First I would say that your mechanic does not understand the dynamics of the C Dory, (flat bottom, with the necessity of putting the "V" of the hull into chop. Mechanics often do not understand boats as well as they understand engines). There are a number of reasons that outboards do not come with fin type plates.
My fisrt C Dory did not have either trim tabs or the fins. It was a very rough ride. When I got the 25, it had the trim tabs, but I still was not happy, so added the Permatrim--and it made a significant difference. (Understand that you have to know how to drive and trim the C Dory to get the most out of the combination. Almost all of the boats on the Delta Cruise have both tabs and fins. I put the Permatrims on the 255 to get a lower planing speed. It achieved that goal. But not a lot of difference in handling. (but no trim tabs on the 255).
This current 22 (my second) came with trim tabs and a "Doel Fin". I had previously used a Doel Fin on a 12.5' inflatable, and it made a huge difference there. I have not decided to switch out to a Permatrim on this 22, but I will most likely take the Doel Fin off (too flexable and disturbs the water more). A lot depends on how the engine is set up also; ideally the permatrim should run just on the surface of the water, thus purssure to lift the stern as mentioned in other posts.
My experience is that the Permatrim is worth the purchase, and makes a difference with going into the chop. It will allow you to get the most pleasure and performance out of a C Dory 22 or 25--and I assume that that holds true, or maybe even more effect on the 19. However, I would put it on with 5200 (perment) since this distributes the load on the anti ventillation plate better than just the bolts.
My fisrt C Dory did not have either trim tabs or the fins. It was a very rough ride. When I got the 25, it had the trim tabs, but I still was not happy, so added the Permatrim--and it made a significant difference. (Understand that you have to know how to drive and trim the C Dory to get the most out of the combination. Almost all of the boats on the Delta Cruise have both tabs and fins. I put the Permatrims on the 255 to get a lower planing speed. It achieved that goal. But not a lot of difference in handling. (but no trim tabs on the 255).
This current 22 (my second) came with trim tabs and a "Doel Fin". I had previously used a Doel Fin on a 12.5' inflatable, and it made a huge difference there. I have not decided to switch out to a Permatrim on this 22, but I will most likely take the Doel Fin off (too flexable and disturbs the water more). A lot depends on how the engine is set up also; ideally the permatrim should run just on the surface of the water, thus purssure to lift the stern as mentioned in other posts.
My experience is that the Permatrim is worth the purchase, and makes a difference with going into the chop. It will allow you to get the most pleasure and performance out of a C Dory 22 or 25--and I assume that that holds true, or maybe even more effect on the 19. However, I would put it on with 5200 (perment) since this distributes the load on the anti ventillation plate better than just the bolts.
A
Anonymous
Guest
Hello again from Iowa,
I installed the “PERMATRIM” this morning and then took the boat out this afternoon to see if it made any difference.
We headed down river twenty seven miles allowing much time, space and conditions to experoment.
The Mississippi River is/has high water levels right now because of heavy spring rains upstream, the Guttenberg Lock and Dam #10 gates are wide open letting the excess water through, totally uncontrolled.
So there is much current and of course every turn of the river is different because of varying river widths, depths and wind direction.
The “PERMATRIM” replaced a Doelcher Doel-Fin Hydrofoil Planer Fins attached to the lower plate, see following photo;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Here are photos of what the installed “PERMATRIM” looks like;
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
From the launch, I could tell that the dynamic of the 19’ CD had dramatically changed after installing the “PERMATRIM”.
I first tried to find some constant/s and quickly discovered that the motor/boat seemed to have a sweet spot at 4100 RPM.
Using the 4100 RPM as a constant, and then leaving the motor tilt/trim at neutral (centred) it became obvious the 19’ was now acting more stable and less “squirley”.
By continuing to experiment, I did find proof of Sea Wolf’s comment “When Bill (Da Nag) bought the first CD-19 produced, he found that the hull porpoised at speed.”
In fact when I found that condition accidentally, the porposing started, then radically accelerated.
Also, this is my first acquaintance with a Honda 90 four stroke, I assume that four stroke motors are heavier than most two strokes.
