New member old Grady

[twoboater]

Hello All,
I'm new to this site but not Grady-Whites. I just bought my 2nd Overnighter 20 and third Grady. I've owned two 24's in the past. this latest one is a "barn fresh" 1983 204 c, to be named, "Retro-Grady". It's really in fantastic shape. The gas tank was replaced when it was re-powered in 2006. My question is how will a 2006 Yamaha 115 HP 2-stroke push this boat? The previous owner said "it goes just fine" but had no GPS or speedo. My 1985 20 had a 175 and was well-powered. Anyone experienced this same combination? Thanks In advance.

 

[Fishtales]

Welcome.
Good luck with the boat. Although I can offer no performance data, hopefully you will find someone here that will help you out.
I wouldn't worry too much, my guess is that will push it just fine.

 

[suzukidave]

i've got a 1986 190 tournament with a 1985 120 v4 johnson looper. it can get to 39mph with a 17" prop but i think it takes a 15" prop better which tops it out at 36 at 6000 rpm.

with the 15" aluminum prop on it planes quickly and can pull a skier or three kids on a tube without an issue.

not sure of the gearing/prop options on a yamaha 115 but i will speculate you will be a bit slower.

 

[Doc Stressor]

My old 204C came with a 135 Johnson. It would run at 36 mph with a 15" prop turning 5400 rpm. With more than 3 people and gear on board, it would struggle to get on plane.

You really need at least 150 hp for that hull. You are going to miss your 175.

 

[suzukidave]

doc was that a v6 135? if not, i suspect you must have had a 17" prop to get that speed at that rpm.

 

[suzukidave]

just thinking further, my johnson 120 is the only year they put a v6 gearcase on the v4 (but with a v4 gear ratio) so it can handle a larger diameter prop than most v4s but is otherwise the same gearing. prop is 15 x 15.5.

consequently, my 15" prop results above would be better than a yamaha 115 turning a 13x15" prop on a bigger boat, but twoboater might be able to turn a 13 x 17" and get about the same speed at 5500 with less bite.

still confused about doc's numbers on a 15" prop but they make perfect sense if he was running a 13x17" on a v4. if it was a v6 135 then it makes sense but that means a 1.85:1 gear ratio and way more torque than a 115 so his numbers are not at all comparable to twoboater's situation.

the v4 135 looper had a 2.27:1 gear ratio so doc's reported speed/rpm on a 15" proper would require -6% negative slip. if it was an old v4 crossfire 135 then the gear ratio is 2:1 and the slip would be 6% which is possible but way better than i can get on a grady.

 

[twoboater]

Thanks for your replies. You Guys really get down to brass tacks! As you discussed, I can try different props if there is any issue. Time will tell I guess! But more about the boat. I put a moisture meter to the transom, dry as a bone! No cracking anywhere. The interior cushions like new, exterior cushions and canvas 3 yrs old. Hull has nice shine to the gelcoat, still has all the original stripes annd decals in great condition. it must have spent a while stored inside. Trailer rebuilt last summer. I will post some pics as soon as I can get it to my house. Boat is snowed in at seller's yard. Could be a while.....
Cheers,

 

[suzukidave]

just googled a 1983 204c to remind myself what it looks like. the one that came up has twin 115s :mrgreen:

http://tsfyachts.com/1983_grady_white_2 ... ghter.html

 

[twoboater]

Yeah, I saw that too! Hopin' it goes ok. at least it was real short money to buy the boat.