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Prop for Honda BF90
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Sea Wolf



Joined: 01 Nov 2003
Posts: 8650
City/Region: Redding
State or Province: CA
C-Dory Year: 1987
C-Dory Model: 22 Cruiser
Vessel Name: Sea Wolf
Photos: Sea Wolf
PostPosted: Mon Oct 04, 2010 6:25 pm    Post subject: Reply with quote

Kevin-

Yes, there's a rule about altitude and power.

You lose 3% of your horsepower per 1,000 feet of elevation after the first 1,000 feet.

So at 8,000 feet (8,000ft-1,000ft) X 3%/1,000 ft = 21%, and

21% x 90 hp = 18.9 hp, and

90-18.9 = 71.1 hp left (!)

I've also seen discussions where high humidity, low atmospheric pressure, and a hot day take a lot more hp away. See:

A Little Foggy About How Weather Affects Horsepower? Allow Us To Explain

If I had to make a SWAG* , I think I'd opt for about a 13 inch pitch by 13.5"-13.75" or so diameter prop as a starting place.

Maybe you could borrow one and give it a test run (?)

No wonder many of us want 90 hp or more on a 22 and would consider a 115 hp motor for high altitude, heavily loaded situations!

*SWAG (Acronym of the Day) Laughing

Joe. Teeth Thumbs Up

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Sea Wolf, C-Brat #31
Lake Shasta, California

"Most of my money I spent on boats and women. The rest I squandered'. " -Annonymous
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KFoote



Joined: 14 Sep 2014
Posts: 93
City/Region: East Bridgewater
State or Province: MA
C-Dory Year: 2006
C-Dory Model: 22 Cruiser
Vessel Name: Foote Loose
Photos: Foote's Rest
PostPosted: Sun Sep 14, 2014 6:40 pm    Post subject: Prop- 13.5 X 15 on Honda 90 Reply with quote

I have a Prop- 13.5 X 15 on my Honda 90, pushing a 22 ft cruiser. After reading through this thread.

After 62 years of not paying attention to more experience. I am going to follow the rule (for once) - "If it Aint Broke - Don't Fix-It"

Idea

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Keith Foote
Foote Loose
2006 22" C-Dory Cruiser
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