Boats fitted without a skeg have been known to lose their rudders. One solution is to drill a locating hole through the top of the rudder post to take a bolt – this will positively secure the rudder and prevent it dropping downwards. Another solution is to fit a skeg with a pintle and pin fitted at the lower end – see pictures below.
Footloose is a junk-rigged Corribee fitted with an inboard BMW engine. The skeg is obviously a different shape, to accommodate the propeller.
The skeg and rudder on Clareen, a 1984 mk3 Corribee. This is a standard factory-fitted skeg shape. Note the identically shaped rudder in both pictures.
Refurbishing a Mk2 Skeg
Charles Riley writes: Dream on, my 1982ish Mk2 Corribee is under refit this year and I’ve been examining the stainless steel pintle assembly which was factory fitted to the skeg. Poking around with a screwdriver revealed that some moisture was weeping from the skeg where the pintle assembly is mounted, so I decided to remove the pintle assembly and see what was going on.
The bolts securing the pintle sheared off when I came to remove them – pitting corrosion had reduced the thread diameter within the skeg to a few millimeters and they soon came out. The pintle assembly was removed and the skeg base exposed.
I am pleased that I looked, not only because I found the corroded bolts, but because the skeg base was in fact exposed hardwood which was quietly rotting away. About 25mm or so was easily removed before I got to solid hardwood inside the skeg. For some reason, the base of the skeg hadnt been glassed over, probably becasue the pintle assembly would not have fitted if it had done. The hardwood seems to extend up into the skeg for about 200mm – easy to determine this by hammer tapping.
Repair was not difficult: I completely dried the skeg out (an easy job this spring!). I epoxied in some new hardwood (I had some teak spare) and then sealed the assembly with more epoxy. I replaced the pintle assembly and refitted new A4 M10 60mm set screws with loc nuts.
At the same time I discovered the tiller headstock was cracked through (as per the warnings / advice on this site) so without doing these repairs I would probably have lost my rudder next season and the skeg would not have saved me as the pintle would have gone with it!
Refurbishing a Mk 2 Rudder
The following has been kindly provided by Peter Willson, who owns Blue Moon, a Mk II bilge keel Corribee manufactured in 1978.
The rudder on Blue Moon was showing a number of problems. There was osmotic blistering especially on one side of the rudder; there were rust stains at the base of the rudder; the rudder was not in alignment in two planes – the stock being bent as might have resulted from hitting an underwater obstruction while the rudder was inclined 20 degrees to starboard; there was also evidence of corrosion of the (phosphor bronze?) stock where it entered the top of the rudder; the head-stock had at some time had a through bolt fitted (good idea to prevent lost rudders) but was drilled out of alignment so the tiller was out of line with the rudder blade.
I had also read of problems with tang failure so decided to open up the rudder and check it out. I had no information on how the rudder was built so used a stud detector to try and find out what was inside. This reveals a stock that goes about 50% of the way down into the rudder with just two tangs running at right angles to the stock and in the top half of the blade only. I opened the rudder by disc cutting and sawing around the edge and finally splitting the rudder with the aid of wedges, trying to preserve the G.R.P. outer shells as much as possible. This was a fairly brutal business, on account of the method of construction the rudder doesn’t just split apart like splitting slate. It shows that the rudder was constructed of the stock and tangs, encased in a G.R.P. shell, with the void being entirely filled with a dense filler of some sort. Although I could now straighten the stock the corrosion at the point where the stock entered the rudder reduced the effective 1” diameter by some 15%, a reduction in cross sectional area of some 38%, also the tangs – two pieces of ¼” mild steel round bar were very rusted and wasted away where they were joined into the stock – no wonder some have reported tang failure.
