|
|
#1
04-30-2008, 05:22 AM
|
|||
|
|||
115 Optimax and 20cc
I just ordered a 115 Optimax for my 20cc. Not really interested in top end speed. Does anyone have an idea of what might be a good prop selection to begin with? I think I can borrow a couple of different units and see how she runs.
|
|
#2
05-01-2008, 12:59 PM
|
|||
|
|||
|
Re: 115 Optimax and 20cc
the 115 Opti uses a 2.07:1 gear ratio. WOT range is 5000 to 5750 rpms. Hull+motor+fuel=2 persons is in the 2400 to 2500 lb range. I'd guess that using a SS prop, 3 blade similar to the Trophy plus, to run 36 mph @ 5400 you'd need a 17"P. If you'd like to keep the rpm's up higher, say at 5700, go with a 16"p.
I have an '06 90hp Opti on my 20' Seafari. 2.33:1 ratio. 3 blade SS 21"P gives 5350 rpms @ 33 mph. 4 blade adjustable composite, set at 20"P, w/ cleaver trailing edge gives 5400 rpms @ 5300 rpms, but gets on plane much faster. Problem is I keep snappping the correction/adjustment tabs off the blades at $25 each. I'll be trying a 20"P 4 blade SS Attwood this weekend. I'll post the results.
__________________
Common Sense is learning from your mistakes. Wisdom is learning from the other guy's mistakes. Fr. Frank says: Jesus liked fishing, too. He even walked on water to get to the boat! Currently without a SeaCraft  (2) Pompano 12' fishing kayaks '73 Cobia 18' prototype "Casting Skiff", 70hp Mercury
|
|
#3
05-01-2008, 03:15 PM
|
|||
|
|||
|
Re: 115 Optimax and 20cc
Fr. Frank, Thank you for a very precise response. I am sure you have saved me hours of experimentation. I look forward to your evaluation of the 4 blade SS Attwood. Thanks again. I wish I had found this site before I began my project.
|
 |
|
|
Linear Mode
