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Permatrims: My 2 cents
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daninPA



Joined: 16 Aug 2020
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City/Region: MOUNT JOY
State or Province: PA
C-Dory Year: 1994
C-Dory Model: 22 Cruiser
Vessel Name: NAVIRE
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PostPosted: Wed Dec 29, 2021 2:03 pm    Post subject: Reply with quote

pcg wrote:
thataway wrote:
As a person who feels both trim tabs and Permatrims are ideal, I would disagree that the permatrim does not help bring the bow up. My experience is that it does.

I have experience with neither, but I thought the purpose of Permatrim was to lift the stern, i.e. bring the bow down.???


Permatrim (essentially an extension of the motor's anti-ventilation plate) reinforces the OB engine's angle (up or down).

https://www.permatrims.com/
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thataway



Joined: 02 Nov 2003
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City/Region: Pensacola
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PostPosted: Wed Dec 29, 2021 2:57 pm    Post subject: Reply with quote

pcg wrote:
thataway wrote:
As a person who feels both trim tabs and Permatrims are ideal, I would disagree that the permatrim does not help bring the bow up. My experience is that it does.

I have experience with neither, but I thought the purpose of Permatrim was to lift the stern, i.e. bring the bow down.???


That is true, but as you bring the motor up to neutral or above, it helps to direct the prop wash up. It is only acting on the upper part of the prop wash however.

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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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ssobol



Joined: 27 Oct 2012
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PostPosted: Wed Dec 29, 2021 3:57 pm    Post subject: Reply with quote

pcg wrote:
thataway wrote:
As a person who feels both trim tabs and Permatrims are ideal, I would disagree that the permatrim does not help bring the bow up. My experience is that it does.

I have experience with neither, but I thought the purpose of Permatrim was to lift the stern, i.e. bring the bow down.???


The way trim tabs are installed they can only push the bow down because they are blanked by the hull in the bow up direction. The permatrim rides in more of a free stream and can give a bow up moment. However, if you install it per the directions (and your engine is at the correct height relative to the hull), the bow up moment will be less than the bow down moment.

I'm sure that different installations give more or less bow up control with the permatrim and won't be the same for all boats. Permatrims are not designed for bow up control, but in some cases it can happen.
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C Sniper



Joined: 17 Mar 2019
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City/Region: South Padre Island
State or Province: TX
C-Dory Year: 2007
C-Dory Model: 255 Tomcat
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PostPosted: Tue Jul 26, 2022 8:19 pm    Post subject: same topic, but on tomcat Reply with quote

So I finally got a tomcat, which I have been dreaming/drooling over for a few years. I starting looking a boattrader and here daily, some times twice a day... and boom one popped up in PA. Fast forward, have been using her mainly as my work boat for a few weeks, figuring out the nuances and such. I have read that permatrims on the tomcat are not as helpful as on the other C Dory vessels. Working, I am regularly out in 20-30 kt winds, always finishing the day smashing up wind into estuary chop. So any thought from those who have tried them in similar conditions? I would say the 20% smoother ride would motivate me to pull the trigger.
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thataway



Joined: 02 Nov 2003
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PostPosted: Tue Jul 26, 2022 8:30 pm    Post subject: Reply with quote

I put the Permatrims on our Tom Cat 255 to see if I could plane and get the stern up at a slower speed, because of similar concerns.

Although I feel that they are almost essential in the monohulls, I don't think that they help much, and may be slightly detrimental on the Tom Cat.

