I run the same sprit on my Capri 22. I leave the sprit in the retracted position on deck In my experience it doesn't cause too much problem there, although YMMV. It should be noted that Selden does not rate the sprit for a roller-furling sail. These sails have a luff wire or rope, and are flown with more luff tension to get a proper furl. This load exceeds the ratings of the Selden sprit.
You can indeed use Selden bowsprit kits for roller furling Sails, both downwind and upwind Sails and spinnaker, and Selden does indeed provide technical guidance. See
http://www.seldenmast.com/files/1441613308/595-261-E.pdf
Strictly speaking, Theload on a the sprit from a furling headsail is the same as the load from a non furling headsail of similar design. However, the loads produced by a big upwind headsail (for use in apparent wind angles - awa- between 40and 90, approx) are approximately 2x greater than a down wind asymm (awa between 90 and 150 degrees).
To chose the right sprit, you need to know the approx righting moments - RM - of the boat for pitching and heeling, the dimension of the unsupported length Of the sprit, and the same for the supported length of the sprit. If we don’t know the RM for the boat, we can use info about the length and displacement of the boat to do a conservative estimate.
Selden engineers have done all the analysis and they do indeed provide technical guidance for selecting the correct size sprit for furlong upwind Sails such as Code zeros.
At the upper range for installations,, I.e., for big boats with large righting moments, the limiting factor is the strength of the attachment rings and deck structured, not the sprit per se.
Advanced Technical guidance is available from Selden from US based tech support and some authorized distributors. For very complicated questions, the US team can ask the engineers in Sweden for support.
Judy B
Selden Authorized Distributor