inboard vs outboard boat ?

[sam111]

I am wondering what the benefits of inboard over an outboard is and visa-versa.
The only one I can think of is outboard much more easily customizable from the point of view you can completely take the engine off your boat and put a new one different make/model where as inboard is pretty much fixed.

But there has to be a reason why boat manufactures make them to different ways in/out board?

Like is it something like eventually if you want higher horsepower engines in your boat then eventually they will get to heavy to install on the sides of the boat. (i.e the side would break). Is this why inboards are made or chosen

Thanks for any help

 

[H20Rat]

Re: inboard vs outboard boat ?

First of all, what kind of boat?

Assuming you are talking a typical bowrider. I/O's and inboards (two different things) give you a engine that is often quieter (yes, I know, not as quiet as a Honda outboard), and you get a nice big sun platform. You also get a swim platform, which makes it far nicer for watersports. Also, at least for an inboard, all the sharp pointy stuff is so far under the boat/platform that you can't get your feet to it if you tried. An outboard on the other hand will slice feet if you touch even a non-moving prop. Inboard engines also are easier to work on for some people, as they are based on car engines. And they often live longer also.

But of course, outboards have their positives also. Lightweight, and the newer generation of 4 strokes and direct injection engines get mileage that is the same if not better than their car engine counterparts. Its far easier for the backyard mechanic to repower a boat, and most things on an outboard are easier to work on. (replacing a starter on an outboard vs an inboard engine, not a comparison!) Outboards are also easier to winterize.

And lastly, pure and simple aesthetics. I/O's/inboards look better on a bowrider!

If you were looking for a simple answer of why does boat X have drive platform Y, there is none. Often a single hull mold can be set up for either power source. Its simply market demand combined with profit margins.

 

[sam111]

Re: inboard vs outboard boat ?

Ok , I see but is normally outboard engine 2 stroke meaning they have the gas and oil mix together have a shorter life then the inboard ones.
And does the outboard engines have less hp then what an inboard engine normally does . Or is it possible to make all outboard engines as powerful as all inboard engines.

Also is there any inboard engines that are not 4 stroke but 2 stroke.

 

[rallyart]

Re: inboard vs outboard boat ?

There are two stroke diesel inboards but almost I/O (sterndrives) and pure inboards (V-dreive or D-drive) are four stroke and based on automotive engines. Outboards are usually an engine just designed for that purpose. They can live a really long time also.
You can get outboards of 350 hp and there is one specialty brand that makes an outboard based on a Chev 350 with 700 hp.
Normally a low horsepower engine is easier to make as an outboard. High hp engines can be either.

 

[Mason78]

Re: inboard vs outboard boat ?

As smokingcrater mentioned; there are different kinds of inboards. The most common on a bowrider is a sterndrive or I/O. They are made by Mercruiser and Volvo Penta. They have an automotive based engine (GM usually) connected to an turnable outdrive that looks similar to the bottom half of an outboard.

A true inboard has the propeller connected to a shaft, and is steered by a rudder. They are most common on ski/wakeboard boats.

The first pic is the outdrive of an I/O. The second is an illustration of a true inboard, last pic is a cutaway of a complete Volvo sterndrive system.

 

[PeterC4]

Re: inboard vs outboard boat ?

The inboard/outboard stern drives are often used in pleasure boats from 18 to 30 feet or more. They are mostly made by GM Marine and then sold by either Volvo or Mercury. There are about 5 configurations from 3 litre, 4.3 litre 5.0 litre (305 V8), 5.7 litre (350 cu.in. V8) and 8.1 litre including an HO version. The 5.7 litre is the venerable GM 350 cu.in. block that is a well known car engine. The basic advantages of these engines are:

Easy to work on and well understood, durable, lots of torque for pulling people, (the 5.7 litre particularly) and you can get up to 420 hp if you wish form the 8.1 litre HO. The Volvo Penta 5.7 GXI develops 320 hp and has gone through a number of improvements as has Mercury's version. Mercury uses a bigger block to produce 320 hp. The 5.7 litre engines at 300 hp are fairly popular. Dual prop applications are good for getting on plane fast.

I believe that outboards are cheaper, and easy to access when you need to do something and you see them in more rugged boats like Whalers and Scouts. But you don't seem to see them in a lot of pleasure boats these days. There is an aesthetic appeal to the stern drive in some people's eyes as it "hides the engine".

 

[Home Cookin']

Re: inboard vs outboard boat ?

it's so regional. around here the "pleasure boats" are outboards and the "rugged boats" are outboards. And outboards look so much better.

They are superior for use in shallow water, and don't need to be winterized, so you can take the boat out year round.

the fact that manufacturers make and sell a lot of things doesn't make them better.

