How fast should my boat go?

[riesesdad]

I have an 18 foot 1991 bayliner with a 90hp Force. I also have a hydrofoil (don't know the brand. It was on when I bought it), so I don't know if that matters.

It planes right away, and handles waves perfectly. All around it's very good. I can only get about 28mph out of it though. Is this about right?

I'm going to try it without the hydrofoil on Saturday as well.

Second question: My throttle doesn't stay in the WOT position, I have to hold it there firmly or it backs off about 5mph. How do I tighten this?

 

[andy6.3]

Re: How fast should my boat go?

for starters Force outboards are not in the same league as mercury etc however speed does seem to be down the hydrofoil helps get the boat up on the plane guicker and should help on fuel economy. The main part is really the prop. 1 is it damaged, 2 is it the correct size and pitch for the outboard 3 could be an idea to get the engine serviced check the hull the smoother the hull the better car polish work well. If all else fails get an evenriude e-tec 115 HP sell the force.

 

[wvit1001]

Re: How fast should my boat go?

I used to have a 19' Bayliner with the 125 hp Force. It was good for about 35 or 40 mph depending on how many people were in the boat. 30mph with a 90 hp seems about right.

If you using the boat speedo your fooling yourself to think it's accurate. It will give you an idea of how fast your going but that's about it.

A lot depends on how much power the motor is really putting out. How's the compression, is the carb adjusted right, etc.

 

[kenmyfam]

Re: How fast should my boat go?

I have an 18 foot 1991 bayliner with a 90hp Force. I also have a hydrofoil (don't know the brand. It was on when I bought it), so I don't know if that matters.

It planes right away, and handles waves perfectly. All around it's very good. I can only get about 28mph out of it though. Is this about right?

I'm going to try it without the hydrofoil on Saturday as well.

Second question: My throttle doesn't stay in the WOT position, I have to hold it there firmly or it backs off about 5mph. How do I tighten this?

You need to post speed, rpm, prop diameter and pitch, load in the boat and maybe a picture showing the bottom end of the motor and the cavitation plate relationship to the bottom of the hull. There are many experts that can help with more info.

 

[scoutabout]

Re: How fast should my boat go?

As for your throttle question, there should be a screw somewhere on the housing or bezel that, when turned to the right, increases friction of the handle. There will be a trade-off setting between so damn tight you have to lean on it to move it and nice and easy but won't hold a setting.

Then there's mine, which won't hold a setting no matter how much I tighten it down. It will however keep it from moving into gear pretty damn good. Arrgh -- I don't geddit.

For top speed comparison, my 90 Yamaha 4stroke will push the Scout (17'5") and me (5'10") along at 38 mph indicated at WOT. The boat with engine, gear, and gas probably weighs 2,500 lbs. Problem is the "indicated" is the boat speedo. I'm gonna try the GPS this weekend, record rpm and pitch.

 

[Liquid_force]

Re: How fast should my boat go?

You may be aware of this, but that hydrofoil can have BIG effect on top speed if you don't trim it correctly.

My old boat was a 16' glassmaster with a 115 Evinrude and hydrofoil.
Trimmed all the way down causes that foil to be below parallel. That helps get on plane, and also helped soften the ride in rough waters, but it would drop 6-8mph off top speed.
It would do 34-36 trimmed all the way down, 41-42 trimmed up a few degrees.

Your 28 may just be a difference in boat/motor, but I thought I'd throw that out there in case you hadn't considered it.