Repowering a 1988 Overnighter 20

Argus

New Member
Joined
Jun 7, 2010
Messages
3
Reaction score
0
Points
0
I recently purchased a GW 1988 Overnighter 20 powered by a 1988 175hp Yamaha mounted on the original factory installed motor bracket. Not having water tested this boat yet, I'd like to know how well this boat planes off with this configuration. I'm considering updating to a Yamaha 150hp 4 stroke. Will this underpower the boat?
 

uncljohn

Well-Known Member
Joined
Mar 24, 2006
Messages
419
Reaction score
0
Points
0
I think you're really going to want 200hp on there. You boat is rated for 230 hps. I have a 228, which is rated to 280 hp, and I have a 200hp OX66, and that is minimum power, and many repower 228s with 225 or 250s (2-Stroke).

The 175 is probably minimum hps for your engine. A 200 would run it right.
 

Argus

New Member
Joined
Jun 7, 2010
Messages
3
Reaction score
0
Points
0
Repowering GW 1988 20'

thanks for the reply. I agree a 200HP engine would be perfect but I'm concerned about the weight. Even the 150 HP Yamaha weighs 25 lbs more than the 1988 Yamaha 175HP I have on there now. I'm concerned about being stern heavy with a 200hp?
 

Got Bass Charters

Active Member
Joined
Jan 9, 2008
Messages
38
Reaction score
0
Points
0
Location
Atlantic City, New Jersey
Watch the weight of your motor, 4strokes are heavier some have had problems with water coming in scuppers after mounting a 4 stroke. I have a 225 two stroke weighs 485 lbs. a 4 stroke would be much heavier.The boats scuppers were drilled for the weight of a 2 stroke.
 

Argus

New Member
Joined
Jun 7, 2010
Messages
3
Reaction score
0
Points
0
repowering GW 1988 20'

A 200hp 2 stroke would be just right but Evinrude is the only company that I know of thats making 2 strokes of that size
 

Bob's Cay

GreatGrady Captain
Joined
Jan 30, 2005
Messages
331
Reaction score
0
Points
0
Location
Atlanta, Ga
My '88 has a 2002 HPDI and it is perfect for the boat but I would not want any additionla weight back there. If you could find a good used one you would probably get many years out of it.

I have not checked the weights but Yamaha has been offering new lighter weight4S engines in this HP range.
 

VeroWing

GreatGrady Captain
Joined
May 21, 2009
Messages
430
Reaction score
22
Points
18
Location
Vero Beach, Fl.
Re: repowering GW 1988 20'

Argus said:
A 200hp 2 stroke would be just right but Evinrude is the only company that I know of thats making 2 strokes of that size

I agree. You should consider an Evinrude Etec.
 

gw204

Well-Known Member
Joined
Jan 31, 2005
Messages
2,481
Reaction score
22
Points
38
Location
St. Leonard, MD
I ran a 2-stroke Merc 150 on my old 204 Fisherman and got about 42 mph out of her. Not once did I ever feel underpowered and I ran that rig heavily loaded in some rough water. The Overnighter isn't that much heavier and how often can you run a 20' boat 40+ mph???

The F150 supposedly dynos at 165 HP. So, I bet you would be fine.
 

uncljohn

Well-Known Member
Joined
Mar 24, 2006
Messages
419
Reaction score
0
Points
0
gw204 said:
I ran a 2-stroke Merc 150 on my old 204 Fisherman and got about 42 mph out of her. Not once did I ever feel underpowered and I ran that rig heavily loaded in some rough water. The Overnighter isn't that much heavier and how often can you run a 20' boat 40+ mph???

The F150 supposedly dynos at 165 HP. So, I bet you would be fine.

the 204 Fisherman is a CC. The overnighter is a WA. There's 500 extra lbs in an overnighter.

You might be fine w/ a 150. I'd prefer to be overpowered than underpowered.
 

bottomline

Member
Joined
Nov 18, 2007
Messages
23
Reaction score
0
Points
0
Location
NJ
204c

I have 1987 204C with 1987 Merc 150. I have no problem going 30+mph (when conditions are perfect - which is rare).

I guess it depends on what your looking to do. If you want to go as fast as possible, then go with 200 or 225. However you ar going to have issues with water entering the stern scuppers.

Honestly in the area that I boat & fish (NJ/NY area) bay & ocean, between the boat wake and 2-4 seas, I can't go that fast anyway. Most of the time I cruise around 20-25mph and thats plenty fast. And when its choppy I need to slow down or risk cracking my teeth or spine :shock: .

Good luck
John
 

Daman858

GreatGrady Captain
Joined
Jul 30, 2007
Messages
318
Reaction score
2
Points
18
Location
Pawleys Island, SC
Guy in my marina has your boat with a 175 Johnson Ocean Runner. he says it's very reliable and his boat has plenty of power with that set up. weight issue is right with it too.
 

jtsailjt

Active Member
Joined
Mar 29, 2010
Messages
35
Reaction score
0
Points
0
Location
Maine
I just went through this with my 78 Overnighter and decided to go with a used motor to save $$$. I ruled out 4 strokes because of the weight/scupper issue. So then it was down to a choice between a traditional fuel injected 2 stroke and a HPDI motor. My mechanic prefers to work on Mercury's so I looked at the Opti's and learned that the 175 had a weight in the mid 400's so would be great if I could find a used one. Lots of 200 or 225 Opti's out there but no 175's for sale that I could find. The 200 and 225 Opti's are 3 litre engines and weigh about 530# so are nearly as heavy as a 4 stroke. So that left me with the 2.5 litre, 200hp conventional EFI 2 stroke weighing in at about 417#. I know I'm going to burn a lot more gas with this engine, but they're reliable and simple to repair so that should help with the extra fuel costs and my toes will stay dry. My other reasonable choice was to buy a new 175 4 stroke or Opti but the cost would have been about 8 to 10K more $$$ and you can buy a lot of Maine boating seasons worth of fuel on that kind of money.
 

Bread

Well-Known Member
Joined
Jul 14, 2008
Messages
53
Reaction score
0
Points
6
Location
NY
repower overnighter

I have a Suzuki 4-stroke DF 175 on a 1990 Overnighter. Good power, weight is 485 lbs. With a full tank of gas my scuppers sit about 1/2 way submerged. If I stand in either corner of the stern a tiny bit of water will come in.
 

Bryansvo

Member
Joined
May 25, 2010
Messages
9
Reaction score
1
Points
0
Location
Ocala, FL
If you end up going with a 200 or so evinrude, please post the performance as that is what I am considering for mine. Anyone threw a 200/225 on a 204/206? :?:
 

F3

New Member
Joined
Jun 12, 2010
Messages
1
Reaction score
0
Points
1
Location
North Shore MA.
I have a 1990 204 Overnighter that I repowered w/ a 2003 225 Mercury Optimax and have put over 1200 hrs on it. The best thing I ever did was go with the bigger engine. The boat originally had a Yamaha 150 on it and w/ 3 guys running offshore to fish, I felt it was underpowered. The 225 Optimax only weights 30lbs more than the 1991 150 Yamaha, and my fuel burn is incredible. My first trip offshore this year, I ran 32 miles out at 27 knots burning 9gph!