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View Full Version : Settle bet on outboard vs inboard!


dichdoc
05-28-2006, 09:39 PM
Slow day at work! Any thoughts out there on the age old outboard vs I/O vs inboard debate? Co-worker says outboard has the least power loss of all boat motors I disagree, my thought is my inboard has no real change in direction therefore less chance of loss of power? Prove one of us right so I can get on with my life! Thanks TB

86Craft
05-28-2006, 09:59 PM
What you doing working today? :rant:

Anyway I would have to agree with you. :banana:

JimN
05-28-2006, 10:04 PM
An outboard has about a 90 degree change in direction, therefore, loss of power. The transmission in an inboard needs an oil cooler, right? That means that heat is generated due to the friction from meshing gears, and since energy can't be created or destroyed (it can only change forms), it's power loss. They both lose power but the only way to determine which is more efficient is by measuring power at the crankshaft on each and then at the propshaft.

dichdoc
05-28-2006, 10:21 PM
We're waiting for something to catch fire or for someone to get hurt (morbid enough). So Jim can you get a few different test subjects together and do a small study for us (measuring all those things) we'll be here intil 7 am tomorrow.... I mean if you're not busy!

86Craft
05-28-2006, 10:32 PM
We're waiting for something to catch fire or for someone to get hurt (morbid enough). So Jim can you get a few different test subjects together and do a small study for us (measuring all those things) we'll be here intil 7 am tomorrow.... I mean if you're not busy!

Hopefully you stay bored! :eek:

Britt
05-29-2006, 04:37 PM
Well avoiding all the specific factual means of discovering a way to come up with a viable solution to the problem.....I have skied for many years and to this day still say there is nothing like the power of an outboard. Ofcourse this is my personal thoughts on a 200 hp outboard compared to 320 + hp inboard boats. However, more specifically in regards to powerloss, what about the overall affect of absolute pitch angle in correlation with the hull/transom. If you go on the basis of inboards generating heat through the trans and that outboards have to overcome a 90 degree angle we can argue that they are even in that respect. I believe the most power loss or gain can easily been found in the absolute pitch or trim in correlation with the boats hull and water displacement characteristics. Long story short....Outboard wins IMHO

Hoosier Bob
05-29-2006, 05:36 PM
I would say the inboard would win if you were operating both dry. The out board wins if you are in water. Our inboards use power very effectively at first but without trim that advantage would be lost very quickly. I do not know how much a BF200 weighs but with 150-200 less horsepower it is quicker and faster than anything MC has today! :confused: Hard to argue with that. :D
You may be able to out turn him though! 8p

jpattigr
05-29-2006, 08:42 PM
But part of the gain of OB vs Inboard is the weight advantage a OB has, the power to weight ratio comes into play. Second the OB is usually a two stroke which makes great power when revved but low torque.

To really be a fair test all boats must be the same weight.

Hoosier Bob
05-29-2006, 09:10 PM
The 1993 BF200 weighs in at 1550 with 200 HP. 7.75 pounds per HP. The 1993 Prostar 190 weighs 2450 with optional 310 hp LT1 is 7.9 pounds per HP. I would guess the LQ in the 197 would be the best HP per pound made. That said the BF200 will outrun and out accelerate the 197 all day. Argue all you want but until you can trim out a Prostar it ain't happenin'! :D
PS. If any of you want to "F" with a BF 200 be my guest! I will enjoy the ole 190 I own that won't slide and move all over course during pull.
PSS. The BF200 goes almost 20 miles an hour faster, can pull just as many barefooters and is quicker! You may want to cut your losses and go for best in show! :worthy:

Hoosier Bob
05-29-2006, 09:37 PM
I almost forgot! I you are alone on your 190 and a BF200 floats by with 10 people on board my advise would be to WALK AWAY! That should settle the weight issue! :banana:

6ballsisall
05-29-2006, 09:55 PM
We had 7 footers on the booms with Rockman's 95' BF200 and it wasn't breaking a sweat! IIRC, we did 44 with all of us out there and some of us were really digging their heels in alot! Those BF200's are bad arse boats!

sizzler
05-30-2006, 03:32 AM
i'm sure my BF 200 was a he11 of a lot ligjhter than my X9 MCX....But those 200 horses certaimly outperformed my present 350 steeds....a great boat they should have kept making and striving to improve IMHO

ajgressette
05-30-2006, 04:55 AM
Slow day at work! Any thoughts out there on the age old outboard vs I/O vs inboard debate? Co-worker says outboard has the least power loss of all boat motors I disagree, my thought is my inboard has no real change in direction therefore less chance of loss of power? Prove one of us right so I can get on with my life! Thanks TB

Iím not sure of the exact date but sometime in the 80ís OB manufactures began rating horsepower at the foot (prop shaft) instead of the head. I can not speak for the new 4 stroke motors because I have never owned one, but two stroke motors have a tendency to loose compression over a period of time. Piston walls build up carbon deposits and become scored and pressure leaks around them. I honestly believe this is largely due to lack of lead in gasoline today. A good quality two stroke oil helps. Just some food for thought. I keep some oil from Yamaha and Mercury in my shop and we are required to have MSDS sheets on them both. Come to find out the Oil Company Citco is the manufacture of them both. Same MSDS Sheet!

