Trim tabs with twin engines?

R

Rokjok777

New member
Hi, I'm sold on the benefits of tabs, but Squidward has twin Honda 50's and there wouldn't be much space between the tab and the engine. I'm thinking about the Lenco 9X12. Should I be looking at narrower tabs? Or are tabs a no-no with twin engines? Also, let's hear some unbiased opinions on whether the hydraulic or electric tabs are better...I'd like to mount the control unit in one of the lazarettes and don't want the hassle of topping off fluid...plus those hydro hoses do seem to add to the maintenance. Any opinions?
 
I just installed the Bennet trim tabs-- Sport 80's with the auto controller. Have yet to get them wet, but SEA3PO has them and work great. Yes, we have twins.
 
Don't know about clearance for twins, but have installed the Lenco 9X12's on our 22' CDory, and am very pleased with the installation and operation. Photos of the install are posted under the Trim Tab Photo Album, under the most creative heading of "Trim Tabs". I'll be glad to give you a measurement on the spacing between the units, if you want, and take a stab at any of your installation questions, if you go with this unit. Like others, I've found trim tabs to be a "must have" piece of equipment, which only take a little while, and some open water, to master.

Good luck!
 
As a followup on Lenco 9X12, we got our's new, in the box, delivered to the front door, for $386. I'll be glad to share particulars, if you're interested.
 
I installed the Bennett M-120s Sport Tabs on our CD22 last spring and we have twin Honda 40s. The installation was straightforward, they work well, and I would not be without them.
 
I also have twin Honda 40's and had Les at EQ Marine install the Bennet tabs. The larger tabs can not be installed because of the limited remaining space to the outside of the engines, but the smaller ones fit fine. You will love them and wonder how you got along with out them.

There is also a thread on the old C-brat MSN Tech site with a lot of discussion about tabs.
 
rokjok777,

I highly recommend trim tabs (and I do like the idea of the Lenco's enough that we'll put them on our current boat); I believe everyone that's installed tabs has been quite pleased with the results.

The M120 Bennett tabs that are typically installed on the twin engined CD22's have a 10" span and a 12" chord. These fit well but I wouldn't push the chord any wider; it's tight enough at 10" that I've had to remove previously installed hydrofoils (like Doel-fins) in order to avoid interference at full lock turns (particularly when tilting the engines).

You've got to be careful on the sizing charts; the tab manufacturers are not consistent in the order of which the span and chord is given; a Bennett 12x9 is 12" in width (span) and 9" in length (chord) but a Lenco 12x9 is just the opposite at 12" in length (chord) and 9" in width (span).

My experience suggests that anything from 80 square inches (per tab) up will work but my preference is for something over 100 square inches. In the Lenco line I would opt for the TT12x9E for a twin engine CD22 and the TT9x12 for a CD22 with a single engine. The TT12x9E tabs will mount just fine on a single engine boat but the 12" chord is going to cause problems if you've got a kicker motor mounted on the transom next to the main engine; the kicker won't clear the 12" deep (chord) tabs.
 
This is one of the many reasons I chose a C-Dory, this great online resource for information. Thank you all. Really superb, now I have a winter project. Lenco TT12 x 9E are my choice, thanks especially to Les.
 
Our Christmas present to Laurna Jo is tabs. But it may take a bit cuz we gotta wait for Les( The Premier Dealer and C-Dory Rigger!) to slow down a bit with all the "births" he is taking care of. Will go with his recommendation.
Jim
 
"Tweaking the engine angles" will only serve to raise the bow more; i.e. they only "tweak" one way. To limit pounding, the nose must be trimmed down and the best way to do that is with tabs. I would not be without them.
 
Iconoclast":2v8k7z9v said:
Can't you all get most of the benefits of trim tabs by just tweaking the engine angles? What more do you get?
Click to expand...

Well, one would think you could come close to the same effect with motor trim, but it isn't even close. Setting aside the lateral trim abilities, the difference on our previous 22 Cruiser was very evident. I found that by setting the motor trim so the prop was running pretty much parallel with the water surface, and tweaking the tabs while watching the GPS speed, I could coax as much as 2 1/2 additional knots in speed without touching the throttle. Just trimming the motor down (even with a Doel fin I tried before the tabs), I could get the bow down a ways to smooth out the chop, but I lost quite a bit of speed, and with it, the fuel economy.

Another neat thing I discovered with the tabs was that I could use less tab trim and more motor trim when running in sloppy water where too much tab down would make the boat squirrelly. That way I could smooth the chop out, and keep the cruise speed higher while still being comfortable.

No doubt about it. Trim tabs on the CD 22 are amazing.

For the record, the tabs I put on were Bennett M120 Sport Tabs. I just looked at the Lenco electrics online, and they do look like they would be a lot simpler and cleaner to install, and at a comparable price. Our new boat has tabs already (hydraulic), or else I would probably give the Lencos a try myself. Ball screws are very efficient, and not likely to wear out given the relatively small amount of work they will be doing. And no hydraulic power unit to find a spot for. The hydraulics unit that came with the Bennetts was trouble free, though, and never required topping the fluid in the two years I ran it.
 
"Can't you all get most of the benefits of trim tabs by just tweaking the engine angles? What more do you get?"


Yes, you can get a little attitude adjustment by "tweaking" the engines. But you lose performance when you do. I have the twin Honda 40s with the hydrofoils and have been able to adjust for list and attitude by raising one engine more than the other. This is not the best way to maintain good performance. I just installed the Bennet M80 sport-tabs. I would have gone with the M120, but I would have had to remove my bait pump.
 
Roger,

That's a perfect example of a good compromise! Sometimes in these posts things come across as more "absolutes" than they really are; we're always trying to choose the best item possible but sometimes (really most times) the best choice is the one that gets the job done while not disrupting the other things about the boat one likes.

Did you keep the hydrofoils when you installed the tabs?
 
Les-
I left the hydrofoils on for the time being. They clear the trim tabs by a couple inches.
The main reason for getting the trim tabs was for the side to side attitude. With the refrigerator on the port side, the boat was always listing to port. As noted above, I adjusted for it by trimming the engines separately- it took most, but not all, of the list out. I will be at Lake Cachuma for the next couple weeks, and will make adjustments and set the auto trim then.
With the limited dash space, I made a small shelf for the trim tab rocker controls just forward of the engine controls and mounted the auto control just left of the wheel. I will try to remember to take a couple of pictures.
 
Hi Roger,

Thanks for the info! One last question for now and then I'll wait for your next report :lol: ; is that "couple inches of clearance" when the engines are at a full lock turn? (so that if you tilt them when they're fully turned the hydrofoil clears the tab then?).

Oops, one more...are the hydrofoils the Honda SST, Doel-fin or?

TIA
 
Got on the water yesterday around 09:30 and played with the trim tabs for about an hour and set the auto controller-- man, what a great system.
Trimmed the engines for optimum performance and set the trim tabs.
Once the auto controller was set, I had PJ move to the other side of the boat and 3-4 seconds later the tabs started adjusting for the change. Rigged two rods for trout and set the lines. Running on one engine, the troll was too fast for my liking, 2.5 mph, set the trim tabs all the way down and slowed to 2.0 mph. Fished till a little after 12:00 and came in with 3 trout (after releasing the ones that were lip hooked) Ya- you know what was for dinner-- oak smoked trout fillets
 
I am curious about hydrofoils. I have a Tom Cat that runs pretty flat at all speeds. What might a hydrofoil on the motor due re: cavataion and economy. Is it overkill on a Tom cat?
Phil
 
Back
Top