Pros and Cons of a True Inboard

[southkogs]

Howdy y'all:

I'm in the midst of weighing out a bunch of options, and one of them that I'm starting to add into the mix is direct drive inboards. I know nothing about them, and don't want to blunder too bad if I start lookin' at 'em (Ski boats in particular).

I'm not afraid of depth: most of the places that I run in are plenty deep enough that not being able to tilt up isn't a big deal. Past that, I've never owned one and really know very little about them.

Pointers?

 

[Chris1956]

Normally the need to trim and tilt the motor is the greatest advantage of an OB or I/O over an inboard. However there is one other thing to consider. A straight inboard will normally be mounted more toward the center of the boat, as the transmission and propeller strut need some room to be installed, and you want the prop under the boat hull. On a boat less than 25' or so, this means the dog house will be behind the front seats. This takes up a lot of room in the cockpit.

V-drive inboard configuration allow the motor to be mounted further back like an I/O. Of course, a Vee drive will create a larger wake with that weight distribution, which is OK in a wake board boat, but not desirable in a ski boat.

From what I hear, inboards are pretty simple and cheap to maintain. I would expect some performance losses, since you cannot trim them up to boost speed and efficiency on smooth water. Also, if you hit bottom with the prop, the propshaft, strut and hull can be severely damaged.

 

[oldjeep]

Pros: Better/safer for water sports
Somewhat less complicated than an I/O - although you now have to deal with packing nuts and shaft alignments.

Cons: Steering at low speed is awful
Steering in reverse is impossible
Lower top speed - ski/wake boats are designed to work best under 40mph
Expensive - take the price of a comparable sized I/O and multiply by 2-4x
Direct drive (not V drive) boats have very little usable interior space when you are skiing off the pylon - basically just the drivers and spotters seats



I switched from a Bayliner 195 this year to a Malibu VTX (20ft v-drive)

 

[oldjeep]

V-drive inboard configuration allow the motor to be mounted further back like an I/O. Of course, a Vee drive will create a larger wake with that weight distribution, which is OK in a wake board boat, but not desirable in a ski boat.

Depends on the boat. Mine is a V-drive but actually designed as a crossover ski boat and skis very well even through a course at 32mph @15 off

 

[robopath]

Oldjeep is spot on. I went the other way, from a (family-owned Mastercraft) direct drive inboard to a (me-owned new Four Winns) I/O so I'll add a few additional things.

Pros:
- More expensive yes, but you also get higher resale. If want to spend lets say 35,000 you will be looking at a brand new I/O or a 7 year old v-drive.
- As above, they also tend to last longer.
- lower planing speed, key for wake boarding.
- incredible, shoulder-popping torque.
- safer yes, but the new I/O's have huge swim platforms now that go way past the prop so that's mitigated a little but not entirely.

Cons:
-Usually not as good in rough/big water, esp direct drive ski boats as they tend to have almost no V in the hull at the stern.
-very thirsty and usually heavier
-my opinion here, they are more task specific. They are either great for ski or great for wakeboard. I/O's are a compromise and can do both OK. Old jeep may disagree but I have yet to ski behind a V-drive that does not have a huge wake.

 

[oldjeep]

Old jeep may disagree but I have yet to ski behind a V-drive that does not have a huge wake.

There are a few that are good to ski behind, even better if they have some bow ballast (I run my bow tank full when skiing), they are mainly 20ft boats with ski hulls. I switch back and forth between a 2004 Malibu Response LXI and my VTX - At 32MPH@15 off I don't think there is a difference in the wake. Shorter rope lengths or speeds under 30 and the advantage definitely goes to the Response.

Decent crossover boats:
Malibu VTX
Nautique Sport 200
Moomba Outback-V
Mastercraft Maristar (the shorter ones)

 

[Ned L]

Personal preference here. I own only inboards (2 @ 16 ft, 1 @ 33 ft). I wouldn't own an I/O. To me they are unnecessarilly complicated and expensive. A straight inboard is just so simple. The weight distribution is much better in the boat too. If you know what you are doing the manuverability of an inboard is just fine.
Inboards are slower? - Either one will do what it is designed for. One of my 16' inboards does about 70 mph, is that quick enough?

 

[oldjeep]

Personal preference here. I own only inboards (2 @ 16 ft, 1 @ 33 ft). I wouldn't own an I/O. To me they are unnecessarilly complicated and expensive. A straight inboard is just so simple. The weight distribution is much better in the boat too. If you know what you are doing the manuverability of an inboard is just fine.
Inboards are slower? - Either one will do what it is designed for. One of my 16' inboards does about 70 mph, is that quick enough?

He is talking about ski boats, not drag boats or crab boats ski boats are slower, they are optimized to run 32-36MPH. Ski boat set up for barefoot might go as fast as 50, but they get pretty sketchy at that speed since the hulls are not designed for high speed.

 

[Ned L]

Yep, acknowledged. As was said, ... because that is what they are designed for (optimal performance at that speed range), it is not a limitation due to the type of propulsion.
(and no drag boats or crab boats here, .......Jersey speed skiffs. lol)

 

[Chris1956]

Jersey Speed Skiffs (for those who do not know) are routinely raced in NJ Bays. I have witnessed several of those races, and am quite surprised no one had died. They go pretty well in a straight line, but the turns are very dangerous, at least to my eyes.... I would guess "the misses" would never get in one, if she had seen it run...

 

[skibrain]

How much water sports do you do behind a Jersey speed skiff?

 

[oldjeep]

How much water sports do you do behind a Jersey speed skiff?

