Repower older Grady with 4stroke - yes, again

[ELMO]

I know this subject has been discussed many times so please bear with me. In 1988 the 24 offshore was rated for a 300 hp outboard according to the catalog online. This is a little puzzling to me since nobody was making a 300 hp outboard in 88 that I am aware of, so was GW just guessing at what a 300 hp might weigh?

The engine put on the boat (I am interested in) was a Yami 225 (397lbs). If a 1990 Yami 250 was put on it, the engine would have weighed 496lbs. If the Yami F225 weighs 596lbs and the 24 offshore was supposed to be able to handle a 300hp, is the weigh difference really that drastically different?

Is anyone aware of hard and fast numbers that GW would have used back in 88 to detertermine engine max weight. I have sent them a couple of emails trying to get this info with absolutely no response. Thanks

 

[jekyl]

I am not familar with your model but guess that would mean 2x 150 hp's so if you know the weight of 2 older 150 hp's then that would give you a ballpark figure as to what it can handle in weight.
My gut feeling is if it is approved for 300hp in '88 then a modern 250f is not going to be a problem. Am I right ? let's see.

 

[whitey]

it's been suggested before.so this time,i will suggest it,call grady customer service,ask them ,then post the results of the conversation with them.
i repowered with 2 strokes after i bought the boat,my yamaha engines have been trouble free till this season.i had a problem with the wiring in the engine,wouldn't transfer oil.

 

[gradyfish22]

It was rated to handle (2) 150's at that time, I've seen a handful with twin 130's that seems popular on that model in my area. They were not guessing what a larger outboard would weight thats impossible, if a rating goes over 250 it likely can handle twins unless it is a newer boat built during or after the introduction of the larger outboards. I agree with Jekyl's theory, but from seeing many repowers, I will have to say this is not a 100% science, for some reason newer 2 strokes and all 4 strokes have more weight aft in the cowling so even though they weight the same the weight distribution is slightly different so that weight on your transom will effect the wa the boat sits more. you may add the same weight, but your boat may sit slightly lower, maybe a 1/2" then an older engine of similar weight. Also, I do not believe 4 stroke weights include liquids, that menas the lower unit oil and oil in the engine aren't accounted for, that adds a few more lbs aft and might be part of why boats with these engines sit differently after a repower.

 

[BobP]

I'm surpised that model and vintage has such a rating, is that what the boat's capacity plate reads?

There used to be an OMC V8 300 HP 2 stroker, but never saw one on an Offshore, usually single 225 OMC original. Never saw twins.

Is the cutout wide enough for twins?

Check the capacity plate to verify HP rating.

 

[dbookman]

I'm not surprised. My '84 Seafarer 226 rated a 280 HP engine, and at least at that time, no manufacturer made an engine of that size either. A rating of 20 more HP for a 2ft longer boat seems quite possible.

I did a lot of reading on this subject when I decided to re-power, and there were several "experts" who said that my boat was not designed for a 4-stroke. As none of these folks could cite any sound engineering reasoning behind why this is the case, I continue to challenge that notion. I believe the issue should be based on the characteristics of size, weight and power (and possibly center of gravity), as these seem to be the primary engineering characteristics which come into play.

With this in mind, I managed to find one manufacturer that made a 275 HP motor back in 1984, and I looked up the stats to check its weight. I reasoned that weight was the main factor, and if I could find a 4-stroke replacement that was close to the weight of the 275 (and preferably less), I should be fine. I ended up getting a Suzuki 200, which turned out to be 14 lbs heavier - a nominal difference in my opinion.

I accept the notion that I may someday come across a marine engineer who finds fault with my reasoning, and I'm o'kay with that. If it happens to be one of the posters to this forum, instead of telling us what technology is acceptable for use on our vessels, please describe for us the engineering requirements an engine has to meet in order to accommodate the limitations of each different hull.

In fact, I'd really like Grady White to provide us with this information, because without it, it almost seems like they are implying that our boats will be obsolete once the outboard manufacturers finally stop making 2-stroke engines, and the only thing we'll be able to do at that point is rebuild old 2-strokes (until the EPA outlaws them), or buy a newer Grady.

