shetland536
Well-Known Member
i want to know the pitch of a prop that has no visible numbers, how do i find out what the pitch is.
ta
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measure pitch
- Thread starter shetland536
- Start date
jfm
Well-Known Member
Very tricky. You could put it in a lathe or on a jig and rotate it a precise number of degrees, say 30 or 60dg. Then use a dial test indicator or engineer's slidey ruler magnetic base measuring kit with the prodder resting on one of the blades and measure the displacement of the dti. Then multiply by 12 (if you rotated it 30deg) to get pitch. I think prop specialists have pitch gauges, set square things that measure blade angle, but I've never seen them for sale. If you're near Wimbledon ask Steel Developments, they know everything about props
BarryH
Well-Known Member
What engine is it off? Most if not all will have the dia x pitch on the hub somewhere.
shetland536
Well-Known Member
the engine is a mercury 70 1978. the prop on the boat at the moment has no numbers that i can see,i have the old engine(the same)behind my garage in bits with a manked prop,this engine was on the boat before i brought it,now then,the one on the boat at the moment is very pitted and blunt and could do with replacing, the one behind the garage looks like it has a courser pitch,i am not happy with the way the boat performs,very hard to get planning if at all.
i am trying to cover all possible equations.
whats really bugging me is when i brought it i was taken out in it and it planned really well,the only thing i have done to it is put the trim wing hydro wing things on from the old engine.
i know what i mean and i`m completly stumped.
and to cap it off i had a boat pass me that was the same but had an old 50hp and we were flat out,struggling.
i dunno
i am trying to cover all possible equations.
whats really bugging me is when i brought it i was taken out in it and it planned really well,the only thing i have done to it is put the trim wing hydro wing things on from the old engine.
i know what i mean and i`m completly stumped.
and to cap it off i had a boat pass me that was the same but had an old 50hp and we were flat out,struggling.
i dunno
Col
Well-Known Member
Have you tried adjusting the trim a bit?
PCUK
Well-Known Member
Pitch measurement is easy.
Put the prop on a flat surface. Measure the height of the leading and trailing edges of one blade from the surface. Then measure the angle from the centre of the leading and trailing edges to give the angle between the two.
If it was (for example 60 degrees) it would move forward six times the difference between leading and trailing edges in every revolution. (Excluding slip which isn't taken into account when measuring pitch)
Put the prop on a flat surface. Measure the height of the leading and trailing edges of one blade from the surface. Then measure the angle from the centre of the leading and trailing edges to give the angle between the two.
If it was (for example 60 degrees) it would move forward six times the difference between leading and trailing edges in every revolution. (Excluding slip which isn't taken into account when measuring pitch)
shetland536
Well-Known Member
god! some of you are too brainy."pitch measurement is easy" i`m a bloody printer not a mathamatician,mathmatision,maths person.
i cant alter the trim unless i alter the engine trim which seems to work best without the manual tilt adjustment bar in at all.( right down).
working 12 hour days at the mo so if i get time at the weekend i`ll have a go at the pitch measurement.will an old school pertracter do for finding the angle?
i cant alter the trim unless i alter the engine trim which seems to work best without the manual tilt adjustment bar in at all.( right down).
working 12 hour days at the mo so if i get time at the weekend i`ll have a go at the pitch measurement.will an old school pertracter do for finding the angle?