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Trim tab size for 26-footer
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Mon Jun 02, 2014 6:19 pm    Post subject: Trim tab size for 26-footer Reply with quote

My 26-foot Cape Cruiser currently has trim tabs that are - in my opinion - too small. They are 9" long, and 12" wide at the hinge. This is the same size that I have on my 17-foot Arima, and they work well in that application. But, on the CC, they are virtually ineffective until they are deployed almost all the way down, so I've decided to replace them with larger ones.

If I get the 12" x 12" units, I think I can swap them out without having to change the mounting position of the actuators. But, I just don't know if they will be big enough.

If I upgrade to an 18" wide tab, I'm pretty sure I'll have to relocate the actuators. But, the larger tabs might be a better match for this hull.

What size trim tabs are other folks running on their 26-foot boats, and can you speak to their effectiveness?

Lenco's trim tab ratings for reference:

9x12 tab (rated for 16-25-foot hull) = 108 sq. in. <---- current tab: definitely undersized

12x12 tab (rated for 17-30 foot hull) = 144 sq. in. <----- option 1: easiest swap, least surface area of possible upgrades (33% greater surface area than current tabs), may still be somewhat undersized

9x18 tab (rated for 22-30 foot hull) = 162 sq.in. <----- option 3: the same complexity to upgrade as option 2, only 12.5% more area than option 1 (50% greater surface area than current tabs)

12x18 tab (rated for 26-36 foot hull) = 216 sq. in. <----- option 2: twice the surface area as current tabs, but more complex swap


** I don't know if this is a valid theory, but... Comparing a known effective ratio of tab size to hull length (9x12 tabs on my 17 foot Arima hull), I come up with a target of 165 square inches per tab to get similar effectiveness from the tabs on my 26 foot CC. [108 sq. in. / 17 ft. hull length = 6.35 sq.in / ft. ... 6.35 sq. in. per foot * 26 feet = 165.1 sq. in.] So, it would seem that option 1 may still be too small, and that option 3 may actually be ideal. But, if I'm going to have to remount everything anyway, I may opt for option 2 to maximize my surface area. ... ... I've never heard of anybody complaining that they had trim tabs that were too big... Is that a concern?


Note: I'm probably overthinking this whole thing... It's what I do.

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89CD16A- The Navicula has been sold...
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NORO LIM



Joined: 24 Apr 2008
Posts: 875
City/Region: Olympia
State or Province: WA
C-Dory Year: 2006
C-Dory Model: 23 Venture
Vessel Name: NORO LIM (sold 12/12/14)
Photos: NORO LIM
PostPosted: Mon Jun 02, 2014 7:10 pm    Post subject: Reply with quote

Can't offer advice on the trim tab size, as I don't have them (and my boat's a 23, anyway). But I do have Permatrims on twin engines (Yamaha F-70's), which work fine for me - I can really lower and raise the bow, and do moderate side to side balancing. Do you have a Permatrim, or other foil? If not, that addition might alter your calculation on the tabs. Just a thought.
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Mon Jun 02, 2014 7:51 pm    Post subject: Reply with quote

NORO LIM - That's a valid question. I don't have Permatrims on this boat. I did have one on the Arima before I re-powered it (I just couldn't bear to drill into the anti-V plate on my shiny new motor). Before the re-power, I tried it both before and after I installed the trim tabs and found it to be more useful without the tabs on that particular boat. So, I wasn't planning on spending $300 - $400 (with freight) just to test 'em out on this boat. That, plus... I'm looking at swapping the twin Hondas for a single Yamaha or Suzuki (I'm gonna give 'em a fair shake, but I just don't think I'm a 'twin' guy), and adding Permatrims to a set of motors that I may very well end up selling soon doesn't seem prudent. So, in this discussion about the proper size of trim tabs, I have to make the assumption that I won't ever have a Permatrim.
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BrentB



Joined: 15 Jul 2006
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PostPosted: Mon Jun 02, 2014 8:39 pm    Post subject: Reply with quote

m2cw

For optimum gain, replace system and increase the width (span) to 30" according to Bennett

and ask Tom
<tabmanhelp@gmail.com> or
info@BennettTrimTabs.com <info@BennettTrimTabs.com>;

for recommendations

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thataway



Joined: 02 Nov 2003
Posts: 20778
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
PostPosted: Mon Jun 02, 2014 8:57 pm    Post subject: Reply with quote

Send a PM or e-mail to "taxman" who is a registered member of this forum. He may pick your question up--but if you ask him, you may bet a more rapid response--and he / you can share this on the forum.

Do the search on member "taxman".

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Bob Austin
Thataway
Thataway (Ex Seaweed) 2007 25 C Dory May 2018 to Oct. 2021
Thisaway 2006 22' CDory November 2011 to May 2018
Caracal 18 140 Suzuki 2007 to present
Thataway TomCat 255 150 Suzukis June 2006 thru August 2011
C Pelican; 1992, 22 Cruiser, 2002 thru 2006
Frequent Sea; 2003 C D 25, 2007 thru 2009
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BrentB



Joined: 15 Jul 2006
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PostPosted: Mon Jun 02, 2014 10:00 pm    Post subject: Reply with quote

Bob means tabman Very Happy
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Mon Jun 02, 2014 10:23 pm    Post subject: Reply with quote

I'm sure Tabman could offer some sound advice about tab size in general, but... 1) I'd feel a bit awkward asking the Bennet rep for advice about my Lenco system, and 2) I was hoping for some real-world experience regarding how the various sizes of trim tabs are working on this particular hull. If nobody with a 26-footer responds, maybe I'll shoot Tabman a PM.

