Three props for a '56 15hp Johnson

[tjandrews]

I have a '56 15hp johnson that was given to me a couple of years ago. I thought I had it ready to go, but found that it needed a new clutch dog to stay in gear, and I also replaced the gearset with one from a '58 Gale-made 12hp Sea King.

Now I have three props to use on this motor. It came with a 9x8 weedless prop, which from what I read is pretty doggone light in pitch, but he told me that he used to use it to pull rafts, so I guess he needed it. I'll be using it on a relatively lightweight 14 ft. aluminum boat with a semi-v hull, most of the time carrying just 225-lb. me and gear, but occasionally with another guy in the front. I'll be on the St. Lawrence River, most of the time motoring upstream and drift-fishing back downstream, if that makes any difference.

I also have a 9x11 weedless prop from the Sea King, and a 9 1/4x11 "standard" prop I picked up on eBay. I don't have a tach. I intend to use one of these props, and not buy yet another, if at all possible.

I'm thinking the 9x11 weedless is best as a first choice to try. What about you guys?

 

[steelespike]

Re: Three props for a '56 15hp Johnson

I used to boat on the St Lawrence and when I was a kid we had 55 10 Johnson on a 14 Crestliner aluminum.To the best of my knowledge it had the stock weedless 9 X8 It planed pretty easily with us 2 100 pounders on the stern seat.Your 15 should do really well with the load balanced well.
Its rated for speeds around 25.
I think the 9 X 11 standard should produce the most speed.Borrow a GPS and try them all out.
The 9 X 8 will surely over rev.

 

[tjandrews]

Re: Three props for a '56 15hp Johnson

I used to boat on the St Lawrence and when I was a kid we had 55 10 Johnson on a 14 Crestliner aluminum.To the best of my knowledge it had the stock weedless 9 X8 It planed pretty easily with us 2 100 pounders on the stern seat.Your 15 should do really well with the load balanced well.
Its rated for speeds around 25.
I think the 9 X 11 standard should produce the most speed.Borrow a GPS and try them all out.
The 9 X 8 will surely over rev.

That's what I was thinking about the 9x8. We also have a '54 10hp Johnson on a 13 ft Feathercraft. The original prop was damaged, but I thought I had it repaired. It lasted less than a day, but it was enough to tell me how it SHOULD run on that boat. I tried replacing it with the 9x11 from the Sea King, but that was much too heavy for it. Worked just OK with just me, and really bogged down with a passenger. Went to the local dealer (Schermerhorn) and the guy there sold me a 9x7. MUCH better. I'm thinking a better use for the 9x8 that came with the 15 is as a backup for the 10hp.

 

[tjandrews]

Re: Three props for a '56 15hp Johnson

I used to boat on the St Lawrence and when I was a kid we had 55 10 Johnson on a 14 Crestliner aluminum.To the best of my knowledge it had the stock weedless 9 X8 It planed pretty easily with us 2 100 pounders on the stern seat.Your 15 should do really well with the load balanced well.
Its rated for speeds around 25.
.

Forgot to mention... Yeah, I know about load balance. I used to have a constant fishing partner (my mother) up in the front seat. With her up there and me, the 9.5, and the fuel tank in the back, the load was balanced just about right. But she's been gone for two years now - or at least if she's with me she doesn't provide any ballast. The stern now is way too low in the water the way things were arranged before. I put an extension on the fuel line and moved the tank to the front, and that helped a lot. But the 15 is a LOT heavier than the 9.5, so I'll probably have to add even more weight to the front. That, or leave my tackle box inside.

Or go on a crash diet. Know a good way to lose 50 pounds in three days?

 

[tjandrews]

Re: Three props for a '56 15hp Johnson

I used to boat on the St Lawrence and when I was a kid we had 55 10 Johnson on a 14 Crestliner aluminum.To the best of my knowledge it had the stock weedless 9 X8 It planed pretty easily with us 2 100 pounders on the stern seat.Your 15 should do really well with the load balanced well.
Its rated for speeds around 25.
I think the 9 X 11 standard should produce the most speed.Borrow a GPS and try them all out.
The 9 X 8 will surely over rev.

Back from vacation, and once I got the trim and tilt worked out, the 9.25 x 11 worked great. I didn't get a GPS, so I went old school. Using a wristwatch and a USGS map scale-of-miles, I determined that on one 4.5-mile run I averaged about 19-20mph. Less than the 25, but I was going against the current into a headwind that was supposed to be close to 10 knots, so I don't think it's bad at all.