Ughh, just found out I have the wrong gear ratio outdrive! Help!

[tarheelebbtide]

So I've mentioned before that every boat mechanic in these parts seems to be a crook and that's why I'm learning to work on the boat myself. Yesterday, when installing my new smart tabs, that was reaffirmed to me. I have a 92' 20' Ebbtide bowrider with a Merc 350 Mag in it and Alpha One drive. The motor is freshly rebuilt but when it came back last year had an aluminum prop on it instead of the stainless it left with. I sent it back and through much harranging (including the owner of the shop calling ME the crook and saying I was lying about the stainless prop even though I had pictures of the boat with it on there before) and they put a stainless prop on. Since then, the boat runs great, but I was thinking they underpropped it because it would turn too many RPM (about 5200). To this point, I've just manually made sure not to exceed max RPM. Now I'm at the point where I want to purchase a new stainless prop to correct the overrevving but yesterday I look up when installing the smart tabs (which are awesome by the way) and see 1.62R stamped on the side of the damned drive. Last year, I wouldn't have a clue what this meant. Now, however, from reading this board, I know that's not the right gear ratio for this 350. My question is this....can I correct this with prop (I'm at 14X19 now and thinking of going to 14X23) and be reasonably ok? I definitely do not ever want to take the boat back there and would rather eat a new drive than have to see the man again. Should I start budgeting now for a new gearbox or just try to bring it back into line with the prop. Thanks guys and sorry for the long post!

 

[Fishermark]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

The general consensus is not to try and compensate an incorrect ratio by simply changing props. In your case I would say try it. It is far cheaper than changing the drive.

 

[SuperNova]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

The general consensus is not to try and compensate an incorrect ratio by simply changing props. In your case I would say try it. It is far cheaper than changing the drive.

That being said, the best way to think of it is the gear ratio is the rough adjustment and the prop pitch is the fine adjustment. As long as you can get where you need to be it really doesn't matter where you make the adjustment, but once you get out of the common range on the prop, your choices start getting slim. The main downside is that the 1.62's are not as thick as the 1.5's and therefore some consider them a little weaker. I had a 20' Wellcraft that originally came with a 4.3 and 1.62 gears. I pulled the 4.3 and put in a hotrodded 355. I kept the same outdrive and ran a 26 pitch 4 blade stainless Mercury Bravo prop without any problems for years. The guy I sold it to is still running it that way.

 

[Limited-Time]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

You have a viable drive which means it has value..................it can be sold to offset the cost of the correctly geared SEI out drive with a 3 year no fault warranty.............from there you can prop on .............

 

[Robj]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

Based on the cost factor, I would just try to change the prop. If you would not have seen the 1.62, you would have never known.

Have a great day,

Rob.

 

[John_S]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

If the current prop is a "standard" ss prop, ie general shape as stock aluminum, you may be better served with a more performance oriented prop which maybe less pitch, because of cupping and other factors.

I would get your current wot rpms and speed, and current brand/type/size ss prop, and repost in prop forum. I would also indicate, what you would like to improve, plane time, top speed, cruise, etc.

 

[SuperNova]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

If the current prop is a "standard" ss prop, ie general shape as stock aluminum, you may be better served with a more performance oriented prop which maybe less pitch, because of cupping and other factors.

I would get your current wot rpms and speed, and current brand/type/size ss prop, and repost in prop forum. I would also indicate, what you would like to improve, plane time, top speed, cruise, etc.

UMMM.....he wants to know whether he should get a new outdrive with the proper gear ratio or attempt to re-prop to make up for the wrong gears.....................you know half the time I believe people don't even bother the read the original posting......

 

[jaxnjil]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

what elevation are you running at?
if your over 2500 ft they did you a favor.
you only droped one range and should be able to prop for that with no prob

 

[John_S]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

UMMM.....he wants to know whether he should get a new outdrive with the proper gear ratio or attempt to re-prop to make up for the wrong gears.....................you know half the time I believe people don't even bother the read the original posting......

Yes, SuperNova, I did read the question, and thought you answered it fine in your prior post. I guess I should have stated that I agree that the ratio is close enough, but more importantly the data doesn't show that it is a major problem, and will be able to fine tune with prop. Before just buying a 23" pitch ss prop, he should get some more info and a better recommendation on brand/type.

 

[rad1026]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

jaxnjil, us people at altitude are the only ones that think about that. I had to regear to 1.62 in order to get my RPM's in range. Albuquerque is a mile high.

 

[jaxnjil]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

jaxnjil, us people at altitude are the only ones that think about that. I had to regear to 1.62 in order to get my RPM's in range. Albuquerque is a mile high.

ya; we run 1.65 down from 1.32. elevation from 3600 to 8000

 

[wca_tim]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

supernova was right on track with his point that rather than go by the blanket concensus (can be right sometimes, usually works, but is not necessarily the best for a lot of situations), you might be best served by spending the cash getting the right prop for the gear you already have. Case in point, I intentionally run a 1.84 gear ratio, typically found behind a v-6, behind my stroked 350 (385), because it's a light boat and lets me access a range or props that perform much better than the available 21" and 23" pitch props with a 1.47 gear ratio (typically found behind a 350). I have and have run a 1.47 gear box, but the boat performs better for my purposes running a 1.81 and 27" to 30" props.

