Motor Tired or Passenger Clueless

[TwistEdFish]

Greetings All,
I have a 1987 16' cc Winchester tri hull with a 1985 50hp Yamaha outboard that does 24 mph with 2 adults and full fishing gear, should I expect more speed out of the boat?
​​​​​​​ A recent passenger says the boat should have a lot more with the motor thats on it. He expects the boat to launch onto plane and run at 25 mph while carrying 4 adults and gear.
​​

 

[Chris1956]

Well, I think that is in the ballpark for that boat and motor. What is max HP rating on the boat? What is pitch of prop and max RPM?

Maybe you could add a couple of MPH, with the right tuning and prop.

 

[littlerayray]

You seem to be running right for that boat

 

[dingbat]

Greetings All,
I have a 1987 16' cc Winchester tri hull with a 1985 50hp Yamaha outboard that does 24 mph with 2 adults and full fishing gear, should I expect more speed out of the boat?
​​​​​​​ A recent passenger says the boat should have a lot more with the motor thats on it. He expects the boat to launch onto plane and run at 25 mph while carrying 4 adults and gear.
​​

In boat terms, an adult weighs #150 per person. In today's terms, could be anywhere from #150 to #300. That's asking a lot of a 50 hp motor.

If in doubt, check the compression. Any "tiredness" will show up there

 

[Scott Danforth]

ISO standard for adult is 185# per person (85kg)

your boat is 33 years old. have you weighed it? you may be carrying 800# of water in the flotation foam.

 

[TwistEdFish]

Max for the boat is 90 hp, at top end I'm running at 5200 rpm and the current prop is a 13

 

[TwistEdFish]

ISO standard for adult is 185# per person (85kg)

your boat is 33 years old. have you weighed it? you may be carrying 800# of water in the flotation foam.

I actually haven't weighed it, was just thinking of pulling to my local weigh station to see if they will do that. I've always been happy with the boats performance as it has been in my family since new. I've fished from it for all of its 33 years and never had an issue as I normally never go out with more than 3 adults and usually maintain 19 mph in that situation. Boat originally had a 40hp Johnson and top end speed was 16 mph with 2 adults and full gear.

 

[mr 88]

You are way underpowered , formula is something like minimum of 75% of rated hp for a boat to perform properly.. So that would put you in the 70 HP and up category . IF it was me I would be looking for a 80-90 HP as a replacement.

 

[roffey]

Personally, I think your WOT is fine. Its a 50 hp with a 13 inch prop on a 30 year old boat... if it works and your happy, why fix it?

 

[DeepCMark58A]

Your passenger is clueless.

 

[TwistEdFish]

Thanks All, I think I will continue to keep running it as I always have and that day when I see the mentioned passenger on the water broke down cause he runs his boat Balls to the wall 99% of the time I'll be sure to smile, wave and tip my hat as I go by.

 

[oldjeep]

My folks pontoon does 17 mph with 8 people in it and a merc 50. I guess I'd expect a v hull to go faster than 24 with the same motor.

 

[roffey]

Thanks All, I think I will continue to keep running it as I always have and that day when I see the mentioned passenger on the water broke down cause he runs his boat Balls to the wall 99% of the time I'll be sure to smile, wave and tip my hat as I go by.

what's even better is stop and tow him back to port, then ask how does my boat run now... :congratulatory:

 

[TyeeMan]

Boat speed is nothing more than a by-product of an outboard (or in in-board, or IO) reaching it's max wide open throttle RPM with the proper propeller.

If your outboards WOT RPM is 5500 for example, if you are achieving that RPM with your "normal load" in the boat that's all you care about. Your boats speed, whatever it is, is result of your OB running at it's proper WOT RPM.

Doesn't matter how big or how small the engine is either.

 

[bchaney]

I found the calculator below to be pretty accurate for my boat, you could plug in some numbers and see what HP you get for your 24 mph speed. My gut feel is that speed seems about right for your setup.

https://btb.fishing/boat-horsepower-calculator/

 

[flyingscott]

Tell your passenger to get out and push if he wants to go faster. Your boat is right where it should be with that motor. For a tri-hull with 2 people that is a pretty good speed. That motor on an aluminum 16' boat would do about the same speed.

 

[DeepCMark58A]

I checked yesterday on the water. I have a 16' Lund Mr Pike. My wife and myself I weight 190 my wife 135. Had a cooler with 8 pounds of ice another with 5. 6 gallons of gas 2 batteries and assorted fishing gear. Top Speed 30 mph. My trim is not currently working so I could possibly coax a little more speed but your fiberglass boat with a 50hp sounds about right.

 

[bassman284]

My folks pontoon does 17 mph with 8 people in it and a merc 50. I guess I'd expect a v hull to go faster than 24 with the same motor.

Can't really compare a pontoon to a planing hull. Whole different animal.

 

[Lowlysubaruguy]

In a nut shell if you want and can afford more cowbells then it its for sure way to slow. You outboards right for what it is is it right for your wallet. Me I cant stand being in a boat that wont plane loaded without struggling. However theres a problem if you add more cowbells and you want to slow troll you may find now you’ve lost the ability to do that toss a trolling motor on and another gas can and now your back to where you started.