Ratio 1.3:
3/4= 0.75
1/0.75= 1.3

Ratio 1.5:
1/1,5 = 0.6 = 3/5

Spinning the engine over twice is actually 1 rpm. If you do that and is it exactly 1.5 that is your ratio

Aha okey, so it isnt 1,35:1?

is it 1,5:1?

With a single rotation of the engine, it is next to impossible to tell the difference. You need to mark the prop barrel at exactly 12 o'clock, rotate the engine 2 full revolutions and the mark should be at exactly 6 o'clock if it a 1.50. If the mark is at 4:30 ish, its a 1.36. You should do this with the spark plugs removed to make turning the engine over easier.

Thank you, I will test that.
The sparkplugs is already removed

I did 2 full revolutions on the engine with the propp exactly at 12 o’clock.

ended up like this.. not at 6 o’clock.
more like 4 o’clock..

That would indicate that it is a 1.36 ratio.

Thank you for the help.

and that is telling me that my theoretical propp slip is about 39,17%

Its a heavy older V bottom. The prop needs to go deeper

Okey, thank you for your help!

The funny thing is that some people here in Sweden, when I show them pictures and they look at my prop shaft height they say it looks fine.
That it should be no problem with the drive that high.. Even if I tell them its a non step heavy V-hull.

They say that I should look at my propeller instead and fix it because that could be the problem.. but maybe they dont really know what they talking about..?

So its really confusing