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Jason
Jason, Marine Mechanic
Category: Marine Electronics
Satisfied Customers: 549
Experience:  Degree in Marine Technology, Also Certified with Mercury Marine, MCM, MIE, VP, Yamaha, Honda, Suzuki
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I have an 1986 18 foot larson delta cuddy 190 with the 5.7L

Customer Question

I have an 1986 18 foot larson delta cuddy 190 with the 5.7L v-8 and OMC cobra outdrive. What is the best size prop to use on this boat? Looking to gain more speed then anything else.
Submitted: 2 months ago.
Category: Marine Electronics
Expert:  Jason replied 2 months ago.

G​ood morning, my name is ***** ***** am I speaking with? I read what you wrote. I would need some more information from you. I would need to know if you are boating at sea level or at a higher altitude. I will also need to know the gear ratio of the sterndrive. The gear ratio is stamped on the upper half of the sterndrive.

Customer: replied 2 months ago.
My name is***** live in Iowa. Lock and dam #10 on the Mississippi River. I can get the gear ratio tomorrow. Maybe. The lower unit has been repainted so not sure if still visible. I do know the high rev of the boat is 4200 to 4800 rpms. When running full throttle now the rpm's max at 4000 and the red line on the tach is at 5000. Hope that helps. What I found on my own is with the 5.7L with the OMC Cobra Outdrive it suggested a 23" prop size? Does that sound correct?
Expert:  Jason replied 2 months ago.

Hi Dirk.

What I found on my own is with the 5.7L with the OMC Cobra Outdrive it suggested a 23" prop size? Does that sound correct? ​

​That all depends on the gear ratio of the sterndrive.

Customer: replied 2 months ago.
Well I can not find any gear ratio on the sterndrive. Thanks anyway.
Expert:  Jason replied 2 months ago.

Okay no problem, good luck.