trouble getting 1980 overnighter on plane

bassmasterrap

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I just recently purchased a 1980 overnighter with an original 175 mercury on it. The boat and engine seem in pretty good shape. I brought it out the first time yesterday and was having trouble getting it on plane. It seemed that i had to get it to about 6k rpms and once i let off a little i would loose too much speed and loose it. My last and only other boat was an 18 foot baylner that easily got on plane in seconds. Is this normal?
 

cdwood

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Does'nt sound good. I'm on plane at less than 4k rpm.

Check your prop, hub spun? right pitch/dia.
 

bassmasterrap

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do you trim the motor at diferent speeds to get on plane. I think the angle of the motor is the problem.
 

cdwood

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No need to change motor angle, new trim tabs help but still did'nt need to go to 6k to plane, you've got something else going on.

Is your motor trimmed all the way down?

Are you running heavy ie; full gas, too many people etc?
 

bassmasterrap

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motor was all the way down. previous owner had said " goes right on plane when you tilt the motor up a bit at higher speeds" Tried that and nothing. We had 4 people, 3/4 tank gas. Going out tomorrow with only 1 other person. Ill see if theres any difference
 

cdwood

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So your talking 45 gallon of gas and 600 to 800 pounds of people?

That's pretty well loaded for that boat. Especially with an older tired engine. Definitely try adjusting your engine angle and shift the wheight on the boat around (fore and aft).

I would also be very cautious about pushing an older engine to 6k with a load like that.
 

uncljohn

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1) what condition is the bottom? Any growth?

2) have a survey done on the hull? Maybe its got some water saturation?
 

phazzard

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I get on plane (1993 208 Adventure) at 33-3400rpm with a 150 Yammie 2 stroke, so would agree that something seems fishy here
 

wanderer200

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You shouldn`t need 6k to plane. Either your props spun or its cavitating. Somethings not right. What pitch is the prop?
 

cdwood

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The fact that your reving to 6k still makes me think you have a prop issue.

Most 2 strokes top out around 5600.
 

bassmasterrap

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No bottom growth at all. It was trailered to the water by previous owner and it is on a rack now and no growth. Previous owner doesnt understand why i cant plane easier. Maybe it was overloaded but idk. Im not sure what pitch the prop is at all i know is its a new SS one.
 

wanderer200

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Maybe its the wrong pitch. There should be numbers stamped on it.
 

no problem

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I would be check that new prop for sure. It could be the wrong pitch, diameter or both. If you're really getting 6k rpm I would think you need more pitch. The size should be stamped on the hub. good luck
 

sfc2113

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a 175 should plane that thing easy at 3200-5500 rmp fully loaded. You must have allot of prop slippage, cavation or something, maybe lower unit ??. try putting it in gear and see if you can turn the prop by hand, it should not move easy at all in either direction fw or rev without allot of effort. GL
 

DB

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Did you check the Bilge...is it full of water...sounds like too much weight somewhere...or the Hub of the prop is slipping.
 

bassmasterrap

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went out last night and noticed the engine went down atleast 5 inches further with the tilt and trim. It just went very slowly and i thought it was all the way down before. I went out with only one of ther person and about 30 gallons of fuel. I got on plane at around 3500 rpm and cruised at about 3800 rpm. Very relieved. Thanks for the help