We found that speeding up and keeping the boat light was the best "solution" for going into the 2' chop. The Suzuki outboards definitely give a faster top end speed. We were running very close to 50 mph with the 150 Suzuki outboards and as I recollect 21" pitch 4 blade PowerTech props.
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T.R. Bauer



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PostPosted: Wed Jul 27, 2022 2:52 am    Post subject: Reply with quote

A good part of the reason the TC 255 rides so nice and is very efficient at speed is the air cushion (and lift) that is created from the cat hull design. I love the concept of permatrims in general - great product. However, I can see why one would not have the most favorable results with them on the Tomcat as they could contradict the inherent benefits of the hull design. Bob said they may even be detrimental and I believe him - makes complete sense. None the less, I'd love to have a TC 255 in my small fleet...even one with permatrims Smile
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Molly Brown



Joined: 02 Nov 2003
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City/Region: Punta Gorda
State or Province: FL
C-Dory Year: 2003
C-Dory Model: 24 Tomcat
Vessel Name: MOLLY BROWN
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PostPosted: Wed Jul 27, 2022 6:40 am    Post subject: Reply with quote

We have the TC24....The hull deck is too low for that "air cushion" to work well. You definitively want permatrims on a TC. Same hull as the TC255, granted it is bigger and set up differently, but you'd be hard pressed to convince me the permatrims are not effective on just about any boat that planes.

Just my 2 cents Smile

James

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thataway



Joined: 02 Nov 2003
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PostPosted: Wed Jul 27, 2022 1:31 pm    Post subject: Reply with quote

It is a very rare day I would disagree with James. But there is enough difference in the boats which I believe makes our experiences different,

The difference between the 255 and the 24 is the engine bracket. The 24 has the engines mounted directly to the hull. The flow of water at the end of the bracket in transition from displacement to planing has increased turbulence, because of this bracket. I was trying to get the boat to plane at a lower speed, and we ended up with a significant increase of water coming over the bracket with the Permatrims as we slowly transitioned from semi displacement to planing mode.

As the boat came up on a plane, the Permatrims worked as in monohulls or a cat which has the motor mounted to the hull. I did not feel that the Permatrims gave a decrease in the lowest planing speed. The Permatrims decreased the top speed a small amount. This is with the Suzuki 150's which I feel are the best engines for the TC 255. Speeds with these engines and the type of props they use (4 blade, stern lifting, higher pitch), are higher than with the Honda's.

We live up near the head of Perdido Bay--there is about 12 miles of fetch during a "norther"; Winds up to 50 knots. As we left the ICW the waves were close to 3 feet. The only way to successfully get up the bay with minimal discomfort, was to take the speed up to over 35 mph--to get this air cushion increase. The 4 blade props and "reverse" (Counter rotation engine on Starboard) engine mounting all help to give more stern lift.

I agree that the tunnel height of the Tom Cat (either 24 or 255) should be about 6" higher. You have a lot of experience in the 24. I have only driven one a few times. So I certainly believe your experience is valid for the TC 24.
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B~C



Joined: 31 Oct 2003
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PostPosted: Wed Jul 27, 2022 2:02 pm    Post subject: Reply with quote

I had Doel fins, a permatrim type outboard attachment, on my twin hondas and later added trim tabs. I ended up giving away the Doel Fins. I found that I didn't need the fin gadgets to trim the boat. I can trim the boat with the trim tabs and then trim the outboards to to run at their most efficient trim.
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thataway



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PostPosted: Wed Jul 27, 2022 5:59 pm    Post subject: Reply with quote

The plastic fins, such as the Doll-fins do not do as good a job as the Permatrims. One can "trim" their boat any number of ways. The goal is to give the best ride in all conditions: especially into chop--the weak point of the C Dory line. The Permatrims plus trim tabs on the monhul C Dory boats appear to do this. There are other benefits, such as in monohulls being able to plane at an even lower speed.

My first 22 had no trim tabs or foil. My first 25 had trim tabs, and after running it for a few months, I added the Permatrim. So my opinion is based on using a boat with no trim devices of any sort, in comparison to a boat with trim tabs only and then both a 22 and two 25's with the foils. I had one boat which came with the Doel-fin, so was able to compare with Doel-fin and Permatrim.

