Grady 20' Overnighter Repower

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Bolio

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I'm about to purchase a Yamaha f225 4stroke to repower my Overnighter, and I'm wondering if this motor is too large for this boat...It's got the original Mercury 115 on it now, and it's god awfully slow. I generally see 150's, 175's, and 200's on these boats. Am I asking for trouble with a 225 Yamaha 4stroke?
 
You would be much better off using an in-line 4 cylinder 200 hp if you want to stay with Yamaha. It's about 100 lb lighter than the V6. The rap on the in-line 4 is that it doesn't have the torque of the 6 cylinder. But your hull doesn't require as much power as the newer SV2 models. Compared to your 115, you will think you are rocket-propelled.

I had an original Overnighter back in 1975. The power options were 115 or 135 hp 2-strokes. Mine had a 135 and it would cruise at 25 mph and top out at 35 mph. It was sluggish with 4 guys on board but would stay on plane just fine. I repowered with a 150 hp 2-stroke and it had plenty of oomph.

Nowadays, everybody thinks that you need a ton of hp and that boats should top out at 45 mph or better. It's a waste on the 204C since that hull doesn't like to go fast. 150-200 hp will be plenty of power. You might also check out the 150 hp Mercury, which is cheap and has established a good reputation for reliability.
 
Doc Stressor said:
You would be much better off using an in-line 4 cylinder 200 hp if you want to stay with Yamaha. It's about 100 lb lighter than the V6. The rap on the in-line 4 is that it doesn't have the torque of the 6 cylinder. But your hull doesn't require as much power as the newer SV2 models. Compared to your 115, you will think you are rocket-propelled.

I had an original Overnighter back in 1975. The power options were 115 or 135 hp 2-strokes. Mine had a 135 and it would cruise at 25 mph and top out at 35 mph. It was sluggish with 4 guys on board but would stay on plane just fine. I repowered with a 150 hp 2-stroke and it had plenty of oomph.

Nowadays, everybody thinks that you need a ton of hp and that boats should top out at 45 mph or better. It's a waste on the 204C since that hull doesn't like to go fast. 150-200 hp will be plenty of power. You might also check out the 150 hp Mercury, which is cheap and has established a good reputation for reliability.
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Thank you, this was a very detailed explanation...exactly what I needed. I'm going to try and find a 200 HPDI instead
 
Hi Bolio,

This may be more than you care to think about right now, but I'd be interested in learning about your prop selection for the re-power, whenever you've made your purchase.
 
An Overnighter with an in line 4 cylinder 200 Yamaha will be best with a 19 pitch prop.
With that it’ll top out at around 42-45mph. Very respectable.
I run a 20 on mine behind a Dt225 Suzuki 2 stroke. (46-48 mph)
I’ve beat this one to death researching it and if my Suzuki ever dies the Yamaha F200 4 will replace it with the 19 p prop.
The F200 has the same bolt positioning as the old 2 strokes and is about the lightest 4 stroke OB you’ll find. It is even lighter than the 6 cylinder 2 stroke OBs available today.
You won’t be sorry.
 
Inline 4 cyl Yamaha. There’s a thread on here by Searosis from when he repowered with the F200XB. After reading that I made the choice to repower from a 150hp OX66 to the F200XB. The comparison is night and day. It’s not cheap but it was worth every penny to me. I definitely wouldn’t go with anything heavier than that. I hope you have a good pair of waterproof boots otherwise you’re going to have wet socks with a F225.
 
Bolio said:
I'm about to purchase a Yamaha f225 4stroke to repower my Overnighter, and I'm wondering if this motor is too large for this boat...It's got the original Mercury 115 on it now, and it's god awfully slow. I generally see 150's, 175's, and 200's on these boats. Am I asking for trouble with a 225 Yamaha 4stroke?
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Are you asking for trouble...yes. Scuppers will be under the waterline, and when u get two guys on the stern..oh boy! Hull not meant for that heavy an engine. HPDI is a great engine til it breaks....way too complicated and way too many parts for me. I have a 95 208 with an F200XB..it's excellent in all respects. If you intend to keep this boat, F200 is your way to go
 
My understanding after looking into the same thing is that yes, you are looking for trouble unless you add an offshore bracket with flotation...
 
sounds too much from here. I'd look for a 150 or 200 Yamaha.
 
How about an ox66 225hp? I found a good deal on one of those with low hours
 
All that horsepower would go to waste with that hull. It won't run over 25 mph in a 2' chop without pounding you to death. And you'll get you soaked as well.

You need an engine that is not too heavy with enough midrange torque to keep the boat firmly on plane with a load aboard at 25 mph or less. The hull is a very stable platform, but it doesn't respond well to tabs. You just can't go fast with it unless the water is close to flat *ss calm. The post-1992 SV2 hull is a completely different animal.
 
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