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Kushtaka
Joined: 17 Dec 2013
Posts: 648
City/Region: Cordova
State or Province: AK
C-Dory Year: 1993
C-Dory Model: 22 Cruiser
Photos: Kushtaka
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 Posted: Fri Apr 01, 2016 7:41 pm Post subject: |
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| Ferg wrote: | Appreciate the replies to my comment, I'm not taking a position, I'm just giving his....but he's a well respected guy.
But I do wonder that if they do improve performance, why haven't the manufacturers incorporated that into their designs.
Honest, I don't have a dog in this fight, I'm just kinda confused |
I don't think they work well on all boats, especially deep V hull shapes, as the motor is often much farther down in the water, often with its anti-cavitation plate fully submerged on step for example creating more drag than we see. And they do add drag, which some would see as a negative compared to the benefits on their boat, and they are very easily added to an outboard.
I really think they make the best improvement with the fewest sacrifices in flatter bottom, heavier (for size) planing hulls like ours. I think manufacturers would be foolish to make this a standard, and are generally very concerned with reducing the drag of their lower units as much as possible from a design standpoint. In other words, it is vastly easier to drill some holes and bolt on a permatrim than it would be to cut down a huge anti cavitation plate to reduce its drag.
Everything in a boat is a tradeoff. The permatrim essentially adds a little bit of rudder effect to the thrust vector that allows you to trim your bow up/down, while simultaneously holding more water near your prop with less exposure to the air, reducing cavitation. If your boat already trims nicely, and doesn't have any cavitation issues, the extra drag is probably not worth it (and those holes in the anti cavitation plate definitely are not!). There may be aspects of the permatrim's performance that I'm not familar with and haven't addressed, but I'm sure if I've missed something someone else will catch it (usually Dr. Bob)! |
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Kushtaka
Joined: 17 Dec 2013
Posts: 648
City/Region: Cordova
State or Province: AK
C-Dory Year: 1993
C-Dory Model: 22 Cruiser
Photos: Kushtaka
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| Posted: Fri Apr 01, 2016 7:44 pm Post subject: |
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| oh, and if you have a giant v8 engine, you might not need any help with your hole shot, plus they would offer no benefit to a boat traveling at displacement speeds. |
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colbysmith
Joined: 02 Oct 2011
Posts: 4916
City/Region: Madison
State or Province: WI
C-Dory Year: 2009
C-Dory Model: 25 Cruiser
Vessel Name: C-Traveler
Photos: C-Traveler and Midnight-Flyer
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| Posted: Fri Apr 01, 2016 8:20 pm Post subject: |
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| Another aspect that may be important, and was pointed out in the online instructions for mounting the Permatrim, is position of your engine. The ideal position puts the cavitation plate just about level/even with the bottom of your hull. This is where the Permatrim works best. (According to various sources.) Colby |
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Rock-C
Joined: 01 Nov 2003
Posts: 521
City/Region: Salem
State or Province: OR
C-Dory Year: 1988
C-Dory Model: 22 Cruiser
Vessel Name: Rock-C
Photos: Rock-C
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| Posted: Fri Apr 01, 2016 11:40 pm Post subject: |
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Dave, thanks for the photos. You did a good job on that hydrofoil. Im going to use marine grade alloy, 6061 or something similar. I hope to run into you this summer and get caught up on your latest adventures. BTW, I just purchased a Suziki 2.5 to replace the Honda 2. Inmar marine had the best price & free shipping. Thank to all that replied to my original post.
_________________
Terry, Ann & Chloe
Rock-C
C-Brat # 26 |
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Thorne
Joined: 29 Mar 2016
Posts: 31
City/Region: Whale Pass, Prince of Wales Island, Southeast Alaska
State or Province: AK
C-Dory Year: 1983
C-Dory Model: 22 Angler
Vessel Name: Persistence
Photos: Persistence
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| Posted: Sun Mar 12, 2017 8:28 pm Post subject: |
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| Does anyone have the dimensions for the Permatrim that goes on a 90 hp Yamaha? Really only need length and width. I have the facilities to make one, and don't want to pay the $150 shipping to AK. |
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