Keel Template for P26

[Justin Henderson]

Hey y'all, 

Have any of you ever used a keel template for fairing the keel of your Pearson's? I found this and thought it looked interesting. I admit the fairing job I did this spring was sort of like shooting in the dark and a template would have been ideal. 

http://www.computerkeels.com/uniboats.htm

Best, 

Justin

[Dan Pfeiffer]

I have this info here:
http://dan.pfeiffer.net/p26/keel_x-sec.htm

I made measurements to see what the section shape was really like on the P26 keel.  Not really very good from a performance standpoint for best lift.   The lower section is thicker and pretty close to a NACA 0009 shape.  I considered fairing the whole keel to that 0009 shape which would take quite a lot of fill.  But I think it would probably improve upwind performance where the lift of the keel really matters.  Might hurt downwind a bit with some added drag?  Probably small differences in either case and less important than good steering?  And you would need to report it to your race authorities and take the customary rating knock. 

The templates would not be hard to make.  I made a spreadsheet to calculate the NACA offsets for the 4-digit shapes.  It generates a table of offsets that could be easily transferred to a template.   I can share the spreadsheet if you're interested.   I transferred the offsets into a CAD file that could be printed at full scale to make a template. 

Best fairing practices are probably to get it good and smooth.  Fairing to a shape is a lot harder.  It would be intersting to see what Computer Keels says the proper shape is.  But not $110 interesting for a P26 or $285 interesting for a 10M? 

I made a similar set of measurements on the 10M keel and found it to be a closer representation of an NACA 4-digit 0012 shape but still off a bit.  But not off enough to make me think the shape was supposed to be a 5-digit shape (which has some advantages).  But I didn't take that too far in the analysis. 

For more info check out these books:
"Principles of Yacht Design" by Lars Larsson and Rolf Eliasson
and
"Yacht Design Explained" by Doug Killing



Dan Pfeiffer

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[Justin Henderson]

Right on, thank you Dan. 

I'm interested in the spreadsheet so I can make a template just for giggles to see how far off the keel is from a decent foil shape. 

I have an AutoCAD license and a full size plotter. 

Justin

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[Dan Pfeiffer]

Attached is a better rendering of my P26 keel profiles.  If your keel is OEM then it will very likely be the same. 

I also attached my spreadsheet.   I don't know how easy it will be to use but I did add a bunch of instructions to remind myself and they seem clear?  But the last time I saved that file was 2003 so it's been a while. 

I am curious where ComputerKeels got the offsets for the Pearson keels they list.  I have never seen anything like that except maybe for the Flyer?  There is a set of profiles on the crude copy of the lines drawing I have for the 10M but I don't think it's good enough to measure from.  


Dan Pfeiffer

[Dan Pfeiffer]

Possible source for p26 rudder

Mass marine parts in Quincy ma, 

[Dan Pfeiffer]

Oops.  Sent that to wrong place.

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[Guy Johnson]

one of our new members is looking for a P 26 rudder. 

so maybe just a small oops :>)

Guy

Sent from Outlook

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From: pearso...@googlegroups.com <pearso...@googlegroups.com> on behalf of Dan Pfeiffer <d...@pfeiffer.net>
Sent: Wednesday, June 8, 2022 4:32 PM
To: pearso...@googlegroups.com <pearso...@googlegroups.com>
Subject: Re: [pearson ] Keel Template for P26

 

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[Bob Maxwell]

If you can't find used, it looks like D&R Marine still makes them.

http://www.drmarine.com/proddetail.asp?prod=P26RD

Bob

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[Tim Smith]

Sad story from a month ago. Called Rudy at D&R about some parts I thought he might be interested in.  

While he was laid up from heart surgery someone stole his rudder mold for P30 type rudders. And his glass people have been busy on other projects so he had not yet replaced the mold as of early May. 

Felt awful about the situation; I offered a rudder I then had to him to borrow gratis for making a new mold. Just no capacity for his glass folks at the time. I no longer have the rudder.

All that to say there may be some delays before he is back online again with new built rudders. Hope soonest possible for him. And if you have a spare rudder consider offering it to him for a new mold. 

Fair winds. Tim 

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[Tim Smith]

Rudder source?

71 Pearson 26.  $1500 Lynn, MA

https://boston.craigslist.org/nos/boa/d/lynn-sailboat-pearson-26/7490570140.html

Tim Smith

tbsm...@gmail.com

617-536-1222 D

720-530-2971 C/T

617-933-7606 F

www.linkedin.com/in/tbsmith/

 

 

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