Time to build a rudder... Best choice of wood?

[Art Read]

I've put this off as long as I could... Running out of other things to do! My instincts and the plans call for white oak, (presumably greenish/unseasoned?) and that has always been my intention. But I would have to buy an awful big hunk of pretty pricy "bending" oak just to get out what I'd need for this one job. I already have a nice hunk of Mahogany leaning up in the corner that looks like it would do the job. Would that be an absolutely unsuitable substitution? I know it's awfully dry, but it seems to me I've heard of a lot of folks building their boat's entire "backbones" out it, so...? Thoughts?

(Here's a view of the construction plan...)

http://www.imagestation.com/picture/sraid21/pffb8c0e290b417c27c092f8453133695/fdb121a6.jpg

[paladin]

I would weld a blade to the rudder shaft, then laminate the rudder around it using the mahogany, nothing more than one half inch thick, opposed grain, shaped, covered with three layers of Xynole epoxy, should hold up for a couple of centuries.

[Hugh Paterson]

Yup, The good old laminated rudder ruse works for me, the last one I done has alternating strips of white oak and mahogany, and although I have seen plenty of bad vibes about the oak and epoxy not working well, the rudder still has not failed and is now 5 seasons old. Oh it still looks the mutts nutts too ;)
Shug.

[Art Read]

Hmmmm... Interesting ideas. I'd also considered a marine ply/googe alternative as described in "WoodenBoat" recently. But I've been studying a lot of existing, old boats with "traditionally" built up rudders lately, and they mostly seem to be holding up pretty well. Most problems seem to be limited to a little seperation at the joints when dried out. Usually more an issue with the deadwood though. And we aren't talking an offshore cruiser here after all.

My current thinking leans towards brazing a couple of bronze rods through, and perpendicular to, the shaft and "drifting" the wooden blade onto them. The pintles should help tie everything together too. A plate would certainly be a stronger solution, but I suspect a sheet of bronze that size ain't cheap! And I'd worry about corrorsion with steel. Any reason to expect diasaster if I use the Mahogany and put it together as shown in the plans? Two parts, opposed grain, drifted together with perhaps a "cleat" along the bottom edge just for luck? I only want it to outlive me! ;)

[Art Read]

While we're at it... I thought I'd bring this up from my "Egyptian Engineering" thread. I'd sure like to hear more about this arrangement...

"Paul H. Morris
.
Member # 40

posted 10-11-2002 04:59 PM
--------------------------------------------------------------------------------
Great work on a wonderful design, Art. I can remember my grand dad pointing out "Daak Haabus" to me as a young person as we would drive around the Cape, New Bedford, Wareham, etc.. Anyway, on the Joel White Sakonnett 23 I'm trying to get time to build, his rudder tube design is a heavy wall copper tube through the bottom and up under the deck in my case (above deck I think on Dark Harbor). Rudder tube 1.25" ID, rudder shaft 1"OD and in both the top and bottom ends of the tube are halves of a cutless prop shaft bearing of the proper diameters to keep the rudder shaft centered and noise free. Under the tiller clamp. there are two large brass washers with a piece of teflon between them to act as thrust bearing that carries the weight of the rudder. Cool, simple design I thought. Keep up the good work ! ! ! Paul"

"(Hey, Paul... Do you have the plans for that Sakonnett 23 yet? Any chance you could make me a copy of the rudder plan detail you desribe? Sounds perfect! Nice choice, btw!)

- Art
--------------------------------------------------------------------------------
From: Seattle, WA | IP: Logged"

[Scott Rosen]

Art,

I've seen mohogany rudders and I've read plans that call for them. I don't know of any reason not to build it as in the plans with mohogany. But then I'm no expert on rudders, if you catch my drift.

[ishmael]

Art,

Can't read your plan for some reason, but mahogany would be a good sub for oak. Better than oak from a stability and gluing standpoint. I wouldn't worry too much about it being dry.

Drifting(ha Scott!) couldn't hurt. Many rudders, in oldy time, were simply well drifted, no glue.

Is this a Dark Harbor 17 you are building? I've always liked that boat. There was one under a tarp in the yard of the MMM when I was an apprentice, and I enjoyed crawling all over it.

Best,

Jack

[David Tabor (sailordave)]

Art: Unfortunately I never took pictures during the build but about 4 years ago the Pearson Triton our sailing assoc. has dropped the rudder and it sunk near the Ches. Bay Bridge. I ended up w/ the job and this is what I did.

The old rudder stock was 1" bronze w/ a bend of about 30 degrees or so down and the rudder was fastened to the bronze rod w/ SS screws. After 35 years of Electrolysis and wear and tear the rudder stock just gave way when someone gave a good healthy heave on the tiller. Didn't help that the pintles were BOTH put on so the rudder slid up into place meaning it slid out and downdowndowndown!

I started by doing lots of measuring and making templates w/ 1/8" masonite. Also looked at another Triton and some other similar boats to get an idea of the shape and prop aperture.

