Glen-L.com

A-Lure 1.50 gear ratio, using displacement as weight 6450lbs, 5.7L carb chev lets say 230 HP which prop would you recommend I start with. Running an alpha outdrive. I would like to go with a three blade , 25mph is plenty fast enough for me but occasionally 30mph depending on sea state. Do not know enough to choose and all thes calc thingys gives me too many choices

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) Champagne dreams and wishes are possible on a beer budget. Just build the boat.
Nice curves are easy on the eyes.
Go sell crazy somewhere else we're all stocked up here."As Good As It Gets" Jack Nicholson.

Solo

What is your max RPM and cruising weight? (Boat's not your's. I know Vida will feed you well. If you can catch it!) I'll try to do a calc. for you in the morning.

Bill

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

http://www.arnesonconsulting.com/Prop.htm This will give you a general pitch, diameter to RPM ratio. Weight and hull displacement will determine the rest. I have a 1:5 ratio paragon vdrive trying to figure how steep of a prop also. Take Care Bill

Bill I figured that my displacement weight + another 1000 lbs would be about my max unless I caught a 200lb tuna. Max RPM lets say 4000. Bill I am just looking for something to get started then when I post performance numbers the Gurus will help dial it in ie Gurus on this forum some that started out as amateurs but have now mastered their craft and can point me in the right direction.

_________________
) Champagne dreams and wishes are possible on a beer budget. Just build the boat.
Nice curves are easy on the eyes.
Go sell crazy somewhere else we're all stocked up here."As Good As It Gets" Jack Nicholson.

Solo

You should be able to rearch about 33 mph at displacement weigh. Displacement already includes You and the tuna. Wt./HP= 28 Shaft rpm 4000/1.5= 2667. With a 15% slip you'll need a 15" pitch. My guess is 15X15 or 16x15 prop.

What diameter prop do the plan reccomend?

Bill

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

Solo,you are using an I/O aren't you?

The factory would probably have some recommendations of some sort to start

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

We've input your numbers into our Gearing and propeller sizing calculator.

Here's your spreadsheet :

Solo's Excel Spreadsheet

Your input data is displayed in the spreadsheet's BLUE cells. Computed values are displayed in GREEN or YELLOW cells. Feel free to correct any faulty input values !
Click on the worksheet tabs at the bottom of the screen to see more data (Theoretical Speed Table, Diameter-HP-RPM Formula etc.).

Spreadsheet Recommendations :

• A 15x16p for general use or a 14x18p for maximum speed
• With 10% slip, approximate maximum attainable speed is 32 MPH @ 3800 RPM. Click on the Speed Table worksheet tab at the bottom of the spreadsheet to see more Slip Data.
• Cruise speed at engine peak torque (358 ft/lbs @ 3200 RPM) = 27 MPH.

Glen-L's A-lure Speed/power Chart estimates 31 MPH for 230 SHP.

Hope this helps !

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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

the correct way to size your prop is by WOT throttle RPM. When your prop makes the engine get wide-open correct RPM then you got the right prop. Whatever boat speed you get is a product of your engine/boat combination.

Most plain vanilla V-8's run approx 4400rpm WOT.

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God Bless our Troops; especially our Snipers

Thanks Guys I really do appreciate the effort . I am building a boat but have absolutely no experience with power boats I have never driven one and except for brief forays at the gathering the only power boats I have been on are the sport fishing boats in SoCal.the smallest of which was a45ft displacement hull.So things like WOT and the knowledge to understand what happens when any why is only theory to me and mostly foggy at best. Warren may relate as a guy who drives Big Rigs he can tool down the hi-way without looking at his tach to know when to shift I would be looking for the little green arrow on the dash that says shift. I understand what porpoising is but I have never experienced it. Were it not for this Forum I would be at the mercy of boat sales and service dept. I have learnt a lot from all here. Hoping to Splash in June by then I should have garnered enough info so it wont be a sink or swim proposition but smart boating. Again thank you.

_________________
) Champagne dreams and wishes are possible on a beer budget. Just build the boat.
Nice curves are easy on the eyes.
Go sell crazy somewhere else we're all stocked up here."As Good As It Gets" Jack Nicholson.

Solo:
How is it going?
Havent heard from your build in a long time.
What's up?

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God Bless our Troops; especially our Snipers

well almost a year later I got me a 15.25 X15 Al prop I figured it would at least get me in the ball park,the problem now is trying to determine the style of zinc to bolt on just above the prop. the one that looks like a fin which I am told also helps with how the boat tracks is really close to the prop, there is less than 1/8" clearance between the prop tip and the anode.Is that too close ? My other option is to get a flat anode. What are your thoughts. I have not set a splash date but I am hoping for early Spring.

_________________
) Champagne dreams and wishes are possible on a beer budget. Just build the boat.
Nice curves are easy on the eyes.
Go sell crazy somewhere else we're all stocked up here."As Good As It Gets" Jack Nicholson.

I want to see that boat in the water, My friend

Bill

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

Solo, what out drive are you using?

If it's a MerCruiser, there is a smaller swept-back trim tab that'll clear bigger props

The second one listed as high performance:

http://marineengineparts.com/shopsite_s ... age46.html

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

Thanks Warren Would not have thought that this existed wereit not for you I might have run into it eventually but now I can go shopping

_________________
) Champagne dreams and wishes are possible on a beer budget. Just build the boat.
Nice curves are easy on the eyes.
Go sell crazy somewhere else we're all stocked up here."As Good As It Gets" Jack Nicholson.

Not sure, but I think I bought one from West Marine in the past.....I know I bought one somewhere!!!

_________________
Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream