Mainsheet Blocks

Springbok · Post by **Springbok** » Thu Mar 15, 2007 5:01 pm

The mainsheet block setup on my old Spark has 2 fiddle blocks resulting in a 4 to 1 purchase. What do the rules say about upgrading these ? Presumably a 6 to 1 purchase is the current standard. Is there a sheave size restriction ? Can I use blocks that have 3 pulleys side by side rather than the current 2 side by side and 1 slightly above and rotated 90 degrees configuration ?

Thanks,
Peter

SSCBen · Post by **SSCBen** » Thu Mar 15, 2007 7:37 pm

Hi Pete,
I have a feeling the current max purchase on the mainsheet is about 12 to 1 but i'm not too sure. My Spark also has a 4 to 1 purchase so it would be useful to know for certain.
Ben
SSC

Kevin Parvin · Post by **Kevin Parvin** » Thu Mar 15, 2007 8:49 pm

I've got some drawings from Panthercraft and they have a sketch of a Dart 15 fun. This seems to have a reduced purchase main sheet arrangement compared with the dart 15 sport.

Steve Willis · Post by **Steve Willis** » Thu Mar 15, 2007 10:01 pm

My Panthercraft manual shows both the old 2+1 piggy back pulley arrangement for the Sport and the more modern integral block of 3.

6 pullies is normal

Steve

Bob Carter · Post by **Bob Carter** » Thu Mar 15, 2007 11:24 pm

Hi guys,
Yes 6 pulleys is standard making a 7:1 purchase system. There are 2 block systems that were sold (ignoring the old Spark Fun which was not a racing format boat)- the old one with 2 stainless steel double blocks plus 2 inner single blocks and the new Dart Special black plastic tripple block arrangement. The later system is by far the best. Several guys with old boats have changed the blocks but kept the lower main sheet pulley/ratchet/cleating assembly. This works well and make the upgrade relatively inexpensive. You can get the blocks from Windsport.
Cheers
Bob

Bob Carter · Post by **Bob Carter** » Thu Mar 15, 2007 11:28 pm

I've just looked it up - 2 Black Dart tripple blocks are just under £114 but you save £74 by not changing the ratchet block assy.

Springbok · Post by **Springbok** » Fri Mar 16, 2007 9:41 am

Any idea what the sheave size is on these triple blocks ?

Springbok · Post by **Springbok** » Fri Mar 16, 2007 9:47 am

Bob, where did you look up the price for the Dart triple blocks please ?

Thanks,
Peter

George Stephen · Post by **George Stephen** » Sat Mar 17, 2007 8:05 pm

Peter,

On the Sprint 15 Home Page, Click on Suppliers and then on catparts.windsport.co.uk, and then follow through on their website via Sprint15 etc

I think you'd have to add some post and packing costs to the £114.

Robert · Post by **Robert** » Tue Mar 20, 2007 2:33 pm

Bob Carter wrote:Hi guys,
Yes 6 pulleys is standard making a 7:1 purchase system. There are 2 block systems that were sold (ignoring the old Spark Fun which was not a racing format boat)- the old one with 2 stainless steel double blocks plus 2 inner single blocks and the new Dart Special black plastic tripple block arrangement. The later system is by far the best. Several guys with old boats have changed the blocks but kept the lower main sheet pulley/ratchet/cleating assembly. This works well and make the upgrade relatively inexpensive. You can get the blocks from Windsport.
Cheers
Bob

Glad you think £114 is relatively inexpensive Bob, maybe I'll get one block one year and the other the following season. I have a 6 to 1 purchase with the old system so there is a double and a single block at the top, under the hook, but only a double at the bottom to which the end of the mainsheet is tied, over the main block assembly. I let the tiller go and use two hands to tension the main in a blow (hiking out).

If I were to upgrade to a 7 to 1 purchase, perhaps by adding another block at the bottom, I guess I would loose some length when the sheet is let right out off-wind (as well as making it a bit more of a "cafuffle" to ease it in light wind). I use a standard Windsport Racelite mainsheet and have have a length of just over 5 ft from swivel end to hook end when all the rope is let out.

I'm not sure the change from 6-1 to 7-1 would be worth the extra single block, let alone over a hundred quid unless it made trapezing significantly more easy when beating.

Robert 1351.

Bob Carter · Post by **Bob Carter** » Tue Mar 20, 2007 2:44 pm

Hi Robert
No you missunderstand. If you have 2 blocks with 3 pullies each you have a 7 to one system As virtually all Sparks and all Dart 15s had. The other block is on the main sheet ratchet assy. The only benefit of upgrading to the black plastic blocks is that they run in and out better than the old Spark stainless steel ones. It is not recommended that you change half at a time as the rope runs would not line up and much friction would result and it would be a retrograde step. So sorry it is an all (£114) or nothing upgrade. Most people manage OK with the old system if you want to save the cash.
Regards
Bob

Bob Carter · Post by **Bob Carter** » Tue Mar 20, 2007 2:54 pm

Hi Robert
Re reading your note I'm not sure I understood it correctly.
If you are a single block short at the bottom you need to get a replacement block to upgrade your system to a 7:1 - you should be able to do this quite cheaply.
Regards
Bob

Robert · Post by **Robert** » Tue Mar 20, 2007 8:25 pm

Bob Carter wrote:Hi Robert
Re reading your note I'm not sure I understood it correctly.
If you are a single block short at the bottom you need to get a replacement block to upgrade your system to a 7:1 - you should be able to do this quite cheaply.
Regards
Bob

OK Bob, it's worth a punt. Just to confirm, at the bottom I have the mainsheet ratchet assembly with just a double block above it. There are only 6 lines of sheet between the top and bottom block assemblies. I did wonder what all this "Block to Block" stuff was that I heard people talking about. If I buy one more block, then perhaps my arms won't complain so much after a blow.

I hope to go to Northampton Sailboats later this week. Maybe I'll finally get that trapeze harness as well! I have some more queries for you, given that money might be spent(!)

I need to upgrade my jibsheets, blocks and strop to something lighter than early standard issue- what do people usually go for?

My longer tiller extension needs cutting down as it is about 9 feet long - should I measure the new length (8' I believe) including the U/J?

How much Grippy Tape for the hulls might I need?

Will it hurt a lot when I experience my first pitchpole on the trapeze, or will George tell me the secret of recovering from the apparently impossible situation in which he is pictured elsewhere on this site?

Robert

Bob Carter · Post by **Bob Carter** » Wed Mar 21, 2007 8:34 am

Hi Robert
Yes you need another single old style inner block to put at the bottom.
The tube length of the Sport tiller is a maximum of 8' but quite a lot of us have it a bit shorter - particularly after it has been repaired a few times. Mine started life at 7ft 9ins until I broke it - when you fall off it is all that you are hanging on to!!!!!!!!!!!
Steve Sawford sells the grippy tape ready made up to fit on your boat.
Cheers
Bob

Bob Carter · Post by **Bob Carter** » Wed Mar 21, 2007 8:43 am

Charles replied:

In 2003 "alternative blocks" were authorised within the class rules, which means any you fancy. You can also get rid of that dreadful carbine hook & use sheets down to 3mm.

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Posted: Thu Nov 18, 2004 8:14 am Post subject: Jib Blocks [Chris]

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Chris replied:

Hi there if you check Shanklin's web site most of the details are there.
http://www.shanklinsailingclub.com/hints.htm

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