I got the bronze rod and a pc of 3/8" 12"x12" bronze plate from Atlas Metals in CO. Had the SCRF at the Navy base cut a channel in the rod, braze the plat into the channel, bend the rod to the correct angle and cut the corners of the plate. (If you can picture this)
I then cut the 3/4" marine ply to a rough shape and routed out a recess for the bronze plate and a slot for the 1" rod. Lots of try and error fitting but got it to fit and had holes in the plate to let screws pass through so I could screw the two pieces together.
(Okay Dave, this is getting long winded!)
Anyway, Screwed and Glued the pieces together sandwiching the bronze plate. Shaped the leading/trailing edges w/ a router and belt sander, glassed it all and coated with epoxy. I had also previously run a dry fit on the boat and designed it so once the rudder stock was inserted up into the boat the pintles would THEN be fastend to the rudder and they opposed each other so it WON'T come out. And yes I overdrilled the fastener holes for the pintles and filled w/ epoxy/mush and then tapped so they won't ever rot. At least not in my lifetime! Oh, and I also made the rudder a tad bigger than what I saw on other boats and it seems to handle really well; better than before. Hope this helps.

[David Tabor (sailordave)]

But to answer your question in the thread header... I saw a rather largish rudder (maybe for a 45'er?) built out of Mahog. when I was fooling around years ago. They took maybe 2" stock 4-6 inches wide, drifted and edge glued and then glued a horizontal piece on the end grain to be a sacrificial piece if the fiberglass covering ever wore through. Looked great.

[True Love]

Art,

Why wouldn't mahogany be good for this? All I know is that my composit rudder - encased in glass, on my former plastic boat, delaminated every year due to fresh water (Lake Michigan) that collected in it over the summer and then went throught the freeze/thaw cycle of winter/spring. I kept having it "fixed" only to have the problem recur.

While I realize you won't be using any glass, I guess I'm not sure why a rudder of mahogany would be a bad thing? After all, it survives pretty well under water as planking material.

TL

PS: I got my plans for the Dark Harbor 12 1/2 from WoodenBoat this week. I'm way behind you in the skill category, so I figure by the time I'm 65 (18 yrs) I might have something close to what your beauty looks like. I anxiously await your rudder choices (and hope I can pick your brain as I study the plans). With respect and encouragement - TL

[Bayboat]

Nothing wrong with (true) mahogany for your rudder. I would stick with the plan--two or more planks drifted with bronze. If the plans are not specific about the stock, Joel White's design for the Sakonnet 23 is good.

Whatever wood you use, it doesn't really need to be glued. During a long winter haul-out a good stickum glue will keep the seams tight but the wood will separate where you don't want it to.

On a drifted rudder, the planks will shrink so you can see through the seams. Don't worry. A few days in the water and they'll take up good and tight. Here in Wisconsin we are hauled out for half the year, and my 3-plank white oak rudder (on a 55-year-old Hinckley) shows gaps 1/2-inch wide by spring. But a few days after launch it's like new.

But you're in Seattle--don't you stay wet all year...the boat, that is?

You're doing a beautiful job on a sweet boat.

[ 10-27-2002, 12:47 AM: Message edited by: Bayboat ]

[PeterSibley]

I always like to see a couple of bronze straps let into the outside faces of the rudder at right angles to the shaft and through riveted.It almost smile.gif guarantees that the construction won't cup as time goes by and everything gets saturated.
Peter

[PeterSibley]

Woops ....we are talking about bone dry mahogany here aren't we? Best leave those straps till everything has finished swelling !! redface.gif

[Todd Bradshaw]

The rudder on my Star was pretty good sized and built from glued mahogany chunks about an inch and three quarters thick. I assume it had some kind of drifts inside, but never needed to take it apart to find out. After 30 years of minimal care before I got the boat, it was still fine and unlike the rest of the hull, only needed sanding and paint. I don't remember having to fill any cracks, though the boat was, at least for the most part, dry-sailed.
http://www.imagestation.com/picture/sraid28/p44de098745dd08d99faeefeba740d688/fd682816.jpg

[Art Read]

Thanks for all the input folks... Sounds like enough of a consensus to proceed. I've been wondering what to do with that "left-over" Mahogany anyway! (It's funny how often during this project I've agonised over buying a bigger hunk of wood, or a bigger box of screws, than I really thought I needed, only to find PLENTY of unforeseen use for 'em down the road...)

True Love... The only hesitation I had about the Mahogany was that the plans specified white oak, and I worried about substituting the kiln dried Hondurus stuff I have in such a critical, and particularly "unsuported", submerged part of the boat. Images of a split, cupped and warped rudder kept running through my mind every time I started eyeing that timber... But, as Bayboat noted, she'll hopefully stay in the water for all but annual routine haulouts here in the Seattle, so perhaps I was just being a bit paranoid.

