V Drives vs. Sterndrives Performance Question

[mwph]

I just read an old document from Power Boat Guide that states that the 99 310DA w/260HP sterndrives will top out @ 6-8 knots higher ("mid 30's) than the same engines w/V drives("26-27").

Speed is not all that important to me but for my research/learning is it really that much different?

 

[Air O'Nautical]

Yes,
Drives can be trimmed to run level with the surface of the water.
They don't have all the drag of an inboard set up either.

Speed and economy with outdrives are traded for better handling and durability with inboards.

 

[Sundancer]

It's not like you run flat out every time you go somewhere. I'm not sure why that is important, but yes the sterndrives are faster. But, they come with impellars and a lot of additional maintenance that the v drives don't have. If you trailer your boat, the sterndrives are nice and you can get closer to the beach with sterndrives. If you intend to leave it in the water and don't have a lot of shallow areas, the v drives get the nod.

 

[mwph]

I just didn't think it would be that much. I guess I never saw the stats side by side.

 

[keokie]

Ride differences depends a bit on the boat. Some boats ride better with sterndrives.

Also, there is a much different feel at the wheel on plane.

For durability, and handling around a dock the v drives are clear winners. On plane performance goes to the sterns.

Long term cost with a v drive is likely to be much lower. But it is not entirely a given. Labor rates can be higher with V's because the bilge is far more cramped on boats in the 30-35 foot range. I can work on my motors and gen very easily in my 310. I have been in the bilges of other 310's with smallblock V's and a gen. It is drastically worse. It takes a contortionist to do much of the simple maintenance and extensive disassembly for a lot of the more serious issues.

Also, while sterndrives are much less durable, they are easy to remove. Rebuilding/replacing Alphas is not terribly expensive (Bravo's are a good bit more).

 

[JimT]

Everything with boats is a trade off. We are currently boating in freshwater. I prefer stern drives for that use for the increased performance and fuel economy. In salt water V drives are the way to go if you keep the boat in the water.

 

[fwebster]

While the specs may show that the i/o boats are faster and a little more efficient, in actual real world experience, the speed and efficiency curves begin at the same point then diverge as rpm's goes up. When you run the i/o and v-drive boats at normal cruise speeds, the curves are fairly close together. It is only when you run at high speeds that the i/o is superior.

The reason is added fixed drag of the rudders, shafts, struts and props on v-drives. But, there is a trade off in maintenance cost with i/o's. Both drives have to be removed and serviced every year, but with inboards, service is just replacing the transmission fluid and either washing or replacing the filter.

In deciding upon which drive system your need consider these questions: Do you really need the last 4-5 mph of speed? Do you really want 2 gear cases with 3 power transmission direction changes running under water, along with the added risk for mechanical failure, leaks, seal failure, tilt/trim woes, etc, vs. having the power transmission equipment inside the boat in a dry area? Do you want to buy into the need to have a trained service technician service your outdrives every year? Do you want the added risk of expensive physical damage if you hit a log or stump......you might damage a prop on a v-drive ($300 at the prop shop) but you can total a $3500 outdrive with the same type event.

Or, do you want a low maintenance propulsion system you can maintain yourself? Do you want a boat that handles in an easy and predictable manner? There is also a point at which i/o begin to negatively affect resale ability and values........in Sea Rays, somewhere at the 32 to 34 ft point, there is significantly less demand for i/o's than for inboards.

Interior working space varies by boat model, but beam is the gotcha. Sure, you have more room in front of the engines on an i/o, but that doesn't help with plug changes, started maintenance/repairs, manifold/riser maintenance...........and what about all the i/o specific stuff (trim pump, trim switch relays, shift linkage, etc.) located behind the engines?

Finally, ask yourself if you are going to save enough fuel with i/o's to pay the added $2000-$2500/year in maintenance.

 

[keokie]

Frank makes good points. I'll offer some additional thoughts.

Value does depend a bit on the market. In AZ, NV, CO, NM, UT the outdrives have no value disadvantage, and often take more money. In Florida and other saltwater areas, outdrives are a big liability.

