Trim Tab Project

[ccroke13]

Thought I would share my experience with adding trim tabs to my 31 Bahia. My 31 is on the slower side, running twin Perkins T6.354 at 185hp each, with Hurth 2.0:1 transmissions, 18x23 Nibral props with a 060 cup and 1 3/8” shafts. After taking with Bennett, Lenco and ZipWake I decided to go with Bennett Bolt 24x12 tabs as I only needed just a little to get the ass end up. I like to run my engines at 2400-2500rpm and they will hit the max rpm of 2800 no problem. 2400 is my slow cruise speed and with tabs I was running 13-14 knots depending on wind and current and fully loaded. Just go back from sea trailing with the new tabs and now at 2400 going against the wind and current I’m running 16 knots. Going with wind and current we’re saw 17 knots. So far I’m super excited. Had to get to a family event and didn’t get a chance to really put her through her paces. So my humble opinion is with lower horsepower I think these 31’s would benefit from a little tab.

[Tony Meola]

Chris

Interesting. Thoughts on tabs on a 31 are mixed. Most find that they help in a head sea.

What did you find out about Zip Works? I believe they were originally a Volvo product. The attractive thing about them is that they won't get in the way when you are fishing. Just not sure how well they work.

[Snipe]

Tony Zipwake looks to be a nice product I believe they are made by Imtra. I know one of the guys on the board doing a repower right now installing them maybe we will hear from him with results when he finishes up. I also looked into these. I think I am going to go in first then see how the boat performs first I can always add them.

[PeterPalmieri]

I was thinking the same thing Jason. I had tabs, so will be interesting to see how it is without.

[ccroke13]

Chris

Interesting. Thoughts on tabs on a 31 are mixed. Most find that they help in a head sea.

What did you find out about Zip Works? I believe they were originally a Volvo product. The attractive thing about them is that they won't get in the way when you are fishing. Just not sure how well they work.

Tony, The only reason I didn’t go with ZipWake was the price. I needed so little tab that I just couldn’t justify the expense. It’s slick design though.

[Tony Meola]

I've never had an issue running with no tabs as long as the crew doesn't shift to one side.

[Carl]

What Chris said is exactly why I put them on my boat years ago.

When cruising slow the tabs make a dramatic difference.

So what's dramatic you ask...well 14 to 17knots is dramatic to me, even 14 to 16 knots is a big difference in speed for the same rpm.

I could get someplace faster or if I liked the 14 knots I could cut the throttle back some and burn less motion lotion. That last part for me was a huge deal when kids were small and bills were large. Going out for a 1/2 hour boat ride wasn't about getting anyplace, but just going. So for me, it was get up on plane and go. Just on plane I was burning 22gph, give her a little tab and I could ease back on the throttles while still being on plane while only burning 16-18gph. Thats a free 6 gallons an hour.
Likewise, if I wanted to get somewhere and didn't mind the 22gph I'd give some tab, bow came down some and I'd pickup an easy 3 knots at the same burn rate. Again "free" fuel.

This year with fuel prices hitting Ridiculous, I just saw $6.78 and 9/10 per gallon for diesel...I think the tabs are going to be my big friend again when going out for cruises to nowhere.



Getting up and going over 20+ knots the tab effect becomes less dramatic. Going faster tabs can become detrimental as they push the bow down.

[Ironworker]

I posted a couple of years ago about adding tabs to my 31. The consensus at the time was they were not needed. I'm still leaning towards installing them while everything is torn apart if nothing else to level the ride in cruise. Any help with fuel economy would be a huge plus.

[Amberjack]

Rick, I have them on Amberjack and they are functional. For several years I fiddled around with then and it always felt as though they were contributing but when I looked at actual speed differential, nothing or maybe half a knot which would have been within the margin of error. So now they ride along in the up position and every year I replace the zincs on them. That being said my experience with them was always within the range of 20-28 knots.

[Tony Meola]

Getting up and going over 20+ knots the tab effect becomes less dramatic. Going faster tabs can become detrimental as they push the bow down.

That seems to be corrected by the Zip Wakes tabs. They actually automatically add less tab the faster you go. Not sure how it figures it out on what to do, it also automatically corrects the pitch of the boat.

[bob lico]

correct tony totally detrimental at upper cruise speeds

[Carl]

They actually automatically add less tab the faster you go. Not sure how it figures it out on what to do, it also automatically corrects the pitch of the boat.

There is an automatic Trim option available on regular tabs too. It figures out the Trim the same way your car runs...with a computer. I am a minimalist that believes computers and boats are a tough match. Actually computers and a saltwater environment...
Like I'd hate to have my motor decide for itself it's better to shut down if it detects a problem without my permission, I'd hate to have a Trim Tab decide to do anything by itself.

If I was on the fence, wanting to make the decision now with money NOT being an issue, the Volvo style wedge tabs is the way I'd go. Almost as clean of an install as recessed tabs and from what I have heard work very well. For me, money was a consideration and I don't mind the tabs hanging off the back. For me to worry about the tabs cutting off a line...hell 12" away is the hull with running gear right under. That and my serious fishing days are less and less, its more all enjoyment now...the thrill is the catching and the fight.

[Marshall Mahoney]

I like mine (Bennett). If mine fail, I would replace them. I pick up a knot or two at cruise and definitely makes for a more comfortable ride in a chop. Easy to level the boat vs yelling at the crew to shuffle ice chests. But better be in the up position if backing down on a fish -- they will rip right off.

[Ironworker]

I like mine (Bennett). If mine fail, I would replace them. I pick up a knot or two at cruise and definitely makes for a more comfortable ride in a chop. Easy to level the boat vs yelling at the crew to shuffle ice chests. But better be in the up position if backing down on a fish -- they will rip right off.

Really a tab will rip off? I've never had one rip off on any of my CC's before and they are used heavily.

[Marshall Mahoney]

Yup -- pulled the piston all the way out of the hydraulic cylinder and lost a tab. I don't back down anymore...

[Carl]

Really a tab will rip off? I've never had one rip off on any of my CC's before and they are used heavily.

I haven't seen one rip off that was fully retracted when backing down. BUT if the tab is down and backing down, yes that does happen. Huge surface for a little plastic ram to hold. Although the little plastic bracket from ram to tab usually breaks off leaving ram attached to hull intact.
If you think about it the tab is ONLY meant to be pushed down.

[Ironworker]

I learned something today!

[Rawleigh]

And I believe that they are only single acting rams with a spring to return them to the up position. That said I have had no problems with mine, but haven't backed down that hard on a fish.

[Carl]

And I believe that they are only single acting rams with a spring to return them to the up position.

Single with spring return is correct Rawleigh.
The electric tabs like Lenco don't like reverse with tabs down either.

[bob lico]

my boat would be downright dangerous with trim tabs .God almighty i doing anything possible to keep that bow up and ride over the waves not into them ,at 30 knots you will "stuff it" and fall forward if your have a stand up bridge you could sail out the top of the bridge like that captain in JUPITAR inlet FL. i have given away at least 4 pair of trim tabs in the past and have one set for anyone on this board with a 31 Bertram that squats from a lesser torque engine .SS tabs free if you pick them up.