Selecting The Best Motor For A 10 Foot Fishing Boat
Selecting the correct Motor and Propeller for your boat is critical, since the motor and propeller must perform well during adverse weather conditions. My previous post was about Mercury's 2.5 hp motor. This particular motor has 2.5 BHP and 1.9 SHP. At full throttle, the propeller is rated at 4500 to 5500 RPM, and it weighs only 38 pounds.
My 10 foot fishing boat is a Displacement Hull, and it's estimated weight is 102 pounds, just making it car top-able. This along with a lightweight, 38 pound motor makes it very easy to take your boat and motor just about anywhere your car or truck will take you.
Determining the exact motor size you need is not an exact science. Your may must want to ask the dealer what size motor you need. This approach is really not the best unless the dealer has design information about your boat. Your best approach for selecting the best motor is to do a little research yourself; determine what motor size you feel will be best, and then contact a dealer and make your final selection.
My small 10 foot fishing boat has a displacement of 300 pounds. The boat will weigh approximately 100 pounds, leaving 200 pounds for boater, gear, and motor. This is more or less a personal use boat depending on your weight. Regulations in my area call for an adult to weight 160 pounds. The motor weighs 38 pounds, so the number look OK from this standpoint.
So now I am left with selecting the smallest (cheapest) motor and propeller possible. The Mercury 2.5 hp motor has a 6.5 inch prop, and is not interchangeable.
Visit http://www.youboat.net/boatPower3.aspx to follow the example below:
My 10 foot fishing boat has an LWL (length on the wateline) of 9'-4". Using a graph as a very simplified method for determining HP, the graph at YouBoat.net tells me about 2 HP will work in calm conditions. To this number, add 35% for adverse conditions. Adding 35% puts me at 2.7 HP, so the 2.5 HP motor is just shy of it's required value. Since all of this is not an exact science, I am going with the 2.5 HP motor; the next size up is the Mercury 3.5 HP motor, which costs more and weights more.
Next, you need to determine the propeller size. Propking is a nice program for this. Propking is a Microsoft Excel Spreadsheet program. If you have all your design information, enter the information into Propking, and the program will calculate the Minimum and Maximum size propeller your boat motor should use. For a displacement hull, you will normally want to go with the largest diameter propeller you can use.
The Mercury 2.5 HP motor has a 6.5 inch diameter propeller. Propking tells me that the smallest propeller I should use is 5 inches, and the largest/best propeller I should use is 7.6 inches. The 6.5 inch propeller falls into the midrange, so Mercury's 6.5 inch propeller should work well.
A very popular book for selecting the correct propeller is the :
Propeller Handbook : The Complete Reference for Choosing, Installing, and Understanding Boat Propellers
, written by David Gerr.
My 10 foot fishing boat is a Displacement Hull, and it's estimated weight is 102 pounds, just making it car top-able. This along with a lightweight, 38 pound motor makes it very easy to take your boat and motor just about anywhere your car or truck will take you.
Determining the exact motor size you need is not an exact science. Your may must want to ask the dealer what size motor you need. This approach is really not the best unless the dealer has design information about your boat. Your best approach for selecting the best motor is to do a little research yourself; determine what motor size you feel will be best, and then contact a dealer and make your final selection.
My small 10 foot fishing boat has a displacement of 300 pounds. The boat will weigh approximately 100 pounds, leaving 200 pounds for boater, gear, and motor. This is more or less a personal use boat depending on your weight. Regulations in my area call for an adult to weight 160 pounds. The motor weighs 38 pounds, so the number look OK from this standpoint.
So now I am left with selecting the smallest (cheapest) motor and propeller possible. The Mercury 2.5 hp motor has a 6.5 inch prop, and is not interchangeable.
Visit http://www.youboat.net/boatPower3.aspx to follow the example below:
My 10 foot fishing boat has an LWL (length on the wateline) of 9'-4". Using a graph as a very simplified method for determining HP, the graph at YouBoat.net tells me about 2 HP will work in calm conditions. To this number, add 35% for adverse conditions. Adding 35% puts me at 2.7 HP, so the 2.5 HP motor is just shy of it's required value. Since all of this is not an exact science, I am going with the 2.5 HP motor; the next size up is the Mercury 3.5 HP motor, which costs more and weights more.
Next, you need to determine the propeller size. Propking is a nice program for this. Propking is a Microsoft Excel Spreadsheet program. If you have all your design information, enter the information into Propking, and the program will calculate the Minimum and Maximum size propeller your boat motor should use. For a displacement hull, you will normally want to go with the largest diameter propeller you can use.
The Mercury 2.5 HP motor has a 6.5 inch diameter propeller. Propking tells me that the smallest propeller I should use is 5 inches, and the largest/best propeller I should use is 7.6 inches. The 6.5 inch propeller falls into the midrange, so Mercury's 6.5 inch propeller should work well.
A very popular book for selecting the correct propeller is the :
Propeller Handbook : The Complete Reference for Choosing, Installing, and Understanding Boat Propellers
, written by David Gerr.
posted by wayne@freeboatresources.com at
10:11 AM
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