20 Overnighter- repower question

[fdheld34]

First post here on this site..I have a 1984 20' Overnighter. Currently redoing transom (pics to follow in other thread/topic)It had a 150 Mercury on it...I was thinking of replacing with a 115hp Mercury...would the boat be underpowered??? Could I compensate with prop pitch. I have only owned Seacrafts in the past so any help regarding hp for the Grady would be greatly appeciated.
-Fred

 

[cdwood]

150 is the absolute minimum for that boat, I'm sorry I didn't go up to 200 when I repowered.

 

[fdheld34]

Thanks for the info...guess I will start looking for a 200 hp...and keep the 115 for another boat!!
What type of performance could I expect with a 200 merc....would it be a considerable difference from a 150???
-Fred

 

[family affair]

Not certain what a 200 merc would do, but a 200 Rude would get ours up to ~48-50mph with 2 people, no hard top, ~40 gal of fuel, and no bottom paint.
If you don't have tabs on it, get them. They make a world of difference on that hull!

 

[sfc2113]

im running a 175hp , all the power I need. took off my bottom paint this year, ran 42 mph wide open the other day in flat seas. You dont want to cross anyone wake at that speed it will ratle some teeth. Agree with last poster, tabs will do wonders for it. Get em if you dont have em.

 

[Fish Tank]

Boat came with a tired 150 johnson that would do mid 30's. Replaced with a 225 Optimax and now just shy of 50 on a very old bottom paint with an enclosure and still not sure of the prop. Engine is on a bracket and no tabs yet.

 

[cdwood]

There is no better feedback than that from end users. Do yourself a favor and listen to these guys.

Before we talk about the transom listen up..... THAT BOAT ABSOLUTELY HAS TO HAVE TRIM TABS!!!

So, the transom's being done??? put it out there..who's doing what?

 

[fdheld34]

I will def. listen to all...going to find a clean 200-225 Merc (already rigged for a merc) and look into tabs for boat..!!! I am not going to go with a bracket on this boat..

I am doing transom from outside in...feel more comfortable doing it that way....plus stringers etc. checked out fine...wealth of knowledge on this site..so I have been snooping for about 2 months now on this site...obtaining more ides etc. etc.!!!!
I will post the pics of my transom job this weekend and brief layup schedule....currently at work now
thanks all for the quick and to the point response--much appreciated!!!
Drought conditions here is S. Florida...been lucky no rain since I started transom redo last weekend...but my grass and landscape plants are taking a beating..no water in retention pond anymore for irrigation....hopefully will hold out this weekend so I can get outter skin back on and tab/fair...sand some more!!!
Terrible smoke down here too!!!!
Thanks all for the hospitality!!!!
-Fred

 

[gw204]

My Dad had a '77 204 CC w/ a 115 Evinrude and from what I remember, he said it would top out around 33. Since your boat is already rigged for a Merc, there's no harm in sticking the 115 on there and seeing what it will do...

Prop it so it reaches max RPM and I would estimate a cruise in the mid 20s between 4000 and 4500. Run it that way until you find another engine.

 

[fdheld34]

Thaks Brian...I just might do that until I can locate other motor...
I am not a speed demon anymore by any means...once transom is complete I will do that until I can shop around for a decent used 200-225...
-Fred

 

[Fish Tank]

What benefit are you seeing from tabs? The boat rides level port to starboard. The bow stays down (almost too much) already. The 225 gets it on plane instantly.

 

[fdheld34]

Fish Tank...again I am unfamiliar with the handling characteristics of a Grady White ...again I have only owned Seacrafts with enclosed transoms/brackets and I/Os. I ran lencos on 2 of the 4..

Not so much getting on plane (if use 225hp) but what about weight distribution (people and gear??) wont the tabs help out in this instance?