So basically, here is a 22’ CD with three foot cut of the back end with a proportionally heavy motor, so why not expect the boat to act “bow high, “butt heavy”?
I found the the motor tilt/trim did not help much but by leaving the motor tilt centred seemed to add tremendous stability, then the fine trimming was with the trim tabs.
However the trim tabs were used much less than they were before the “PERMATRIM” was installed.
Here is what I do know, the 19’ CD has some dynamic characterises that are greatly improved by adding “PERMATRIM”.
We, very much like this boat and “now” how it acts after “PERMATRIM”.
The “genius marine mechanic”, Eric is only “parroting” what the Mercury and Evinrude companies (he has the certified service center for both) would be expected to say about anything attached to their motor products, particularly items that they do not manufacture.
Ok, I’m quite please and glad that I have added “PERMATRIM” to my CD 19’.
Thank you all for the discussion and civil sharing of information.
Best regards,
Ron Fisher
I installed the “PERMATRIM” this morning and then took the boat out this afternoon to see if it made any difference.
We headed down river twenty seven miles allowing much time, space and conditions to experoment.
The Mississippi River is/has high water levels right now because of heavy spring rains upstream, the Guttenberg Lock and Dam #10 gates are wide open letting the excess water through, totally uncontrolled.
So there is much current and of course every turn of the river is different because of varying river widths, depths and wind direction.
The “PERMATRIM” replaced a Doelcher Doel-Fin Hydrofoil Planer Fins attached to the lower plate, see following photo;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Here are photos of what the installed “PERMATRIM” looks like;
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
From the launch, I could tell that the dynamic of the 19’ CD had dramatically changed after installing the “PERMATRIM”.
I first tried to find some constant/s and quickly discovered that the motor/boat seemed to have a sweet spot at 4100 RPM.
Using the 4100 RPM as a constant, and then leaving the motor tilt/trim at neutral (centred) it became obvious the 19’ was now acting more stable and less “squirley”.
By continuing to experiment, I did find proof of Sea Wolf’s comment “When Bill (Da Nag) bought the first CD-19 produced, he found that the hull porpoised at speed.”
In fact when I found that condition accidentally, the porposing started, then radically accelerated.
Also, this is my first acquaintance with a Honda 90 four stroke, I assume that four stroke motors are heavier than most two strokes.
So basically, here is a 22’ CD with three foot cut of the back end with a proportionally heavy motor, so why not expect the boat to act “bow high, “butt heavy”?
I found the the motor tilt/trim did not help much but by leaving the motor tilt centred seemed to add tremendous stability, then the fine trimming was with the trim tabs.
However the trim tabs were used much less than they were before the “PERMATRIM” was installed.
Here is what I do know, the 19’ CD has some dynamic characterises that are greatly improved by adding “PERMATRIM”.
We, very much like this boat and “now” how it acts after “PERMATRIM”.
The “genius marine mechanic”, Eric is only “parroting” what the Mercury and Evinrude companies (he has the certified service center for both) would be expected to say about anything attached to their motor products, particularly items that they do not manufacture.
Ok, I’m quite please and glad that I have added “PERMATRIM” to my CD 19’.
Thank you all for the discussion and civil sharing of information.
Best regards,
Ron Fisher
A
Anonymous
Guest
Good morning from Iowa,
The same can be said about the outboard motor manufacturers.
After all, they manufacture products that are applied on endless boat configurations, obviously some will be more successful than others.
The same could be said “PERMATRIM”.
At the end of the line are the guys that are installing and servicing these motor products on whatever boats, “obviously some will be more successful than others.”
It could be said that outboard motor manufactures “don't have a clue about the performance characteristics of the boats” their products are installed on, how could they?
In this situation, with this boat, with this motor, in this slice of time the “PERMATRIM” proved it’s worth, however could the same be said “in every situation”, probably not?
Obviously the “PERMATRIM” may or will have different results with different boats and motors, which will require a commitment or choice to “experiment” or "not experiment” .
Referring to my previous comment/s, “Otherwise, “I would always wonder” and have to accept someone else's (proven or unproved) assumptions, conclusions or fears.”
I’m glad I followed through and took the objective position, willing to change my mind as new information or experiences come along and not be closed minded.
