Key West design speed in knots

Designs for inboard or outboard power

Moderator: BruceDow

Post Reply
rblevens
Posts: 36
Joined: Sun May 13, 2007 4:15 am
Location: Alton, IL

Key West design speed in knots

Post by rblevens » Sun Aug 12, 2018 8:34 pm

What top speed in knots was the Key West hull designed to safely operate?
What is it design cruise speed?
35 knots?
50 knots?
Will be using a 7.4 with ~300 hp and a 1:1 gear.

Thanks
Rick

User avatar
Bill Edmundson
Posts: 11812
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Key West design speed in knots

Post by Bill Edmundson » Mon Aug 13, 2018 9:46 am

Rick

The Key West at max weight and 300hp could run about 45 MPH or 39 knots. You said 1:1, I don't know your WOT for that engine. About the max shaft RPM for a 12" dia.. prop is 4000. It's about 3700 for a 13" prop. After those numbers you start getting blade tip cavitation. You could go to a reduction gear and more pitch on the blade.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

rblevens
Posts: 36
Joined: Sun May 13, 2007 4:15 am
Location: Alton, IL

Re: Key West design speed in knots

Post by rblevens » Thu Aug 16, 2018 5:52 am

Thanks Bill- they say the design was 31 knots which seemed a bit slow- but I don't want it breaking up either... ?
What was your max weight number? (With people onboard)?

User avatar
Bill Edmundson
Posts: 11812
Joined: Wed Nov 23, 2005 6:45 am
Location: Birmingham, AL, USA
Contact:

Re: Key West design speed in knots

Post by Bill Edmundson » Thu Aug 16, 2018 6:05 am

Rick

I used the displacement weight. Displacement is the max. safe design weight of everything, the boat, people, gear, engine, fuel... Think it was 4000#.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Post Reply

Return to “Power Boats”