Hi all

I have a problem trying to get my main sheet blocks to align correctly and for the sheet to come forward off the top block without rubbing on the cheek of the block as it shows in the second photo

I found a diagram on the net a while ago on how to correctly thread as 4 to 1 system and i think i followed it but it just does not seem to want to sit correctly

Regards Don

Your top block is mounted so that it can swivel. Dissasemble and refit the plate, with the bends, under the hex turned over so that the block is held in line with the boom. Rethread the reassembled block and the one on the traveller clockwise looking from the starboard side. Use common sense, not silly pictures.

Hi Patrigo

Thanks for you thoughts

I will rethread it tomorrow as you have described and see how they sit

The diagram that i used was actually off a reputable site (ronstan or harken from memory) but it obviously doesn't work so i will have a play

Regards Don

Looking at the photo i posted (the top 4 i took this afternoon) and the last one was from before i redid it, it appears that in the last photo it was done as Patrigo suggested (but the boom mounted block could probably still swivel) and i had the problem then as well so perhaps it is the fact that the block can swivel that is causing me the problem.

For some reason it appears that the traveler mounted block doesn't want to sit inline with the boat but maybe that is because the boom mounted block is twisting

Regards Don

Another thing you could try is to have the top block fore & aft and the bottom block side to side. Come down from the knot, through the front sheave left to right, through the top sheave front to back, through the bottom back sheave right to left then up to the top from back to front and forward from there. There would be less crossing over and all the lines would be basically vertical so less twisting moment.

In one of the pics of your top block there is a small square plate between the shackle and block that is designed to not let the block swivel more than about 45deg. Remove top block from the boom, remove the shackle and then the plate. Re-assemble and re-install.
The top block should the be free to swivel and should fix you issue.

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rumblefish said..


In one of the pics of your top block there is a small square plate between the shackle and block that is designed to not let the block swivel more than about 45deg. Remove top block from the boom, remove the shackle and then the plate. Re-assemble and re-install.
The top block should the be free to swivel and should fix you issue.

Hi Rumblefish

You guys are confusing me because Patrigo 28 suggested i lock the top block in line with the boom where as you are suggesting that i let it swivel

With the plate where it is at the moment i am not sure how much movement it has but i will have a look and perhaps try both ways

It appears to me that the top block will not sit straight because one side of it is being pulled downwards where as the other side where the sheet exits forward is not

Regards Don

hi Donk,
before you start fiddling around with swivel vs no swivel on your top block attachment, I would try re-threading the falls / drops so that the system ran in an anti-clockwise direction when looked at from starboard. you are currently crossing over your first drop, then running clockwise. if everything is lining up straight, it is more likely to behave itself.
also, I cant see from your photos how the top block is attached to the boom (hanging from a fixed bail, or sliding in a track ?) if possible, you may want to get it a little further forward.
If you fix the top from swivelling, you should also fix the bottom one at the traveller car that way it will all keep in line.
cheers.

Hi Mike

The block is in a fixed position fore and aft on the boom so moving it forward is not a option without removing the bracket and refitting it in a different position

I will try the various suggestions that have been made by yourself and others (starting by rethreading it) and see what happens

Also the original main sheet was 14 mm and a bit ratty so i replaced it with some new 12 mm i had laying around and i am wondering if the larger main sheet would keep the blocks aligned better

Regards Don

12 mm is more than enough. Much easier to handle & will run thru the blocks better.
Good luck.

Don, I have exactly the same problem! So far I just lived with it. But I did look in some of the boat shops for a new system that would work better but they are mega bucks.

I would be very please if you could post your solution.

Would not two sister blocks, one with a becket serve you better in this application?

Yeah, this style of block may be better for the application. I had a similar issue with my furling lines. This is also the style of blocks on my Main sheet.

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Crusoe said..
Yeah, this style of block may be better for the application. I had a similar issue with my furling lines. This is also the style of blocks on my Main sheet.

Hi all

The blocks as shown above i reckon would work nicely

Not sure what brand the ones shown are but i would i be safe in assuming that these Ronstan ones would be suitable for a cruising 28 footer with the only problem being i would need to go from a 12mm mainsheet to a 10mm to suit the blocks

www.ronstan.com.au/marine5/product.asp?ProdNo=RF51500

www.ronstan.com.au/marine5/product.asp?ProdNo=RF51510

Regards Don

If you can hang a single block a bit in front of the double on the boom, then flip the doubles the other way round. That way the pull from the last exit on the double will be further around it.

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Donk107 said..

Crusoe said..
Yeah, this style of block may be better for the application. I had a similar issue with my furling lines. This is also the style of blocks on my Main sheet.

Hi all

The blocks as shown above i reckon would work nicely

Not sure what brand the ones shown are but i would i be safe in assuming that these Ronstan ones would be suitable for a cruising 28 footer with the only problem being i would need to go from a 12mm mainsheet to a 10mm to suit the blocks

www.ronstan.com.au/marine5/product.asp?ProdNo=RF51500

www.ronstan.com.au/marine5/product.asp?ProdNo=RF51510

Regards Don

Had a look today and I already have a 10mm main sheet so it would be a easy swap if i decided to change

Regards Don