I decided to replace the stock with 1” 316 grade stainless steel, to lengthen it to reach ¾ of the way down the blade and to fit three 8mm round bar tangs (an interference fit into the stock protruding slightly from the ahead side) also of 316 stainless in order to prevent any problems with galvanic corrosion caused with dissimilar metals being in contact in a saline environment. The shells were then cleaned up – a long job with the angle grinder – (most of the gelcoat and anti foul removed from the outer and all traces of filler from the inside) and the two halves re-enforced with chopped strand matt on the inside before being joined together enclosing the stock with woven roving tape. A 25mm hole was made in the one of the shells so the filler could be introduced. All was then carefully aligned before filling the void. After some research and advice from CFS resin supplies I decided to use a mixture of polyester resin mixed with talc. This was mixed resin plus 1% catalyst first to ensure thorough mixing then the talc added to an equal amount by volume. The resulting mix was added through the hole in 500mg amounts and allowed to go off before introducing the next amount. (how was this done in the factory – does anyone know?) This was all to keep the temperature from rising too high as can occur with large castings. Finally the hole was closed. It was now time to grind out the osmotic blisters some of which were very deep and smelled of the characteristic vinegar when opened. These were filled with a polyester/talc mix. The surface was then covered with G.R.P. flow coat. Sanding this off to provide a smooth surface is another long job as flow coat doesn’t self level like paint. Finally, and after advice from International Paints the surface was finished with Intercoat epoxy primer and Trilux hard anti-foul as Blue Moon is dry sailed.
The head stock was refitted with a through bolt but I also added a stainless steel collar just below the head stock which has a set screw into the stock to ad an extra degree of security to guard against rudder loss (Blue Moon has no skeg). Blue Moon sails well with her renewed rudder and should now be set for another 30 years.
Jonny Moore has kindly allowed us to reproduce this article:
When we first purchased Casulen II, she had lost her rudder in the Clyde, and the previous owner had made a new one for her. The only problems with this were the excessive turbulence and the fact that the rudder was at lest 5 degrees misaligned. After sailing on Windermere for one winter season, we decided that we needed to make a new rudder. Having looked at several other Corribee rudders, and listened to advice from a yacht designer, we decided that we should make a semi-balanced rudder without a skeg, but also make the rudder as strong as possible and reinforce the rudder tube. The reasoning behind this is not straightforward and there was a lot of conflicting advice. The main argument in favour of a skeg-hung rudder is that it offers protection from impacts with submerged objects or fishing lines and also in big seas when the rudder is under immense pressures. However, as Casulen II is fin-keeled, we reasoned that the rudder would be fairly well protected from lines and floating objects. Also, no modern racing yachts have skeg-hung rudders and these are taking on some of the biggest seas in the world. We decided to make the new rudder longer and narrower than most Corribee rudders, as we had been advised that this would make the helm lighter and by making it semi-balanced, far more responsive.
A NACA 0012 profile was decided upon. This may sound overly complex, but is a fairly safe compromise for the average yacht, and well worth the extra effort if building from scratch. The rudder shaft was made from 1inch solid bar with three sets of tangs welded on the sides of this before being brought together and welded. All of this was 316 stainless steel. The rudder was made by laminating four pieces of ¾ inch plywood around the rudder post using thickened epoxy to stick them all together, having first routed out the shape of the tangs and rudder post. After shaping, this was coated in epoxy before being sheathed in epoxy and woven cloth to seal it. It has since received a further coat of epoxy, when we epoxied the hull, prior to applying coppercoat antifouling.
As the old head fitting was cracked and suspect, we bought a new Plastimo head fitting (part no. 13383), and made a new teak tiller to fit this. One of the features of this head fitting is that it has a bolt running through the whole assembly, including the rudder post, this making it almost impossible to lose the rudder, a fate not unknown to many Corribees, ours included! This rudder has now been on the boat for 2800nm, the helm is very light but responsive and even in winds over 25kts requires little effort when helming.
Rudder Troubles – Corribee Owners Association member experiences kindly reproduced with permission:
Reading members’ letters and various articles in the Blue Book, Magazine etc., it seems that one of the few weaknesses in the Corribee design was the method of rudder mounting. In the early design the only thing holding the rudder to the boat was the tiller headstock fitting, consisting of a pinch bolt at the rear of the headstock and a “dog” screw at the front, going into a shallow hole in the top end of the rudder stock. With a phosphor bronze stock, and a brass or aluminium tiller headstock, there is plenty of potential for wear. Later Corribees were fitted with a skeg, which supported the rudder from below. This saved it from falling off if the headstock gave way. Also some boats were fitted with a modified design of headstock, which had a bolt going transversely right through the headstock and rudder stock. This gives extra security and takes some of the load of the pinch bolt and dog screw.