Oh yes, before going out yesterday afternoon, I did fill up with more fresh gas and added three tents of diesel in each tank “Otherwise, “I would always wonder” and have to accept someone else's (proven or unproved) assumptions, conclusions or fears.”
The “PERMATRIM” definitely helped our 19’ CD, but every application could have different results, my advise, “be willing to experiment”.
Thank you again for the helpful comments and civil exchange.
Best regards,
Ron Fisher
The same can be said about the outboard motor manufacturers.
After all, they manufacture products that are applied on endless boat configurations, obviously some will be more successful than others.
The same could be said “PERMATRIM”.
At the end of the line are the guys that are installing and servicing these motor products on whatever boats, “obviously some will be more successful than others.”
It could be said that outboard motor manufactures “don't have a clue about the performance characteristics of the boats” their products are installed on, how could they?
In this situation, with this boat, with this motor, in this slice of time the “PERMATRIM” proved it’s worth, however could the same be said “in every situation”, probably not?
Obviously the “PERMATRIM” may or will have different results with different boats and motors, which will require a commitment or choice to “experiment” or "not experiment” .
Referring to my previous comment/s, “Otherwise, “I would always wonder” and have to accept someone else's (proven or unproved) assumptions, conclusions or fears.”
I’m glad I followed through and took the objective position, willing to change my mind as new information or experiences come along and not be closed minded.
Oh yes, before going out yesterday afternoon, I did fill up with more fresh gas and added three tents of diesel in each tank “Otherwise, “I would always wonder” and have to accept someone else's (proven or unproved) assumptions, conclusions or fears.”
The “PERMATRIM” definitely helped our 19’ CD, but every application could have different results, my advise, “be willing to experiment”.
Thank you again for the helpful comments and civil exchange.
Best regards,
Ron Fisher
A
Anonymous
Guest
Marty,
Before I installed the “PERMATRIM”, our 19’ CD always seemed on the verge of being unstable, requiring constant vigilance, adjustment in trim settings etc.
I believe that the reason “PERMATRIM” works and others may not is the down turned edges that confines and channels the water adding lateral/horizontal stability, see http://www.c-brats.com/modules.php?set_ ... _photo.php
As speed increases, this channeling effect added the much needed stability that our 19’ CD lacked.
However, the other “whale tales” out there might/could add lift but really do not control the water flow like “PERMATRIM”.
I’m now a believer and would not consider using the add on “fins/whale tales” see http://www.c-brats.com/modules.php?set_ ... _photo.php as I have in the past.
The 19’ CD is now a pleasure to operate after adding “PERMATRIM”, we are quite pleased with the results and the investment was very small with big results, a good value.
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
Before I installed the “PERMATRIM”, our 19’ CD always seemed on the verge of being unstable, requiring constant vigilance, adjustment in trim settings etc.
I believe that the reason “PERMATRIM” works and others may not is the down turned edges that confines and channels the water adding lateral/horizontal stability, see http://www.c-brats.com/modules.php?set_ ... _photo.php
As speed increases, this channeling effect added the much needed stability that our 19’ CD lacked.
However, the other “whale tales” out there might/could add lift but really do not control the water flow like “PERMATRIM”.
I’m now a believer and would not consider using the add on “fins/whale tales” see http://www.c-brats.com/modules.php?set_ ... _photo.php as I have in the past.
The 19’ CD is now a pleasure to operate after adding “PERMATRIM”, we are quite pleased with the results and the investment was very small with big results, a good value.
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
Our boat came with Doel-Fins and trim tabs were briefly considered until it decided to stick with the KISS principle.
I don't doubt that Permatrims may be better than the Doel-Fin setup for performance but I'm concerned about access to the prop if it gets fouled by sea weed, a crab pot line or the Kraken.
Photo of the Doel-Fin;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Photo of the Permatrim;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Photo of the Kraken;
http://www.unmuseum.org/kraken.htm
I don't doubt that Permatrims may be better than the Doel-Fin setup for performance but I'm concerned about access to the prop if it gets fouled by sea weed, a crab pot line or the Kraken.
