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 Post subject: Skeg flaps: wearing the rudder's leading edge
PostPosted: 11 Feb 2023 23:18 
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Navigator

Joined: 06 Sep 2020 10:08
Posts: 99
There are two sets of flaps covering the leading edge of our rudder. The top set is attached to the hull and was rubbing pretty tight on the rudder. We found it's worn through all the bottom paint and gel coat in the tightest places and is getting in to the rudder glass. The bottom flaps are part of the hollow skeg and only rub on the starboard side. A previous owner rebuilt this rudder sometime around 2009.

To reduce the amount of rubbing and wear, we cut off a 1.5" strip from the top flaps. Previously their trailing edge was in line with the bottom flaps.

Any thoughts on whether trimming the flaps is a good idea or not?


Attachments:
File comment: starboard side
rudder starboard.jpg
rudder starboard.jpg [ 3.85 MB | Viewed 0 times ]
File comment: port side
rudder port.jpg
rudder port.jpg [ 4.08 MB | Viewed 0 times ]
 
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 Post subject: Re: Skeg flaps: wearing the rudder's leading edge
PostPosted: 12 Feb 2023 11:53 
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Skipper

Joined: 13 Feb 2011 21:19
Posts: 337
Location: Canyon Lake, TX
This is just MY opinion and worth everything you paid for it. Snicker

The flaps are there to smooth out the water flow from the skeg to the rudder. This is highly important if you are racing. You might need that 0.05 knots. But for the cruising sailor, not so much as most cruisers are not trying to get that last 0.01 knots out of the boat. Plus it is hard to get bottom paint into the area between the skeg and the rudder and you might end up with a few pounds of oyster reef in there.

I just had my rudder and skeg rebuilt from Hurricane Sally and the yard brought her back to factory condition with the flaps. so.....

_________________
Wayne
Master and Commander of the Sailing Vessel Impetuous
I'm not a complete idiot, some parts are missing.
Subservient to no man except SWMBO
Any day without dock lines is a GOOD day!


 
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 Post subject: Re: Skeg flaps: wearing the rudder's leading edge
PostPosted: 13 Feb 2023 10:37 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 725
Location: Maine/USVI
I curved the flaps slightly when I rebuilt everything down there. A piece of luan covered in wax paper with the edge lifted on a 3/4" piece of wood strapping screwed to a table. Screwed down the luan away from the strap and laid up biax. No touch. Installed with lightly countersunk stainless screws and glassed in. Note the little stainless bar to keep lobster warp out of the slot in the rudder.

But this boat hadn't had a skeg during the entire ownership of the last owner. He capped the rudderhead inside with a hose clamp and a piece of innertube. Said "no problem ever" without the fairing flaps. I think I've got a photo of how I found the boat . . .


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 Post subject: Re: Skeg flaps: wearing the rudder's leading edge
PostPosted: 23 Feb 2023 10:00 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 725
Location: Maine/USVI
Photos. Click on them and they'll orient correctly. No touch on the rudder.


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Rudder fairing stbd.jpg
Rudder fairing stbd.jpg [ 122.45 KB | Viewed 0 times ]
Ruddeer Fairing Port.jpg
Ruddeer Fairing Port.jpg [ 98.82 KB | Viewed 0 times ]
Fairing stbd.jpg
Fairing stbd.jpg [ 84.45 KB | Viewed 0 times ]
 
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 Post subject: Re: Skeg flaps: wearing the rudder's leading edge
PostPosted: 18 Jun 2023 10:46 
Offline
Navigator

Joined: 06 Sep 2020 10:08
Posts: 99
Follow-up: It looks like the amount I trimmed off the flaps wasn't optimal. When we're moving fast on a beam reach we hear intermittent vibration from the rudder. From the cockpit it's not very loud, but from the galley or nav station it sounds pretty bad. Best guess is that the flap on the port side is vibrating because of hydrodynamic forces and tapping on the rudder. The new bottom paint on that side shows a little bit of wear.

I haven't yet thought of a way to solve this problem with the boat in the water, so we might be living with it until our next haulout.

For completeness of the documentation, attached below is a photo of the original-to-us condition when we bought the boat. That was about 2.5 years before the "worn rudder" photos on my original post.


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File comment: Rudder and flaps when we bought the boat in 2020
IMG_20201102_132130.jpg
IMG_20201102_132130.jpg [ 5.6 MB | Viewed 0 times ]
 
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 Post subject: Re: Skeg flaps: wearing the rudder's leading edge
PostPosted: 27 Jun 2023 06:08 
Offline
Skipper

Joined: 21 Oct 2006 18:12
Posts: 325
I made my flaps the full length with 1/16" G10 material, with some finessing you can keep clearance with the rudder fully turned,

Richard


 
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