Removing the Centreboard of a 2009 SO30i Lift Keel
After procrastinating for too long, we finally dropped the centreboard out of our 2009 SO30i at the recent haul out in November 2017. We could still push it down with the system supplied, but no matter how many times we pushed it down, it jammed once we hauled it back up. We had to tackle the job. The boat is one of the first with a centre stub keel containing the swinging board, and twin rudders to allow it to dry out at low tides. Previous models had the centre board located between twin bilge keels.
The main issue for me was lack of information. Probably even worse, so much conflicting information about weights and lifting schemes, none of which seemed to clearly identify the models to which it applied. Before tackling this job, I wanted to understand the keel arrangement and how it was assembled, so I could be well prepared, but it was not clear which drawings actually applied to our boat. Now we have removed and replaced the board, I can finally see which are the correct drawings for my boat. However, other articles show that perhaps the confusion is that different systems have been used over the years, so the trick is to work out which of the many systems you have.
The following sketch shows the important parts of the system. You can see that it is quite simple, with no submerged sheaves or other bolted items that could corrode and be difficult to remove. The board is ballasted so that it goes down under its own weight, provided the boat is not heeled, when the friction due to the side force would stop it from going down. There is a u-bolt on the back of the board, with a shackle and a rope that goes up through the high part of the trunk to well above the water line, through a tube which guides it up to the cabin roof and a turning block/exit sheave, then back to a clutch at the winch on the cabin top.
I also found the following two drawings which show the keel. There are three nylon pads 60 mm diameter, on each side of the board which provide the side force necessary to resist the side forces on the board. The pin is just a pivot, which is not loaded in bending.
Drawing 1 – Keel Details.
Drawing 2 – Longitudinal section
First, it was not a big or difficult job, I think it added about 2.5 hours to the normal haul out work required by the time it was reinstalled. More than that in worry. We started right on knock off time rather than worry all night, and it came out in 30 minutes or so. The boat was supported in a high cradle with the bottom of the keel about 700 mm above the longitudinal beam of the cradle, so the keel could be lowered using the cabin top winch until the bottom end rested on the beam.
Photo 1 – Supported on a High Cradle
Photo 2 – Board lowered after pin removal
The pin is plain stainless steel, 24 mm diameter, drilled and tapped M8 axially at each end. Well, I measured it at 24 mm, but the drawing shows 25 mm. Enough to make me doubt my sanity. I have to admit that despite my care to measure accurately, I am no longer sure which is correct. Hex headed bolts hold a 30 mm diameter washer on each end to retain the pin in the keel. Both the keel and the board seemed to have Delrin or nylon sleeves for the pin. The heads of the bolts and the washers were all bogged in sikaflex, which had been faired out level with the outside of the keel, and was easily dug out with an old chisel. The pin and bolts were all in quite good enough condition to reinstall with some anti-seize paste on the bolt threads and new sikaflex. The washers were a bit dished and it would not hurt to be prepared with either 2 or 3 for each end, or thicker washers 2 to 3 mm thick for reinstallation.
Photo 3 – Pin and Retaining Bolts
With the pin removed and one person to just hold the keel on edge, the top end was lowered, again by a second person on deck using the cabin top winch to support the weight, until the board was resting on edge along the centre beam of the cradle, then the rope was cleated off. It was quite stable like this for us to clean out down, and antifouling the board and the keel casing. We did not have a scale, but once the board was accessible for a clean lift, the shipwright estimated it was about 30 - 40 kg in total, no handling problem so long as we were careful to keep backs straight and position ourselves carefully. (The board on the SO33i with the similar configuration may be a little heavier. Based on the information I have seen, I suggest it is likely to be in the 40 - 50 kg range.) You get a very good idea of the weight, even with the pin in, once you are able to rest the bottom end on the ground. It is not heavy.
Photo 4 – Head of the Board
Clearly visible in photo 4 are the pads which protect the board in the full up and full down positions. We found the head of the board was still white gel coat, surprisingly only needing a minimum of light scraping to clean it. Similarly, the keel cavity did not appear to have ever been antifouled in the area of the head of the board. The cast iron had rusted to form a high volume oxide, very lumpy and uneven under the paint, fortunately soft enough to easily scrape out. Not easy to photograph, but photo 5 gives you a good idea of the condition around the head of the board. It does not look like antifouling had ever been applied. That was clearly what was stopping our board from going down the last couple of outings.
Photo 5 – Inside of the casing, front end
We did not have access to a small sandblaster that would have allowed us to clean the inside of the cavity properly, so we did our best with a scraper, applied some vinyl primer, and applied anti-fouling to the whole board and inside the cavity. Unfortunately, this was not really enough, and the board still does not go all the way down easily. I suspect we will experience extra leeway until we do the job properly next year. Fortunately the light weight board is about leeway, and all the stability is provided by the fixed keel.
Finally we used the cabin top winch to lift the board for inserting the pin, reinstalled the axial location bolts with some anti-seize compound and reapplied the sikaflex to make a smooth outside surface.
Photo 6 – Reinstalled and freshly antifouled
We will do it again next year and are planning to have the sand blaster, and drop sheets to catch the grit, to do a longer term job. If anyone feels this is the wrong thing to do, considering that it has lasted 9 years already without anything, please let me know. Also, if you have any recommendations for the type of primer which should be used on the cast iron before starting on the antifouling. If you have never done it, I would recommend don't defer it, plan for it at the next haul out and periodically thereafter.
When first delivered, the whole hull had arrived in gleaming white gel coat, but with the board installed, probably for transport, so it was clearly intended that the agent had to apply the antifouling, and he obviously only did what was accessible by lowering the board with the pin in place. I can only say in his defence that he did other things quite well and just had no instructions on the board. There was nothing in the owners manual. I think all owners would be appreciative if the owners manual had at least a recommendation for the board removal, initial antifouling and most importantly, for ongoing maintenance. And dealers taking delivery need clear instructions on the factory preferred procedure. I know there are a couple of dealers on the forum who I hope will let us know if they are in the same position, or if things have changed.
Rene460 - SO30i
Editor: Also refer to the article on the Sun Odyssey 33i lift keel bush replacement, which may well also be helpful.