How to calculate maximum horsepower for a boat

Length 12 Transom width 46 Tiller steering and 15 transom height. Boats powered by outboards.

To use this method of finding horsepower your boat must be.

How to calculate maximum horsepower for a boat. 22 rows Use this Boat Horsepower Calculator to estimate the power required to efficiently move your. There are two different ways the federal government uses to determine the maximum horsepower for any given boat one is a computation and the other is a performance test. The way that is used depends on the boat.

For the majority the computation method is best to use. You multiply your boat length by the transom width. Boat length x boat width boat square footage.

First find out the square footage of your boat by multiplying its length by the width of the transom. Then use our calculator and the table here to find out your boats maximum horsepower. Length x Transom Width X 2-90 HP 195 X 70 X 2 - 90 273 - 90 183 136 KW Horsepower 185 138 KW Example 2.

Length 12 Transom width 46 Tiller steering and 15 transom height. Length x transom Width 4596 Horsepower from table 10. Your boats capacity plate will include the following information.

The maximum passenger weight in lbs and the equivalent number of adult passengers. The total maximum weight in lbs including the gear the engine and the total number of persons or the total amount of passenger weight. The recommended maximum horsepower capacity.

To use this method of finding horsepower your boat must be. 13 feet or less in length. Minimum 19 inch transom height or.

For boats with a motor well height of at least 19 inches a 15 inch transom height. Maximum persons capacity of 2 or less. Horsepower only has to do with engine weight.

If you put too big an engine on a boat you throw the flotation off Last the manufacturers set the Coast Guard capacity maximum which they reach using an accepted formula and they also determine the horsepower since they know how much engine weight will still allow their boat to float level. The total maximum weight in lbs including the gear the engine and the total number of persons or the total amount of passenger weight. The recommended maximum horsepower capacity.

Person Capacity Some capacity plates will tell you the maximum number of people that can safely be carried on your boat. Use this information as a guideline only. A rough estimate of horsepower for displacement type hulls is fairly simple.

Maximum hull speed in knots is equal to about 13 X the square root of the waterline length of the hull in feet. The manufacturer should be following federal guidelines to determine the maximum horsepower capacity and that number should be listed for you on the boat. Any powerboat thats less than 20 feet in length is required to have that capacity plate available for you.

Its a straightforward calculation that can be done in horsepower per pound or vice versa. For example lets take a 5000-pound boat powered by a 300 hp engine. The power-to-weight ratio is calculated by dividing 300 by 5000 for 006 hp per pound.

Or swap the formula divide 5000 by 300 and it would be 166 pounds per hp. Starting with the boats LWL from the graph you determine the boats C-value. You then calculate the predicted speed by using the formula.

Speed kn C SqrtBHPdisplacement Once again all this is valid for high speed planing hulls speedlength ratio 3 or. Use a calculator if there are several passengers to multiply the top horsepower rating by 110. If the plate says a 120 horsepower engine is the largest you should use then.

120 x 11 132 or a 130 horse motor since the horsepower of outboard motors is rated in multiples of 10. A displacement boats propeller has to pump a mass of water equal to the displacement of the boat each time the boat advances one waterline length. So the HP to displacement ratio makes sense.

Dave Gerr in a recent. For any outboard-powered boat over 20 feet in length the maximum horsepower rating is essentially at the discretion of the boat builder. If the boat is less than 20 feet long the power rating is determined by a formula.

For remote-steering boats the formula is. Stern width in decimal feet x length in decimal feet x 2 90 max. The calculator below uses the above formula.

Plug in your info and click Calculate on the item you want to compute. By using known values for the weight power and speed you can come up with a more accurate constant for your boat. You can then see what effect changes to.

H 134 L M H 11508 N H 1852 Where H Hull Speed in Knots M Hull Speed in MilesHr N Hull Speed in KilometersHr L Boats Waterline Length. It is otherwise called as displacement speed is the speed at which the wavelength of the bow wave wave formed at the bow of the ship or boat when it travels in. 115hp has become the starting point for horsepower and can be a very suitable boat for lots of boaters.

150-175hp choice is a great all-around pontoon and can truly be a versatile do it all boat. 200hp is the way to go if you have a need for speed and want the best performance out of your pontoon. Also while many engines have fuel flow readouts the ability to estimate fuel burn while shopping for a boat or engine is important.

You measure fuel efficiency in pounds of fuel used per horsepower developed per hour. The pros call it brake-specific fuel consumption. The true speed of the boat taken at the same throttle setting.

45 MPH The Gear Ratio between the engine and the prop shaft. 21 The Pitch of the propeller measured in inches. 19 Pitch First you calculate the theoretical speed of the boat by using the following formula with your calculator.

Boats powered by outboards. The maximum persons capacity in pounds and maximum weight capacity persons motor and gear in pounds and maximum horsepower capacity. Boats powered by inboards and stern drives.

The maximum persons capacity in pounds and maximum weight capacity persons and gear. The Coast Guard Safe Powering Standard does not apply to inboards stern drives etc.