Commander #256 (Ceili)

[Chance]

Jerry,
Excellent questions.
1) I used 18 mm, way overkill, as I had to remove most of it in my tapering jig. I wanted and should have used 12mm like you indicate but they were out of stock when I was down that way to make the purchase.

2) I'm aiming for a final rudder thickness (at the aft end of the shaft) of between 1-1/4" and 1-3/8" after fiberglassing.

3) On Ceili the aft keel area that receives the rudder post fluctuates between 1-1/2 inches to 1-5/8 with the majority of spots I checked measuring 1-9/16 across the cove area and to the outside of the flats that run along each side of the cove. When I take two straight edges and press them up against the hull, the trailing edges of the straight edges continue on a merging course, and eventually make contact. I looked at the area where the rudder sits and feel that the measurements above closely match this measurement point. Of note: I have measured an unmolested original rudder and it was 1-1/4" at the shaft. My rudder was heavily molested by POs and it's hard to say what the original measurement was. Currently the old rudder I recently removed measures just under the original rudder I referenced.

4) Yes, you are correct. I did radias the leading edge of the core where it mates up with the shaft. I did this to facilitate an area to receive thickened epoxy and the starting point where the glass cloth will be laid on.

5) No, I do not plan to wrap the rudder post (shaft) with glass. The area is sealed with a heavy cove bead of thickened epoxy, and will also be covered with cloth. The cloth will terminate at the aft end of the shaft, but will not ride up on it.

6) Here's some photos to illustrate the above.

[Chance]

Today I finished the tapering of the new rudder core. The jig that clamping fixture was a bit of a challege for me because it involed compound angles. It's easy to taper a project when both sides of the jig run parallel to one another, but on this style of rudder (constellation profile), that's not the case. The trailing edge jig runs at two different angles to account for the rudder profile. I did a lot head scratching and discussed the chanllenges with my wife for some time, before proceeding. In the end I'm happy with the outcome. My first side had a little goof where the straight bit dug in a bit too much in one pass, as seen in an earlier post. Needless to say, I perfected the process on the second and last side.

[Chance]

A few more shots.

[Chance]

A few more pics to see the rudder core. I still have to profile the bottom and top edges so that the glass will go on smoothly.

[Commander 147]

Chance

I know you have been a wood worker for a while when I see your approach to projects. I built a jig like your tapering jig to level the top of my workbench when I built it. And I have used similar jigs in the past for other things. Your application of the jig is a very good approach. I like it.

So tell me, now what is the glass layup schedule to encapsulate the rudder? How many layers of what material do you plan to use?

[ebb]

Great looking rudder!
Jerry asks an interesting question. It is a well built structure. The armature is embedded in epoxy and therefor sealed and tight.
Chance has designed his rudder in such a way that he could round off the leading edges of the meranti like the original mahogany rudder was made.
So that the bronze shaft is left bare!!
Always thought that was really sweet and shipwright.

Have to glass with gossemer material to make the tuck over the round at the shaft.
Not around the shaft itself.
I think the aluminum will benefit with the support an encapsulation of the blade with glass would provide.

Assume of course that the rods of the armature where dapped into the shaft befor welding.

We'll have to see what Chance has in mind,
can't wait!

[Chance]

Jerry,
Yes, I have loved working with wood for many years, but I am definately an amatuer, especially when I see work like yours, Mr. professional! I discovered the tapering jig when I re-did Ceili's compression post base in the bilge. Under my glass work I made a teak wedge with the grain running verical (to orient with the compression loading) and that wedge had to be tapered. I utilized the original white oak wedge to base my taper profile on. Anyways, in both applications that I have used such a jig, it has worked very well. For me, it took more time in designing and setting up the jigs fences, than it did to actually perform the router machining.

As to your question regarding the lay-up schedule. I'm sure your well aware of that from a structural standpoint, many thin layers of glass fabric can equal one layer of thicker cloth. Of course there are some variables that can influence this, like resin rich or starved fabric, chemical versus mechanical bonding of the layers, etc..

I have many different weights (ounces) of fabric, but will most likely utilize 6 oz, boat fabric. The down side is it takes much longer to achieve the desired thickness, because it is so thin. The up side is that it bends very easily. There are lighter weights, of which I don't currently have in my possession. EBB, I had to look up the word "Gossemer", have never heard that before, thanks for the educational lesson tonight.

I anticipate that the 6 oz, in this application will work just fine, although it'll be more time consuming. I'm shooting for the skin (glass) thickness to be 1/8". This will in turn widen the entire rudder by 1/4". Humble my simple arithmatic.

