There is no single standard for any GP14,  whatever the model.

What most owners use is a single control line system  –  and I have known precisely one GP14 owner (and also one Cornish Shrimper owner) use a twin-line (endless loop) system,  and I strongly suggest that you lead the control line to a camcleat on the foredeck close alongside the mast.   Necessarily that will be not quite the centre of the boat,  but it will be near enough not to matter.

In passing,  the endless loop system worked well on the Shrimper when I borrowed her,  but I have no first-hand experience of using it on a GP14.

If you have washboards fitted you will need to either drill (and preferably bush) a hole in one of the washboards to allow the line to pass through,  or alternatively pass the line across the top of the washboard.   Personally I would not recommend the latter,  for reasons of chafe,  and of inevitable wear on your wood and on your varnish.    A hole drilled in the right place,  and bushed (with epoxy,  or otherwise) seems a far better approach.

However I have known occasional owners with GRP boats get round the problem of drilling the (hollow or foam-cored GRP moulding) washboard by instead leading the control line to one end of the washboard.   They claim that it works well;   but inevitably that means that it is led to one side of the boat  –  and if that happens to be the lee side when you are unexpectedly caught out and urgently need to reduce sail in a hurry that could compromise your safety.

I note that you reference Wayfarers in which the control line is led down the side of the centreboard case,  and cleated abaft the thwart.    That strikes me as an unnecessary complication in a GP14,   but the Wayfarer is a larger boat,  and it may be of benefit there when single-handing.   In my extensive single-handing in a GP14 I have never found any problems with having the control line cleated on the foredeck alongside the mast,  as far aft as possible.

I can reach it easily when single-handing;   indeed if one cannot reach it one is sitting too far aft,  which is a very common fault when sailing GP14s.   When single-handing and sailing to windward one should be sitting either astride or abeam of the thwart or forward of it,  in order to keep the transom out of the water.

When sailing two-up my crew can reach a cleat on the aft part of the foredeck easily.

Hope this helps,

Oliver

I have my roller furling on the jib run to the Starboard side.  I can agree with Oliver on the occasional need to be able to speedily reef the jib, but if that happens, I will be either turning into the wind to take the pressure off the drum anyway or letting the jib sheets go for the same reason.  I do not like swimming, I avoid it at all costs, especially as the water here is shallow, murky, and rather full of sticky mud.

If your new genoa is cut with a higher clew I would hope that you shouldn’t need those extra control lines;   I developed those when I was using a standard genoa on a modern boat with through-deck sheeting,  but once I bought my new genoa with a higher clew I never used them again.

Incidentally I had never needed them with that same standard sail on my previous boat which had on-deck sheeting;   I just moved the genoa cleat forward a little as necessary.

But if you do find that you need them,  I had a single line right across the boat,  via turning blocks below the deck,  and I had cam-type jamcleats on the underside of the cockpit coaming.

Hope this helps,

Oliver