78 115 Johnson SS prop?

singledoubt88

Seaman
Joined
Mar 29, 2010
Messages
61
What's up fellas,

Ok so heres what I'm workin with. I've got a 78 Johnson 115 model 115ml78c. It's a swapped powerhead on a 85 Evinrude with power TNT. The hull is a 1977 starcraft SS 16 footer. I've got the motor mounted on the first hole ( highest point out of the water) without ventiliation.

Right now I'm turning 5500 rpms WOT on an aluminum Solas Amita 13.25x17. I would like to switch to SS as my prop has some wear on it as far as little dings and scratches. I've heard that even at 5500 I might be lugging a bit.

Just trying to get an opinion from you guys on which pitch/ diameter I should go with in switching to stainless. I'd like more top speed if possible. Right now I'm pushing 41.5gps with an average load. What brands should I consider? Any advice on aftermarket versus an oem? Thanks in advance guys!
 

singledoubt88

Seaman
Joined
Mar 29, 2010
Messages
61
Re: 78 115 Johnson SS prop?

Some additional information I should have included in the first post.

The hull for those that are unfamiliar is an aluminum riveted vhull, which weighs around 700-800 lbs. It seems to be a little stern heavy as I've had some porpoising issues in the past which is why I had to raise the motor and this cured it, unless trimmed out way to far. Not sure how much this effects prop type, but I do know there are bow and stern lifting props. Also the aluminum prop I have on it now is a 3 blade. Hope this helps!
 

singledoubt88

Seaman
Joined
Mar 29, 2010
Messages
61
Re: 78 115 Johnson SS prop?

I probably wasn't to clear on what my actual questions were so, give the info above...

1.) if I'm currently at 5500 what pitch in SS should I try out to achieve 5800 rpms?
2.) what brands should I look at?
3.) is there any benefit of a vented or raked prop in my application?
4.) the current prop diameter is a 13 1/4 any need for change?


Thanks
 

trdan

Recruit
Joined
Jan 24, 2011
Messages
3
Re: 78 115 Johnson SS prop?

Hi, not meaning to hijack your thread, but I have a similar situation and have nearly the same questions. I have 74 Evinrude 85 on a 74 17 foot Fabuglas trihull. I am also running a solas anita 13 1/4 by 17. All I can find is the hull weighs around 1000 lbs. The boat has a great hole shot and will run 42 gps at 5400 rpm. I too am looking for maybe another 3 or 400 rpm. Question is should I go to a 15 inch pitch solas or maybe go with a 17 inch omcSST. Haven't really tried any other props. Will be interesting to see what you find out
Oh, also I am running on the second hole from the top for mounting height and I don't have power trim.
Dan
 
Top