SO 37 - replacing the swivel blocks at the mast base

[svejk]

Had a bit of a surprise to day furling the main when the line became caught between the sheave and the cheek.  Finally got her furled but the block is shot.

Does anyone know what size blocks are at the base of the mast?  I'm assuming they're swivel shackles?  The sheave looks to be about 2.5 inches and I figured I'd replace all 6 (just bought the boat and she's my first).

Any recommendation and blocks other than Harken?

May Thanks.

[ianpowolny]

Take a look at this post. I recently change two of our blocks to a Selden double block purchased from Jimmy Green Chandlery. Having the main sail furling and outhaul through a double block has reduced to time we get these lines interfering with each other.

Jimmy Green also has some good information about sizing and the delivery cost outside the UK isn't too heavy.

jeanneau.proboards.com/thread/3859/improved-performance-so45ds-furling-main

Ian

[debenboy]

Try Garhauer.
I have loads on my SO36i, and even with delivery plus VAT on the gross cost, they are very competitive. Beautifully made too.

[svejk]

Jun 1, 2015 15:02:43 GMT ianpowolny said:

Take a look at this post. I recently change two of our blocks to a Selden double block purchased from Jimmy Green Chandlery. Having the main sail furling and outhaul through a double block has reduced to time we get these lines interfering with each other.

Jimmy Green also has some good information about sizing and the delivery cost outside the UK isn't too heavy.

jeanneau.proboards.com/thread/3859/improved-performance-so45ds-furling-main

Ian

Thanks Ian.  My apologies as I am a complete novice at this point - how did you determine the size of the block?  Also, did you have any issues replacing the block at the mast baseplate?  The offending block is the blue striped.

[svejk]

Jun 1, 2015 15:57:04 GMT debenboy said:

Try Garhauer.
I have loads on my SO36i, and even with delivery plus VAT on the gross cost, they are very competitive. Beautifully made too.

Thanks Debenboy - I'ver heard good things about Garhauer's blocks.

[ianpowolny]

Don't worry about being a novice - we are only in our 4th season and have had a huge learning curve and have travelled about 3000Nm. You'll soon catch up.

I look at this web site for information www.jimmygreen.co.uk/p/technical. It's simple to understand but expensive to buy so just use the info and buy where you can.

There are some very techy articles about determining the size of blocks but I just measure the sheave diameter and get the nearest size. A good investment is a set of Vernier callipers like these but in a box:Vernier Calipers

From the photo I think you have Base Blocks like these. You can buy the blocks as a like for like replacement or pawls that go into the mast base and then buy any block that is the correct size. Z-Spars sell base pawls as well.

Hope this helps. Ian

[svejk]

Jun 2, 2015 9:30:16 GMT ianpowolny said:

Don't worry about being a novice - we are only in our 4th season and have had a huge learning curve and have travelled about 3000Nm. You'll soon catch up.

I look at this web site for information www.jimmygreen.co.uk/p/technical. It's simple to understand but expensive to buy so just use the info and buy where you can.

There are some very techy articles about determining the size of blocks but I just measure the sheave diameter and get the nearest size. A good investment is a set of Vernier callipers like these but in a box:Vernier Calipers

From the photo I think you have Base Blocks like these. You can buy the blocks as a like for like replacement or pawls that go into the mast base and then buy any block that is the correct size. Z-Spars sell base pawls as well.

Hope this helps. Ian

Thanks very much, Ian!  Great resources!  The base block is exactly what I have.  Did you have any problems removing the old blocks at the clevis pins?  I'm not sure if I can re-use the clevis pins or if I have to install new ones.  Is there any trick to it?  (somehow this seems like a larger undertaking than I initially thought).

Fair winds, my friend.  Quite the accomplishment in only 4 season!

[ianpowolny]

If you buy base blocks they come as single unit so you don't reuse anything you have right now. Speak directly to Z-Spars. They have always been very receptive and will advise on both the blocks and pawls. If you go to pawls you'll need an additional small shackle from the pawl to the sheave. I think in your case just go for the Z-Spars blocks. Make sure you add grease to the new nut/bolt assembly at the mast base - easier to get out latter.

It's not so difficult to change the blocks but you do need a way of getting the nut out of the base - I use a bent over end of a wire coat hanger from the dry cleaners. Just bend it with pliers to the size you need then flick out the nut. Be careful it doesn't end up in the sea!!! I suggest you use new nuts as well.

Keep going and keep asking questions here. The guys are great even for the smallest thing.

Ian

[hoppy]

I have 6 brand new mast foot blocks from Z-spars waiting to be fitted (or stored for later).

Removing the pins is dead easy as they just screw into a nut. Removing the nut is a little fiddly if you are unlucky.

Previously I replaced a couple of the blocks with non-zspars and it did not work so well. As you can see in your photo, where the z-spar blocks connect to the pin, the metal is bent inward so that its a snug fit. On my first non-zspar replacement it was a normal mast foot block and in the end the pin slipped to one side and eventually the block mount bent and another broke. For others I ended up using washers to keep the pin centred.

If you know your mast model number, then you can find the correct block to order and if you don't, just contact z-spars and they should know the correct block for the SO37. Unfortunately there is no marking on the blocks to say which model it is.

[svejk]

I've decided on the easiest solution..  a new U.S. SPARS replacement block was ordered this morning and has already been shipped.  Easy decision, easy shipping and fast return to the bay.  I've got to rebed some things in the fall which should give me time to look at some mast block options but until then it's all about enjoying the warm weather.

Thanks to all for weighing in and I look forward to continuing my sailing education!