All of this is somewhat subjective, so persons' opinions may vary.
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T.R. Bauer



Joined: 17 Nov 2007
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PostPosted: Thu Jul 28, 2022 12:41 am    Post subject: Reply with quote

I have had trim tabs, doelfins, and whale tails on various boats. They all do something. The hydrofoil (SE Sport I think plastic thing) on my ski boat long ago made some difference - it would get on step with a boat full of people and pull a skier with relative ease. Before....yeah...but it took forever and was harder to get the skier up. I remember I lost some top speed, but I'm not completely sure because I put a 4 blade prop on it at roughly the same time.

The Davis whale tails on my 22 with twins drastically changed the boat - for the better. It hauls weight easier, planes a bit slower, and they created an unexpected amount of lift on the stern which puts the bow right into the waves. I was actually shocked at the difference. Fuel consumption didn't change either, nor did top speed. If it did, it is not perceptible after having them on the boat for hours upon hours. I'm sure the permatrims do as well - probably work better actually.
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C Sniper



Joined: 17 Mar 2019
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City/Region: South Padre Island
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C-Dory Year: 2007
C-Dory Model: 255 Tomcat
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PostPosted: Thu Jul 28, 2022 9:42 am    Post subject: Reply with quote

Hopefully my hondas will last a long while (fingers crossed). I keep my vessel expedition-ready with kiteboarding lesson, fishing, spearfishing and diving gear always loaded. So light is out of the question. I will have to try speed = air cushion more to better understand how that works. Thanks for all the comments thus far.

If I put on permatrims what size/model is suggested? I went to the website recently and it was not clear briefly reading their suggested uses which ones to go with. Suggestions please.

So if I do put on permatrims on the future, and don't like them, what do I patch the holes with when they are removed. Guessing JB weld has some metal in it which might increase aluminum oxidation on lower unit???
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C Sniper



Joined: 17 Mar 2019
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City/Region: South Padre Island
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C-Dory Year: 2007
C-Dory Model: 255 Tomcat
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PostPosted: Thu Jul 28, 2022 9:54 am    Post subject: Reply with quote

Also any thought on whether they would allow for hole shots in shallower water than without them? The lower laguna madre (my inshore waters) has lots of very skinny areas. Seems like my TC needs 30-36 inches to get going. Any tips on shallow water starts appreciated. Can't roll a cat out in shallow water, works well with a mono though.

I almost aways have a mud cloud trail following me around I have noticed...
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daninPA



Joined: 16 Aug 2020
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PostPosted: Thu Jul 28, 2022 11:23 am    Post subject: Reply with quote

Our C22 came with 115HP Yamaha. It was stern-heavy with 1/2 tank or more of fuel (we travel light -- no overnights, equipment, etc).

After installing the Permatrim the rough water became much easier to handle. The only lesson I had to learn was tilt up when running with following seas.
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thataway



Joined: 02 Nov 2003
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PostPosted: Thu Jul 28, 2022 12:48 pm    Post subject: Reply with quote

C Sniper wrote:
Also any thought on whether they would allow for hole shots in shallower water than without them? The lower laguna madre (my inshore waters) has lots of very skinny areas. Seems like my TC needs 30-36 inches to get going. Any tips on shallow water starts appreciated. Can't roll a cat out in shallow water, works well with a mono though.

I almost aways have a mud cloud trail following me around I have noticed...


My impression was that the Permatrims actually decreased the "hole shot"--but with the Suzuki it was pretty good to begin with. Time to plane was not decreased--and might have been slightly increased.

Once the holes are in the anti ventilation plate, there is noting which will guarantee that they will stay filled. JB Weld is about the best--and generally works well. Keep the plates well painted. (Spray on silver Rustoleum works fine)

We have a sand bar at the entrance to our bayou--generally it is kept at 36" by a trawler which lives down the street--but in winter low tides it gets down to 18"--and we just raise the motors up--power until we are out of the shallow areas--(Most of Perdido Bay is 6' depth MLW)
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