Thanks
-Fred

 

[Sitkasun]

175 is the safest minimum HP for this hull. I just finished a repower job putting on a 200 Mercury Verado (the lightest 4 stroke option for 200s, it’s a 4 cylinder with a supercharger). The stern does sit low with a big boy motor on it, so you’ll really want to do a good job updating the scuppers, seals, and so forth. This outfit with trim tabs and a full load (50 gal fuel, 4 in the family, and lots of gear) produces 25 knots at 3900 rpm with a burn rate of 5.8 GPH.

 

[cdwood]

That hull will pound you to death. Tabs will keep the bow down when on plane and ride much smoother thru a chop.

 

[FlemIslGator]

I repowered from a (1987) Evinrude 140 to a (2002) Yamaha 200 HPDI. The 140 would run about 30 - 35 under good conditions, but really struggled to get on plane (especially when heavy). The 200 is a huge difference jumping on plane & the speed is there if I want it. It will go 50+, although I never run that fast. Cruises great at 3500 - 4000 RPM. One other thing to consider is type of steering. I still have cable steering, and definitely have to fight the torque on the motor till I get up to cruise speed. Really need to change to hydraulic steering with a larger engine.

 

[fdheld34]

Looks like around a 200hp it is....good point about the steering there...I had a chris craft with a 225 and I forgot about the torque...I dont think I had "no feedback sterring"on it ...
Thanks all so far for the input...
-Fred

 

[Bryan3536]

Re: 20 Overnighter- GPH & Tabs

Saw this good thread and wanted to ask two related questions. Doing some winter trip planning/dreaming. Wondering what my realistic range is on my 1990 204c with a 2005 150 Merc 2 Stroke. This boat is new to me, and I have yet to run it. Really no clue what to expect. Not looking for firm numbers - just rough estimates of fuel burn at likely cruise.

Second question is tabs. I see several of you urge getting them. Most of you doing the urging also repowered to 200 hp or larger/newer 4 strokes. Weight issue, hull issue, or both? Going to run it for a bit before I put tabs on, but wondering if you guys think it likely?

Thanks.

 

[GulfSea]

Re: 20 Overnighter- GPH & Tabs

Saw this good thread and wanted to ask two related questions. Doing some winter trip planning/dreaming. Wondering what my realistic range is on my 1990 204c with a 2005 150 Merc 2 Stroke. This boat is new to me, and I have yet to run it. Really no clue what to expect. Not looking for firm numbers - just rough estimates of fuel burn at likely cruise.

Second question is tabs. I see several of you urge getting them. Most of you doing the urging also repowered to 200 hp or larger/newer 4 strokes. Weight issue, hull issue, or both? Going to run it for a bit before I put tabs on, but wondering if you guys think it likely?

Thanks.

Bryan, indeed these guys know all the in's and out's of Grady's. Start a new thread with the questions and you'll probably get more feedback. But, IMHO, tabs are needed on any boat going offshore and many inshore. They allow you to level with varying loads of people and equipment. And in larger/varying waves, they allow you to maintain plane at slower speeds, etc. by controlling the entry point of the bow. As a 1 1/2 year new Grady fan, run that boat for 9 months to a year to really get a feel for it's quality and abilities. By then you'll know it inside out.

 

[BUZZCUDA]

I have an 86 overnighter that I put a suzuki four stroke 150 on . When I got the boat it had a 150 two stroke that was spent. Now I would have went up to a 175, however I was gung ho on suzuki and found a left over left hand motor nicely discounted. I can tell you that this boat is not a speed demon and I would not want this boat to do much more than the 40 mph under good conditions and bad conditions not many 20 foot boats will treat you well above 30mph in the average chop. Cruising with crowded waters and the captain aboard 23-27 mph cruise is plenty. Trim tabs on this hull and many others do make a difference. I can tell you that Grady White still makes the 208 with a 150 option. I don't think they would sell an unsafe underpowered boat. I would not want any less power but I have been in all kinds of seas and weather and I have never felt unsafe underpowered. I do plan on moving the batteries forward to take some weight out of the back of the boat. I would also like to add that I only have a bimini top with enclosure, no hard top or added weight. I may add an arch in the near future.