Yara said..
Cisco I think you are imagining the old trailer-sailer system with a swivelling halliard at the top end of the stay. These units have the halliard sheave fastened to the top of the foil. So all the compression is in the foil, and the forestay is not involved.
I know what you are saying but that is not what I am imagining. I put a Reefurl on the Peterson 42 I had years ago which was in survey and I was chartering out of Cairns. The reason I put it on of course was to make life easier with sail handling on these two day one night trips. In that it worked well but when sailing longer distances and having to reduce sail at times, it was not very effective as a reefer.
Admittedly I did not spend much on modifying the sail as it was fairly old. Just cut the cringles off and sew in a bolt rope and no luff cushion. Also my back stay was fixed with no means of tensioning so I had to live with forestay sag.
The compression in the foil acts against the fore stay. If there were no fore stay the halliard tension would bend and collapse the foil. So these units usually get a permanent bend in the foil away from the side of the halliard which in turn spoils the sail shape especially when reefing. When reefed the bend will always trail away from the wind and if you have no back stay tensioner the luff sag will exacerbate the bend in the foil.
For what they are these units are quite ok but you have to say they are a price compromise for which the down side is a reduction in sailing efficiency.
If you are going to have a reefing furler I say don't compromise. Spend the money to get a top quality reefing furler designed for that and get a sail also designed and built for that purpose.
Everything with boats is a balance between budget and best practice. If you do not have the bucks to buy the right thing, wait until you do. I love my yacht and when I spend on it , I spend first class.