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S&S Swan Maintenance - Genoa blocks on a 411
25 August 2009 - 21:44
Join Date: 30 January 2007
Posts: 461

Genoa blocks on a 411
I realize that the genoa blocks on a 41 were alredy treated here but this is the turn of a 411 where they are slightly different and I need help.
I succeeded in unscrewing the four 19mm nuts and the central 24mm nut placed in the under side but I am not able to go further. The bolts are stuck and the black body of the block assembly would not move. I wonder if the lower grey aluminum plate is also threaded and the bolts are screwed in it.

Daniel, 411-004

28 August 2009 - 12:57
Join Date: 03 March 2007
Posts: 241

Hi Daniel,

If it is like my 40, the aluminum is not threaded. There are nuts below for the bolts.. Not easy to see but they are there. The block is probably corroded to the aluminum... big hammer...heat. I seem to recall using a big hammer and a flex saw. It has been 10 years since I replaced them...

Hope that helps


07 September 2009 - 18:06
Join Date: 02 February 2007
Posts: 202

Hi Daniel.

Alumine is very hard. So if all the nuts ar out, its only alumine holding the lot together. So hitting HARD with a large wooden hammer one top side of the block, then the other, alternatively should do the trick.... It was already very difficult for us with only four screws so I can  understand what you're up against..

Good luck.

Philippe Vidal (41/022)


07 September 2009 - 18:32
Join Date: 30 January 2007
Posts: 461

Thank you friends. I would like to have an official confirmation (Lars?) that, after the nuts are out, the only holding comes from aluminum oxide and then I will start banging without mercy.

I was thinking also of getting an air impact screwdriver but I found too much choice and stopped shopping around. Do you have any idea of how much torque I would need? They range from few tens up to several hundred Nm.
It sounds like some of them might be able to shear the head off the bolts which will do the work as well but I would not enjoy shearing the deck off the boat while I am sitting on it! :-)

Actually there is another question in case I go for the air impact driver: is the central bolt head really 24mm or is it an odd fraction of an inch?

Daniel, 411/004

08 September 2009 - 15:51
Join Date: 02 February 2007
Posts: 202


The 4 smaller screws are most probably stuck with alumine on the whole heigh of the block, so no chance with an impact screw driver there.

They are probably stuck with only about 4mm on the aluminium stand.

We tried to get them out (after taking them off their support as explained) with an hydraulic press without any effect. So, one was drilled down (what a job!), on the other we just left them as they were.

No idea for the central one, 41 is different.

kind regards. Philippe.

08 September 2009 - 16:19
Join Date: 30 January 2007
Posts: 461

thank you for the help. Do I understand well that if I succeed in getting rid of the large central bolt, the two sheaves should get free and let me service them? At the end this is the only important job I am trying to do.

Daniel, 411/004

09 September 2009 - 18:18
Join Date: 02 February 2007
Posts: 202

Sorry Daniel, I am not competent on this one as the central axle on our 41 was threaded into the bottom aluminium plate of the block, and this was the difficult bit to undo. You might nevertheless be right with your assumption.

All the best luck to you.


17 November 2018 - 14:39
Join Date: 07 October 2014
Posts: 74

hello, i am at the same job now and corious to know, if and how you got the job done.

i tried the impact driver but no heat for now.

is there a plastik bearing or something that can melt?

i dont want destroy more than necessary.

for me it is only the top sleve of one block, this one is not spinning well.

may i can get rid of it by scraping it out and put two half moon sleves back!

fair winds, stefan


17 November 2018 - 15:30
Join Date: 02 February 2007
Posts: 202

NO HEAT Goosyboy there!!.

There are plastic central bearings, and also probably tufnol sides in these blocks.

In any case alumine produced by this corrosion stands heat very well indeed!

The only way is to undo the four nuts hidden inside the gray aluminium piece supporting the blocks and then shock the blocks with a wooden or plastic hammer.

This should not be too difficult since the corrosion should not be more than 5 or 6mm deep. 

You probably will need to shorten a spannner to access the nuts, have specially thin hands... and be patient!

Maintenance: I never leave these blocks out during the winter, take them off as part of my winterizing procedure, and rince them regularly.

Also I am using nylon gaskets under the blocks and under the nuts to reduce electric contact between the bloks and their supporting piece.

Good luck, this is not and easy job!

Philippe 41/022 

17 November 2018 - 20:42
Join Date: 07 October 2014
Posts: 74

hi philippe, writing again, because wasn't logged in and all lost. think that happens to somebody of us - for me it is not the first time.

thanks for your reply, helped me realy, was close by to heat the center bolt.

i could disasemble all nuts but not the black block. with strong force i am having here.

but by that i figured out, what was the reason for not spinning well. the block got a strong impact by something and got deformed. that was stopping the wheel - stupid that i did not saw that.

i could fix this and "voila" it spins well again.

for now it is fine - i need to go forward to go sailing one day.

the block will need some more love to be perfect again. may i try a machine shop here in grenada.

thanks for opening my eyes on that - and i will remember "NO HEAT" 


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