Photo of the Doel-Fin;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Photo of the Permatrim;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Photo of the Kraken;
http://www.unmuseum.org/kraken.htm
A
Anonymous
Guest
Hello from Iowa,
Fortunately, or maybe unfortunately, we don’t have much worry on the Mississippi about “sea weed” or “a crab pot line”.
This experiment with “PERMATRIM” was about taming a situation that apparently is a chronic dynamic that exists with the 19’ CD’s.
Obviously, I have no first hand information about using “PERMATRIM” on other CD’s except comments on this and several other threads.
If what you have works to your satisfaction, good, another “if it ain't broke, don't fix it” situation.
I don’t believe any of us are/were trying to sell “PERMATRIM” except to share information and solve a problem I/we were experiencing with this boat/motor combination.
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
Fortunately, or maybe unfortunately, we don’t have much worry on the Mississippi about “sea weed” or “a crab pot line”.
This experiment with “PERMATRIM” was about taming a situation that apparently is a chronic dynamic that exists with the 19’ CD’s.
Obviously, I have no first hand information about using “PERMATRIM” on other CD’s except comments on this and several other threads.
If what you have works to your satisfaction, good, another “if it ain't broke, don't fix it” situation.
I don’t believe any of us are/were trying to sell “PERMATRIM” except to share information and solve a problem I/we were experiencing with this boat/motor combination.
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
A
Anonymous
Guest
Now I notice that there is obvious evidence of Cavitation.
While installing the “PERMATRIM”, I installed the newly reconditioned prop that was original equipment on the 90 Honda.
With the fresh paint job the cavitation is quite noticeable.
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
I’m not at all saying that the addition of “PERMATRIM” is the direct cause of this Cavitation damage, but something changed.
Now what do I do to change this dynamic, any ideas?
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
While installing the “PERMATRIM”, I installed the newly reconditioned prop that was original equipment on the 90 Honda.
With the fresh paint job the cavitation is quite noticeable.
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
http://www.c-brats.com/modules.php?set_ ... _photo.php
I’m not at all saying that the addition of “PERMATRIM” is the direct cause of this Cavitation damage, but something changed.
Now what do I do to change this dynamic, any ideas?
Regards,
Ron Fisher
_________________
1983 22' Classic, sold April 2011
1990 16' Angler, sold January 2012
2004 19' Angler, purchased January 2012
"We Have Met The Enemy and He Is Us"
Hi Ron
I am far from an expert on cavitation cause or affect, but my inclination would be toward preexisting condition covered by paint on a reconditioned prop. Just supposition from 2000 miles away though...
Another can of worms, and everybody has their opinion:- I found that a 4 blade prop (4x13x15) smoothed out the ride on my 19 considerably. Faster to plane and a little slower overall, but how fast can we really go?
Rob
I am far from an expert on cavitation cause or affect, but my inclination would be toward preexisting condition covered by paint on a reconditioned prop. Just supposition from 2000 miles away though...
Another can of worms, and everybody has their opinion:- I found that a 4 blade prop (4x13x15) smoothed out the ride on my 19 considerably. Faster to plane and a little slower overall, but how fast can we really go?
Rob
A
Anonymous
Guest
Fortunately or maybe unfortunately, in a previous life I worked for a well known company that manufactured control valves.
Cavitation was regularly and purposely produced in their flow lab and at the time I had the good fortune to study the effects of cavitation.
This is cavitation with surface damage, the areas without paint are not just loss of paint but pitted.
This pitting is caused by “the process where a void or bubble in a liquid rapidly collapses, producing a shock wave.”
see http://en.wikipedia.org/wiki/Cavitation
Regards,
Ron Fisher
Cavitation was regularly and purposely produced in their flow lab and at the time I had the good fortune to study the effects of cavitation.
This is cavitation with surface damage, the areas without paint are not just loss of paint but pitted.
This pitting is caused by “the process where a void or bubble in a liquid rapidly collapses, producing a shock wave.”
see http://en.wikipedia.org/wiki/Cavitation
Regards,
Ron Fisher
Ron,
Living on a river I often end up at the prop. and have my prop repaired they paint it black. The paint comes off about like the pattern you have. Like you I spent my working life in aircraft hydraulics and fuel pumps. What I see on my prop is not cavitation so I may not be seeing the same thing.
