I noticed that in the specifications portion
of the web site that the propeller listed for the Downeast 38
is a16X11.
Not wanting to contradict the original specifications but I had
an experience where I had to re-prop. I have a RH Michigan 3-blade
15X15. Due to an unforeseen situation (oh, that’s another
story entirely) I had to pull the boat out of the water in the
Outer Banks. I happened to run into a new generation prop shop
complete with computers and formulas, etc. I gave them the specifications
of the boat and then the size of the prop I was using. Their
computer program came back as my 32 hp Universal diesel being
able to turn
a 16X15 prop. So, I invested in a Michigan 3-blade 16X15 (same
powerplant) and I was amazed at the difference.
First, the economy didn’t change at all – still running
at ½ gal per hour at around 2200 rpm. But, performance went
to 6.6 knots per hour. I was amazed at the difference one number
could make on the overall performance of this boat - but it did.
I will soon be changing powerplants and going to the new, updated
Universal M-40B which puts out around 37 hp. With that modification
I’ll have the formula run again and see if I can gain another
notch or two and get even more performance from it without putting
strain on the transmission or engine.
This performance difference is important for those who plan to
do any long-distance sailing and might find themselves in calm
areas. It might take an extra day or two of motoring to find some
wind and the so the increased speed and economy would make a significant
difference over a few hundred mile haul.
Thought you’d be interested in this first-hand information.
Rick Stierer
(Editor comment: The specifications page
mentioned above may have errors or there may be boats that are
slightly different. I have
already
been corrected at least once for typos there. The graphic at the
top of this page is a scan from the Owners Manual of a DE38.--GA)
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Propeller Size Increase
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