Outdrives are quite easy to service. The key is the boat has to be out of the water. So, if you don't have a means to do that conveniently, that will be a challenge. Repairing outdrives is not overly complicated, but there is very little room for error. So, if you don't know what you are doing, don't try to fix them youself.

Corrosion is a very real issue with outdrives, especially in salt. The Bravo III's are the worst. I have openly stated on this forum that I would not own Bravo III's if I was slipped in saltwater.

I'll disagree with Frank on the serviceability of sterndrives in boats 30-35 feet. There is a big advantage to sterns. I can work on my engines easily, and service items that Frank mentioned are all well within reach. As I menioned, I have been in the same boat with samller engines and V-drives. It was a nightmare. Plugs and impeller on gen was terrible, rudder and shaft seals, starters, would probably require engine removal, bilge pumps were well out of reasonable range (would hate to have to clear one in adverse conditions), etc.

I have run a number of cruisers in the 30-35 foot range with stern and v's. To me, the sterns handle better (except around the dock), use less fuel, produce higher cruise and top speeds, are quieter and smoother.

My boat spends most of its life on a trailer, and we boat a lot at Powell where we back in to the beach. If you get pushed into that beach by a storm, outdrives do fine. V's would likely bend a rudder, prop, or shaft.

To me, the issue is how you will use the boat. If it will be trailered, or dry stored, I would go with outdrives without question. Some people will recommend outdrives by saying it is very difficult to trailer a V drive. This is incorrect, a properly set up trailer will make trailering a V-drive no problem.

If you slip in freshwater, I would lean towards v's, but it is iffy depending on other factors.

If you slip in saltwater, v-drives first by far. Then MAYBE, MAYBE Alpha's or Bravo I's. If you had a gun to my head, I MIGHT do Bravo III's.

I and many family friends have been boating extensively with outdrives for 20 years. None of us have had catastophic failures (excepting the very early years that involved an OMC 800). The closest has been a couple inexpensive seals and one thrust assembly (about 2K).

 

[Kameroo]

Another thing to consider: you're personal preference. In the end, that's what matters.

 

[Uplate]

Do you want the added risk of expensive physical damage if you hit a log or stump......you might damage a prop on a v-drive ($300 at the prop shop) but you can total a $3500 outdrive with the same type event.


Finally, ask yourself if you are going to save enough fuel with i/o's to pay the added $2000-$2500/year in maintenance.

Frank, you are certainly have more boat knowledge than I, but:

I understand that outdrives will kick loose if they hit a stump to prevent damage as if they were otherwise "hard mounted". Fortunately, in the 30 years of running IO's I have never had to test or question this feature.

I have to agree with Keokie. I was in the bilge today checking fluids and other maintainence stuff. I could almost put a hammock down there between the engines and genny.

I can even get under the engines and remove the oil drain plug. Not sure if you can do this with the Vdrives in my size boat.

For my use and area I boat they are a great thing. I like the option of raising the props up. If I was to have a larger boat, there would be no question as to Vdrives would be a better option...

We replaced our Outdrive on our bowrider this year for about $1600 including installation and removing of old drive. It was a rebuilt to Merc specs with same as new warranty...so far so good! I think it came from East TN.

 

[Woody]

I did get to test mine on the 270SD. I hit a submerged log and it was quite a jolt felt against the hull and outdrive. The drive kicked up and then went back down. There was no visible damage to hull or drive. When I had the alignment, etc checked everything was OK. My friends older B3 does not kick up like mine. I don't know when this ability became a feature....maybe his just doesn't work right.

 

[Uplate]

Keokie-

I notice that your boat has twin 496. what is your top end speed? I would imagine that set up screams in that size boat with IO's.

 

[JV II]

Let me start by saying Frank is a valuable source of info on this site. While I agree with most of his post, I respectfully disagree on the following points:

When you run the i/o and v-drive boats at normal cruise speeds, the curves are fairly close together. It is only when you run at high speeds that the i/o is superior.

Frank is correct on this point as this article demonstrates, but these is an appreciable difference in speed and efficiency between the two drivetrains. http://www.boatingmag.com/article.asp?article_id=877&section_id=4

Do you want the added risk of expensive physical damage if you hit a log or stump......you might damage a prop on a v-drive ($300 at the prop shop) but you can total a $3500 outdrive with the same type event.