From the pictures I googled it looks like it would be safer to be behind one than in one

 

[Ned L]

Admittedly no one really uses them for water sports (towing). ....... HOWEVER they are actually a really good boat for water skiing behind. Lots of power to get you up quick, and at skiiing speed they are a comfortable riding boat that leaves almost no wake at all. They will pull two skiiers without even knowing they are back there. Growing up we used to ski behind one of my speed skiffs all the time.
Yes, they are a bit of a love it or leave it kind of boat, kind of like a ride on a vintage 'Harley'. An unbelievably thrilling ride. Most people that want to go out in them love it. They are actually much safer on those turns than they look. In a tight turn you can get the passengers finger tips wet if thery are holding onto the gunwale and you're not even close to any trouble. In all of racing (60 yrs) people can really only remember two or three times that one has rolled over. The concern during competative racing is one boat bouncing and going over the top of another boat, that is the reason for the 'cages' that have been required for racing since the early 90's.

 

[southkogs]

LOL ... wow! So, what kind of oil do you guys use in your inboards? :evil:

Seriously, thanks for the responses so far. Good things to think about! I was indeed thinking more about the ski boats, as I think the kids would get a kick outta' more water sports. However, I am actually looking for general answers mainly because I've seen a few inboards that I would consider if I decide to replace the Silverline. I'm not bailing on I/Os or even outboards - this is more some recon on what I have no experience with yet.

In I/Os, some of us (I'm not saying me of course, you see ... I've got this friend ...) have learned a valuable lesson about which ones not to buy (see below) without knowing what you're getting into. Are there similar things to pay attention to in looking at older inboards? Ford based engines vs. Chevy? OMC vs. Mercruiser vs. Chrysler Marine vs. Bob's Boat Engines?

Is the maintenance terribly different than an I/O?

 

[oldjeep]

Unless you are buying a really old boat (or a 2015 with an Indmar Raptor) you are going to see just Chevy engines.

Maint is about the same as an I/O. You change the oil, impellers and have a transmission that is either full of oil or ATF. You don't have any bellows to deal with. Unless you have a newer boat with a water cooled shaft seal like mine, then you have seal packing and packing nut adjustments to do periodically.

 

[southkogs]

Thanks oldjeep - and BTW, I got a kick outta' looking through your web page. I either hadn't looked through it before, or had forgotten about looking through it. I messed with a '43 Willys years ago, but never got to a point where I thought I could truly recover it. It was fun playing for a while though.

If I buy something else I won't be looking at terribly new boats, but I would like to come up a decade or two out of where I currently am.

 

[rallyart]

When my I/O was getting old and my young kids were starting to want to do more watersports I t best drove many I/O and inboard boats. There are substantial differences between brands in both and taking a test drive is important before buying. I went with an inboard and my whole family is enormously happy that we have it instead of a sterndrive.
Swimming from the boat is much better with an inboard. The swim deck is lower and there is no prop to bang. This is actually a big part of our time on the water.
Watersport are much better. Starts are faster and more controlled and the wake is smoother with less froth. The boat turns tighter and never gets pulled by what it is pulling.
Cruising is better. (With my boat, at least) The economy at speeds from 25-35 is as good or better and a 21' inboard is bigger inside than most 21' I/O boats because the size does not include the swim platform. Mine is also good in rough water but many are not. Strangely there is less wind on the passengers at the back in mine than on many of the sterndrives I tested. I think that's more of a quirk than a design tendency between them.
Loading on the trailer is harder if there is some cross wind and steering in reverse is random. Parking at the dock in high winds can be more difficult in strong crosswinds also with an inboard. Once you have the hang of it parking is easier with an inboard.
Top speed is slower and more expensive to run at due to high power engines and hulls not designed to clear the water. This you really notice if you need to get somewhere. Almost all inboards max out in the 40's so if you need to get somewhere in a hurry maybe take the SeaDoo hot rod.
In shallow water you can't trim up but remember that you have about a foot more clearance to start with so you normally would not need to.

There are many from the 90's that are nice but when you get into boats from the 2000's almost all are pretty good. Mine is a D-drive but more people seem to like the openness of a V-drive with no narrow walkways.

For me, I would not go back to an I/O.
For my kids, they feel a bit sorry for those that have 'regular' boats.

 

[OrangeTJ]

If the boat is primarily going to be used for watersports, it would seem that an inboard may be the best choice. For a more "general purpose" boat, maybe not as much. One thing you can do behind an inboard that you really can't (or at least shouldn't) behind an I/O is wakesurf. This is a VERY fun thing to do.

 

[skibrain]

The backing limitations of a direct-drive just take getting used to. R-hand prop rotation (malibu, mastercraft), the boat will back up to the right and you can easily "walk" the back end over to the dock on the starboard side of the boat. With L-hand rotation (correct craft) the boat will back nicely to the left, and you can walk the back over to the port side. It actually feels MORE maneuverable to me for carefully/slowly pulling up to a downed skier or when needing to carefully pull up to a dock.

 

[oldjeep]

The backing limitations of a direct-drive just take getting used to. R-hand prop rotation (malibu, mastercraft), the boat will back up to the right and you can easily "walk" the back end over to the dock on the starboard side of the boat. With L-hand rotation (correct craft) the boat will back nicely to the left, and you can walk the back over to the port side. It actually feels MORE maneuverable to me for carefully/slowly pulling up to a downed skier or when needing to carefully pull up to a dock.

Once you get to a boat with a deeper V and more weight in the back they don't walk quite as well. My FIL's 04LXi will slide sideways pretty predictably, my vtx really doesn't. My bayliner you could parallel park like a car.