I had problems with the headstock last year, which resulted in losing my rudder in Poole Harbour. The problem has now been solved by having a new rudder built using two halves of rudder “mouldings” obtained from the Baltic Wharf Boatyard (formerly The Osmosis Centre) at Totnes. I use inverted commas as the “mouldings” were actually two halves of a plug for making a new mould. Norco G.R.P. Ltd of Poole produced a new rudder by using the plug as if it were a moulding. This may seem a waste of a plug, but the alternative was to create a new female mould from the plug, then mould a new rudder from that. As the plug was in poor condition for taking moulds from, and needed considerable work to clean it up, my Insurance company would definitely not have stood the extra cost involved. The plug makes a perfectly good rudder, although it is heavier as it has much thicker GRP.
Anyway, as I was creating a new rudder, I took the opportunity to extend the rudder shaft by 11/2″ upwards and incorporate a collar below the headstock fitting, secured to the shaft by an M8 through bolt. When the rudder was fitted to the boat I inserted thrust washers under the collar to spread the load on the top of the rudder tube. My other modification was to have a spigot extended from the bottom of the rudder shaft for use with a skeg – if I ever pluck up the nerve to install one! The new metalwork was all in stainless steel, being cheaper, stronger and more readily available than phosphor bronze.
The final result gives me a securely mounted rudder but, as it involved losing my original rudder, I would be loath to recommend it as a course of action.
My new rudder is 2″ shorter in height and 2″ longer in length than the original. This has made it slightly heavier to operate, but it doesn’t wander off course quite so readily when not being held.
Derrick Thorrington’s letter in the June 1999 edition of the COA Newsletter gave a method of fitting a thrust collar which didn’t entail losing a rudder first. He suggested cutting a gap in the rudder tube in the stern locker, well above the waterline, and inserting a loose collar in there, fixed to the rudder stock with an M6 through bolt. The stern tube would need extra GRP reinforcing back to the bulkhead, each side of the gap. If I used this method on my boat, the gap would probably need to be carried into the bulkhead, as the rudder tube is fitted tight up to it.
Ron Lunney has a simple method of making a new rudder blade. This involves using two pieces of 3/4″ marine quality ply, shaped to be the left and right halves of the blade, and hollowed out on the inside to take the rudder stock and cross members. Screw the two halves together round the rudder stock, using West resin as an adhesive. After this has set, fill the screw holes and heads to give a smooth surface finish, coat it with more resin and clad it with woven glass cloth, tamping well to remove all air bubbles. Overlap the cloth from the two sides at the edges, and sand smooth when set. Finish with epoxy paint.
As Ron has helped build some 150 Corribees in his working life, and has also used this method to replace rudder blades on other boats, his idea is very welcome
One member has met a different problem with his rudder. As it is skeg mounted it cannot fall off, but the internal cross members have given up, resulting in the rudder staying stationary when the tiller is moved. His proposed solution is to drill carefully through the rudder leading edge and the rudder stock, then insert studding or similar bars through the holes and down the internal length of the rudder blade. The holes in the leading edge will then be resealed to finish.
Rudder and stock Knuckle – Corribee Owners Association member experiences kindly reproduced with permission:
Moonwisp’s tiller had so much play in it that at times it used to feel as if I had lost the rudder.
My fix for last season was to pack the knuckle tiller pivot hole, which had become elliptical, with plastic metal. This proved to be a good fix for two weeks, but soon slowly the play returned.
Having visited a number of chandlers without success, I visited the London Boat Show in search of a new 1 inch knuckle and tiller fixing. At first it appeared that all chandlers and boat yards had gone metric, but on close examination of the McNulty boat stand I was able to identify a beautiful stainless steel Knuckle and Brass tiller fixing that looked as though it came from the same mould as my Corribee’s aluminium set.
I was quoted approximately £100 for the complete assembly (less laminated wood tiller) but alas it turned out to be metric – 2.5cm.
Well 2.5cm is as close to an inch as one would want to get, so I got and it fitted.
It only needed the length of the rudder shaft (bronze) and the bottom of the knuckle to be fine tuned with a file to allow the horizontal lock bolt (12mm) to line up with the hole in the shaft, and hence prevent the rudder falling off.
The whole task was completed on one turn of the tide on the beach at Weston Super Mare. (work time with hand tools approx = 1 hour including transferring the tiller which did not require modification).
McNulty Boats – 0191 483 4836
PS if you want the brass look be quick! McNulty are changing it to all SS.
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