I'm aiming for the trailing edge to be no more than 3/8".

Of a related note, and one I don't have an explanation for: Upon measureing my rudder core at three specific points along the shaft, following the tappering, I had three different measurements:
Upper was 31/32", Mid (near where the rudder strap opening will be made) was 1-1/16", and the bottom was 1-1/32".

Prior to measuring, I would have thought that it would have been consistant along the entire length, but no dice, even though the fence that was pressed up against the forward edge of the rudder was parrallel. It must have been to do with the other (trailing) edge fence, at this one had two different angles that came into play. Yes, I did much head scratching. Now, what I really need is a good
thinking" chair that I can post my rear in when I'm confronted with challenges like this. Bottom line, I'm pleased with the initial machining of Ceili's new rudder core and don't expect the minor measurement differences to be an issue.

Ebb, no, the rods were not "tapped" as you might have suspected. Although a great idea, assuming one has the addtional funds that a machinist would charge to do that, I made the decision and felt comfortable with having the holes bored to receive the 3/8" rods and silver brazed. Of course the the joints had to fit very tightly, just likely the keyway and key for the tiller cap assembly.

[Chance]

Jerry,
Sorry, to mention. In response to the number of layers required. I'm not sure at this point. Other folks, who have experience with a multi layer schedule of 6 oz, might know. I'm going to have a scratch block with release fabric on it and will use that as a guage to determine my thickness as I go along. I have used the same method when making my own glass sheets.

[Chance]

Just found this on the net, can't say how accurate it is though. If so, I'm in for a long layup schedule.

8 plies of 10 oz fabric will produce a strong 1/8" laminate weighing 1 lb per sq ft.

[Chance]

Okay,
This is my last research for the evening. Jerry, thanks for stiring my interest in the forthcoming lay-up schedule.

1/8" = .125"
a single layer thickness of hand lay up 6 oz fabric = .010"
Total layers requred to achieve 1/8" = 12.5

So it looks like I'll be applying 12 layers of fabric to the core.

Good night!

[Commander 147]

Chance

Can I make a suggestion? If you build a jig to support the rudder at a convienient working height that allows you to suspend the rudder between two supports from the rudder shaft in a manner that will allow you to pivot the rudder 180 degrees and have access to both sides of the rudder during the layup stage it should speed up the process significantly. You could attach the tiller head to the keyed end of the shaft and use it to lock the rudder in place with one or the other face up to work on. Just a suggestion.

[Chance]

Jerry,
Of course, I'm always open to suggestions and feedback. A most interesting suggestion and one that I may very well try out. Thanks again.

[Commander 147]

Chance

Any more progress on the rudder yet? I'm VERY interested on how things progress for you. I think you are doing a great job and I will in some ways follow your example.

[Chance]

Jerry,
The rudder progress has been slow, but I have taken care of the opening for the strap and have applied (2) layers of cloth to each side. After considering my layup schedule and approach, I determined that I'll have to do one side at a time, alternating between the port and stbd sides. This way I'll have the alternating overlapping glass layers on the bottom and top edges, thus doubling the thickness in these areas.
For the rudder strap opening, I milled the opening, initially with a chisel, then did a final tappering with sand paper. I made the opening larger to allow for the glass layup in this area which is about 1/8" thick, utilizing many small stips of 6 oz. I would love to use heavier cloth but it will not lay nicely around my small rounded over edges along the top and bottom of the rudder foil.
For each layer, I use a roller to apply the epoxy. This ensures even distribution and prevents excess resin rich cloth lay ups.

[Commander 147]

Chance

I continue to be impressed with the level of your craftsmenship. You do mighty fine work my friend. The rudder looks like it is indeed progressing very nicely.

I have been a woodworker for the past 45 or so years. But working with fiberglass and epoxy was new to me when I started this project. I learn a lot from watching you and others here. For example I would not have thought of the blue painters tape to define the limits of the glasswork. I assume you will cut the glass at the edge of the tape and the just peel it off. Do you do that at each layer or will you do it at the end? I would think it would be necessary at each layer.

Also the aluminum trailing edge seems to be good for more than just a strong edge but it also allows you to glass over the exposed face of it and grind the glasswork flush with the trailing edge while all the time keeping the wood totally encapsulated. A brilliant solution to the problem.

I assume you will fair the rudder out after the last of the glass with micro ballons and cabosil mixed in to thicken the epoxy prior to painting.

Are there any other tips you can give me that you learned while doing this? My rudder I think will be much more complicated since I will have a propeller aperature in it. So any guidence would be appreciated.