Need help with outboard size

Thread starter Daba1g3g
Start date Jul 13, 2011

D

Daba1g3g

Cadet

Jul 13, 2011

#1

I just picked up a 20ft center console vhull boat today. The stamp says rated to 180 hp . I have been told to use an outboard from 115hp to 175hp. What would be the best size for performance and fuel

Ciera2450

Lieutenant Junior Grade

Jul 13, 2011

#2

Re: Need help with outboard size

More performance=More fuel

115hp if fuel is main concern.
175hp if performance is what you desire.

JB

Honorary Moderator Emeritus

Jul 13, 2011

#3

Re: Need help with outboard size

60 degree looper V6 JohnnyRude. I would use a 150HP

BaileysBoat

Senior Chief Petty Officer

Jul 14, 2011

#4

Re: Need help with outboard size

Gonna be a dog with 115. 150 hp would be good, 175 best. Never heard anyone complain about having too much power.

C

CaptOchs

Petty Officer 1st Class

Jul 14, 2011

#5

Re: Need help with outboard size

Welcome to the forums.

More info is needed.

What type of boater are you? Speed important?
Do you plan to use it for fishing, skiing, tubing?
What size are the bodies of water you're looking to go to?
You also didn't say how old the boat was. How old?
What's the condition of it?

Keep in mind, the 180HP rating is if your transom is 100% perfect. Rot will weaken the transom and reduce your actual HP rating. If the transom goes while your in the water you could sink.

ezmobee

Supreme Mariner

Jul 14, 2011

#6

Re: Need help with outboard size

Personally, I'd go with the largest 4 cylinder I could find (probably around 140HP) to avoid the greater complexity and fuel consumption of a V6. That's just me though.

D

Daba1g3g

Cadet

Jul 14, 2011

#7

Re: Need help with outboard size

Ok here is a little more info. The boat is a 1979 power cat.20ft vhull. Transom in solid . The water I fish in are lakes, St Johns river and and ocean just not out to far. I am really not into speed or just something to get me out and get around in. here is a pic of the boat

metriccrescentwrench

Commander

Jul 14, 2011

#8

Re: Need help with outboard size

Most of the time I'd say go with the most power you can, but I gotta' agree with ezmobee - a 140 would work great on that boat.

S

sublauxation

Lieutenant

Jul 14, 2011

#9

Re: Need help with outboard size

Another thing to keep in mind is that when your boat was built horsepower was rated at the powerhead and now it's rated at the prop. Not sure when that changed but at least on a newer motor a 140 would probably be pretty close to a 1979 180 horse motor.

D

Daba1g3g

Cadet

Jul 16, 2011

#10

Re: Need help with outboard size

Ok guys since reading about how the motor rating are different back then . What would you think about me putting a 115hp on this. The reason I am asking is a have a friend that need to get rid of his and he will give me a good price on it.

1980Galaxy

Petty Officer 1st Class

Jul 16, 2011

#11

Re: Need help with outboard size

sublauxation said:
Another thing to keep in mind is that when your boat was built horsepower was rated at the powerhead and now it's rated at the prop. Not sure when that changed but at least on a newer motor a 140 would probably be pretty close to a 1979 180 horse motor.

thats only if it comes from the factory, tho, i think... i might be wrong.

thats what i was told when i was buying my boat. i have a bass boat rated at 50hp max. i have a 60/40 jet motor (60hp engine making 40 at the impeller)

A

aerobat

Master Chief Petty Officer

Jul 17, 2011

#12

Re: Need help with outboard size

Daba1g3g said:
Ok guys since reading about how the motor rating are different back then . What would you think about me putting a 115hp on this. The reason I am asking is a have a friend that need to get rid of his and he will give me a good price on it.

i think a 115 will do a very good job on this boat, why not. it should plane it without any problems

Fishgeek

Recruit

Jul 17, 2011

#13

Re: Need help with outboard size

1980Galaxy said:
thats only if it comes from the factory, tho, i think... i might be wrong.

thats what i was told when i was buying my boat. i have a bass boat rated at 50hp max. i have a 60/40 jet motor (60hp engine making 40 at the impeller)

Nice! I registered on the site this morning to find the answer to that question! But just to clarify, if I have a boat that's rated 25hp, I could put a 35hp outboard converted to a jet on it that would be ~24hp at the impeller and still be legal?

jigngrub

Fleet Admiral

Jul 17, 2011

#14

Re: Need help with outboard size

oops!

JB

Honorary Moderator Emeritus

Jul 17, 2011

#15

Re: Need help with outboard size

sublauxation said:
a newer motor a 140 would probably be pretty close to a 1979 180 horse motor.

No way is there a 40HP difference.

If economy is such a high priority go to a Suzi DF140 or DF150 "big block 4".

dingbat

Supreme Mariner

Jul 17, 2011

#16

Re: Need help with outboard size

Speed is not the concern with an underpowered boat. There are many situations where you need HP that is not speed related.

A four stroke will save you 30% in fuel consumption over the same HP carbureted 2 stroke. You could put the 150 four stroke the back and still get the fuel economy is a 115 two stroke.

1980Galaxy

Petty Officer 1st Class

Jul 17, 2011

#17

Re: Need help with outboard size

Fishgeek said:
Nice! I registered on the site this morning to find the answer to that question! But just to clarify, if I have a boat that's rated 25hp, I could put a 35hp outboard converted to a jet on it that would be ~24hp at the impeller and still be legal?

from what i understand: ONLY if you order the boat from the factory like that... NOT if you do it yourself. some sort of a loophole, i guess. once again, i could be wrong.

silveraire

Petty Officer 1st Class

Jul 18, 2011

#18

Re: Need help with outboard size

Looking at the pics you show, it appears that your boat has a fairly shallow deadrise. That = less hp to get and stay on plane. That being said, and assuming your going to stay with a 2 stroke, I agree with others above. A nice late model 140hp johnson/rude v4 would be the ticket for you. Light weight, simple, cheap parts and fairly decent on gas. Also has enough hp if you ever get into a situation that you need to get out in a hurry.

chad

H

Home Cookin'

Fleet Admiral

Jul 18, 2011

#19

Re: Need help with outboard size

my 21' Sea Hunt is similar to yours and it has the factory package 150 Yam 2 stroke. I am very happy with it. My use is similar to yours.
It is important to have enough power, not for top-end speed, but to deal with adverse conditions. In that regard, though, spped can be important for outrunning weather.

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