Rudder position on mac26

[sbcwolff]

Sorry I don't have a picture (boat is under a tarp for winter) but our rudder has two bolt holes in it, and depending on how you mount it, you can easily lift it up, but when it is down it isn't perfectly vertical. I noticed the boat had quite a strong weather helm compared to our other boat (compac 16), and am wondering if we are installing the rudder incorrectly. If I remember the manual correctly, the thinner side should be downward/toward boat? (the rudder is tappered/asymmetrical)
Thanks!

 

[Rowlando]

My 26D is also under winter wraps. I had to rework my rudder with a composite material as it was wallowed out badly in the aluminum channel and had lots of sideways play. It now sits perfectly vertical and snug and seems to work great. And like an airplane wing, the thicker side should point forward.

 

[sbcwolff]

We have lots of wiggle in ours as well! what composite material did you use?

 

[sbcwolff]

 

[sbcwolff]

Looks like I figured out my winter project... rudder rehab

 

[Rowlando]

I used a material called fibrefrax (came in a sheet, mine was a1/4” thick IIRC) that I had left over from an aircraft project (many years ago). I’m sure someone can chime in on other suitable materials. I used a 3” hole saw and cored out the inside rotted wood, then rebuilt the”bearing” area. Much improved. I believe it is critical to ensure the rudder is vertical and has no movement. I also added an extra block to aid in pulling the rudder tight and secure into the aluminum channel. My tiller also has no “play” in it. There is much info about how poor the original rudder is........I have had no issues since I reworked mine. Mind you I use my boat only for pleasure sailing......no racing etc. Hope this helps!

 

[Rowlando]

You’re rudder has a different profile than mine........I would guess the forward edge on yours is where the rope is. It should work great if you can eliminate any play and get it vertical. Have fun!

 

[sbcwolff]

So any suggestions on steps to rehab this puppy? Sand down... paint (with what kind of paint?) then fill in bolt hole with something rigid.... would some sort of polymer work? (RGranger, your chem knowledge would be helpful here Even though it is more of an o.chem q.

 

[rgranger]

I'm not sure if I got this right but it sounded like you said the thin side of your rudder faces forward. That does not sound right. A naca foil produces lift which helps to turn the boat with less drag. But the fat side of the foil needs to face forward. When you turn the rudder to port the lift component vector pulls the back of the boat to starboard and you do not have to put so much of the blade in the flow of the water... so less drag and you don't slow your boat as much by turning

Here are some good articles about it...

Foil FAQ

www.boat-links.com

Foil Rudders

New replacement I-20/M-20 foil rudders are available for US$750. fob Minnesota, for a pair . These are made with I-20 class legal aluminum (6061T6) shafts, and the blades are made with Gougeon's...

www.williecrear.com

Rudder craft actually makes a rudder for the Mac 26 but it is not cheap.

Rudder Craft

store.ruddercraft.com

 

[sbcwolff]

yeah, so we had installed backward for an entire season
Wondering about what to fill the bolt hole in with for extra support?
And the foil reference makes total sense now that I think about it! The foil factor alone will probably help the boat steer better when we install it correctly next year

 

[rgranger]

Wondering about what to fill the bolt hole in with for extra support?

Thickened epoxy. Don't use Bondo! Bondo expands with water and is not a good choice below the water line. Jamestown Marine is one of my favorite suppliers if you want to mix it up yourself however, you don't have a big area to fill. In the marine section of Walmart, you can find this "emergency" epoxy stick. There are several brands but it looks sort of like this...

It is a two part epoxy putty separated by a filler. You kneed it like dough and that starts the curing process. Then press it into the hole, fair it and let it cure. That should do it. Clean out the hole first and make sure to put some rubber gloves on before you start the kneeding process.

 

[rgranger]

Regarding weather helm. If your sails are old it is most likely the sails. When I got my H26 it had serious weather helm and I could not control the boat at all in winds over 10 mph. I got a new sail.

JOY!!!!!

But there are things you can do to help balance the helm. Here is a set of very crude drawings...

The drawing on the left is missing a rudder and head sail in order to simplify the idea. If your "center" of force (the belly of the sail in this pic) is behind the center of lateral resistance (the center board in this pic) then you will get weather helm. The pressure on the sail makes the boat want to pivot around the keel. So in this pic I could reduce weather helm by either raking the mast forward a little or by tilting the swing keel back a little bit. Or a combo of both approaches. Alternatively, there are other ways to move the belly of your sail forward. Tightening the luff helps in this regards.... but a blown out sail is still my guess and a new sail will bring you much joy. The calculation gets a bit more nuanced when you add in the effect the rudder has on lateral resistance and the effect the head sail has on the center of force. Opening up the belly of your headsail moves the center of force forward and should help with weather helm... but the trade-off can be more heel. Playing with the genoa tracks helps here too. One unique advantage that you have (and I have it on my boat also), is the ability to sail with the swing keel partially raised. Raising the keel moves the pivot point aft. After you install the rudder correctly, if you are still having a lot of weather helm, try lifting the keel just a little bit until the helm balances. It is not a bad idea to keep just a little weather helm. That way if a gust comes along and tilts you over the boat will round up as soon as the rudder clears the water. It can be scary but everyone survives and you don't swamp.

 

[rgranger]

... and you can also try tightening your fore stay and slaking the back stay. You may need to play with the shrouds a bit also, but that will rake the mast forward a tad and that can also have a big effect on weather helm.

 

[douglaskjensen@gmail.com]

I really like the Rudder Craft rudder. I have purchased 2. One for our V25 we had for several years and then got one for our 1995 Macgreor 26S. The shape is much better than the original. I still have that one as a spare just in case. I would not go back to.the standard rudder unless something broke.

I did rebuild the center board. Previous owners had hit too many rocks. I guess I hit some as well. I improved the shape of the center board and the boat sails much better now.

Jemardo II

 

[rgranger]

I really like the Rudder Craft rudder. I have purchased 2.

I had a rudder craft rudder on a Balboa 26 in the past. It was noticeably efficient.

 

[sbcwolff]

Getting ready to get this rudder ready for some sailing! Any paint recommendations? Bottom paint below waterline, should I over or under estimate waterline? Ie better to have a little topside go below waterline vs bottom paint be exposed?

 

[ScourgeOfTheHudson]

here's my factory rudder next to the improved one the PO had built to help with stalling. I think it's a lil overbuilt, but that's never a bad thing.

 

[rgranger]

Getting ready to get this rudder ready for some sailing! Any paint recommendations? Bottom paint below waterline, should I over or under estimate waterline? Ie better to have a little topside go below waterline vs bottom paint be exposed?

I think it is better to have a little bottom paint showing than to have a line of scum growing on your boat right at the water line....