Damage to a shaft, strut, and bearing are common when striking logs and bottom in a VD boat. When this happens you can expect a repair bill with four digits. Those stories are all over CSR. In the worst case, a shaft can be ejected from the boat leaving a nice big hole below the water line.

In Sea Rays, somewhere at the 32 to 34 ft point, there is significantly less demand for i/o's than for inboards.

My dealer had four identically equipt 330DAs in August this year. Two other nearby dealers had 5 others. The first one to sell was the only one with the I/O. In fact, there was a back-up offer on it. There remains six VD 330DAs to be sold.

Finally, ask yourself if you are going to save enough fuel with i/o's to pay the added $2000-$2500/year in maintenance.

I strongly disagree. I have the dealer service contract for my winter lay-up and spring commissioning. It itemizes "Lower unit gear oil change, removal and inspect: bellows, gimbal bearing, universal joint, and pressure test drive (per drive)" at $230. The anode kit is a little more money for the I/Os than the VDs. Aside from that, you pay the same for either the VD or I/O for annual service. So, the difference in annual service cost is ~$500. That's assuming you do nothing to change the transmission oil, inspect the transmission, shaft, strut, and bearings in the VD, which I imagine has an annual price attached to it. I typically put 100 hours on the engines each year. If I save 1 gph, that's $350. So, additional service cost is offset by the fuel savings.

We all have our biases and specific circumstances. I have an I/O, my second and I boat in salt water. This one is a Sea Core model, so I'm less concerned about corrosion, however, my last boat showed zero corrosion in one season, except for the anodes. All other things being equal, I do prefer the high speed performance of the I/Os. Combined with a bow thruster, maneuverability around the dock is magical, so don't believe that the VD is easier to dock.

 

[JV II]

Keokie-

I notice that your boat has twin 496. what is your top end speed? I would imagine that set up screams in that size boat with IO's.

My displacement with half fuel and water is ~16,500#. My top end speed is 50 mph, half fuel and water, two onboard, clean bottom, and calm seas. That's been confirmed by GPS. Incidentally, the same boat with VD, tops out at 40.3 mph according to Boating Magazine's test.

 

[keokie]

Uplate,

My boat is propped to run heavily loaded at 3800 ft elevation. In that environment it will run high 40's.

It will run very low 50's in the rev limiter at 1200 feet elevation and lightly loaded.

Oh, I would comment, though, that the kick up mechanism is a very good design (take apart the hydraulic rams on the drive and you'll see how it works), but if you hit something, you are still very, very likely to break something expensive. I know guys that make a fine living repairing impact damage to outdrives. BIII's are particularly susceptible becuase of the shaft-inside-shaft design combined with counter-rotating steel propellers. But still, impact and outdrives commonly busts off teeth on gears, and bends or breaks shafts.

It is my understanding that impacts can be catastrophic to underwater gear on v-drives, but the transmission itself usually does fine.

 

[my3sons]

My 2 cents, as my twin bravo III 33 da is still fresh in my memory. We just finished (hauled today) our first season with an inboard boat.
Your original question of speed...I would say 8 to 10 mph on my 95 da over my dock neighbors same year and model v-drive. Mine would do 47 mph lightly loaded with the two of us on it. 44 mph normal loading.
1.25 MPG running 3000 RPM at 28-29 MPH, proven several times running the length of lake Erie on long trips.
Lot of good points made by others in previous posts, most of which I agree with. I did not see mentioned running attitude. My 33 would run at normal cruising speed with the bow much lower than the V-drive boat. making visability much better and much more comfortable at the helm.
My boat was noticeably louder than my neighbors boat (drives made a whine)
My boat sucked in exhaust fumes (station wagon effect) badly. It was the one thing we disliked most about that boat. The V-drive boat does not seem as bad.
As far as our current inboard boat compares, It it MUCH quieter, and there is very little exhaust fumes. When running at cruise with no tabs (most economical) the bow is higher to the point where I have the helm chair fully raised and I sit on the throwable cushion.:grin:
So far I have changed the tranny oil and filters and aligned the shafts. (Shaft alignment should be checked every couple years unless you pick up a vibration that can not be otherwise explained.) THat should be all that ever needs doing to the drives
I owned my 330 for almost 10 years and never had any problem with the drives, But every year I pulled them and brought them home, and painted them, and changed the oil, and dumped the oil in the reservoirs, changed the anodes, and greased the splines and the u-joints, and checked the teeth on the couplers and greased the gimble bearings and...well you get the picture. In a boat the size that both drive options are offered, you have to decide if you want to do all that work (or pay to have it done) to get that 8 MPH and better fuel economy. Or, you don't have to do all that, but don't plan on keeping the boat 10 years.
Both have advantages, so thank God stern drives aren't offered on 360's, I don't have to make that decision, and besides, my back can't take that any more. Take care

