Nice thought making the boat more suitable for running. Sounds like the aft intermediates were really designed with lazy day sailors in mind.
Firstly I'd go over with a rigger whether you can make two points of attachment such that you can leave the runners set up closer to the original landing for the aft intermediates and thus be able to work to windward without shifting stays all the time.
Having had runners - and I liked them well enough - I know that it's one more thing to do tacking and if you can eliminate that, all the better. However, the strength needed for the stay when it lands further forward is considerably greater than what's needed for a true runner that lands back by the cockpit and the idea, while do-able, might not be cost effective.
I don't like highfield levers. If you land the runners to a fibre tackle it's well to spread the strain. If 3:1, have a block with becket at the end of the wire. Run the fibre part around a block on the deck, up over the block on the wire, back to a block further aft on the deck, and thence fair lead to a sheet winch. This spreads the load but you still want the eyes for those two blocks to be properly bolted and backed. It's nice to make the wire long enough that that block can just clear the turnbuckles of the aft lowers so the stay can lay there when not in use. Have a clip on the stay for long runs.
The mast fastening could be a problem. From your description I didn't get whether this was a T with the hole for the stay's pin at the bottom or some sort of inverted T, but more likely the former. Leading at a noticable angle away from the bottom of the T could put some wrack on the fastenings and if the length of unsupported tang is long enough could cause the lower part of the T to bend. I'd give serious thought to a V shape that you can aim properly but that's also more able to withstand an unfair strain.
G'luck
|