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bogle
12-05-2003, 04:03 PM
What is the best species for a plank rudder? I am going to build a replacement for my 1965 vintage phillipine mahogany rudder to the same design: 1" dia. bronze shaft, bolts and wood screws, drift pins.

http://www.bway.net/~bogle/rudderdwg.JPG

For example, I would like to know if Honduran mahogany, being stronger, would be significantly better than phillipine. How concerned should I be regarding grain to prevent cupping? Should joints between planks be profiled and glued - rescorcinol?...Many questions...Maybe there is a good reference book I need. Thanks in advance.

This forum was valuable to me a few years ago when evaluating the rudder. My "rudder problem page" is at: Rudder Problem Page (http://www.bway.net/~bogle/rudder.html)

windfall
12-05-2003, 06:13 PM
With out studying the plan in detail it would appear that there are2/8"bronze bolts/drift running through the wood perpendicualr to the grain. That should be suficeint to minimize cupping, but it is always best to use quarter sawn stock for this application if possible. Stronger woods are better but stability is mor iportant and I don't know how the two species compare. Glue cant hurt, but the bolts are what will hold it all together.

Jack Heinlen
12-05-2003, 08:51 PM
The traditional material here in Maine is red oak. Any of the three would make a good rudder if properly constructed. Quarter sawn is good.

I like just drifts and no glue. It's going to move, and glue joints working against the drifts are bound to cause problems. Without glue you will have to live with open seams after drying, but they'll close again. Glued seams are likely to open anyway, and you've got goop in there to catch and hold junk and water.

My two cents.

sawcutmill
12-08-2003, 01:05 PM
Red oak is definetly not the choice wood to use!that is nova scotia wood,like yellow birch.Red Oak is ring porous,meaning it is like a giant straw,sucking up water to no end,making it very heavy andf prone to rot like no other wood out there,it may last 10 years if your lucky!White oak would be best for some situations,where applicable,but usually the original material should be used again ie mahogany!

Jack Heinlen
12-09-2003, 06:47 PM
The traditional use of Red Oak in Maine for this is due to two things: inexpensive availability and it works.

It's been discussed here before, but using RO for framing in decked boats is a demonstrated mistake, but a rudder is a different matter, especially in northern salt water. The rot in RO framing is due to its porosity combined with its confinement where the moisture content stays nicely in dryrot's range.

I've limited experience, only two boats with RO rudders, neither transom hung(which would make a difference since the head would be exposed to fresh water). Neither were a problem after quite a few years. One reputed virtue of the red over the white is its resistence to cupping.

All that said, Honduran Mahogany would be a safe bet. Then you could sail anywhere you wanted and not worry. smile.gif I can't speak for the Phillipine, but on another thread someone pointed out that the good Phillipine is commercially extinct.

Best of luck.

bogle
12-09-2003, 11:35 PM
Thanks to everyone for the advice. Though I have some phillipine, I will get some quartersawn Honduran for this project.

Another question, though: How should the ends of the drift pins be terminated? Should the aftmost plank be captive somehow. The existing ones just seem to end, but may have had a nut or riveted end originally.

I'd really like to get more details about these things. Surely there is a book or two about wooden boatbuilding.?.?

Jack Heinlen
12-10-2003, 12:19 AM
Either Chapman's or Seward's boatbuilding books. Both are still in print. Bud McIntosh's is an easier read, with better illustrations, but I forget his rudder descriptions; could be quite good.

It takes some thought and planning to drift a rudder together. Everything has to be laid out quite well. It's not hard, but if you aren't used to doing the work it will take you awhile.

Drilling acurately after the marking is a skill worth practicing, with your chosen weapons, on a piece of scrap, if for no other reason to gain confidence. Take your time.

I'm sure WB has several articles on this, if you have access to a good library.

And stock selection. I suspect if you go to a lumber dealer and say, "I want quarter sawn mahogany," they will look at you like you are nuts. All the mahogany I've seen was plain sawn. Maybe someone with more experience will say otherwise, and I'm sure you can buy mahogany quartersawn, but...

This is where a friend, someone who knows wood, would come in very handy. And it's difficult to describe what I mean, but quartersawn isn't necessary, but sawn with alot of 'close rings' v. a broad expanse of grain would be good.

Do you have anyone you know who knows wood, even a little? We could talk you through it. I could pick through a stack of mahogany and find you some good pieces, but describing it is dicey.

Hm. Another option would be to call Condons in NJ and tell them you are building a rudder, and you want some good, stable stock for it. They deliver.

Good luck.

thebob
12-10-2003, 12:24 AM
I can't speak for the Phillipine, but on another thread someone pointed out that the good Phillipine is commercially extinct.
I have a house in the Philippines and I built my stair treads from 24"x 4" x 5' cut from 30' lengths just last year.

It's available and cheap but I don't think you are allowed to import it!

Be careful Philippine Mahogany, isn't mahogany.

Need me to send you some?

werner
12-10-2003, 12:36 PM
Hi,
hope the following will help:
from the LLoyds's "1916" tables for main piece of rudder
best = east india teak
second: english, african french adriatic italian spanish portugese and northern continental oaks,
greenheart,and acacia
third: mahogany of hard texture and not less than 35lb weight per cubic foot when well seasoned, and american white oak
greetings,
Werner