 

[Campylobacter]

Re: inboard vs outboard boat ?

Hi Sam111. Not to be rude but with this and some other questions you are asking it makes it difficult to figure out how to answer.

Are you looking to buy a boat, start a new career, or are we doing your homework for you?

 

[ricohman]

Re: inboard vs outboard boat ?

I agree with the regional thing. Locked inland, outboards are outsold by i/o's 50-1 around here. Plus you take a kicking on your outboard when it comes to resale. But since its so hard to even buy a new "family" boat with an outboard the resale thing isn't an issue anymore.
The only outboards seem to be the fishing boats.
I've had both i/o and outboards. I find both have their advantages and disadvantages. When I bought my new Starcraft Islander I had to choose between the i/o and the outboard versions. I chose the i/o but there really wasn't a bad choice. And as a former GM mechanic working on a 4.3 is a snap.

 

[dingbat]

Re: inboard vs outboard boat ?

I believe that outboards are cheaper, and easy to access when you need to do something and you see them in more rugged boats like Whalers and Scouts.

Obviously haven't priced an outboard lately. You an buy a lot of "pleasure" boat for the price of a new high HP outboard alone.:laugh:

 

[Bamaman1]

Re: inboard vs outboard boat ?

Inboard outboards are quiet, they are efficient on fuel and they'll run fast on top end due to having the trim on the outdrive. They're also relatively affordable--a lot for the money.
Disadvantages are that they're relatively heavy and difficult to trailer. The outdrive bellows are rubber, and they eventually weather and leak. I/O's are pretty trouble free the first few years, and then they're a pain in the *****.

Modern 4 stroke outboards continue to improve. They're now quiet, smooth and get great fuel mileage. Outboards maximize the room inside your boat hull. They're replaceable, though repowering engines is relatively expensive. They're good on trailered boats, as they're 500-700 lbs. lighter than a comparable I/O boat.
Disadvantage is that they're hanging on the back of the boat in sight. V-Hull open bow runabouts are relatively hard to find in outboard version.

Ever notice how many I/O's are in the marine salvage yards? It's because people forget to winterize their engines and have to replace'em. And they get tired of expensive repairs on the outdrives. Outboard hulls can be repowered if they're kept out of the weather and carefully maintained.

I've switched over to aluminum tritoons (and pontoons) for the last 28 years. I've never seen one wear out to this day.

 

[PeterC4]

Re: inboard vs outboard boat ?

Inboard outboards are quiet, they are efficient on fuel and they'll run fast on top end due to having the trim on the outdrive. They're also relatively affordable--a lot for the money.
Disadvantages are that they're relatively heavy and difficult to trailer. The outdrive bellows are rubber, and they eventually weather and leak. I/O's are pretty trouble free the first few years, and then they're a pain in the *****.

Modern 4 stroke outboards continue to improve. They're now quiet, smooth and get great fuel mileage. Outboards maximize the room inside your boat hull. They're replaceable, though repowering engines is relatively expensive. They're good on trailered boats, as they're 500-700 lbs. lighter than a comparable I/O boat.
Disadvantage is that they're hanging on the back of the boat in sight. V-Hull open bow runabouts are relatively hard to find in outboard version.

Ever notice how many I/O's are in the marine salvage yards? It's because people forget to winterize their engines and have to replace'em. And they get tired of expensive repairs on the outdrives. Outboard hulls can be repowered if they're kept out of the weather and carefully maintained.

I've switched over to aluminum tritoons (and pontoons) for the last 28 years. I've never seen one wear out to this day.

Good points. I think Outboards do maximize the room inside your hull, and they are lighter. Maybe they should be more prevalent over I/O's....I think it is happening to a degree...check out Glastron and Sea Ray...

 

[PeterC4]

Re: inboard vs outboard boat ?

Obviously haven't priced an outboard lately. You an buy a lot of "pleasure" boat for the price of a new high HP outboard alone.:laugh:

I stand corrected. After looking up outboards, they do seem expensive. More so than an I/O based on my quick review.

 

[Taxus812]

Re: inboard vs outboard boat ?

Rule of thumb it seems is approximately $1000 per every 10hp for new outboards. Are you sure I/O when you add up the outdrive and the motor and everything needed to install (new) isn't comparable? Dont forget to add labor (I know many could install it themselves but I don't have the tools so that counts for me).

Evenrude E-tec is very fuel efficient, quiet and smoke free.

 

[Texasmark]

Re: inboard vs outboard boat ?

Having had both I'll take an OB, 2 stroke recent mfgr to get the fuel economy savings.

Mark