1977 Ranger 1750 w/Johnson 115 only hits 39MPH

mudweiser

Petty Officer 2nd Class
Joined
Jun 21, 2007
Messages
115
I bought a 1977 Ranger 1750 Fish/Play. It's the Sport or tri-hull design. Plains out right away, the engine is running at 4,800 trimed down (5,000 is max). Prop is a SeaBold 13 X 19 Stainless. The tilt is not working properly, but i took off while trimed up (slowly to not overrev) and i was able to get 40MPH and spining at 5,200. The MPH was figured on GPS so it's right. Calm water, average to cool air temp, 2 people on the boat, livewells empty, and otherwise lightly loaded (the boat, not me). Any ideas what this hull should run?
 

redtech

Seaman Apprentice
Joined
Jun 23, 2007
Messages
45
Re: 1977 Ranger 1750 w/Johnson 115 only hits 39MPH

do a compression test sounds like you have low or dead hole
 

mudweiser

Petty Officer 2nd Class
Joined
Jun 21, 2007
Messages
115
Re: 1977 Ranger 1750 w/Johnson 115 only hits 39MPH

Already been done. Compression is about 125 in all holes. It varies maybe a pound or 2 at the most. About 1,100 above sea level.
 
Last edited:

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1977 Ranger 1750 w/Johnson 115 only hits 39MPH

The engine's horsepower is rated at 5000. The normal operating range is 4500-5500. Suggest you try a 17 pitch. You need to be in the 5500 range. It's only 92.6 cubic inches-the small displacement engine.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 1977 Ranger 1750 w/Johnson 115 only hits 39MPH

being a 77 check for extra weight, such as water saturated form.
 

kenmyfam

Supreme Mariner
Joined
Aug 10, 2006
Messages
14,385
Re: 1977 Ranger 1750 w/Johnson 115 only hits 39MPH

You need to get the trim up and running and make sure the motor is not too low in the water as well.
 
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