Slycat777 10:56am, 24 February 2011
Assuming that a sheave box like this is suitable:

How are these typically attached? Two rivets/screws seems a bit light to handle the spinny load!
pjbharrison Posted 8 years ago. Edited by pjbharrison (member) 8 years ago
RS200 is a 13' dinghy!
This one might be a better option, takes up to 10mm halyard and has 6 rivets/screws
Andrew Curry 8 years ago
Remember these will only be of use if you are going to have internal halyards.
Slycat777 8 years ago
Thanks. Yes, my mast has internal halyards.

6 rivets looks better! Will order one up. Looking forward to trying the spinny out.

Unfortunalty the heel doesnt have sheeves to take the internal halyards, the halyards exit through slots near the bottom of the mast and then cleat off.

Would have been handy to have heel sheeves to run the lines back!
pjbharrison 8 years ago
Could sheaves be fitted to mast near bottom and lines run to blocks on deck or would this weaken mast too much?
Slycat777 8 years ago
Interesting idea.
I've been mulling it over and it's probably more important I feed my outhaul and spinny up/downhaul back rather than the jib/mainsail halyard?

I'll probably use roller reefing initially so adjusting the mainsail halyard is usually done at the mast anyway, and I rarely adjust jib tension.

Spinny halyard run back would be useful too, so might use the bottom sheave idea for that one?
NormanKlipspringer 8 years ago
On some of the Achilles the halyards exit the mast about a metre from the step and pass through turning blocks attached to the step. Look at this, which is Klipspringer's mast. There is a closeup of the turning blocks in Farmer boys photostream. I am ahving prob;ems at the moment freing off the sheaves, but will make them work. You may be able to configure something similar. Lines that feed abck are main, spinny and jenny halyards and spinnaker pole uphaul. I also intend to feed back the spinnaker pole downhaul, but have to install blocks at the mast base to enable this.
phayes2011 Posted 8 years ago. Edited by phayes2011 (member) 8 years ago
I don't know the diameter of the spinny halyard on an Achilles but the spinny has an area of 350 sq ft whereas an RS 200 spinny is 89sq ft. The spinny halyard on the RS is 4 mm so the first sheave you are looking at is likely to be too small.

From experience with dinghy’s I would recommend that you get a sheave the can take a max diameter line greater than the line you plan to use. Using a sheave that is only just capable of coping with the diameter of line being used can lead to fouling problems as they age.

I am not sure that putting another sheave at the base of the mast will have a great influence on its strength. The load on the mast near the base is predominately compression. The cross section of the mast is needed to cope with bending further up the mast so losing some area low down within reason for a sheave should not cause a problem.
pjbharrison 8 years ago
See blocks on deck for spinny halyard, uphaul, downhaul topping lift
Slycat777 8 years ago
Great photo very infomative. Do the eyelets for the blocks on deck have a backing plate?
Taking my mast heel to a rigging place next week ,they say they have an off the shelf step that seems to be the right dimensions. If it is, I'll be close to getting the mast up!
pjbharrison 8 years ago
Close up of block

There is a small plate on inside of cabin roof
Stand up spring keeps block upright and protects deck when not under load
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