Trim Tabs

Sean B · Post by **Sean B** » Wed Jul 26, 2006 5:09 am

I know we've beat this issue around before, but I want to see if there is any new information out there. My trim tabs have been dead for a while, presumably because of a hydraulic fluid leak (don't know where yet), and I've come to realize that without them my boat is really a dog, especially when loaded down. Those little stock tabs do have a significant impact on the running angle, and are doing much more to help the boat plane out than I had thought they were. The boat plows terribly without them, with a huge rooster tail just astern. SO...I'm considering installing wider and longer ones to see if they can be more useful, along with a new bottom job I'm planning to do shortly. The stock ones are certainly sized too small for the boat. I've been talking with Bennett about this too, and am considering adding wider tabs and mounting the hinge for that just in front of the hull pocket, with the extra width towards the centerline of the boat. The chine is stopping me from moving up the sides of the hull. Might also get tabs with a longer "chord," the term they use to describe the legth of the tab parallel to the length of the boat, so they would poke out further behind the boat more. Has anybody added larger tabs to their boat, and if so, to what effect? Here are some pics from my last Jan 2005 haul/bottom job to help picture what is going on. [img]http://www.bertram33.com/images/uploads/IT Trim Tabs 001.jpg[/img] [img]http://www.bertram33.com/images/uploads/IT Trim Tabs 002.jpg[/img] Sean Burlingham "Island Time" 1987 Bertram 33 SF Melbourne, FL SBurlingham@cfl.rr.com [img]http://www.bertram33.com/photogallery/p ... d_Time.jpg[/img]

Post by **dougl33** » Wed Jul 26, 2006 5:28 am

Sean, Like you said, its been debated many times before and there seems to be 2 distinct camps. Those with stock tabs and like them and those with larger tabs. I have the stock tabs and Bill Dunlop has the larger ones (I keep telling him they look like barn doors!). Both are FBC's (mine an 86 and Bill's an 88). Having driven and ridden both boats, I have to say I am not crazy about the steering characteristics of the boat with the large tabs. It seems like Bill's boat doesn't respond to steering input as quickly as my boat does. Maybe if I owned Bill's boat rather than just driven it from time to time I could get used to the steering. Having seen pictures of both boats running at the same speeds, I will say that Bill's bow is down considerably more than mine is at the same speed which I'm sure contributes to the steering differences I notice. That being said, I know Bill can acheive the same speed at a lower rpm though he is running 2.5:1 as oppsed to my 1.9:1 so its hard to do a direct comparison as far as thats concerned. My feeling is that Bertram put the small tabs on for a reason. I find that over 20 knots the tabs do very little other than to assist with an uneven load or people shifting around. Sorry if I've asked this before, but what speed are you cruising your Cats at? If I'm not mistaken, you're Cats are the 270hp variety correct? Regards, Doug L. 1986 33 Bertram FBC Queen Elizabeth Marblehead, MA [img]http://www.bertram33.com/photogallery/p ... sabeth.jpg[/img]

boat bum dan · Post by **boat bum dan** » Wed Jul 26, 2006 7:30 am

Sean I have a 1980 S F with 3208 cats As I have stated b4 I added angle to the out bound edge and now have a lot more bow down trim than b4. Have not seen any negatives. I beleive Bertram new what they were doing with the small tabs and the only problem on my boat is the addidtion of a new 7.5 kw 3cyl diesel gen set. Captain Dan Devendorf

BECCA ROSE · Post by **BECCA ROSE** » Wed Jul 26, 2006 9:16 am

Larger trim tabs will require two cylinders per tab. Added cost and work, probably not worth it. I like mine, I can really bury the bow on a nice calm day, making the boat really efficient. Other then that, I'm not sure why they are so big, and why they put them on. I think they are 36 inches. Bill 33 FBC Ipswich, Ma. [img]http://www.bertram33.com/photogallery/p ... a_Rose.jpg[/img]

