Propeller Calculator

dimitris · 03 May 2003, 16:13

I've found a (theoretically) nice calculator for calculating a number of parameters about your propeller.

Have a look at http://go-fast.com/Prop_Slip_Calculator.htm

Regards

Dimitris

-<=[Tw18]=>- · 03 May 2003, 21:23

nice find sir

here is one that was pointed out in another thread, a bit simpler

http://ribs.loughlin.tv/propeller/default.asp

Alex Brown · 03 May 2003, 22:31

ok then from the first link, assuming a prop slip of 10% which I guess is what most people work on, then with 21" prop on my engine, 2.38 ratio, running at 46mph, my engine should be revving to 6104 revs.

However, at that speed, my engine is actually revving just under 5800rpm...... do I take it that I don't have much prop slip, or is the tacho likely to be slightly out, or is there something else that I'm missing here? - I can't quite get my head round this one

-Alex

Manos · 03 May 2003, 22:49

-<=[Tw18]=>- yours makes more sence!! and have to say is VERY ACCURATE!! gives me the same speed as I get with the current prop that I have on the boat
Now I know what to do with the prop!!! I was just getting very confused

jwalker · 03 May 2003, 23:17

Oops, sorry.

dimitris · 04 May 2003, 19:02

They both worked fine for me.

They calculated my speed with only one mile difference .
The first one calculated 1 mile less than my tachometer, while the second one exaclty what my tachometer reads.

According to them I don't have a propeller slip !!!

Manos · 04 May 2003, 19:11

Dimitri
may be is me. I have been trying all these prop calc programs for years. Never got the correct answer. The one which gave the correct answer was TW18s.
Was never good with math so may be the secret lies there LOLOL

Any way, will be in Greece next Friday, shall we have a bash on the boat the coming weekend?? Possibly you can bring yours too in Sounion (weather permiting but as I hear weather is WONDERFUL RIGHT NOW)

Dirk Diggler · 04 May 2003, 19:33

Quote:

Originally posted by dimitris

According to them I don't have a propeller slip !!!

Then you are doing something wrong!!

Manos · 05 May 2003, 20:06

Quote:

Originally posted by dimitris
According to them I don't have a propeller slip !!!

IMPOSSIBLE

Daniel · 05 May 2003, 20:11

Anyone know the gearbox ratio for my Yam v4 grarbox?

Pete7 · 05 May 2003, 20:32

Daniel, think you need to send Rene an e mail. He has a 115 / 130 manual but has changed his engine recently, so it might be up for grabs. From memory I think its 13/26 though why they quote it like that I don't know.

Pete

jwalker · 06 May 2003, 00:10

13 teeth on one gear and 26 on the other - 2:1

JW.