help with WOT on 50 hp merc

[FinS]

hey guys thought someone on the board may be able to help me out

 

i took the boat for a run today and at WOT i only get top speed of 23mph i know that isnt right its a 4 cyl

it runs fine idles good put new plugs

any ideas

 

maybe run a little sea foam thru her

but how do u do this since ive never done it before

any help would be appreciated 23 mph is not enough for a 50

[cranks bait]

First off it depends what you are pushing. I had a 50 rude on my boat and top speed in the right conditions was 28-30 mph. Most of the time it was around 25. The boat can play a lot into what the speed is. Now if it is the same boat and you have had it at much higher speeds, then I can't help you.

[Meegs]

we have a brand new 50 merc on our 16' legend... top speed when its glass calm out there is only 28mph. good enough to get out there and back but we cant get any more speed with it! 4 strokes definately dont have the power the 2 strokes do!

[FinS]

thanks just thought she would go faster for some reason

 

ok if i put a hydrofoil on it will this speed things up a bit espeacially getting on plane quickly

[forrest]

There are a few things not mentioned:

-prop size and pitch

-boat weight and type

-you are on plane right?

 

someone may want to clear this up: at WOT 50HP is 50HP....2 stroke or 4...its the power output....2 strokes usually have a bit more pep I think

 

my manual was pretty spot on in telling me mt boat/prop combo would go xmph....34mph for a 40hp on a 16ft tin.....I could change props and do as much as 53mph (but I will never try this).

 

 

forrest

[Daplumma]

How many RPM's?Boat size and prop pictch will also detemine speed.Check Manufactorers rpm recommendations and prop the motor to that rpm.That will give you your max.

Joe

[jwl]

we have a brand new 50 merc on our 16' legend... top speed when its glass calm out there is only 28mph. good enough to get out there and back but we cant get any more speed with it! 4 strokes definately dont have the power the 2 strokes do!

 

 

that is quite the difference between a 4 stroke and a 2, I have an oil injected 2 stroke 40 Merc on my Legend Viper, and with 2 guys in it can get the better part of 40mph out of it..I GPSed it beside another boat with a GPS on it before at 38 mph, 2 guys loaded up for fishing, and against the current of the upper Niagara

 

I have the manual for my motor right here has the specs for 40&50...says WOT rpms should run between 5000-5500 it's the same for a 40 or 50

Edited July 11, 2008 by jwl

[Fisherman]

I can't find the reasoning in stating the "difference in power" between a 2 or 4 stroke, if they both put about 50 HP, then by all rights the boat should go pretty much the same speed, whether it takes an extra second or two with a 4 stroke to get up to speed, but that's about it. A 2 stroke may be faster from start and the 4 a bit heavier, but not to cause that much difference. I drive a Honda 25 on a 16' Princecraft and have no trouble hitting 40km/h(25mph)