BrentB - I'd have to look, but I'm not so sure that 30" tabs would even fit... Two tabs would take up 5 feet of transom space! Shocked
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BrentB



Joined: 15 Jul 2006
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PostPosted: Mon Jun 02, 2014 10:28 pm    Post subject: Reply with quote

I understand
Longer the span (Width) that is possible

Tabman is the best
Check his THT site
http://www.thehulltruth.com/tabmans-trim-tab-discussion-15/
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NewMoon



Joined: 21 Dec 2008
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City/Region: Holladay
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C-Dory Year: 1991
C-Dory Model: 22 Cruiser
Vessel Name: Cindy Sea
Photos: Cindy Sea
PostPosted: Tue Jun 03, 2014 9:13 am    Post subject: Reply with quote

On our very heavily-built 26-footer, I replaced the original 9x18 Bennett tabs with 12x20 tabs that also have a section that points downward at each end. They were the biggest I could squeeze in with appropriate clearance from props transducers etc. The actuators are a bit off center on the bigger tabs, but they did not have to be relocated. The new tabs made a huge difference, and have worked perfecly for 15 years now.
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Dream Catcher (Nordic Tug 37, 2016 to present)
New Moon (Bounty 257, 1998 to 2016)
Cindy Sea (CD 22 Cruiser, from 1991 to 1998)
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Tue Jun 03, 2014 3:45 pm    Post subject: Reply with quote

NewMoon - Thanks for the input. The 26-footer to which you are referring is a Bounty 257, not a C-Dory or Cape Cruiser, correct?
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Jack in Alaska



Joined: 17 Aug 2004
Posts: 1190
City/Region: Anchorage/Ninilchik
State or Province: AK
C-Dory Year: 2005
C-Dory Model: 26 Pro Angler
Vessel Name: HIGH TIDE II
Photos: HIGH TIDE II
PostPosted: Tue Jun 03, 2014 10:46 pm    Post subject: trim tabs Reply with quote

Ak Angler.....

On my 26' ProAngler C-Dory (14 degr. deadrise) I have 18"x8" Insta-Trim tabs. I just put on my slippers, set down my adult beverage and went outside and measured my tabs just for you.
THey work just fine IMHO. Boat is very responsive to them.
I am sure they were on it when the boat was new (2005).
THe only problem I had was the dash control was inop. when it came from Fla. I contacted Insta-Trim and they sent a whole new controller but I had to send the old one back to them. So far it has been fine, 5 yrs.

You should have told me you only wanted the boat hull towed up. I could have ditched all that other stuff, engines, tabs etc

Good luck on the remodel.

Jack

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On the HIGH TIDE-II, wife Carolyn and I.....Another summer fishing on the HIGH TIDE II in the Cook Inlet at Cape Ninilchik, Alaska.

HIGH TIDE-II; 2005 26' ProAngler; 2003 200 Honda / 2009 9.9 Honda high thrust
No. CD026021I405; AK-5008-AK
MSSI No. 338143486(cancelled)

HIGH TIDE; 1983 Angler Classic 22'; 90 Honda/ 9.9 Tohatsu-sold 2009 to son Dan (flatfishfool)
Stolen & stripped in Aug. 18
Bare hull & trailer sold in Nov.
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Wed Jun 04, 2014 12:01 am    Post subject: Re: trim tabs Reply with quote

Jack in Alaska wrote:
Ak Angler.....

You should have told me you only wanted the boat hull towed up. I could have ditched all that other stuff, engines, tabs etc

Good luck on the remodel.

Jack


That's funny, Jack. If I had only known... if I had oooooonly known. Rolling Eyes

I don't know about ditching the motors just yet. I really am going to give the twins a fair shake.

And, thanks for the input on the tabs (I hope your drink didn't get too warm while you were out checking for me! CoolSmile). So, if someone gave you a set of bigger ones... say, 18x12... do you think you would spend the time to swap 'em out? Or do yours work good enough that you wouldn't bother?
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forrest



Joined: 02 Nov 2003
Posts: 381
City/Region: Chehalis
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C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Long Story
Photos: Long Story
PostPosted: Wed Jun 04, 2014 12:37 am    Post subject: Reply with quote

Wow, I hardly ever use my trim tabs and I only fill the water tank half full so I don't dig into a wave and bow steer while crossing the bar at Westport. About the only time I use trim tabs (the 9x12 that you described) is in 2 foot chop in Puget Sound or out in the ocean in 2 foot chop with minimal swell.
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AK Angler



Joined: 18 Nov 2003
Posts: 327
City/Region: South Central
State or Province: AK
C-Dory Year: 2007
C-Dory Model: 26 Venture
Vessel Name: Rod Holder
Photos: Rod Holder
PostPosted: Wed Jun 04, 2014 1:32 am    Post subject: Reply with quote

That's interesting, Forrest... The same sized tabs that are basically ineffective for me seem to work well for you. I wonder if there's a substantial difference in fore-to-aft balance between our boats at play here...? Your Honda 200 weighs almost 200 pounds less than my twin 90's. Plus, we haven't yet fully outfitted and stocked our boat yet, which would account for our balance point being even further aft.

Hmmm... it gets curiouser and curiouser...
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Sunbeam



Joined: 23 Feb 2012
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PostPosted: Wed Jun 04, 2014 3:23 am    Post subject: Re: Trim tab size for 26-footer Reply with quote

AK Angler wrote:

Note: I'm probably overthinking this whole thing... It's what I do.


Mr. Green Thumbs Up
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