Truth be told, there is only a slight difference between a 1.5 and a 1.61... nothing like if you had a 1.98 - that would be a tough one to get around with props. 1.5 - 1.6 is only going to change your prop pich a couple inches. As long as you prop right your boat will probably be just a little bit faster on the upper end with the higher gear in it...

like don said, post a brief descrition of the hull and details about what prop you're runing now (including the specific prop - not all "14 x 19" props are created equal), and something about what you us it for / performance performance characteristics you're interested in most (all around, top end, pulling heavy slalom skiiers out of the hole, etc...).

 

[tarheelebbtide]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

Sorry to be so slow in replying guys, you know...work getting in the way of the important things like boating! Anyhow, since I know very little (nothing) about props, I figured I would yank her back out of the water and take you all a few pics. As they say, a picture is worth 1000 words. I photoed all of the engravings I could find on the prop as well as a couple of pictures of it so you all might be able to tell more about it. It also included a hull shot in there. Thanks again for all of the help!

Oh, as for what I use it for, generally just cruising with 2-4 on board. I might pull a tube from time to time, but that's about it. I'm also in eastern NC so pretty much at sea level. Right now I know it'll run up to about 5200 at WOT if I let it (which I don't) and it's doing about 52 at that RPM. At 4500 or so it's doing about 48-49. These are GPS speeds, not speedo. The smart tabs have really cleared up the bow rise now (though I know with a steeper prop it'll have more of that, might have to adjust the tabs to a higher lift level). Anyhow, hope this is the info you might need to help me out. Thanks as always! Slowly but surely I'm learning!

http://s525.photobucket.com/albums/cc335/diamondheels02/Ebbtide/

 

[tarheelebbtide]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

Also, have an opportunity to get a stainless Mirage prop in like new condition on the cheap. It's a 15X23. I don't know anything about the Mirage props though I plan to ask in the prop forum...my question here is would the 15 be too large of a diameter since I'm running a 14 now?

 

[wca_tim]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

How far east are you in nc? Might be able to suggest a mechanic / shop...

 

[John_S]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

IMO, the prop you have and how you are controlling the overrev is OK. You don't have to change it. It sounds like you are happy with the boats overall performance. Keep in mind, upping the pitch will lower the wot rpms down, and have a higher top speed, but it will also lengthen your onplane time.

I would retest the boat at wot, normal load/number of people, gear, plus full tank. This would provide a good baseline to then make the decission. A 21" pitch of a similiar type prop, may be a much better choice than jumping to 23".

I wouldn't jump on the Mirage, unless there is test/return agreement. Even if your current 5200rpm is with full load. The extra diameter, plus there might be additional blade cupping (which acts like addition pitch), could put you in an under propped situation, which is much more damaging to the engine.

 

[achris]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

I happen to agree with the previous poster. I'm running a 17" and will bang on the rev limiter at WOT with 'normal' load.... But if I try and run a 19", which keeps my WOT in the right area, in the mid range it's a dog. You'll also find that you'll be using less fuel with the smaller prop... engine's not working as hard... same revs, slightly less throttle. And you've improved the longevity of your engine....

My 2c worth.

Chris........

 

[tarheelebbtide]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

Thanks guys for the replies. I'm thinking I'm going to pick up a 21" prop and go with that. I'll have the 19 as a spare or if I'm going to be heavily loaded or pulling a skier. The new smart tabs have the thing popping out of the water almost instantaneously so I think I can afford to lose a bit on the low end. I'm just eccstatic to know that I'll be ok with the 1.62 drive on there.

 

[wca_tim]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

sounds like a winner. The reason I asked wherebouts you are is that I live in pirate / pamlico country, and have at least a couple of props that you might experiment with. I don't have any I want to sell, but if local and convenient might let you try a couple one afternoon... (21" 4-blade solas, vented 23" laser 2, come to mind right off the top, may have a turbo and one other but would have to look in the kitchen and see) Can also recommend some shops that keep an inventory of used props in the back if you ask, they'll often let you try before you buy... .

Something to consider before making the leap is which 21" prop you're going with. as I'm sure you realize, they're not all created equal. For example on a relatively small boat with an alpha drive, you should be able to go with more pitch on a laser 2 than a mirage, see similar out of the hole performance and better top end. the mirage has a lot more blade surface area to bite with bravo drives and bigger horsepower rigs... and might be outperformed by other props...

Also, if going with a given pitch gets you the right / best top end, and since you're running your exhaust through the prop, a vented prop will get back a lot of your hole shot under heavy throttle with the same pitch for more top end - if you balance the two you can get the best of both worlds. I like the merc props that come predrilled and take the cheap plastic insterts to change the vent size in the hub. You buy a couple didfferent sizes of vents as well as the plugs and see what gets you the best launch without starting to ventilate in turns, etc...

Just some things to think about.

 

[wca_tim]

Re: Ughh, just found out I have the wrong gear ratio outdrive! Help!

I happen to agree with the previous poster. I'm running a 17" and will bang on the rev limiter at WOT with 'normal' load.... But if I try and run a 19", which keeps my WOT in the right area, in the mid range it's a dog. You'll also find that you'll be using less fuel with the smaller prop... engine's not working as hard... same revs, slightly less throttle. And you've improved the longevity of your engine....

My 2c worth.

Chris........

note that having more gear reduction helps this issue - torque at the prop is increases proportionately with a higher gear ratio.