Bookicker Model K0400
Rick,The proper size for the 170 is the Boomkicker Model K0400. As for portability, the following is a direct quote from the Boomkicker site referenced below. I have no personal experience with one, and to be honest, what follows I just learned the other day. Apparently, the Model K0400 does not affix into a permanently mounted base on the boom. Read the quote and reference the site for more information."The two sketches below show the basics of Boomkicker models 312 and 400. They work the same as the larger models, but instead of attaching directly to the boom, a nylon sling, suspended between the two spring rods supports the boom. Since the sling does not attach directly to the boom it can not push the boom back off a gooseneck pin or restrict the boom from rolling around its central axis to follow the sail. This design also makes rigging and derigging a snap for trailersailors. Simply remove the boom and fold the Boomkicker up against the mast for storage. The other great feature of the sling is it totally avoids having to drill and tap. The sling is positioned by a line to an eye located under the gooseneck. All parts fit in the luff groove of the mast" Reference: Boomkicker Web site, Models and Specs Section.Hope that helps.As for MJohnson, I always untie the topping lift from the boom once the main is up. This decreases the wear on the sail (or so I have read). Dick is correct as this does cause one to do a little forward planning prior to dropping the main. At times I still forget to reattach the topping lift line and drop the darn boom into the bottom of the boat. Damn near took my daughters ear off one day doing it. I guess it is up to the Skipper as to whether the hassle is worth the effort and potential additional wear.Happy easter all!!Godspeed,Rusty