I currently own a 1978 Cal 39 with a folding propeller powered by a Perkins 4108 with an inch-and-a-quarter shaft, a Borg-Warner transmission, and an illegible inspection plate on the transmission. What propeller would my boat require in order to reach hull speed?
Mark Matthews responds:
Thanks for the question. There are a number of factors to consider when choosing a propeller, but it's somewhat less than an exact science all together. The type of boat, the way it’s loaded, and the sailing (or motoring) conditions you encounter all factor into how well a prop will work.
I’d recommend a couple of things. First, there are a number of articles on propellers posted on SailNet's website: Choosing the Right Propeller by Sue & Larry would be on the list of recommended reading as would be Tom Wood’s Check the Propeller. For an even more precise answer, you might want to check the Cal owners e-mail discussion list that's hosted here at SailNet. By way of that list you can query other Cal owners on the arrangements that they found most suitable. Here's the link to all our discussion e-mail lists, Join E-Mail Lists. That will take you to the index page and from there you simply click on C for Cal, post your question, and start fielding responses. Good luck.