I will rebuild my Nacra 5.0 mast. Where I am it's hard (expensive) to get a complete mast, but I will be alble to get a mast extrusion and work it out myself. The easiest way to do it, in order to make a sealed mast, seems to be using an external halyard for the main. I would appreciate advice on this, particularly on where the main halyard should be driven down: on the front of the mast, or on the rear, on one side of the luff. The second alternative seems simple, I can use a slightly longer mast and just use a pulley on the rear part of the mast, at the top. But I'm not sure if it will be convenient to aplly the halyard force on one side of the mast, it could bend it differently on one side.
If I use a ring on the halyard, to lock it on the top of the mast, this wouldn't be a problem, but I'm not confident with this, I feel it could be difficult to release. (or is it absolutely necessary to use it?)
Thanks a lot.
Andres

If you want to get the proper amount of downhaul tension on the rig, then you're going to need a ring. I suggest you find the N5.0 rigging manual and mimmic that setup as best as possible, that way, when you have problems or questions, there are other people in the know that can help you out.

Go for the ring hangup on the mainsail. Easy to release and easy to get up. Also easy to build/mount. The only other usable system I have ever seen is with a stainless steel wire secured to the bottom of the mast when the sail is raised.

To achieve best performance and the cleanest setup, let the halyard run inside the bolt rope track.

Be careful to isolate all stainless steel fittings from the aluminium! Use special Sikaflex or epoxy as a barrier coat.

Use only monel blind rivets, seal the rivet holes! Dont use aluminium or steel rivets!

Good luck with your project. If you have the time, I KNOW many readers here would like to se how you do this. Please consider making a website and document your project.

Good luck!

The main halyard should run trough the mast track. It should be no problem when the main and haylard are together in the mast track. Drill 2 holes at the bottom of the track, one 1 feet under the mast top the other 3 feets above the mast foot. Make sure that the holes follow the direction of the halyard.

Use a light micro block on top of the mast and a ring (aussi style) or a hook on your main that goes over the top of the mast.
The haylard and the block allone, won't hold the combined forces of the cunningham and main sheet.

good luck!
Andi