I will avoid answering your question since others in your area can give you a better answer, but will rather provide you with an alternative. If you are leaving your boat for the Winter and cannot check on it, shrink wrapping may not be the best or least expensive method of protection. Firstly, if you opt for shrink wrapping, do not allow them to shrink wrap over the stanchions but around them leaving them exposed. In two storms on Lake Michigan in the last five years, I had to replace 5 bent stanchions as a result of 60 plus mph winds blowing against the tarp/shrink wrap. They were bent over 45 degrees. Secondly, if you don't add sufficient vents, your boat will be prone to mildew and cannot breathe properly. Thirdly, if a "yard boy" does the job, (which is usually the case), there is the potential to cause damage from the heat to your fiberglass
, trim, etc. And, lastly, here in Lake Michigan, the shrink wrap is frequently torn during storms and very few yards will notify you of the damage or bother to fix it. We kept our boat in Florida
for 10 years and never had any damage. Here in Illinois ,as where you live, damage is a real potential during the Winter months. What we have done to prevent/minimize damage is to build a wood frame, similar to the roof of a house, and use heavy duty tarps that we cut to fit around the stanchions and over the hull
that are attached with simple clothesline. Although no method is perfect (unless you want to spend $3K plus for a custom fitted tarp) this is more cost effective and, in my opinion, a better alternative to shrink wrapping. Total cost for a 34 foot boat under $200. and your framing may be re-used yearly. Hope this helps and gives you something else to consider. Good luck and keep the dream alive.