Brian Davin · Post by **Brian Davin** » Wed Jul 26, 2006 9:42 am

Sean, My 1990 does not have the integrated trim tabs mounted on the bottom, nor is the hull cut-out there, but has Bennett tabs mounted on the transom. My guess is that they are factory original and that they are approximately 10"-12" deep x 18"-20" side. Brian '90 Bertram 33' FBC Never Say Never Guilford, CT (Homeport) Kinnelon, NJ (Home)

Sean B · Post by **Sean B** » Wed Jul 26, 2006 11:02 am

Something interesting: Bennett looked at those same two pics and says my tabs are from Insta-Trim Boat Leveler Company, their competition. I always assumed they were Bennett's. They are recommending leaving those tabs alone, and to add two more small tabs outboard of those, mounted on the transom directly. I'm not sure if I want all that complication back there or not. They say that I can tee-in the new smaller tabs to the existing Insta-trim pump system so they will all move together, but I'm thinking if I do add two more tabs, perhaps I would rather them be independent of the old ones and have two sets of switches. Then if I loose one set (like now) the other set is still there. Without the tabs, when loaded down my boat just plows until about 21-22 knots, which to attain is too much RPM on my 3208T to cruise at (260 Hp variety) with current props. So with broken tabs I'm plowing aroung at 16-17 knots at 2400 RPM, not on plane, and smoking like a locomotive. It all cleans up at about 2600 RPM but I don't like to run them there, but with current conditions it's probably actually better for the engines, lighter load. I do have a bent prop blade right now, and the bottom is always fouled to some degree in the summer, all of which certainly contributes. When I've got less than a third a tank of fuel it behaves like normal (the way it does with the tabs working). I agree they don't change things much at 20+ knots, but when loaded down and with imperfect props and bottom, my boat really seems to need them just to be in the 20 knot range without taxing the engines. Remember I've got those big heavy CATS and a 8KW genny back there too, which might make my girl a bit heavier in the ass and behave a little differently. I can't see why the larger tabs would have such a bad effect on the steering of the boat. I'd like to know more about that. I wonder if everything else relating to steering (rudder size, steering pump condition, rudder toe-in) is equal on those two compared setups. I would also think that with a larger tab extended down a small amount (or not at all), the boat should behave/steer the same as it would with a smaller tab extended further. I'm thinking that I'd like more tab area, just not sure when and how I'm going to go about it. I suppose I could remove what is there and add big new transom-mounted ones like Brian's, but Bennett's idea of another small set of ooutboard tabs has its appeal too. Could really mess around with the running angle adjustments, having four tabs to play with, and a built-in backup system. Sean Burlingham "Island Time" 1987 Bertram 33 SF Melbourne, FL SBurlingham@cfl.rr.com [img]http://www.bertram33.com/photogallery/p ... d_Time.jpg[/img]

smanni · Post by **smanni** » Wed Jul 26, 2006 11:23 am

Sean- I have been going back and forth with this one for a while. I have lost my tabs 2 times this year ( hydraulic leal in the bilge - replaced and added chafe guard - and a leak at the connection from the hytdraulic line to the tab itself) and both times i notices just how helpful the littl;e 1.25 inch of play they give us helps. Without the tabs these boats run like crap and very slow. I know some people say not to do it - but anyone with the same engine config as sean and I done it yet. A slightly bigger tab cant hurt? - and the potential for help is there? I dont like the idea of 4 tabs - to much crap to deal with.

franklyprice · Post by **franklyprice** » Wed Jul 26, 2006 12:55 pm

One other thing to think about Sean, the tabs on the boat now are actually specially made for our boats , limited in their travel to (i think) 1 1/2 inches . I just got some parts from boat leveler to replace a leaking hose and new switches etc. came to about $160.00 . I am pretty happy to have them working as original and maybe add that little winglet on the sides of the plates. I think the reason for their small size is to keep them from bow-steering , especially in a following sea. Of course , as you mentioned, with an extra ton in the engine bays, your boat is less likely to have a problem with bow-steer. It's obvious that the SF especially was designed to have those heavy cats in there . I am interested to see what your opinion is of my boat after you try it out, with gas engines.

