|
|
Posts: 14
| I just bought a 2012 alumacraft trophy 175. has a 2012 Yamaha F115 motor. Prop size is - 13X19-K . The motor is mounted on the transom using the top holes on the motor. The boat runs 38 mph GPS speed at 5900 RPM's. Recommended prop shaft HP is 5800 RPM's. Full throttle RPM's range is 5300-6300. This is according to Yamaha owners manual. I would like to know if the prop that is on it now (13X19-K) is the correct prop.. I thought I would be able to get more speed than 38 mph. I had a friend run the boat with me today to see if I was doing something wrong, but we both could only get 38 max speed, and he is a very seasoned boater. He suggested that I post on here and see if someone could help me out.
Am I running the correct prop? OR Is that pretty much the top speed I will get out of a 115hp.. Any help would be helpful. Thanks. Matt |
|
| |
|
Posts: 5874
| Is this a SS prop? |
|
| |
|
Posts: 14
| No, it is not a Stainless Steel prop. |
|
| |
|
Posts: 5874
| OK, then I would suggest the best way to get better performance is to go to a SS prop, that you find works best on your boat/motor combination.
I'm not familiar with what Yamaha has to offer for props, but I would try to find a dealer that has a prop tryout program. Start with the same style and pitch prop you have now, and go from there.
I'm sure Steve(VMS) will have some good info for you.
Edited by Shep 5/21/2014 10:33 AM
|
|
| |
|
Posts: 162
Location: Metro, MN | I run a 2002 115 yamaha with a SS prop on a 17 foot crestliner and the max speed with nobody in the boat is 38-39, maybe 40 on a really lucky day.
It is the best motor Ive ever owned in terms of reliablilty, but not built for speed or holeshot. Never had one issue with it and it still fires like DAY 1.
Edited by MuskyKarma 5/21/2014 3:39 PM
|
|
| |
|
Posts: 558
| I have a 2011 Alumacraft navigator 175 with that exact motor and prop, I can get 42 to 44 mph by myself, but with 3 people and gear I can get 38 to 40 mph. What you said makes perfect sense because your boat is heavier than my boat. Your not doing anything wrong, that's probably the correct speed.
Edited by Musky Face 5/21/2014 8:09 PM
|
|
| |
|
Posts: 3508
Location: Elk River, Minnesota | Hiya,
I would bet when you are at highest trim and wide open throttle, the side spray is not very far behind the console?
With the motor flat on the transom and using an aluminum prop, I truly believe you can find more speed by changing to a steel prop and moving the motor up off the transom.
The Yamaha Pro Series in a 13-1/2 x 17 will be an excellent choice for your rig. It will do two things for you: First, it will actually act more like an 18 pitch prop because it is aggressively cupped, and being steel will flex quite a bit less than the stock white aluminum. Changing to this prop will be close to the same RPM level as you are running now with the motor on the transom. This is because switching to steel will drop your rpms by about 200, going to a larger diameter will drop the rpms another 200, but going to a 17 pitch will bring you back up 400 (200 for each inch in pitch).
Now...if you then raise the motor to the 3rd bolt hole up off the transom, you will be sitting right around 6000 rpm give or take.
With a guesstimated approximate 15% slip factor due to being higher off the transom, This would put your rig running right around 42 - 43 mph, which is right in the ballpark for that motor when you are loaded with just you and your gear.
Please keep in mind, these are just ballpark numbers as all boats will perform differently.
another prop to consider would be a michigan ballistic in a 13-5/8 x 17 as well..Very aggressive prop and would do well also.
I definitely think there is room to get a little more out of the boat... 40 is definitely possible...
Steve |
|
| |
|
Posts: 14
| Thanks for all your help guys... |
|
| |
|
| I have a tracker targa 175 with a merc 90 optimax and I get between 40-44 mph with myself and gear.
|
|
| |
|
Posts: 134
| Fish n ski, I run an '01 trophy 175 w/ 115 ficht. I just upgraded prop to 13 7/8 x 17 ss prop. I haven't had boat out not loaded with gear, people or fuel. I'm getting about 38-39 loaded at about 5400 rpm. I believe your beam is wider than mine so u may have a few more pounds of hull weight. My previous prop was a ss prop but diameter was closer to 12" and was cavitating like crazy, actual had burn on slag. Max speed win old prop was 36.3 at just over 6k rpm. Guy I bought boat from couldn't figure out why he couldn't keep the paint on the prop.
Trophy 175
115 ficht
T8
Terrova 80
3 batteries
56 lbs of anchors
|
|
| |
