30hp Johnson

R

rockbreaker

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Jun 16, 2008
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I have a 30hp johnson and it is mid 80`s.I just purchased it a month ago and it works ok but I thought it would have a faster top speed.It has a 10x15 prop on it now what recommendation for prop size should I have or is this the proper one.
 
tashasdaddy

tashasdaddy

Honorary Moderator Emeritus
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Nov 11, 2005
Messages
51,019
Re: 30hp Johnson

we need to know the wot rpms, what boat it is on. moving to props.
 
R

rockbreaker

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Jun 16, 2008
Messages
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Re: 30hp Johnson

It is on a 16ft aluminum fishing boat with no floor etc. and I do not know what wot rpm is thanks.
 
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steelespike

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Joined
Apr 26, 2002
Messages
19,069
Re: 30hp Johnson

rockbreaker said:
I have a 30hp johnson and it is mid 80`s.I just purchased it a month ago and it works ok but I thought it would have a faster top speed.It has a 10x15 prop on it now what recommendation for prop size should I have or is this the proper one.
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Your motor is rated for a little over 30 under ideal conditions.Your 16ft would no doubt be slower.I don't have the specs for an 80s motor but 15" pitch seems a lot to me.You shouldn't make any changes without rpm readings.A "Tiny Tach"is easy to install reasonable and will fit any 2cylinder without regard to stator poles.
As a starting point Your anti vent plate(just above the prop) should be even with the bottom of the boat.Might be able to raise higher.
The less motor in the water the better.Just be sure it pumps water. Wouldn't hurt to check the compression.
 
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