Big Prop vs Little Prop

codhw

codhw

Well-known member
advice and guidance from the experts would be much appreciated.:confused: I have an Enfield 130 Z drive pushing my 23ft boat the trouble is I cant get above 1800 revs, subsequently Im only getting between 6 to 8 knotts. Ive been told to downsize the prop as its not the engine size causing the propblem. My boat currently has a 11inch prop on it Ive been told if I down size the prop that this would increase the revs and perhaps get her backside up out of the water and increase her speed. This mail is two questions really 1 do you agree with the advice? 2 anyone know where I can get hold of a smaller prop for and enfield 130 z drive? (ive been looking on ebay with no success).:question::question:
 
Last edited:
codhw said:
advice and guidance from the experts would be much appreciated.:confused: I have an Enfield 130 Z drive pushing my 23ft boat the trouble is I cant get above 1800 revs, subsequently Im only getting between 6 to 8 knotts. Ive been told to downsize the prop as its not the engine size causing the propblem. My boat currently has a 11inch prop on it Ive been told if I down size the prop that this would increase the revs and perhaps get her backside up out of the water and increase her speed. This mail is two questions really 1 do you agree with the advice? 2 anyone know where I can get hold of a smaller prop for and enfield 130 z drive? (ive been looking on ebay with no success).:question::question:
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might be the prop pitch rather than the diameter, 11" is quite a small prop but it might have a very steep pitch

to work it out accurately, need to know max revs the engine is rated for, the gearbox ratio and the HP of the motor

as a general rule of thumb
every extra inch of pitch cuts engine revs by about 225rpm and every inch of diameter looses about 200rpm

a bigger prop delivers more torque, so a bigger prop with less pitch is better

without knowing any more details I'd say a 13" prop, maybe 15" pitch, but need more info

plenty place that sell props, but they ain't cheap, but is an investement that will pay itself back quickly as yopur probably burning more fuel than you need to as well, so propped right you'll go faster and burn less

what boat is it as well?? hull shape can make a huge difference,
 
sorry for the delay in replying, just got back from watching the darts at the marina....i have 2 12x11 props and 2 13x11 props, your more welcome to try them to see if it makes any difference to your boat, also have some doel fins
 
Thanks all for the advice its really appreciated. boblydon could I get back to you with your kind offer as I will need to check what props we have already tried. Once again lads thanks alot. :thumbup:
 
read it yesterday and was going to reply, but then started reading a different thread and forgot, you can try them as soon as you like, either collect from royal quays or wallsend whenever is good for you

bob
 
hi bob I could come across this Saturday around 12ish how do I contact you? if you could ring me on my mobile we could sort the time etc
 

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