1969 85hp Johnson Prop. question

[TSBoatman]

Hello again! Another thanks to all the previous help I rec'd on my last querry, you been great!
Now, I have finally got to the point where i'll be getting to the water soon but I have no idea which prop I should use. The original prop. that was on it when i got it is garbage which is a 13.25/17 i believe. I have this motor mounted on a 1972 Arrowglass Cobra trihull 15.9 ft with at any given time 2 ppl total with some fishing gear. I'm hoping I can get away with a good all around pitch and diameter for fishing with a descent load and maybe some water skiing if applicable (not as important). So my question is: "Any known dia./pitch sizes that anyone can reccommend??"

 

[TSBoatman]

Re: 1969 85hp Johnson Prop. question

SS or Alum.- either or if that helps.

 

[TSBoatman]

Re: 1969 85hp Johnson Prop. question

Is there anymore info. you need???

 

[JasonB]

Re: 1969 85hp Johnson Prop. question

Not sure what your boat weighs, but i have a '76 Glastron 16' tri-hull and a '76 Johnson 85hp. My "cruise" prop is a 13 1/4 x 17 cupped michigan wheel aluminum. I also keep a 13 1/4 x 15 cupped MI Wheel for pulling skiers on occasion. I tried a 13 3/4 x 17 or 19 and just couldn't turn it well. Not sure if this will translate into your situation well, but it gives you a similar combo to think about.

If it were mine, I would probably start with another 13 1/4 x 17 and go from there.

 

[TSBoatman]

Re: 1969 85hp Johnson Prop. question

YES! I think you have a very similar combo and that is just may be what i'm looking for thanks for the post!

Any other suggestions will be much appriciated!

Jason, what are your speeds in your situtations if you dont mind me asking?

 

[JasonB]

Re: 1969 85hp Johnson Prop. question

With full fishing load (2 tackle boxes, dozen rods, trolling battery, tmotor on bow, 15gal fuel, etc), I can get 36-38mph out of her. My hull is about 850lbs. Add another adult and I run about 35-36. Not a speed demon, but fast enough to fish.

With the 15,, speed isn't much different, but it winds a bit high. Holeshot is great though.

 

[TSBoatman]

Re: 1969 85hp Johnson Prop. question

Thanks Jason,I appricate you sticking with me on this .Thats exactly the info. I was looking for

 

[JasonB]

Re: 1969 85hp Johnson Prop. question

No problem. Good luck.

 

[Devonaaron]

Re: 1969 85hp Johnson Prop. question

I have a 16 foot glastron v16 stinger aqua lift. I have a 85hp johnson I have this big thick heavy cast prop no idea what its made out of some kind of iron or steel mixed with other alloys to prevent rust and corrosion. This was a random prop this guy gave me with the motor I think its to big and to high pitched for my boat. My question is I am going to be island hopping with this boat in the inter coastal water ways in FL going about 20-35 miles round trip and I need a prop where I can reach a good RPM that wont suck gas but will at leased take me 30MPH so i can get where i need at a reasonable pace. Do you think I should go with a 4 blade from what im reading im guessing I need something about a 17" pitch but I just rebuild them and fix them I have a good idea what I need but I dont have a tach on this motor due to its age and problem with finding a tach that will work off the voltage if anyone has any advice about that as well im all ears. Thank you so much keep in mind this is a very strong motor, good spark 130 compression carbs rebuilt everything perfect. I need to tune the low idle a bit but that will just take some tools and a day out on the water by myself. Im anxious to hear some ideas thank you

 

[steelespike]

Re: 1969 85hp Johnson Prop. question

Welcome,you should really create your own Thread its less confusing and you should get better results.
Typical prop on these motors is 13 3/4" X 17" Don't worry about exact diameter
but avoid excessively large props.Check out the tiny tach.Uses plug wire pulses.
Be sure to read all info. They have a web site.You definately need a tach.
Your 85 will use about 8.5 gallons per hour(GPH) at wide open throttle.(WOT)
Whether your pushing a runabout or a house boat.Of course it uses less at reduced throttle.A 4 blade prop probably a 16" will usually allow it to stay on plane better at reduced throttle.It will have a slightly lower top end.

 

[Devonaaron]

Re: 1969 85hp Johnson Prop. question

I have a glastron 16 foot trihull 1978 is the year. A very good boat I had a 1977 Hp Johnson pushed me about 34 mph with a 17 pitch thick stainless prop. Just bought a looper 120 Johnson and the prop that's on it is so bad I'm scared to run it to see but the looper has way more power I'm just not sure what pitch stainless high performance prop I should get also do anyone know anything about ballistic props vs stiletto

 

[Home Cookin']

Re: 1969 85hp Johnson Prop. question

are you sure you want a 120 on a 16' tri-hull, and on open water at that?