70 horse johnson on 17 ft glassmaster trihaul

[rdischar]

i was just wondering what kind of prop yall think would give me the highest top end speeds but also be good for the motor?<br />thanks <br />russell james

 

[Dhadley]

Re: 70 horse johnson on 17 ft glassmaster trihaul

The one that allows 6000 rpm with an average load and about 10% slip. <br /><br />What have you tried so far?

 

[rdischar]

Re: 70 horse johnson on 17 ft glassmaster trihaul

i dont know what is on there right now. this is the first boat ive ever owned. its a 61 glassmaster trihaul with a 1982 70 horse johnson, i have a manual for the johnson but it does not say what kinda prop to use just tells all about pitch, diameter and # of blades. i cant really make much outta it all except that the pitch is how far the prop should move in one rev, and that i should expect 10-20 % slip. i cant find what the wot rpms should be.

 

[ob]

Re: 70 horse johnson on 17 ft glassmaster trihaul

rdischar, As dhadley states for your particular motor , select a prop that will allow your motor to rap out to 6000 at WOT.I would recommend that you use an OMC brand prop as they are designed for the torque curves of your motor.A prop of 13 3/4 X 15" would be a good starting point for rig of your size.Your motors recommended WOT rpm range is 5500-6000.Find out what prop you currently have and post back.

 

[rickdb1boat]

Re: 70 horse johnson on 17 ft glassmaster trihaul

web page

 

[rdischar]

Re: 70 horse johnson on 17 ft glassmaster trihaul

my prop is currently 13 1/4 x 17 i am planning on buying a tach when i get paid. i have a performance tach out of an old car is there anyway i could hook it up to my johnson.

 

[Jim@KSC]

Re: 70 horse johnson on 17 ft glassmaster trihaul

rdischar -<br /><br />OB turned me on to tinytach. If you use the boat in Florida (salt everywhere) an automotive tach won't last long.<br /><br />Tinytach is solid state, and under $40.<br /><br />jim