Nearly 2 months ago I ordered rudder bearings and was told a week. They finally arrived this week. So over the next couple of weeks I hope to get the rudders hung in the boat. I had hope to have this done last month so I could spend December finally getting the rear steps into the boat, alas I probable wont get them in now until January. Probably late Jan.
About 2 years ago we bought our rudders rather than make them. For no other reason than the deal was good. I felt confident, having made the daggerboards that I could make the rudders, most builders do, and there are a number of very good methods for doing them. A lot of builders make them as a warm up to learn the building materials and methods before starting the main build. Schionning favour the glass over a shaped foam core method, but you could also make them with ply webs with thin ply tortured around them in 2 halves then glassed together as another fairly easy method. Rudder shafts there is really only 2 options, stainless steel bought as a tube and machined and welded, or carbon fibre.
The rudder blades would have been more difficult to shape than the daggerboards were, had I opted for the foam core shaped method, which I most likely would have. The daggers are the same foil shape from top to bottom and once shaped, a large triangle out of the top rear corner is cut out to reduce the weight of the board as the rear top corner doesnt do any work. So shaping is relatively simple to use a router to cut the shape because the shape does not change, so you can set up jigs with former shapes on each end set up to guide the depth set on the router and the rest is done with rasps and sanding boards. See method here. http://www.mahnamahna.com.au/April%202008.html
The problem with making the rudder blades that were not faced making the daggers is that they taper from top to bottom so they are not the same shape all the way along. This makes them more difficult to shape and also means that there is no way to make a jig to use a router, shaping by me at least, would have been by hand. Not impossible but harder. And of course, because they have a shaft down the middle they need to be made in 2 halves then glued together before being glassed and faired. So when I was told by Mike in Perth, building the same boat as me, that he had a guy that could make them for us for a good price I opted to go that way.
I mentioned the completed rudders were a good deal. The reason is that I heard, perhaps erroneously, how expensive it is to have stainless steel rudder shafts made. These were something I knew I would have to buy if I decided to make my own rudders . Usually the shafts have to be machined perfectly round (round stainless steel tube is not perfectly round), then have the tube flattened to fit inside the tapering rudder blade (being careful not to effect the machined bearing surfaces) and then have tangs welded to them that will be embedded in the blades. And apparently this process along with buying the stainless tube with thick walls of at least 5mm (they need to be thick to be appropriately strong) is very expensive. My understanding is that we paid for a completed rudder, about what stainless shafts would have cost saving ourselves the blade cost and the hours of work.
Another factor that convinced me, is that there were some rumours that the Radical Bay 8mt tramp deck bi rig cats had trouble steering through a tack so we (Mick and I and a couple of other Bi Rig builders) thought that we should make our rudders larger than the plans specified in order to help the boat steer more powerfully through tacks. And the guy making the rudders made them from carbon, in a mould that was about 10% bigger than the plans called for. Exactly what we wanted.
The rudders have a foam core and a carbon fibre cloth sheathed blade made in a mould in 1 piece with the shaft all at the same time. Not sure exactly how as I have not seen them made But by the look of the one photo I have and the finished rudders, there must be a top half to the mold not in view, the 2 halves are dry filled first to ensure the correct lengths and depths, then wet out and placed in the half mould, then the dowel is placed in one half then the 2 halve moulds joined while wet. Then after set, taken out of mould and sheathed in more carbon, especially the shaft which has a number of layers wound around the shaft as well as along it like in the pic. After that it is faired. Importantly the blade must be correctly shaped and balanced, each side a mirror image of the other, but other than that it doesnt have much stress on it, its the shaft that has all the stress and most likely to break. The shafts timber dowel core is about 30mm and then there is 15mm solid carbon fibre walls for an overall thickness of 60mm. 15mm solid carbon fibre walled tube for a total of 30mm is going to be very strong. And quite lightweight.
The only work I have had to do to them so far is to add a couple of layers of glass to the top of the shaft so that when I fit the stainless steel tillers to the rudders I dont get electrolysis of the steel. Carbon is a conductor of electricity and the tillers will not be albe to be kept completely dry or free from salt water. My meagre understanding is that electrolysis usually occurs in the least noble of 2 dissimilar metals via electronic current with sea water as the catalyst. I dont think carbon will corrode so that means the stainless might. Nevertheless, the easy solution is to isolate the carbon with a couple of layers of glass. I did this before having the tillers made.
