| Author |
Message |
    
Jim Hopple
Member
Username: jim_n_sc
Post Number: 4
Registered: 06-2008
| | Posted on Sunday, June 28, 2009 - 06:36 pm: | 
|
Let me first say I don't have a tach so I can't match RPS's to various props. There is a label on the foot above the prop with a 13 on it. Does that me that it came originally with a 13 pitch prop? |
ian summerfield
Member
Username: budgie14
Post Number: 27
Registered: 06-2009
| | Posted on Sunday, June 28, 2009 - 06:48 pm: |
|
Hi Jim,my only suggestion would be to get a PROPULSE prop,then u can adjust the pitch to suit your application,cheers |
Graham Lamb
Senior Member
Username: galamb
Post Number: 5487
Registered: 05-2007
| | Posted on Monday, June 29, 2009 - 01:52 am: |
|
It probably came with a 15 or 17 pitch from the dealer.
What kinda of boat do you have it on? how heavy? any estimate of your normal load weight?
Without a tach you will always have to "guess" - charts or prop calculators can get you close but they can not account for every variable.
I would expect an 80 horse on say 1000-1300 pound rig that normally carries 2 adults plus their junk for the day to be spinning a 17 pitch (give or take)... |
Jim Hopple
Member
Username: jim_n_sc
Post Number: 5
Registered: 06-2008
| | Posted on Monday, June 29, 2009 - 07:39 am: |
|
It is a 16' Starcraft aluminum boat. The boat loaded with me in it weighs about 1,000 lbs. It currently has a 19P prop on it. The boat run's about 35 mph wot. Seems to me a 1,000 lb boat with an 80hp should run closer to 40mph. |
Graham Lamb
Senior Member
Username: galamb
Post Number: 5490
Registered: 05-2007
| | Posted on Monday, June 29, 2009 - 11:59 am: |
|
Jim, that does sound a touch slow on that rig. That particular boat should max out at just a hair over 40 mph (the hull design won't allow it to go any faster no matter what you hang on the back).
Since you are running "light" with that motor you should be able to easily move up to a 21 pitch and squeeze out a couple more mph - however, without the tach there is really no way to easily determine if you are "underpropped" or perhaps the motor is not running at it's potential.
Maybe start by grabbing a can of Merc's "powertune" (sells for about 5 bucks) and just follow the directions on the spray can - gets carbon and other "cooties" out of the powerhead - you may just have a bit of a carbon problem robbing you of some top end performance (if the motor is running well otherwise). |
