 B28)They seem to work great , no complaints or improvements I could suggest....but I obviously never tried any other size.

Never had trim tabs on my 31, but it's been sitting on a trailer since 2006 waiting on a repower...someday soon I say ;))

Ray

[bob lico]

a 28' Bertram with gas engines would benefit from tabs especially with tanks filled and boat loaded. i have 9" x 18" with cylinders no pump free on my end however a donation to site is required.the captain will give me the word he received and i mail.

[Kevin]

My tabs are 18 by 11.5 inches.
I have found that I really don't use them much. The exceptions would be going into head sea with short period in wind greater than 13 knots. I am not out much if it is windier than 13 knots. I noticed that when used to counter "people weight", once you get boat level the person moves negating the adjustment to begin with. If everyone is comfortable and not moving around on a long haul I may just shift some cockpit weight around rather than use tabs.
Contrary to what Bob said, my 28 actually runs a lot better with more fuel/weight aft. I have diesels but they weigh about the same as gassers.
My thoughts are that tabs don't create stern lift at all, they just plant the bow down creating more wetted surface area and loss of speed.

[bob lico]

kevin not contrary to what i said concerning OEM. SBC gas motors with no wares near the torque of diesels at getting up on plane speed.

[Yannis]

Kevin, hi,

What motors do you have?
I agree that although tabs can be very effective in balancing misplaced weights, reality, as you're saying, defeats the point. It suffices for someone to take 2 steps aside to ruin the equation.
However, I find they're very useful in the leveling of the boat, and I think that they help lift the boat out of the water, as opposed to just nose it in the water and create more surface friction. Otherwise I can't explain why, when I deploy about two thirds (I can't be more accurate), the revs pick up 100+ and the speed too (more than a knot).
Also, another point is that with my 240 Yanmars I should not, and do not, have any problem in bringing her to plane, with whatever weight.
So, as a conclusion, for me the tabs are useful while underway with any chop and any weather, as much as they are less useful in bringing her to plane and in lateral weight balance.

[Kevin]

Yannis,
They are 212 hp Steyr from your side of the pond.
I am surprised to hear that with tab you gain RPM and speed. I would like to better understand how the same hull can react so much different with tabs.
I know some boats have a "pad" or flat spot at the back of the hull and the boat rides on it: but that is more of a high speed hull feature and often associated with stepped hulls, sometimes they just need a bit of tab for a brief period of time to get that extra speed. Our boats are not that!
I assume with your Yanmars you run a ZF/Hurth with 8 degree down angle? How much fuel do you carry?
You have more power than me but I think our engines are similar in weight. What prop dimension?

[Yannis]

Kevin,

I don't know what gearbox, down angle and propeller size. I promise to ask my mechanic and will come back.
What I do know is that I can carry 550 liters of fuel and 300+ liters of water, and there is practically no difference if full or empty, and that my tabs are 61 X 22 cm, or 24 X 9 inches approx. My WOT speed is 31 knots, my cruising speed is 22-23 knots at 2700 rpm and the fuel burn is 2.5 liters per nautical mile. Always with 2/3 of tabs button time for more speed and economy.

[Hyena Love]

Agree with Kevin. Basically no need for me on a 28 with D's. The stern lift provided by D's is far different than what I had with gas. Might be an occasional leveling issue, but that is easily addressed by simply shifting the load.

[Carl]

I can't speak to the B28...but with dads 28 Hatteras, my 31 and my last boat... I found at slow planing speeds the Arse squats in as it goes along. Add a bit of tab and the nose comes down...but more important the butt comes up. My thought is boat skims over the water more with the tab... instead of running thru water like a wedge breaking. Yeah...more wetted surface and friction I know, tabs are like a break...heard that too...but in my mind I see that surface of hull skimming along the top of water and not acting like a break....actually I think the tab makers recommend wider tabs so as to be considered a continuation of the hull.

Whatever the case...I can give tab at 17-18knots and boat will increase speed to 18-19 with same burn. I can choose to leave it there or come back on throttles and watch the burn rate drop a couple gallons an hour. Free money or faster...I like them both.

Goose it up a bit and the boat naturally levels out without tabs...go a bit fast and nose starts dropping further. this is when I think tabs are dangerous. Fast and rough seas....no tab.

[Navatech]

Yes, trim tabs add wetted surface as well as drag HOWEVER, when you push the bow down by pushing the stern up you direct more of the power towards forward motion rather then into the depths of the sea... So yes, all things being equal, by using tabs to push down the bow you will realize a forward power increase and thereby an increase in speed as well as in efficiency...

[bob lico]

you got it carl! can and will cause death in a 30knot cruse boat in rough seas with a occasional 8 footer.riding on inside strakes,BOW proud to meet the 8 footer however this is not bow proud like a 18knt. 31 Bertram this means the entire bow in out of water and bottom contacts water directly below pillars and transom bottom is a few inches in the water "running like the devil" basically the rudders are in water thats all you are ridding the top of the waves however must be 30' or more hull and 29knots or more in the Atlantic ocean the Gulf is easier and no comment on Pacific.

[PaulJ]

Hillary,
I have Bennett Tabs on my B28. I think you've gotten great advice here. I see you're my neighbor. Is that your boat at Telemar? I keep mine in Ft Pierce. Let me know if you'd like to check out how mine are set up and take them on a sea trial to see them in action. Cost of the trip is a six pack!

I often go out alone and find that without the tabs, she tends to list to the port as the galley and head are on that side. With slight tab adjustment she rides level. With 1-2 people on board, depending on where they decide to sit, more adjustment is needed. With a group, I end up barking at them when they all go to one side to gawk at something (usually to look at some bikinis). 4-5 200 lb guys suddenly shifting to one side and you heal over pretty quick. I cruise at 21-22 knots and dont see much difference in performance in a chop, but definite increase in handling and speed if it's calm. In bow down attitude and sudden weight shifting by the lookie-loos causes some bow stearing which is very unsettling.

PM me if you want to arrange a ride.

PaulJ
1973 B28 - PALADIN
GM 350/5.7L 4bbl FWC Velvet Drive 1:1.51

[Cturtle]

Thanks to everyone, I think LOL, who chimed in on Tabs vs No Tabs. My 1979 28'FB didn't have tabs on her when I bought her a couple of years ago and now that she has been re-powered blah blah blah I am shopping for Trim Tabs. One web sight suggested 2 inches of Tab over the length so for a 28' that would be 30. I didn't see anyone using that size. At some point, after researching, I'll have to make a decision but thanks again for all the insight.

[Carl]

Keep them in the ballpark of where everyone has them and you'll be good.
Personally I like wider and shorter to avoid cutting lines when fishing and less chance of bumping them around docks.