In short, I'd say
yes you can and remain class legal.
I suspect Mr Carter has been waiting for me to spot this post & exercise my love of documentation & the rules.
Amendments to section 10 of the Class Rules
– all are optional:-
a) Jib Leads - Two to one purchase with cleating blocks
b) Jib Sheeting – the carbine hook (SK954) is optional and jib sheets (SK946) down to 3mm diameter with alternative blocks (to SK953) are approved for use
c) Forestay Assembly - Self-furler
d) Forestay Assembly - Wind indicator e.g Cat Hawk or similar
Section 10 states:-
The following Spark Jib kit must be carried when SJ856 is set.
This is the single line jib sheeting.
And the Spark Jib kit rigging may be wholly substituted by the following Dart 15 Sprint (now Dart 15 Sport) jib rigging which is used with jib boat part SK936.
Given that I doubt anyone knows the difference (if any) between the 2 jibs, I would suggest sailors can reasonably use any combination of the parts listed.
I suspect the 2:1 sheeting came in around the time that the Dart15 began to be seen as a racing boat similar to the Dart18, which has a larger jib & perhaps needs the 2:1, along with other, more modern designs.
If you are still awake, I hope that helps
