The Noob Sailor
Recruit
- Joined
- Apr 11, 2017
- Messages
- 5
First thing first: Please take a look at this link, and take a note especially what the topic-starter JerryS writes:
http://forums.fishusa.com/m/tm.aspx?m=447315&p=1
I'm thinking of changing the propeller on my Mercury 4-stroke 20hp engine. After reading quite a bit on the Internet, I have decided to try out a Solas Amita 4 prop. I have been discussing a bit with fellow countrymen on a norwegian forum, some saying the 4-blade would cause to much drag, due to one extra blade. When reading the thread in the link above, I see that a 4-blade could work just fine on a 20hp motor, as long as the pitch is correct according to the boat weight and hull design. My boat is a Smartliner 170 aluminum boat (check Google pics) and is not a typical V-hull boat. Dry weight on the boat is 460 lbs, and me including gear and gas tank will be aprx 280 lbs. Comparing to JerryS's boat my boat is much easier on the motor, less hull drag I guess. The OEM 3 blade prop on the Mercury F20 is 9 1/2 x 10p. When reading JerryS's thread on the 4-blade topic, I convinced myself I should get an Amita 4, 9 1/2 x 8 prop, since I sometimes will bring wife and kids along on a boat trip, adding aprx 200 lbs weight. But since I mostly go fishing alone, I'm eager to find out if perhaps a 9 1/2 x 9 would be the best fit for the overall setup. Maybe the engine will over-rev and the limiter kicks in with a 8 pitch 4 blade... The latter propsize is also the pitch which is the rule of thumb when converting from 3 to 4 blades. I did check rpm with a tach with the OEM propeller, and it messured 6140 rpms WOT. Speed checked with gps; aprx 24 mph on calm seawater.
Anyone got a hunch which Solas Amita 4 prop would fit the boat and overall setup and use best? 9 1/2 x 8 or 9 1/2 x 9?
http://forums.fishusa.com/m/tm.aspx?m=447315&p=1
I'm thinking of changing the propeller on my Mercury 4-stroke 20hp engine. After reading quite a bit on the Internet, I have decided to try out a Solas Amita 4 prop. I have been discussing a bit with fellow countrymen on a norwegian forum, some saying the 4-blade would cause to much drag, due to one extra blade. When reading the thread in the link above, I see that a 4-blade could work just fine on a 20hp motor, as long as the pitch is correct according to the boat weight and hull design. My boat is a Smartliner 170 aluminum boat (check Google pics) and is not a typical V-hull boat. Dry weight on the boat is 460 lbs, and me including gear and gas tank will be aprx 280 lbs. Comparing to JerryS's boat my boat is much easier on the motor, less hull drag I guess. The OEM 3 blade prop on the Mercury F20 is 9 1/2 x 10p. When reading JerryS's thread on the 4-blade topic, I convinced myself I should get an Amita 4, 9 1/2 x 8 prop, since I sometimes will bring wife and kids along on a boat trip, adding aprx 200 lbs weight. But since I mostly go fishing alone, I'm eager to find out if perhaps a 9 1/2 x 9 would be the best fit for the overall setup. Maybe the engine will over-rev and the limiter kicks in with a 8 pitch 4 blade... The latter propsize is also the pitch which is the rule of thumb when converting from 3 to 4 blades. I did check rpm with a tach with the OEM propeller, and it messured 6140 rpms WOT. Speed checked with gps; aprx 24 mph on calm seawater.
Anyone got a hunch which Solas Amita 4 prop would fit the boat and overall setup and use best? 9 1/2 x 8 or 9 1/2 x 9?