Congratulations on getting the plans, BTW! But be careful... Next thing you know, you'll start laying a sheet or two of plywood down, just to see what some of those lines look like lofted out full size... It's not a real big jump from that seemingly innocent little step to piles of sawdust starting to accumulate in the corners at an alarming rate... ;)

Seriously... Don't let yourself be fooled by the "selectively" chosen photographs I've posted of my project. A lot of "sins" can be hidden by putty and paint! This is my first and only boat building project. And my first "real" woodworking project, period. I have done lots of routine mainenaince on various, other, old wooden boats and I've built a few wooden models. (Both good preparation for a project like this, btw...) But patience, an open mind and the willingness to ask advise, and heed it, will make up for any lack of experience to at least some degree. ("Efficiency" is a whole other matter...) If you want one badly enough, build it!

[True Love]

Hey Art,

As I look at the plans, it seems they recommend the outer rudder piece to be oak attached to hardpine which attaches to the rudder post. Just curious, did you use hard pine on your deadwood?

[Art Read]

I'd forgotton that, TL... You're right. In fact that was one of the first questions I ever asked on the "old" forum. After finding out that the "H Pine" specified on the plans for the deadwood, sternpost and trailing edge of the rudder most likely refers to "Heart Pine", or more commonly, Long leaf yellow pine, and that none of the "proper" old growth was available locally, I was told green or air dried white oak would be the best substitute. That's what I've used. You'll probably notice a few other little "liberties" I taken with the original plans as you continue to study them... ;)

[Paul Morris]

Art - - I've sent a private message requesting snail mail address to send details to. I've got them ready to go. Bronze shaft with bronze blades brazed to it (I think 3 in your case); your mahogany stock; lots of CPES; some good below waterline primer; several coats of your bottom paint; - should be good to go for a long time.
If you want some suspenders, think about using some 1/8" bronze or copper pencil rod drilled through mahogany and blades with roves on each side and peened over neatly. Would never come apart! ! ! Paul :D

[Ross Faneuf]

Ceol Mor has a rudder hung on a skeg, so experiences different forces than a traditional design like yours. Still, it's built up of layers of 1 3/4" mahogany glued with System 3, with bronze threaded rod in place of drifts, covered in 2 laters of Dynel. It's been through the stress of a serious grounding on the skeg & rudder; neither has shown any signs of failure. It will certainly take ordinary rudder forces.

[True Love]

Art,

I've spent the last 3 days slugging through Alan Vaitses' "Lofting." I must say, I'm more than knee deep in aligators.

Back to the swamp...

TL

[Art Read]

LOL! Understood. First, get yourself some good knee pads... Don't ask me why I "emphasize" this... Then get yourself some plywood and start in actually doing it with some of the easy stuff as you're still reading about, and trying to figure out, the fussier, "mysterious" stuff. Get yourself a good "moaning chair". Find something that will make good, fair battens. (I just used pre-milled "trim" from Home Depot 'cause I didn't know enough to suspect they wouldn't work fine. They worked fine anyway.) Lay down the baseline, waterlines, stations and maybe a few buttucks and the profile. All you're doing 'till you get to the profile is drawing out a carefully measured "grid". That will get you used to reading the offsets and "orient" you to the three views. But WEAR those knee pads! Then, start transfering some of the plan view lines from the offsets. Things will become clearer the more lines you get down on the floor... It's actually kind of neat as the two-dimensional image on the floor starts to come together in the three "views" and suddenly you can see a three dimensional BOAT in your mind's eye. You'll just have to trust me on that. (I told you to wear those knee pads! ;) )

[ 10-31-2002, 01:01 PM: Message edited by: Art Read ]

[Todd Bradshaw]

About 20 years ago, I lofted out a D.H.12.5 to about 5' long on paper using the W.B. plans. Never did get around to building the model that size, but it was a pretty good trial run at lofting and might be worth a shot.

[Art Read]

Still got it, Todd? That would make a fun "pond yacht", I'd bet! ;)

[Todd Bradshaw]

It's rolled up somewhere in the "Pile'o Plans", right next to the "Box'o Rigs". I remember thinking that it would be about as much work to do it well as it would be to build a real boat. In the mean time buying the Mini-12 gave me a whole new perspective on what constitutes a proper "Pond Yacht"....
http://www.imagestation.com/picture/sraid28/p6201efd98d2a13ac22698efc4b96dde6/fd682b1c.jpg
http://www.imagestation.com/picture/sraid28/p42cef518392ba56c58576f1d5bcbd826/fd682b06.jpg
http://www.imagestation.com/picture/sraid28/pb910bbd6d110e92e129f300cd2caead9/fd653386.jpg

Remember when you were a kid and you sat there with your face nearly on the floor watching your first electric train go around in circles, wishing you could shrink yourself down enough to ride in the engine? Well, sometimes fantasy can become reality. If I ever build a DH model, it will probably be 12' long and deep enough that I can fit inside.

[Buddy Sharpton]

We've have sevral in the water year round Cal 20's here, many much under maintained. All have solid (2") mahogany rudders . These boats are freshwater to boot and at least 35 years old. Never have I seen a rudder problem-it's the cast iron keels and plywood interior overheads put in without insulation and consequently always damp from condensation those are the hoo-doos. I would imagine mahogany to be PERFECT for your rudder. Much easier to fair to a foil cross section. I would consider routing it for pirs of external straps welded to both sides of your rudder post. You will be able to examine the condition of those welds at any time.