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Mike_J
Joined: 26 Mar 2012
Posts: 373
City/Region: Victoria, BC
State or Province: BC
C-Dory Year: 2011
C-Dory Model: 22 Cruiser
Vessel Name: Natural C-lection
Photos: Natural C-lection
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 Posted: Mon Dec 31, 2012 1:56 am Post subject: Effect of motor trim |
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I am sure most of you have figured this out, but I did not realize how much effect trimming my engines up could have on speed and performance. Today I was playing with the trim at full throttle and discovered that I could get more than 20 % increase in top speed from just over 40 kph to over 50!
I also found that the handing was also much improved - the CD22 seemed to turn more cleanly and be less likely to "grab".
Anyway, a nice discovery for me! |
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hardee
Joined: 30 Oct 2006
Posts: 12637
City/Region: Sequim
State or Province: WA
C-Dory Year: 2005
C-Dory Model: 22 Cruiser
Vessel Name: Sleepy-C
Photos: SleepyC
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| Posted: Mon Dec 31, 2012 2:11 am Post subject: |
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Mike, do you have trim tabs or a permatrims on your boat?
(Permatrim) = a hydrofoil of some type, dolphin etc?
Harvey
SleepyC
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Though in our sleep we are not conscious of our activity or surroundings, we should not, in our wakefulness, be unconscious of our sleep. |
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Mike_J
Joined: 26 Mar 2012
Posts: 373
City/Region: Victoria, BC
State or Province: BC
C-Dory Year: 2011
C-Dory Model: 22 Cruiser
Vessel Name: Natural C-lection
Photos: Natural C-lection
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| Posted: Mon Dec 31, 2012 2:40 am Post subject: |
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| I have trim tabs, but have not yet figured out how best to use them. I had a per matrix like hydrofoil on my old runabout. It worked well, but I am not sure if it makes sense to try them on my twin Yamaha 50s. |
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T.R. Bauer
Joined: 17 Nov 2007
Posts: 1808
City/Region: Wasilla
State or Province: AK
C-Dory Year: 1993
C-Dory Model: 22 Cruiser
Vessel Name: C-Whisperer
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| Posted: Mon Dec 31, 2012 11:53 am Post subject: |
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| Trim advice: If you have flat water, motors and tabs in the middle is a good place to be. If you are going into chop, then trim the tabs and the motor (s) down and slow down. If the seas are large, or have a following component, go back to a trim in the middle as the boat handles better. |
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Mike_J
Joined: 26 Mar 2012
Posts: 373
City/Region: Victoria, BC
State or Province: BC
C-Dory Year: 2011
C-Dory Model: 22 Cruiser
Vessel Name: Natural C-lection
Photos: Natural C-lection
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| Posted: Mon Dec 31, 2012 1:16 pm Post subject: |
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| Thanks T.R. I am not sure what you mean by tabs and motors in the middle. My CD22 does not have any indication of where the tabs are, and I am nit sure how much "range" I have with the motors while running. Still new at this! |
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T.R. Bauer
Joined: 17 Nov 2007
Posts: 1808
City/Region: Wasilla
State or Province: AK
C-Dory Year: 1993
C-Dory Model: 22 Cruiser
Vessel Name: C-Whisperer
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| Posted: Tue Jan 01, 2013 2:00 pm Post subject: |
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| Mike_J wrote: | | Thanks T.R. I am not sure what you mean by tabs and motors in the middle. My CD22 does not have any indication of where the tabs are, and I am nit sure how much "range" I have with the motors while running. Still new at this! |
Well, not having gauges really sucks. In the middle means the bow of the boat isn't trimmed up and isn't trimmed down. The tabs and trim in the down position give you the option of plowing into the waves giving you a better ride. This position will also produce the grabbing and goofy handling you noted was gone when you changed the trim settings on your boat and gained speed.
I have found that trimming everything all the way down makes for a decent ride when matched with the right speed. If there is significant swell, the boat is quartering a beam sea, or has a nasty following sea, I trim in the middle - meaning the bow isn't being raised up or down, and pick my way through it at a slow speed. It really gives the boat a nice solid feel with predictable handling.
Considering a boat in the Gulf of Alaska more than anywhere else, my boat is rarely trimmed down. However, in PWS and Cook Inlet, I trim it down frequently as there really isn't a swell component to deal with and the waves are usually just annoying chop. If you are running in Puget Sound or thereabouts, I can see you running the boat with the bow trimmed down a lot of the time.