There is a similar problem with carbon shafts to stainless shafts, that is that the shaft is not perfectly round. But unlike a steel shaft before you attach the blade, a carbon shaft made with a rudder blade already attached cannot be machined (neither can a steel shaft if the blade is already attached). So the solution in this situation is poured bearing surfaces, which would not work with steel but work fine with carbon. How this works is that we have uhmwpe (pronounced umpwee Ultra High Molecular Weight Poly Ethylene) bearings made in the shape of top hats with an oversize (to the rudder shaft) hole in the middle machined perfectly smooth and round. These bearings are eventually glued into a tube that gets glassed into the boat with the flat flange top and bottom forming a secondary bearing surface (the tube being the primary surface) and glued in so that the bearings are stationery. It doesnt really matter if the bearings can rotate in the tube some may even advocate it or at least believe they should be replaceable but I think the less moving parts the better. You cannot really glue anything to uhmwpe but if you rough up the surface the groves and troughs are filled with hardened glue and stop the bearing from moving in any direction. I may just push them into the tube as it is going to be a tight fit and leave them unglued. They cannot fall out, the buoyancy of the rudder will push the bottom one up and gravity will keep the top one down as will the heavy steel collar above it.
The rudder tube is necessary as the bearings are underwater, water lubricated and dont seal against the rudder shaft so water will get past them and into the tube. Without the tube the entire well where the rudders are mounted would flood, and given that the area in front of the rudder bulkhead is the outboard well and already a wet well, its not a good idea to have 2 flooded wells. We were initially planing on kick up rudders but have decided on fixed rudders. The rudders will be the lowest part of the boat and add about 200mm to our draught, but the kick ups add a fair bit of work especially in the stainless steel tillers as you need a universal joint exactly at the hinge point off the kick up boxes (if they are not exactly aligned the kick up hinge wont work) and present another point of possible failure. I figured that I can live without them, most boats dont have them. Either way, fixed or kick up would have required a tube and bearing set up anyway.
The tube is also to ensure the top and bottom bearings are exactly in line when mounted and glued into the boat. If they are not in line again they wont work properly but more importantly getting the rudder shaft through the top bearing is going to be tight as it it, almost impossible if the bearings are not aligned. We made straight fibreglass tubes by using the cardboard roll upon which the 50 meter rolls of cloth fibreglass came on (I should have thrown these away years ago as I used each roll of glass but I kept them, you just never know). We need to be able to remove the former, and we dont have proper tube making steel mandrels so this was what we came up with. By sealing the cardboard with clear tape so that the glass releases the tube we could wrap them in lengths of fibreglass, some lengthwise some wrapped around it to give strength in all directions, in all about 5 layers of glass for about 3mm walls and then once set we soaked them in a bath to remove the cardboard formers leaving just the fibreglass rudder tubes.
Jo helped me remove the soaked cardboard as her arms would fit inside the tubes, she wanted it noted for the record, that she helped with the rudders, duly noted. Unfortunately for Jo, all the photos I had of her doing this are on a corrupted media card I had to remove from my phone and are irretrievable.
Once the glass tube is glassed into the boat and uhmwpe bearings glued into the top and bottom of the tube the rear steps will be built around it to seal off the back of the boat once and for all. The bottom bearing is under water, the top is above the waterline at the top of the last bulkhead and will end up under the steps, with just an inspection plate access above it for removing the stainless steel tiller collar so that the rudders can be removed should that ever be required and also for access to the emergency tiller attachment bolt should the hydraulic steering ever fail and manual tiller steer is necessary to limp to port.