 

[sb in gp]

My 2 cents, as my twin bravo III 33 da is still fresh in my memory. We just finished (hauled today) our first season with an inboard boat.
Your original question of speed...I would say 8 to 10 mph on my 95 da over my dock neighbors same year and model v-drive. Mine would do 47 mph lightly loaded with the two of us on it. 44 mph normal loading.
1.25 MPG running 3000 RPM at 28-29 MPH, proven several times running the length of lake Erie on long trips.
Lot of good points made by others in previous posts, most of which I agree with. I did not see mentioned running attitude. My 33 would run at normal cruising speed with the bow much lower than the V-drive boat. making visability much better and much more comfortable at the helm.
My boat was noticeably louder than my neighbors boat (drives made a whine)
My boat sucked in exhaust fumes (station wagon effect) badly. It was the one thing we disliked most about that boat. The V-drive boat does not seem as bad.
As far as our current inboard boat compares, It it MUCH quieter, and there is very little exhaust fumes. When running at cruise with no tabs (most economical) the bow is higher to the point where I have the helm chair fully raised and I sit on the throwable cushion.:grin:
So far I have changed the tranny oil and filters and aligned the shafts. (Shaft alignment should be checked every couple years unless you pick up a vibration that can not be otherwise explained.) THat should be all that ever needs doing to the drives
I owned my 330 for almost 10 years and never had any problem with the drives, But every year I pulled them and brought them home, and painted them, and changed the oil, and dumped the oil in the reservoirs, changed the anodes, and greased the splines and the u-joints, and checked the teeth on the couplers and greased the gimble bearings and...well you get the picture. In a boat the size that both drive options are offered, you have to decide if you want to do all that work (or pay to have it done) to get that 8 MPH and better fuel economy. Or, you don't have to do all that, but don't plan on keeping the boat 10 years.
Both have advantages, so thank God stern drives aren't offered on 360's, I don't have to make that decision, and besides, my back can't take that any more. Take care

Sorry to hijack. You mention shaft alignment every few years. Is that necessary, and approximately what does it cost? Thanks.

 

[my3sons]

Sorry to hijack. You mention shaft alignment every few years. Is that necessary, and approximately what does it cost? Thanks.