Anyway, hope that clarifies and Happy New Year! |
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thataway
Joined: 02 Nov 2003
Posts: 21385
City/Region: Pensacola
State or Province: FL
C-Dory Year: 2007
C-Dory Model: 25 Cruiser
Vessel Name: thataway
Photos: Thataway
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| Posted: Tue Jan 01, 2013 8:01 pm Post subject: |
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Many trim tab controls have an option of LED lights to show position. It is a fairly expensive option, depending on brand. I had it on one boat. It was nice. Also these usually have "auto retract" when you turn the tabs off.
If not, you get a feel by moving the tabs, and seeing how much the bow depresses. You will find a point where the bow does not go up or down, and that will be the limit. I usually judge by time--you get a feeling for it--and I use short bursts of power to the trim tabs.
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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
KA6PKB
Home port: Pensacola FL |
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Sunbeam
Joined: 23 Feb 2012
Posts: 3990
City/Region: Out 'n' About
State or Province: Other
C-Dory Year: 2002
C-Dory Model: 22 Cruiser
Photos: Sunbeam
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| Posted: Tue Jan 01, 2013 8:21 pm Post subject: |
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| thataway wrote: | | Many trim tab controls have an option of LED lights to show position. It is a fairly expensive option, depending on brand. I had it on one boat. It was nice. Also these usually have "auto retract" when you turn the tabs off. |
Some "beginner-tab-user" comments:
I recently purchased a set of Bennett Sport 120 trim tabs for my 22. I considered the switch with the LED lights but ruled it out for a couple of reasons. One is that it was expensive (~$300 if I am remembering correctly), and the other was something about the way they work that I decided wouldn't please me, but darned if I can remember what it was :blush
I had a chance to use a non-lit-switch set of Lencos on someone else's boat at Lake Powell (same switch as comes "free" with the Bennetts), and although maybe I would have liked the lights, I actually forgot about them even being an option while I was using the tabs - I never looked at the switches. I just kept my eye on bow trim, on where the spray was coming up from the chine on starboard side (how far back on the window was it), and on the speed and fuel usage displayed on the main instruments, and went by those factors. I did sometimes run them all the way one way or the other at the beginning, so I would "know where I was."
I understand that adding the LED-lit switches is less expensive on the Lenco tabs than on the Bennetts, because they don't automatically include either one, so you are just choosing A or B, and B (lit) costs a bit more. With the Bennetts, they come with the non-LED switch included, so to get the LED one you are "buying it from scratch" but you have also paid for the standard switch because it comes with them "for free." So it ends up being more out of pocket to get it on the Bennett Sports.
I wanted the Bennett tabs (for other reasons), so didn't go with the Lencos. Given what I perceived as the excellent functionality:cost ratio of the basic Bennett Sport trim-tab kit vs. the functionality:cost ratio for the lit switches (didn't seem as favorable), I decided against the lit switches. But I would still have gotten them if they were really important to me (as it is I'll be spending that money on other things for the boat  )
Again, just a "rank beginner" trim-tab report, so take it with that sort of grain of salt vs. the folks who have used them extensively.
Sunbeam |
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Mike_J
Joined: 26 Mar 2012
Posts: 373
City/Region: Victoria, BC
State or Province: BC
C-Dory Year: 2011
C-Dory Model: 22 Cruiser
Vessel Name: Natural C-lection
Photos: Natural C-lection
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| Posted: Tue Jan 01, 2013 9:21 pm Post subject: |
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| Thanks for all the feedback. Very helpful! |
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C-Nile
Joined: 09 May 2008
Posts: 638
City/Region: Connecticut
State or Province: CT
C-Dory Year: 2012
Vessel Name: Betty Ann
Photos: C-Nile
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| Posted: Wed Jan 02, 2013 9:08 am Post subject: |
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A quick note on trim tabs -- on our Marinaut, we purchased Lenco Trim Tabs with the LED display, because only the LED option allowed for trim tab auto retraction when the boat is powered off. It was well worth the money, because we store our boat in valet storage, and if we ever were to forget to retract the tabs, they would be torn off by the fork lift.
As for engine trim, it does seem to make subtle improvements in performance. In cases where we need to keep the bow down in very heavy seas, we need both full engine trim and trim tabs. The one thing I have not done is to quantify the impact on performance of engine trim on a boat with trim tabs under light seas conditions. Has anyone ever done that?
Rich
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Marinaut 215 - "Betty Ann" Sept-2011
CD 16 Cruiser "C-Nile" Sold 06/2011 |
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