In our case the carbon rudder shafts are 60mm. And ideally we want about 8mm walls on the uhmwpe bearings which adds up to 76mm. The largest cardboard tubes we had were 85mm, so it means that the poured bearings will only be 4.5mm. (85mm – 60mm rudder = 25mm – 8mm uhmwpe bearing walls [x 2 sides = 16mm] = 9mm left which = 4.5mm poured bearing wall) x 2 sides. I would have preferred a little more space to work with, say about 8mm poured bearing walls but 4.5mm will be enough. In fact on the bottom bearing, where the hole needs to be a little bigger than the top bearing so that the top bearing can pass easily through the bottom bearing hole with some clearance, we made the top bearing to have a 4.5mm poured bearing wall thickness (so the uhmwpe bearing has .5mm thinner walls) and the bottom has 5mm poured bearings (making the opening at the bottom 1mm bigger than the top poured bearing. That was a bit confusing. Anyway, the tube is 85mm top and bottom, the shaft is 60mm top and bottom and the combination of uhmwpe and poured bearing is 25mm top and bottom but on the top the uhmwpe is 16mm of it and the pour is 9mm and on the bottom the uhmwpe is 15mm and the pour is 10mm. Crystal?
So the process will be that we place the machined uhmwpe over the rudder shaft and centre it using spacers cut to exactly 4.5mm (5mm for the bottom bearing) all around and then seal the bottom gap around the shaft (I have been told that plasticine is good for this) and pour epoxy mixed with graphite power into the space and let it set. ATL sell West System epoxy and suggest about 10% graphite is about right and sets to a very hard wearing bearing surface and is consistent with the carbon shaft. Nothing will stick to the uhmwpe and it is machined perfectly smooth. And of course the rudder shaft is sanded epoxy over carbon fibre so the epoxy/graphite will stick to it so when set the 2 smooth surfaces are the married bearing surfaces. Once the poured bearings are set the uhmwpe bearings are glued into the glass rudder tube, best left on the rudder shaft for this task to ensure they are glued into the tube perfectly in line with each other. Then the rudder can be removed and the tube complete with uhmwpe bearings glued in can be glassed into the boat. The only thing I will need to watch out for is that I glue the tubes in square and plumb, but with the 2 bearings perfectly in line, whilst this is important, it wont be as critical as the bearings being out of alignment.
At the top of the tube will be a ply shelf to give strength to the rudder tube mount and to provide a platform for the inverted high hat shape of the top bearing and onto that flat bearing flange would be the base of the stainless steel mini tiller collar/flange. It is not a thrust bearing, in that the rudder does not hang off this stainless collar, because the rudders are positively buoyant, so the rudders will be pushing up against the bottom uhmwpe bearing flange. To stop the rudder pushing too high and rubbing on the bottom of the boat, a fibreglass ring is glued (and glassed on the bottom) to the shaft, making the bottom bearing a thrust bearing as well as a shaft bearing. When final fitting the rudders, we push them up against the thrust bearing surfaces and then pushing the stainless steel collar down onto the top of the shaft so that it stops the rudder from being able to move either up or down. And that will mean the rudders are pretty much hung. Job done apart from paint. I will probably just roll them with copper epoxy.
All that will be left will be to attach the stainless steel mini tillers and then to mount all of the hydraulic rams and the rudder work is all but done. The hydraulic rams will be mounted onto a shelf that will be glassed in to the boat abutting the top of bulkhead 8, in the outboard well side of bulkhead. Once the rudder tubes are in the rest of the rear steps below it will be glassed in as buoyancy boxes so there will be no access to that space, but the outboard well will give access to the shelf on which the hydraulic ram will be mounted, as of course, there will be times I will need to service them.
As I mentioned in a previous post, the hydraulics were purchased in the US. On the advise of another builder of the same design (Sean), who has sailing experience, I have bought the same system that he has, he sent me a parts list and I found an ebay seller with them. He suggested a seller but their quote had gone up substantially since he purchased and their shipping was $500! So here is a good tip for those of you still a bit new to ebay or buying via the web; set yourself up with a US postal address on shipper, I use www.gateway.com and use ebay.com (instead of ebay.com.au as you can only access sellers that will ship internationally from .com.au) even though you are not in the US. Many US sellers will not ship outside of the US but often ship for free to a continental US address, so you often only pay for shipping from your service to you. But with a US address you get access to the competition that 300 million consumers creates. The other great advantage of using on shipping services is they have very good freight rates. Many ebay sellers use international freight as a way of making extra money or for them shipping internationally is more work filling in forms etc so they charge for it and perhaps because even with the higher freight rate they know you are still better off than buying in your own country. But when you ship to a US address and use your own shipping they you can even save on the shipping. For example, I bought a BEP 240v power boards from a great retailer called Great Lakes Skipper, no complaints with them. But they wanted US$130 to ship them, but would ship to my on forwarder for free. My on forwarder shipped them for US$68. By the way, the same power boards here with 2 extra switches on them which can be added for about AU$100, wholesale for AU$650 and retail for over $1000. I paid less than $200 and intend to upgrade them with the extra switches, so $300 instead of $1000. Last week I won an auction on the US ebay for a brand new Plastimo Olympic 85 compass that retails here for about $120, I bid $20 and won it, and shipping here is $40. So again a 50% saving. Anyway you get the idea, back to the steering….