 

[Tuna Man]

I had an 88 Offshore for a while. Mine had the notched transom and I am almost certain it was made to handle twins. From what I recall, most 88 Offshore's here in the northeast were fitted with Evinrudes or Mercury's (the same was true for many Grady models back then). Mine was fitted with a Evinrude 225 V6, however it looked lost on the transom when you looked back underway. I am not certain but pretty sure Evinrude did in fact make a 250 and a 275 V8 back then, maybe even a 300 V8 as Bob suggested. These motors were real beasts from what I remember. Basicaly a V6 block expanded into a V8; the V6 was around 3.0 liters, the V8 would have been 4.0 liters. Eight carbs instead of six, different (heavier) lower unit, much bigger cowling, etc. Very heavy motors for those days, I would guess at least 650lbs with prop and two cycle oil and holding tank. The twins would weigh at least that with the same required equipment.

In my opinion, you would be fine with a 225 four stroke as far as weight goes. If yours in on a bracket (not transom mounted) I'm guessing you'll still be ok.

 

[Glassmann]

I Repowered a 1982 carribean with a F250 Yamaha. It was rigged with a omc sea drive. I couldn't be more happy with the results[/img]

 

[smontgomery]

Elmo:

I've recently hung an F225 on my '95 208.

I love it. Absolutely love it.

I could tell I made the right move, right off the bat, when I saw the expression on my mechanics face the day I told him what I had done.

I did lots of homework. I spoke to the folks at GW. I called more than a couple of dealers. I spoke to lots of mechanics.

I also had a 200lb friend sit on top of my '95 Evinrude 175 OceanPro so I could see how the boat would sit in the water. The F225 is about 200lbs heavier than the Evinrude.

The boat sits a little lower aft with the F225 than with the Evinrude 175. However, Not as much as I expected.

The scuppers are both out of the water. That was my biggest concern.

The boat gets up on plane with no problem. I have trim tabs and do use them a bit more now.

45mph at WOT is faster than I ever need to go on a 208. I cruise at 32 mph at under 3650 rpms. Nice. I think it's sipping fuel. I'll know for certain when I install a fuel flow monitor soon.

I could never carry on a conversation while underway with the Evinrude 175 2s without almost yelling. Now, it's more than comfortable. At idle, the motor is almost silent. All you hear is the cooling H2O exiting the water jacket. Plus, no smoke. Nice.

The F225 might be a little overkill for a 208 but I bought it used, and got a smokin' deal. (no pun intended). It weighs the same as the F200 and the F150 would have been a bit of a weakling when those few extra horses come in handy.

It is amazingly pleasant for trolling compared to the 2 stroke Evinrude. No smoke. Ahhhhhhhh.

You'll be fine. Go for it.

Cheers.

 

[ELMO]

Guys,

Thanks for the feedback, I really do appreciate all of it. I feel like an idiot because it never crossed my mind that GW was possibly talking about twins to get to 300hp but I was also talking about the 242G with the bracket. Is the bracket designed to handle twin 150's, I don't know?

If the boat does not get bought out from under me, (I believe someone on this site is looking at the same boat), I will be sure to consult GW as well as the dealer who would do the repower to be sure I am not doing anything detrimental. Again, I appreciate all the insight. :wink:

 

[GulfCoast242G]

Repower

Elmo,
I have the same boat 88 242g and repowered last yr. We ended up w/ twin Etec 115s. That was the only option for twins b/c of weight issues. I have talked w/ a few people w/ single f225 repowers and they reported no problems. Twin 4four strokes are out of the question in my opinion b/c that would put both scuppers solidly under water--not good. I should also mention that we did have to have the transom re-enforced on installation b/c of some delaminatiin in the middle of the transom. we had twin Johnson 140's (4cyl) prior to the repower. We were also not successful in getting a water tight seal on the bracket and will deal w/ that soon. best of luck.
tight lines.

 

[plymouthgrady]

re-power

I believe Evinrude actually made a 300hp back in the day.
It was a colossal (sp) V8 that couldn't get out of it's own way let alone get a boat on plane.
I repowered my 228G (bracket) w/ a Yami 250 SWS II a few years ago and absolutely love it. I'm a 2 stroke fan all the way. The 4 strokes are great reliable engines but don't get tunnel vision on your options.