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B25 Trim Tabs

Posted: Apr 12th, '21, 06:54
by CamB25
Installed 12x12 Lenco electric trim tabs on the B25. They work very well as positioned on the transom bump out. MUCH easier than trying to install outboard of this position. They are probably not as responsive in this position, but they are doing a great to keep the bow down, lower the cruise speed, and enable flat launches. Lenco was concerned that they might introduce bubbles/turbulence to the prop. I can detect no ill effects other than the wake behind the boat is not as clean as it was before the tab install. Very happy. Easy install.

https://www.amazon.com/photos/shared/F5 ... NzyRZUgc1q

Next up is the shorter setback jackplate. BTW, the jackplate came in really handy yesterday. Long story but it's tough to move with 6 inches of water under the boat. Raise the jackplate, tilt the engine and voila!, we are off the bar and running again.

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 10:08
by ktm_2000
Cam,

I am glad they are working well for you, to me this is a wait and see as I've run the boat for quite a few years without them

Some questions and thoughts

Where is your transducer? thru-hull?

I was also thinking of doing the same config as you on my boat. I am somewhat concerned in that I will have a rather large transducer on the starboard side and I would guess that while the tabs might not affect the ride, they would cause issues with how well the transducer works if they were to close together.

my thoughts are the stock location is kind of swiss cheese on my boat as the tabs must have been put on and changed a few times before I owned her, I had filled the holes with epoxy / thickener and covered the area in 1 layer of 1708 when I removed the tabs. I am slightly worried about putting them back in the stock locations. The mounting holes would also put the hoses in an exposed area inside my transom.

I may want to use my new found "extra" project time and fill in the area under the perimeter lip and use that area to allow tabs to be installed further outboard of the centerline if I do need them sometime in the future.

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 12:08
by CamB25
I'm using a B150M thru-hull transducer - https://www.airmar.com/productdescription.html?id=72

The tabs are nice, but not 100% necessary. The ability to plane comfortably at lower speeds is a winner for me.

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 12:11
by HotSpot
Thanks for posting this,Cam.

What are your thoughts on the difficulty of installing outboard of that position? Would the same model (12”) ones fit in that recessed notch just outboard of the position you selected?

I had searched the board for the appropriate size and placement for a 25 with dual outdrives, with no definitive answer. Sounds like you thought this through as you usually do.

And gawd... from any angle, even the business end, that’s a pretty boat.

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 14:21
by CamB25
The simple answer is yes, but bring a grinder with a cut off wheel. You'll need adjust the backing plate to fit. Two primary reasons I decided not to install there: 1) Swim platform interference - need 14" clear to mount the ram, 2) hard chine - I'm not sure how the water flow would change around the hard chines and didn't want to find out! Well...3 reasons. 3) that area may not perpendicular to the hull side. I didn't measure it, but I think it's an angle.

I had the boat out yesterday for joy ride. It's running well, so I'll have to find something to fix quick, or I'll get bored! Ha! My engine is out warranty now, so I'm running it like I stole it. Fun!

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 14:56
by beachbum
Very nice indeed - yeah I guess in that position the tabs will have much more influence on the bow height than positioned further out (where mine are).

You guys in the US keep your boats in such unbelievably good condition, at least that's how it looks from the photos!

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 15:26
by ktm_2000
Beachbum, I don't think you can put Cam in the group of average boaters. His boat looks like a work of art.

Re: B25 Trim Tabs

Posted: Apr 12th, '21, 16:32
by beachbum
Well let's just say that my 1968 B25 looks like it was built in 1968, every picture of a 31 / 28 / 25 on this site shows really top condition boats.

That stern photo of Cam's boat looks like something that's just rolled out of a factory!

(On the plus side, I got my mini gas stove working today so I can make a cup of tea at last :-D )

Re: B25 Trim Tabs

Posted: Apr 13th, '21, 07:27
by HotSpot
CamB25 wrote: Apr 12th, '21, 14:21 Two primary reasons I decided not to install there: 1) Swim platform interference - need 14" clear to mount the ram,
Ya, looks like the rams had just enough clearance from the platform where you put them. Thanks for the info, this is really helpful.

Re: B25 Trim Tabs

Posted: Apr 13th, '21, 11:49
by Carl
beachbum wrote: Apr 12th, '21, 16:32 Well let's just say that my 1968 B25 looks like it was built in 1968, every picture of a 31 / 28 / 25 on this site shows really top condition boats.

That stern photo of Cam's boat looks like something that's just rolled out of a factory!

(On the plus side, I got my mini gas stove working today so I can make a cup of tea at last :-D )


Well take a look at mine and that will change your opinion of "all" the boats on here and make you feel quite at home.

Cams boat looks nothing like a boat rolling out of any factory I know...maybe more along the lines of a High End Custom Boat Builder.



If tight for space consider the Volvo QL Wedge Tabs

https://internal.bdoutdoors.com/2014/07 ... 1bce09.pdf

Re: B25 Trim Tabs

Posted: Apr 13th, '21, 19:30
by HotSpot
Regarding the related switch gear... Are the ones that have the lighted trim position indicator necessary? Or somewhat useful?

Seems to be a couple hundred dollar premium over standard switches.

Re: B25 Trim Tabs

Posted: Apr 14th, '21, 05:13
by Sheer Folly
I know I’d like to have them, if I forget to bring my tabs up all the way I can’t back into my dock slip worth a dam!

Re: B25 Trim Tabs

Posted: Apr 14th, '21, 06:21
by Carl
HotSpot wrote: Apr 13th, '21, 19:30 Regarding the related switch gear... Are the ones that have the lighted trim position indicator necessary? Or somewhat useful?

Seems to be a couple hundred dollar premium over standard switches.


If you can't remember to bring them up when your slowing down coming off plane a light on the dash isn't gonna help you much.

For me, bringing tabs up is part of throttling down and becomes a habit.

Re: B25 Trim Tabs

Posted: Apr 14th, '21, 06:25
by Sheer Folly
Carl, you’re right, but the older I get the more “forgetter” I get. I’m 74 and counting.

Re: B25 Trim Tabs

Posted: Apr 14th, '21, 08:35
by CamB25
I bought the controller with the indicator lights and the auto-retract function. I like the lights, but with enough experience with the boat and the tabs, I'm sure they are not necessary. Auto-retract is nice - 12volt sensing circuit off the key switch. Key off - tabs retract.

I have about $800 in parts for the system, including anti-fouling paint, anodes, cables, tabs, actuator switch, etc. I spent about one full working day installing everything....maybe an hour or two more. Not difficult.