Sean and I are using Ultraflex or Uflex as they are known in the US. I got a quote from the leading AU made hydraulic steering firm and it came to about $2800 (about $600 each for the rams, about $1200 for the helm pump and $400 for the tie bar kit). They did say they would give me a discount, which they would not stipulate unless I committed?? huh, you will tell me the final price only after I agree to the full price?? come on guys, I didnt press them on this and perhaps they would have told me, but I knew from the get go I was not going to buy from them so why waste their time, I figured even with a generous 20% discount it would still come to about $600 more than I could buy it for in the US and I was pretty sure the discount would have been single digit. So, the Uflex system with 2 x UC215-1 rams US$380 each, a UP39f front mounting helm pump US$500, and an LTB-1 hydraulic tie bar kit US$180 (needed to re-align rudders should they go out of alignment). I also got a remote filling kit so that I dont have to open up my steering binnacle to top up fluid should I ever have to bleed the unit, and a Kit 95/2 for joining hydraulic hose for 2 rams and they threw those in for free. Shipping all up cost me $180 so and I got .98 exchange rate so all up I paid AU$1650. And it arrived within 2 weeks of me buying them. The only thing I did not buy was hydraulic hose and fluid figuring they at least are available here for reasonable prices. I bought my system from a Florida boat dealer called SeaHunter boats. I highly recommend them, honest and go out of their way to help. They dont ship outside the US, but had no problem shipping to me, knowing I was in Australia, to my Portland Oregon shippers address (opposite side of the country for those that dont know). Be patient, because some people dont check their computers more than once a day, so because of time differences it could take a few days to hammer out a deal, but hey, its worth it.
And on the subject of shopping around, even when buying locally it pays. The stainless steel rudder shaft mini tiller attachments cost me $250 each, but my first quote from a different fabricator was $455 each. I was actually shopping for the parts required to have a welder weld them for me when a supplier said we fabricate too would you like a quote. Ok, why not. $155 plus tax ($170) each. Wow, $300 each difference. Needless to say, it pays to get a second quote. They ended up being $250 each because I made a couple of modifications to the initial quote basis because his price was so cheap I decided I could afford to get a little more of the work done by a professional rather than risk ruining them by doing it myself and getting it wrong. I had a slot cut into the tiller rather than a single bolt hole for connecting the hydraulic ram (so I would have some adjustment if needed) and side cover plates welded to close the gaps of the tiller bar to the stainless steel tube (this was their idea to make them look better and a bit stronger). The initial quote was so much better than I expected that I dropped the idea of buying the parts and finding a cheap welding firm and immediately accepted, and also I took the risk of getting the mods done before I knew the price, and they did come out to be a bit more than I had expected, I figured if the entire thing initially cost $170 to make, then making a hole into a slot should cost what? $30 and welding the top sides on what? another $20. So I was expecting them to be say $220 each. But I wasnt going to complain. I thought maybe he under quoted me a little and took the opportunity to correct that with his added labour cost on the mods, and fair enough. Even at $250 each they were a great deal and I would have thought that $250 each was a fair quote.
All of the above work is a step by step process that cannot be done out of sequence. So the next step is to pour the bearings. I hope to do that next week, I have spent this weeks budget on the bearings. Next week I will get some graphite and start the rudder hang. In the meantime, I have an industrial bin coming and am having a once in 5 year shed clean out. I am finally throwing away all the little bits and pieces I have collected or kept over the years.