Sean B · Post by **Sean B** » Wed Jul 26, 2006 1:16 pm

Well now I'm driving lots of boat next week. Scott has me piloting his B31 from Marion to OB, now I'm taking yours for a spin too? I guess next weekend my name will be Hooper Sean Burlingham "Island Time" 1987 Bertram 33 SF Melbourne, FL SBurlingham@cfl.rr.com [img]http://www.bertram33.com/photogallery/p ... d_Time.jpg[/img]

lobsta1 · Post by **lobsta1** » Wed Jul 26, 2006 3:05 pm

Sean. my gas 1078 FBC came with Boat Levelor 8 x 18 transom mounted tabs. I replaced them with 9 x 30 Bennets. Spoke to Tom McGow from Bennet & he recommended not going over 30" unless I used two pistons per side. To complicated for me so just installed the 30's. They work great. I pick up about a kt at 3000 rpm. Cruise is about 18 kts now. You do have to pay attention to bow steer, even in a flat sea. So I'm one of the few that has driven my boat with both sizes of tabs & have seen the difference. Al 1978 33 FBC NITES OFF

captgene · Post by **captgene** » Thu Jul 27, 2006 2:55 am

I have the original small Boat Levelers. One started leaking and throwing the boat off every couple minutes. I got 2 new pistons and hoses from some mailorder that sold them. Hoses and pistons came all put together. They also have pins in each end of the hinge so you don't have to unscrew anything from the glass. I cut the hoses, pulled the old ones off. Reinstall, and 5200 the hoses where they went thru the transom. Inside you have to trim the new hoses to the proper lenghth, slip them on the pump and clamp them. I did this sitting in the water too. Just don't doo it with a full load of fuel. As for bigger...maybe, but not much. In the owners manual they explain the use of the tabs. Bertram really didn't want people getting on them a lot is how I read it. Especially in following seas. Might have been some liability thing when somebody broached a boat and sued. Gene Dugan

sbeer · Post by **sbeer** » Thu Jul 27, 2006 5:19 am

In the 33 sf you have one main hull stiffener in the bow. When I bought the boat this stiffener was broke. This was caused by burying the bow by useing to much tab. I have the original tabs. The hull is not as thick as you may think. Stuffing the bow to much can really do some damage. It caused quite abit of gel cracking on mine. In my opinion, if you own a sf and can not cruise at at least 22 knots, you need tabs. I cruise at 23 to 24 knots and do not use them at all. The boat needs to get her ass out of the water to run properlly if it can't you need more tab. If you can't get any more than 17 to 18 knots you need more tab to make up for power or you need to power her up to get out of the hole than back her off or your just under powered or you got an engine issue or your overproped..... ect, ect, ect..... Just my opinion guys. Mike

Sean B · Post by **Sean B** » Thu Jul 27, 2006 3:37 pm

Thanks for all the responses guys. Not sure when or how but I will be adding more tab, now I've got a lot of experience to draw on for the decisions. Will post on subject when I make a change, and the results. I guess nobody caught the "Hooper" reference Sean Burlingham "Island Time" 1987 Bertram 33 SF Melbourne, FL SBurlingham@cfl.rr.com [img]http://www.bertram33.com/photogallery/p ... d_Time.jpg[/img]

franklyprice · Post by **franklyprice** » Thu Jul 27, 2006 4:03 pm

Sean, I know as soon as you mention it ,something will come back to me but you're going to have to refresh my memory.Whatever you want to call yourself, you can still drive my boat if you wish.

BECCA ROSE · Post by **BECCA ROSE** » Thu Jul 27, 2006 5:17 pm

"Hooper drives the boat" Jaws, duh!!!!!!!!! Bill 33 FBC Ipswich, Ma. [img]http://www.bertram33.com/photogallery/p ... a_Rose.jpg[/img]