But cavitation normally appears on the negative pressure side of the blade or back side. Because Cavitation is caused by negative pressure usually in boating around 13 psia. If you are truly see cavitation I would suspect your prop geometry is not correct.
Guy
Living on a river I often end up at the prop. and have my prop repaired they paint it black. The paint comes off about like the pattern you have. Like you I spent my working life in aircraft hydraulics and fuel pumps. What I see on my prop is not cavitation so I may not be seeing the same thing.
But cavitation normally appears on the negative pressure side of the blade or back side. Because Cavitation is caused by negative pressure usually in boating around 13 psia. If you are truly see cavitation I would suspect your prop geometry is not correct.
Guy
When I tested Dave's Marinaut 215, he had a large surface area, home-made hydrofoil on his engine that could easily have been used as a diving plane on a nuclear submarine. All kidding aside, on the test ride, I hadn't realized it was present. So I set the motor trim down too far, and the bow of the Marinaut came close to submerging. The water followed up the bow and headed right for the driver's side window. So I can attest that hydrofoils are very effective at getting the bow down. That said, Permatrim is only one of many hydrofoils out there. The one advantage of the Marinaut is that it is a level trim boat. So, it does not need a hydrofoil to get the bow down; trim tabs and motor trim do just fine.
What makes me nervous about hydrofoils is that some manufacturers like Suzuki prohibits their use (as my dealer informed me); use of any hydrofoil will void their excellent engine warranty. It's too bad, because my CD-16 Cruiser had a 40 HP Suzuki, and it would have benefited greatly from use of a hydrofoil like a Permatrim.
I was informed that Honda, on the other hand, allows use of a hydrofoil, and makes one for their engines, and that this would not invalidate Honda's warranty. Why does one manufacturer allow use of a Hydrofoil, while others do not? Perhaps it is possible that all motors are not alike -- that some have sufficiently robust construction as to not be affected by the greater forces a hydrofoil exerts on its engine and lower unit?
So if one does not select a neutral trim boat, and one is intent on using a hydrofoil like a Permatrim on a C-Dory, in my opinion, it would be prudent to select a boat with an engine that does not prohibit its use.
Rich
What makes me nervous about hydrofoils is that some manufacturers like Suzuki prohibits their use (as my dealer informed me); use of any hydrofoil will void their excellent engine warranty. It's too bad, because my CD-16 Cruiser had a 40 HP Suzuki, and it would have benefited greatly from use of a hydrofoil like a Permatrim.
I was informed that Honda, on the other hand, allows use of a hydrofoil, and makes one for their engines, and that this would not invalidate Honda's warranty. Why does one manufacturer allow use of a Hydrofoil, while others do not? Perhaps it is possible that all motors are not alike -- that some have sufficiently robust construction as to not be affected by the greater forces a hydrofoil exerts on its engine and lower unit?
So if one does not select a neutral trim boat, and one is intent on using a hydrofoil like a Permatrim on a C-Dory, in my opinion, it would be prudent to select a boat with an engine that does not prohibit its use.
Rich
A
Anonymous
Guest
Hello Bill,
Really enjoyed browsing through your your photo album.
Please tell me/us about photo;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Regards,
Ron Fisher
Really enjoyed browsing through your your photo album.
Please tell me/us about photo;
http://www.c-brats.com/modules.php?set_ ... _photo.php
Regards,
Ron Fisher
Connie Fisher":6fq6cajp said:
This picture is perhaps more demonstrative for purposes of this thread. So, do Permatrims cause ventilation wear? Could you ask for more ambiguous test results? Personally, I don't think so. I think there was something peculiar going on with the port engine set up. I never could determine the cause. At any rate. I'm now running stainless steel props. No problems.
I love my Permatrims.
I could not be happier with my Permatrim. Installed it last year and got great results, I can actually trim the boat now. The only negative I have is it added a little bit of length to the overall boat / trailer combination. When backing into the driveway I checked my usual reference point in the driveway, determined I needed to back a bit more and promptly spudded the garage door. It now has a nice Permatrim imprint. I should have used a spotter.
Regards,
Dave
Regards,
Dave