Boat builders share an old rule of thumb for sailboats. The maximum speed ๐พ in

knots is 1.35 times the square root of the length ๐ฟ in feet of the boatโ€™s waterline. If a customer is planning
on ordering a sailboat with a maximum speed of 8 knots how long should the waterline be? How much
longer would the waterline have to be to achieve a maximum speed of 10 knots?

Robin/Jill/Bill/Vince -- please use the same name for your posts.

Jim -- not Jill

I am only Bill and Vince not the other ones

Thanks for not answer my question though :) really appreciate it

To determine the length of the waterline needed for a sailboat with a maximum speed of 8 knots, we can use the formula provided: ๐พ = 1.35โˆš๐ฟ.

1. Let's substitute the given maximum speed of 8 knots into the formula:
8 = 1.35โˆš๐ฟ

2. Now, we can solve for ๐ฟ by isolating the square root term:
โˆš๐ฟ = 8 / 1.35

3. Simplifying the right side of the equation:
โˆš๐ฟ โ‰ˆ 5.9259

4. Squaring both sides to isolate ๐ฟ:
๐ฟ โ‰ˆ (5.9259)^2
๐ฟ โ‰ˆ 35.0571

So, the waterline length of the sailboat should be approximately 35.0571 feet to achieve a maximum speed of 8 knots.

Next, let's find out how much longer the waterline would have to be to achieve a maximum speed of 10 knots:

1. We'll use the same formula: ๐พ = 1.35โˆš๐ฟ.

2. Substitute the new maximum speed of 10 knots into the formula:
10 = 1.35โˆš๐ฟ

3. Isolate the square root term on one side:
โˆš๐ฟ = 10 / 1.35

4. Simplify the right side:
โˆš๐ฟ โ‰ˆ 7.4074

5. Square both sides of the equation:
๐ฟ โ‰ˆ (7.4074)^2
๐ฟ โ‰ˆ 54.7613

Therefore, the waterline would have to be approximately 54.7613 feet longer to achieve a maximum speed of 10 knots compared to the initial maximum speed of 8 knots.