Mast collar block pin puzzle

[gpshome]

I have a few turning blocks at my mast base that I'd like to replace (since the 25 year old sheaves are starting to deteriorate). I have found replacement blocks online, but before I purchase, question is how hard is it to replace blocks in this style of base? See attached picture. It's an Isomat NG31 base with 12mm holes. The block pin fits through the base hole into the nut. However the nut slots are pretty small so using a wrench is out of the question. Is it just a matter of jamming a screwdriver in there to hold nut? ...or some other trick? Surely there's something short of removing mast and plate that will work.

 

[centerline]

it might be a good idea to get in touch with rig-rite, to figure out how it works as that is their product....

 

[Stu Jackson]

Also try Garhauer. With that picture they should be able to help. The springs on the blocks seem unnecessary.

 

[NYSail]

I replaced mine a few years ago.... Nuts stay in place. I put a wrench on the old block and turned.

 

[gpshome]

I replaced mine a few years ago.... Nuts stay in place. I put a wrench on the old block and turned.

Well that's too simple, obvious and convenient for me to have even tried. Will give it a shot next weekend - thanks.

 

[RoyS]

Springs are to hold blocks upright when lines are slack.

 

[OpenRange2025]

Hi @gpshome ! Revisiting this old post and hoping you may be able to help... I have a 1990 Beneteau 50 with a similar mast base collar. I'm wondering if your turning blocks have pre-attached studs or if they are a pin + block setup. Previous owners of the boat removed the hardware that ran the lines back to the cockpit, and I'm trying to revert that, so I'm shopping for mastbase hardware!

I'm looking at these pins/studs that I can later add a block to, but I'm not positive they'll fit as the measurements on the CD site are a bit unclear.

If you could share anything about your setup that would be awesome. Thank you so much for your help!

It's an Isomat NG31 base with 12mm holes. The block pin fits through the base hole into the nut.