I_5320
Seaman
- Joined
- Jan 3, 2011
- Messages
- 59
Hello all,
Trying to zero in sizing my prop in completed Project Boat.. I?ve done some homework and some initial field testing.. Overall goal is hoping I can get this 50 hp to perform well enough to stick with it and not be tempted to up the HP.
Motor = 1980 Merc 50 HP Tiller (Canadian version if that makes a difference)
Boat Hull = 1985 Sylvan Super Sportster completely modified into fishing boat
Boat & Motor weight = 1,450 lbs.. Incudes everything on except fishing gear;
RPM Range = 5,000 -5,500
Gear Ratio = 1.83 (double checking this)
Weigh distribution = 12 Gal Gas tale in the Stern,, 3 Battery?s under fron deck platfom . ? plywood Deck
Current Prop = 10 3/8 X 14 3 blade Alum Merc
Prop condition = Blades look like they?ve been ground previously a bit and has lots of nicks.
Motor Height = Cavitation Plate 1 inch above bottom of hull. Was told this is just about right for this boat Appears not to be cavitating at all.
WOT Test = 4,950 RPM with me and 1 other 160lb passenger
Speed Test = No Speedometer and forgot about using GPS
Problem Symptom = Hard to plane with 4 persons.. Not as fast since I added all the crap.
Where I?m at:; = Bought a 10 3/8 X 12 Vortex 3 blade.. Was thinking to get close to 5,400 with me alone.
Questions.. Knowing how to rig up a shop tach now I can go it alone.
1 .Is goal to get as close to 5,500 RPMS as possible with just me and a light load?
2. Also ,I?ll be sure to check speed (with trim at optimum) when testing the 12 pitch.. Anything else I?m missing?
3. Last, is 10-11% slip considered good/normal? .If so is my math is right and the best I could expect with this motor/boat setup is about 30 MPH?
Mark
Trying to zero in sizing my prop in completed Project Boat.. I?ve done some homework and some initial field testing.. Overall goal is hoping I can get this 50 hp to perform well enough to stick with it and not be tempted to up the HP.
Motor = 1980 Merc 50 HP Tiller (Canadian version if that makes a difference)
Boat Hull = 1985 Sylvan Super Sportster completely modified into fishing boat
Boat & Motor weight = 1,450 lbs.. Incudes everything on except fishing gear;
RPM Range = 5,000 -5,500
Gear Ratio = 1.83 (double checking this)
Weigh distribution = 12 Gal Gas tale in the Stern,, 3 Battery?s under fron deck platfom . ? plywood Deck
Current Prop = 10 3/8 X 14 3 blade Alum Merc
Prop condition = Blades look like they?ve been ground previously a bit and has lots of nicks.
Motor Height = Cavitation Plate 1 inch above bottom of hull. Was told this is just about right for this boat Appears not to be cavitating at all.
WOT Test = 4,950 RPM with me and 1 other 160lb passenger
Speed Test = No Speedometer and forgot about using GPS
Problem Symptom = Hard to plane with 4 persons.. Not as fast since I added all the crap.
Where I?m at:; = Bought a 10 3/8 X 12 Vortex 3 blade.. Was thinking to get close to 5,400 with me alone.
Questions.. Knowing how to rig up a shop tach now I can go it alone.
1 .Is goal to get as close to 5,500 RPMS as possible with just me and a light load?
2. Also ,I?ll be sure to check speed (with trim at optimum) when testing the 12 pitch.. Anything else I?m missing?
3. Last, is 10-11% slip considered good/normal? .If so is my math is right and the best I could expect with this motor/boat setup is about 30 MPH?
Mark