As seen in Figure 2 above, the orientation of the primer bulb is vertical, but the direction arrow indicating fuel flow is pointing downward. Orientation of the primer bulb should be with the direction arrow indicator pointing upward. This will cause the check valves in the primer bulb to work much better, and obtaining a stiff primer bulb with a few pumps will become possible.

Alibertucci wrote:The propeller calculator shows a 22-pitch propeller will produce more speed than a 19-pitch propeller at a given RPM of say 5,200 RPM.

You don't need a propeller calculator to postulate that at a given speed of rotation of the propeller, the higher the propeller pitch the greater the speed of advance.

But you cannot assume that your 90-HP engine is going to be able to turn the 22-pitch propeller as rapidly as it can turn the 19-pitch propeller.

The greater the propeller pitch, the more power needed to turn the propeller. The 90-HP engine can only supply a certain amount of power. When the engine power output reaches the amount of power needed to turn the propeller at the speed the engine is then producing, the engine stops accelerating. The power needed to turn a propeller as a function of the rotation speed is known as the propeller power curve.

The optimum propeller for a particular engine will be the propeller whose propeller power curve meets the engine power output at the engine's highest rated engine speed for full-throttle. If the propeller has too much pitch, its power curve will stop the engine from accelerating below the maximum rated engine speed.

If you are interested in a greater understanding of the propeller power curve, read my article on that topic:

PROPELLER POWER CURVE

https://continuouswave.com/whaler/reference/propellerPowerCurve.htmlNow that the gear ratio of the engine under discussion is known, the Propeller Calculator can be more useful. For example, looking at the claims that a similar boat could accelerate to 46-MPH can be analyzed. If the engine speed were kept to the recommended 5,500-RPM, and here we are assuming the engine was able to accelerate to that speed, and assuming a SLIP of about 8, the necessary propeller pitch to accomplish that is calculated to be 22-inches.

So far the ONLY DATA provided about your boat is the top speed is 35-MPH and the propeller pitch is 22-inches. If that data is entered and the engine speed calculated (assuming a slip of about 15 because the propeller is not working as efficiently at that boat speed) the engine speed should have been around 4,500-RPM.

Another way to estimate the speed is to use a calculator that predicts boat speed as a function of weight and power, with allowance for a certain type of planing hull. For the classic Boston Whaler hulls like a MONTAUK 17 hull, there is a good estimate of the hull coefficient: 190. Using a speed predicting formula based on that hull coefficient and a power of 90-HP, we can calculate the total boat weight that can be allowed to reach 46-MPH. There is another calculator that I have created for this purpose. It is based on well-known principals developed by a naval architect, George Crouch:

Crouch's Calculator

https://continuouswave.com/calculators/crouchCalc.phpWith input of hull coefficient 190 and horsepower of 90, to be able to accelerate to a planing speed of 46-MPH suggests the total boat weight must be no greater than 1,535-lbs.

Given the bare hull weight of the c.2000 MONTAUK 17 is 950-lbs, and the engine weight for a Mercury 90 is about 310-lbs, that leaves only 275-lbs for EVERYTHING else on the boat, include the driver, the fuel, and all the rigging and gear. If the boat had 12-gallons of fuel aboard, then that fuel alone adds 75-lbs of fuel, leaving only about 200-lbs for everything else, including the boat driver. Let's say the boat driver is a svelte 175-lbs, so now we are down to 25-lbs for ALL THE OTHER STUFF on the boat. In other words, the claimed speed of 46-MPH must have been accomplished with an extraordinarily light MONTAUK 17.

Even boosting the hull coefficient to 200, to hit 46-MPH with 90-HP still limits boat weight to 1,700-lbs, a rather modest increase of 165-lbs in allowed weight.

I think a better target speed is probably 40-MPH. Going back to the propeller calculator with a 19-pitch propeller with SLIP=8, the engine speed needed is only 5,560-RPM. That sounds much more attainable than 46-MPH.