prop calculator

[kapnD]

does anyone know of a prop calculator (online, preferably) that will allow a dummy like myself to experiment with variables and achieve reasonable figures?
Surfbaud is the only one I can find, and it doesnt seem to be working, or maybe it doesnt like my computer!
Im recessing the prop into a pocket, will this have any effect on my calculations?
mahalo, KapnD

[dougfrolich]

I would suggest the propeller handbook by Dave Gerr.

Doug Frolich

[ISLNDMRN]

This one always worked for me
http://www.boatramp.com/prop_applet/...erAppletG.html

SNAME (http;//www.sname.org) has a propeller program for sale called "PSOP".

Note also that the Bp-delta diagram in Gerr's book is for Waginengen B series props. Use of this data on segmental props (more typical of stock propellers) will tend to result in overpitching.

The SNAME program has both B and segmental series data.

[Dim]

Dear KapnD,

may be:

http://www.yosc.ukgateway.net/propcalc.xls , or

Good luck, Dim.

[Dim]

Has recollected, where for me to be the basic workbook.

Good luck, Dim.

http://www.surfbaud.co.uk/

http://www.surfbaud.co.uk/download.php?view.5

the surfprop has moved due to site and server changes, enjoy.

[lancingmike]

If you care to E-mail me a sample set of data:-
Total laden weight
Waterline length
Number of engines
HP
RPM
Gear reduction ratio

I will do you a sample calculation on my program which is available to buy.

[kapnD]

Wow, this is an old thread! I have learned a lot in the time since I first posted it, and have used lots of different prop calculators. To answer my own question, one of the best is on boatdiesel.com, and though it does require a paid membership to use it, is well worth the $25. There is a wealth of other information also, and a rich forum complete with resident gurus, much like this one. Don

[Brent Swain]

Skenes elements of Yacht design has a chart that I use for diameter. For pitch it is simple calculator math.A 12 inch pitch gives you one ft per rev. Multiply this by 60 and you have ft per minute, Multiply this by 60 and you have ft per hour . Divide this by the number of feet in a nautical mile and you have knots per hour .
Adjust for slippage ( around 50% for sailboats) and you have knots. Compare with other boats to find how many knots you can expect for your type of boat, and the same HP and you have what you are looking for . Divide by 12 , then multiply by 11 to find what you could expect from a 11 inch pitch , etc etc trial and error.
My book explains this, as well as measureing the pitch on any prop, and changing it, balancing a prop, etc.
Brent

[lancingmike]

There was a certain amount of cooperation between me and boatdiesel.com when his program was written, so I am well aware of it.
We use slightly different approaches to achieve the required results.