PDA

View Full Version : 75mph Panther, Spring 1969 Boat Builder



onesubdrvr
04-01-2006, 01:05 PM
As I sit here playing single dad for the weekend, pondering things to come with my X-18, I decided to drag out my old boat builder magazines, and flip through, and see if there was anything Donzi in there.

I came across this article that I had bookmarked with the thought of building at one time, but what grabbed my interest in the article was he side note on propellers,...

"Contact surface of Panther and the water is comparatively small. Consequently, propeller of minimum diameter, and maximum pitch should be used. (Large diameter props are adapted to boats with maximum wetted area, such as slow moving runabouts and cruisers.) Diameter should be kept 11 inches to 12 inches at the most, while pitch is adjusted to allow your particular engine to develop maximum HP at peak rpm.

,......The best method is to try two or three different propellers with your particular endine until you find one that is just right. To generalize again, for utmost speed use a two blade propeller of hydrodynamic shape. For general usage, such as water skiing or passenger carrying, use three blades, still retaining the 11 inches to 12 inches diameter."

I found this pretty interesting - this design was an inboard, so you didn't have the out-drive casing to contend with, but I wonder how many of the principles remain after 40 years?

They also had a speed computation chart for inboard hydros (not what your thinking for hydro's though), 4 lbs per hp yields 65mph. 6 is 62, 8 is 59 and so-on (65mph was the top of the chart). My ragazza was 3100lbs, 365hp,.... wich is a little over 8 lbs per hp, their chart shows 59,....pretty close!

Just thought I'd share
Wayne

18FOOTER
04-02-2006, 05:40 AM
1 1/2 years ago or so I found the original owner of your X and talked to him about the performance. He told me he tried many different props on it, and got the best overall performance and top speed from a 4 blade cleaver. When he sold the boat years ago, that prop was still on it.

onesubdrvr
04-02-2006, 08:42 AM
1 1/2 years ago or so I found the original owner of your X and talked to him about the performance. He told me he tried many different props on it, and got the best overall performance and top speed from a 4 blade cleaver. When he sold the boat years ago, that prop was still on it.
Cool, I'll have to look for one when the time comes,....left hand 4 blade cleaver,.... won't be the easiest to find I don't imagine, but I'll find one

Thanks
Wayne