Unknown sheaves on bow

[kingfisher]

Here's a picture of the pointy bit of the fine ship Obi-Wan. Does anybody know what those two green sheaves are for?

The head stay is in front of the sheaves, so the sheaves are on the inside of the rigging.

 

[snowleopard]

The arrangement suggests a line running down the port side deck and leading to the foot of the headsail. Best guess is a foresail luff tensioner or downhaul for hanked sails.

 

[DeeGee]

..or could be a preventer arrangement?

 

[Salty John]

My guess is they are for a jib cunningham.

 

[Roach1948]

More common to see this on classic yachts. the sheaves would lead to a 'Cunningham' tensioner - normally set up as shown below. I have an small offset cleat for tensioning and a larger centralised cleat for mooring/anchoring.

 

[DanTribe]

I have an almost identical arrangement. Is this an IOR rig?
The original headsails all had reefing points. I assume that the sheaves caried a wire downhaul for reefing. could also be used as a cunningham.

 

[kingfisher]

Yep, IOR rig on a half tonner (sirocco31). The reefing theory was already mentioned to me, but I have got 5 head sails to choose from (all hanked on), so why the need for a reefing arrangement, if you can change the sail?

 

[Talbot]

If you dont use it for the purpose already discussed, I reckon it would work well as a cruising chute tensioner, for when you need to go closer to the wind.

 

[DanTribe]

Gives a bit more flexibility with sail options. Also it's usually quicker to reef than lose time with headsail changes, especially if only for a short windward leg.
Foredeck hands can sometimes come near to mutiny if frequent sail changes were called for.

 

[yindoor2]

could it be a tripper for the anchor?

 

[VicS]

Too far forward for a pole foreguy I suppose?

 

[sailorman]

Genoa Luff Cunningham down-haul lead back aft

 

[ColinHuggins]

Re: Making a sternboard??

IF it's for a clew as indicated then isn't something back-to-front?

 

[Pye_End]

Not designed for roller furling?

 

[DanTribe]

Re: Making a sternboard??

OK. Missed that. It would make the sail set strangely.

 

[Guest]

Line comes along deck on port side .... thru steel hoop .... into stbd side of horizontal block then into vertical block .... its a tack downhaul for your LARGE genny ..... allows you to control luff tension and also to heave down to a reef point if necessary.

If you look back at photos of race boats many years ago ... they would have reef points in their foresails as well as their mains ............... why sweat changing sails ?

 

[kingfisher]

OK. I'm getting the consensus that it is the downhaul for the large genny. So how do I set it up?
From the genny:
1) clip hook to clew
2) line (diameter of sheave? Are those wire or rope sheaves) through vertical sheave, to horizontal, lead via eye to cockpit.

How much tension can I expect? Does it need to go to the winch? Or can I do a 1:2 or 1:4 purchase?

Why use it? Genoa halyard goes to cockpit anyway, so luff tension can be regulated via halyard tension on dedicated winch.

 

[sailorman]

A "Cunningham" is a cringle on the luffs racing Mains & Genoas apporx 300m/m above the tack.
it comes into use when the sail is at "Full Hoist" ie up to the "Black Band" at the mast Hd, one then hauls the Cunningham to "Flatten" the sail thereby reducing its Draught & center of effort thus heeling effect reduced enabling the boat to point higher

you might not have a Cunningham hole. /forums/images/graemlins/shocked.gif


PS Cunningham died about 3 weeks ago see the Times obits

 

[isandell]

Was the inventor not Briggs Cunningham, who died a few years ago?

Ian

 

[michael_w]

To be pedantic, a cunningham doesn't flatten the sail. It just moves the maximum depth of chord (draft) closer to the luff. It also has a lesser effect of opening the upper leach.

Useful,if like a lot of boats, you have stretchy old dacron laundry.