I suppose a lot of people don't do it, but checking it is easy. Our boat definitely ran with less vibration after I did it, and I have read too much on this forum about broken shafts and leaking tranny seals to not check this rather simple item.
I can't help you with cost because I did it myself, It can't be to much, start to test drive was 4 hours and I had never done it before. It involves moving your engines on the mounting systems, so if your not sure about doing that, maybe hire it out the first time. There is plenty writen on the procedure. Start with the motor installation instructions in your owners packet. All the things I read went into detail on how to adjust the motor angle to meet with the shaft couplers, not enough was said in my opinion on just checking it, and if it's out of spec. have someone else adjust it.
To check it, make sure boat has been in the water for a week or so and is loaded normaly for how you use it. (do not check it if it is on the hard, blocking and stands distort the hull and stringer system from what it would be in the water) unbolt the four bolts and nuts that join the shaft couplings and note the alignment of the two couplings, mine had aligning dimples drilled into the edges of the coupling halves. If your alignment was as wacked as mine you will see a gap in the mating surfaces where they come together. I pulled the shaft back just enough to clear the center hub on the shaft coupler from the recess on the tranny coupler that it fits into. The hub and recess is there to make sure everything is straight when assembled.Slide a peice of cloth in between the mating surfaces to be sure no grit or paint peelings fel in between when you pulled them apart and then by hand, put them back together, tapping them slightly with a rubber mallet to be sure they are in good contact. Now see if you can insert a .003 to .005 feeler gage in anywhere around the circumfrence of the set up. If you can, something is amiss. Now turn the SHAFT half 180 degrees,(yes the shaft and prop and all turns), and repeat. If the gap, if there was one, is still in the same place in relation to the TRANNY coupler half, the alignment needs to be adjusted. If the gap is in a different place, or disappeared, the shaft may be bent, in which case you have other things to deal with before aligning the motor.
My starboard side had a gap of .015, roughly 4 times what it should have been. The port was .008.
If they are out and you do not want to get into moving the motors around, I would just bolt them back up (make sure the halves are aligned the way they came apart) and let your yard do them in the spring. (don't do them now if you're hauling for the season in northern climes. The time to do alignment is in the spring about a week after it is back in the water.
Keep in mind It's the first time I did it, I'm not an expert by any stetch of the imagination, but I have a mechanical backround so I am not afraid to do this kind of stuff. (my beam is 12.5 feet, that is definitly a help) I can't imagine it would take a professional any more than an hour and a halve per side to check and adjust.
Maybe some of the guys here who have had inboards for years may know that every time you check them, you end up adjusting them. If that's the case, just have the yard do it all every year. How 'bout it guys, anybody have any input on how often it had to be adjusted? I'm pretty sure mine had never been done, there wasn't a sctatch on any of that black paint on those nuts and bolts
Take care
P.S. if for any reason you have to replace those bolts and nuts, (drop one in the bilge never to be seen again) be sure to use grade 8 hardware.

 

[fwebster]

julia valentine seems to disagree with several points in my post above:

Physical damage-
While damage can occur with a v-drive, the exposure is no where near as great as Mike's statement leads one to believe. Only about 1/2 the prop is exposed below the keek or pad on the bottom of the boat since nearly all Sea Rays have tunnels in the bottom to partially protect running gear, unlike an I/O where an entire gear case is exposed to impact by underwater obstruction. I have never heard of an inboard transmission being damaged by hitting something because the internal clutches protect the gear assembly, but damaged lower gears is quite common on outdrives.

Resale values/demand -
While your dealer may be successful with i/o's in this day and time, boat shopping is national thanks to the internet. Nobody cognizant of the corrosion potential on outdrives who keeps a boat in salt water is a potential buyer and that rules out coastal Carolinas, FLorida, MS, AL, TX etc. The fact that you leave a boat in salt water a few months a year and haven't seen corrosion yet, only means you haven't owned the boat long enough......it doesn't mean it isn't going to happen, but is certainly does mean your potential market is significantly smaller with i/o's at t he time of resale.

Maintenance cost-
Your extra $230 /year for maintenance to pull the drives is based on one huge assumption.........that nothing is needed but fluid replacement. That is one huge faulty assumption. Stainless props put large loads on the i/o propshaft, bearings and seals. You will be paying for resealing the lower unit.........on i/o boats here that are used 12 months a year, on 2 outdrives, careful owners pull drives and service them every 75 hours, and end up resealing at least one drive every other year.


Give your self time to get a little experience with twin outdrives and I suspect you will learn that higher speeds and a little better efficiency isn't worth the added cost and hassle.

 

[Southpaw II]

As I recall the original question regarded a 310DA. This is one of those borderline models that was regularly produced with both I/Os and V-Drives; you see a lot of both out there. Also, this is a model that I have seen residing in slips year-round, and trailered on a common basis. Complicates the answer....yes the I/O boat "real" and "published" speeds are a bit faster, but the real need for that extra 5-6 mph is up to the user. If you run your boat WOT and utililize that eatra WOT for any length of time, it's gonna be for sale soon, and I don't want to buy it.

If you trailer your boat to the lake, and pull it home at the end of the day, I/Os will be fine. Corrosion should not be an issue, but you should still expect to spend more on maintenance in the long run than on a V-Drive boat. For me, on this particular boat, in any environment, V-Drives are the only way to go. There is a reason I/Os are cheaper and scarcer on the used market. There is less demand for them in this size and larger.