8o's 15 hp Johnson

[FLBert]

I have a johnson 15 hp from the 80.s Not sure of what year cause all the numbers have faded. (just got closer to the year 87-90).The numbers on my prop are bss 49174. What do they mean? I want to switch to an Amita Aluminum Propeller (2111-093-07) 4 bladed 9-1/4 " with a 7" pitch. Will it fit? My prop is a 13 spline throuhg hub exhuast.

 

[steelespike]

Re: 8o's 15 hp Johnson

Number indicates it will fit.
What are you trying to accomplish?Prop you describe is for a pontoon or other difficult to move boat.A Turning point Rascal will give close to Stainless
performance at aluminum prices.

 

[FLBert]

Re: 8o's 15 hp Johnson

The boat is a 12' hull Skift type. I put in a wood floor and stringers. Which added about 60 lbs. It's slow out of the hole and rides low on a plane. What I am really looking for is more top end speed and less vibration in the motor.I can get 18 Knots out of it now. Before I put in the floor I could get 25 Knotts out of her with three people, but I only had PVC bench seats in it then. I do not know what my RMP's are as I don't have a guage set up yet

One thing I found out today is that my transom is waterlogged, Ugghhh!

In the next two months I am planing on re-do the whole inside which may make it lighter or heavyer depending on the material I use.

Thanks,
FLBert

 

[steelespike]

Re: 8o's 15 hp Johnson

When you start adding weight to a small boat/motor it has a big effect on speed.
A 4 blade will give a better hole shot and better low speed operation.
Generally will reduce top end. The Turning Point Rascal will help you.
Stainless performance at aluminum prices.Really can't suggest a size without present prop size(prop shop can measure)rpm.and speed. A tinytach is reasonable easy to install.
If it was mine to do I would get a nice big aluminum 14 (a full size 14)And if you do any modification weight is the primary concern.A big 14 will get up better with a load.and feel like a ocean liner compared to your little 12.
If your boat is glass and you have a water logged transom better check
other parts of the boat.
If your redoing the boat I would trim as much weight as possible and still maintain strength. When redoing the transom rig it so you can adjust the height of the motor Raising the motor can help hole shot and top end especially if motor is lower than needed now.Most applications the anti vent(cavitation)plate even with the bottom is considered a starting point.

 

[FLBert]

Re: 8o's 15 hp Johnson

Thank you Steelespkie for your imput. After looking into the Turning Point prop. I have at agree with you. I went to their web site and they suggested a 9x9 R4-0909 with a #202 hub unit. Can't upgrade the boat at this time, better half and all that, if you know what I maen.

Thanks for your help,
FLBert