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View Full Version : Making a rudder



AlanH
02-07-2017, 04:42 PM
The S2 7.9 class rudder is a swing-up job that is 1.) freaking enormous 2.) has an unknown foil shape, but it's got to be almost 3 inches thick. 3.) bears no resemblance to the rudders put on the 4-6 custom boats that were built for the MORC worlds back around 1985.

I don't know what those MORC rudders looked like but after poking around the web for a while I'm guessing that they looked a lot like a slightly balanced J-27 rudder. Custom Composites.. aka Phils Foils sells a nifty rudder that they designed for the Hotfoot 27, which while substantially lighter than my boat, is otherwise not terribly different. However, one of those babies is about $2k. Ouch. Rudder Craft sells a wood-core rudder which is pretty close in size to what I want and it's a NACA 0012 foil. It's about $900, which for me is not chump change. i wish it were about 6 inches longer, but I still might go that route for a new rudder.

However, I'm thinking about laminating up some hardwood and doing this:


https://www.youtube.com/watch?v=55_TunTfXj4&t=53s

you can see a different router jig, here...but same idea:http://i57.photobucket.com/albums/g227/lcasambre/SB18/IMG_0063_640x480.jpg


Have any of you clever folks ever done this?

PS: I know that I can get foam cores from Flying Foam, but I think I want a wood core rudder. My rudder is hung off the transom.

Lanikai
02-07-2017, 06:23 PM
Nope, but that's indeed pretty clever. If you really want to go nuts, ~$200 will get you a month at TechShop and access to their Shopbot. Might have to try that myself for a DIY e-rudder.

Wylieguy
02-07-2017, 07:45 PM
Hey Alan, Want your old e. rudder back? It hasn't appreciated in price since you sold it to me. -- Pat

AlanH
02-08-2017, 12:43 PM
Hey Alan, Want your old e. rudder back? It hasn't appreciated in price since you sold it to me. -- Pat

Probably, but not yet. Sell it to someone who's heading for Hawaii in 2018. Then they can sell it to someone who's heading to Hawaii in 2020. Then I'll buy it for 2022, which is the next time I'll be going. OR....give me a few months to save my nickels. I REALLY need a boomkicker on the boat and I'm eyeing a Pelagic autopilot. After that, though.....

AlanH
02-08-2017, 12:46 PM
Nope, but that's indeed pretty clever. If you really want to go nuts, ~$200 will get you a month at TechShop and access to their Shopbot. Might have to try that myself for a DIY e-rudder.

The TechShop thing has occurred to me. The only thing is, our local TechShop CNC mill is only 2-D not 3-D.

If I ever decide to cut out and make a Phantom Dinghy, I could go there to knock out the hull pieces, though.

https://farm9.staticflickr.com/8554/10184198993_09acb9e517_z.jpg

Lanikai
02-08-2017, 03:32 PM
The TechShop thing has occurred to me. The only thing is, our local TechShop CNC mill is only 2-D not 3-D.

Was just thinking: I'd have to do one side, then flip it and do the other, but need a carefully measured jig to hold in place, at the right angles...then, *duh*, I'll have to use a larger blank than the finished product since a couple inches on each end are needed for securing to the shopbot work surface anyway. Saw them off when done. (still new to this whole working-with-non-virtual-objects thing). Now I really want to do it for no other good reason than I can. Off to find CAD/CAM files for foil shapes appropriate for a Cal 2-27 e-rudder, whatever that would be.

Daydreamer
02-08-2017, 06:55 PM
Here is a site with info for NACA foils.

http://airfoiltools.com/airfoil/naca4digit

The most popular seem to be the 0012 and 0009. They are the numbers I hear most frequently.

pogen
02-09-2017, 09:38 AM
Just a reminder, there are a ton of resources on e-rudder design and build on our own website

http://sfbaysss.org/main/resources/