The right props help

[Seastoke]

Hi all the boat is coming out for its arse to be painted and last year noticed one of the props had a chip in it so i thought to replace them ,so the idea is can fit a different size or pitch to get more speed ,we are on shafts with perkins sabre 225 how do i know i have the right props any help would be grateful.r

 

[bigwow]

http://www.castlemarine.co.uk/pitch-calculator.php

 

[burgundyben]

What revs do you get full throttle?

 

[Seastoke]

What revs do you get full throttle?

HI i am not sure what top revs should be i think i get about 3k

 

[Bandit]

What is the boat?

You will need, engine spec, normal max RPM of engine, gear box ratio, weight of boat.

Speak to Clements marine http://www.clementsengineering.co.uk/stern-gear

 

[Seastoke]

ok the max revs should be 2500 i dont know what revs i was getting when o full throttle i suppose this is key to the answer ,but can changing props give you more speed or is it down to reaching max revs ,all weird to me

 

[Seastoke]

http://www.castlemarine.co.uk/pitch-calculator.php

wont let me down load

 

[Latestarter1]

ok the max revs should be 2500 i dont know what revs i was getting when o full throttle i suppose this is key to the answer ,but can changing props give you more speed or is it down to reaching max revs ,all weird to me

Just listen to burgundyben's voice of simple sense. Paul at Clements is in business and can be the source of trouble.

As a boat owner you have to be sure that your engines can make their rated speed plus droop when you are clean with half tanks, this a key piece of any sea trial.

Taking your Perkins Sabre 225's as a case. With sensible 40 degree fuel your engines are capable of developing about 195 hp at 2,500 rpm. In order that engines are not overloaded you HAVE to be to make 2,750 rpm i.e rated speed plus 10% governor droop, which represents about 80% engine load. This safety margin allows for increased propeller loading due to hull fouling during the season.

Simple rule of boating like is that you can never have all the potential power that your engines re capable of developing. Propeller is a brutal instrument treat it with respect, just remember failing to make rated speed by say 200 rpm depending on you propeller exponent could amount to your engines being overloaded by as much as 150%.

Just answer burgundyben's question and we can take take it from there.

 

[Seastoke]

Just listen to burgundyben's voice of simple sense. Paul at Clements is in business and can be the source of trouble.

As a boat owner you have to be sure that your engines can make their rated speed plus droop when you are clean with half tanks, this a key piece of any sea trial.

Taking your Perkins Sabre 225's as a case. With sensible 40 degree fuel your engines are capable of developing about 195 hp at 2,500 rpm. In order that engines are not overloaded you HAVE to be to make 2,750 rpm i.e rated speed plus 10% governor droop, which represents about 80% engine load. This safety margin allows for increased propeller loading due to hull fouling during the season.

Simple rule of boating like is that you can never have all the potential power that your engines re capable of developing. Propeller is a brutal instrument treat it with respect, just remember failing to make rated speed by say 200 rpm depending on you propeller exponent could amount to your engines being overloaded by as much as 150%.

Just answer burgundyben's question and we can take take it from there.

thanks looks like i will have to take the boat out before i can answer honestly

 

[omega2]

Just listen to burgundyben's voice of simple sense. Paul at Clements is in business and can be the source of trouble.

As a boat owner you have to be sure that your engines can make their rated speed plus droop when you are clean with half tanks, this a key piece of any sea trial.

Taking your Perkins Sabre 225's as a case. With sensible 40 degree fuel your engines are capable of developing about 195 hp at 2,500 rpm. In order that engines are not overloaded you HAVE to be to make 2,750 rpm i.e rated speed plus 10% governor droop, which represents about 80% engine load. This safety margin allows for increased propeller loading due to hull fouling during the season.

Simple rule of boating like is that you can never have all the potential power that your engines re capable of developing. Propeller is a brutal instrument treat it with respect, just remember failing to make rated speed by say 200 rpm depending on you propeller exponent could amount to your engines being overloaded by as much as 150%.

Just answer burgundyben's question and we can take take it from there.

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