Need prop size help

[Hilo boy]

I have twin yamaha 70's with 13 5/8x14 props right now. I'm hitting my rev limit of 6200 rpm at only about 2/3 throttle. I'm trying to get it to about 5800 rpm at wot. What size props should I try? Thanks

 

[Sea Rider]

Welcome to Iboats

Will need to go at least + 2 pitch to (16) to be around 5800 wot rpm, check if same diam is available, just change pitch.

Happy Boating

 

[steelespike]

Calculator says that at 6200 speed would be about 31 mph.What is your gps speed at 6200? 4 stroke?
What size,weight boat, Deep V? Does the rev limiter cut in?

 

[steelespike]

My info indicates 5300-6300 wot for the 4 stroke 70.
He says he's at 6200 at 2/3 throttle I guess 5800 could leave enough room for wot.

 

[Hilo boy]

Yes, speed is about 32mph. Boat is a 20 seacraft with a deep vee and weighs around 1700 pounds + 60 gal gas and another 700 pounds with ice,gear and 2 people. Yes rev limit kicks in as there is no difference from 2/3 throttle to wot. Thanks

 

[Hilo boy]

Thanks Sea Rider. I will look into that. Do prop brands make a difference?

 

[Sea Rider]

Prop brands and types should make a difference. I usually stay with same engine brand props, have worked fine for me. Just play with 1-2 next pitch size to be very close to factory wot parameters, that should stop the rev limiter kicking in. Yam has many props to play with...

Happy Boating