Brand-new vs. brand-new I would have to say the two stroke outboard has the least loss of power.

Just my 3 cents worth. Hope everyone had a safe weekend. :D

bradamerry
05-30-2006, 08:04 AM
Just a question, can a BF200 pull up 10 plus skiers from a deep water start??? Just asking.... Not trying to start something here...

Jorski
05-30-2006, 08:33 AM
One other note on the outboard vs inboard debate:

Besides the power to weight ratio difference, another key difference in the past was that the vast majority of large outboards were two-stroke engines, while outboard engines are 4-stroke engines.

To review: 2 stroke engines have a power stroke (explosion) in each piston chamber every 2nd stroke, while 4 strokes (inboards) have a power stroke (explosion) on every 4th stroke. This results in outboards (as they have powerful explosions twice as frequently) being able to generate a lot of torque very quickly (BTW, torque is what creates acceleration and the feeling of power from your engine) ; in fact, they create peak torque at very low RPMS.

Horsepower, although a generally accepted measure of "peak" power is actually theoretical at best. Horsepower is derived from torque times RPM. If you can build an engine to tolerate operating at higher RPMs you would actually increase the horse power, but you may lower the torque.

sizzler
05-30-2006, 08:43 AM
Just a question, can a BF200 pull up 10 plus skiers from a deep water start??? Just asking.... Not trying to start something here...
how much do they weigh???? :cool:

bradamerry
05-30-2006, 08:57 AM
how much do they weigh???? :cool:
Avg. 100lbs.

We used to pull up 10 to 13 at one time, but most were kids around 100lbs. 190 w/slot..

T Scott
05-30-2006, 09:00 AM
Avg. 100lbs.

We used to pull up 10 to 13 at one time, but most were kids around 100lbs. 190 w/slot..

Maybe that is what did in your tranny !! :( :(

bradamerry
05-30-2006, 09:25 AM
Maybe that is what did in your tranny !! :( :(
I don't do it with my boat. 3 on slalom is all I have done. It was an 83' S&S with 351 and slot...

ajgressette
05-30-2006, 10:33 AM
Just a question, can a BF200 pull up 10 plus skiers from a deep water start??? Just asking.... Not trying to start something here...

Thatís a good question! I have never pulled that many with my boat. 4 is the most I have ever pulled. I doubt it would have the torque to come out of the hole like an inboard. :eek: I think the biggest advantage of these boats is the hole shot, top end speed and small wake.

sizzler
05-30-2006, 10:35 AM
we pulled up 4 long-line deep footers......had to hold our breath a bit.....

3event
05-30-2006, 11:04 AM
Last boat was an outboard, until I saw the light and bought a MC. The other key diff is wetted surface. An OB boat has less, it's going to ride with less wet, maybe half or less. So the power to weight tells part of the story, but it's also important where the weight is located. The OB also has trim. If you tuck the engine under against the transom, it will pull ya out nice but keep the bow in the water and get no top end. Once you hit the trim, you're GONE. Old boat did mid 50s at zero trim and 68mph trimmed out, with very little boat in the water.

Because of weight distribution and hull differences, I don't think you can compare - they all have their performance niche. You have to decide what you want to do on the water and buy the right rig for it. Because the DD inboard is heavy in the middle it needs more punch to get thru the water, but properly set up it can do more well than any other option , imho

Kevin 89MC
05-30-2006, 11:36 AM
Yep, I agree, wetted surface is a HUGE factor. I've never seen a BF 200, but I'd guess there is very little of the hull in the water at top speed. What is the top speed of a BF 200 with trim all the way down?

It would be interesting to see what the HP ratings are at the props of inboards, outboards & I/Os compared to the rated HP. IIRC, vehicles tend to be 10-20% loss between flywheel & tires, I'd guess it would be lower for boats. If I had to guess, I'd say I/O's least efficient, outboards most efficient and inboards somewhere in between. Someone needs to invent dynamometer that you can hook a prop up to!

Rockman
05-30-2006, 06:33 PM
:popcorn: :popcorn: :popcorn:

dichdoc
05-30-2006, 06:58 PM
I just told him I was right and moved on which fits into part of our motto of, "never let the facts get in the way of a good story!" it started out at which motor would lose the most power but he became very confused so we tucked him into bed with his pacifier. Thanks for all the input. TB

jeffbare
02-11-2011, 05:01 PM
The BF200 pulls like mad, and has a great mid-range accelleration.

Just wanted to put this back to the top.

CantRepeat
02-11-2011, 05:05 PM
I really don't know nor do I care.

Had this post been which feels and looks better saline or silicone I'd care more.

funk
02-11-2011, 05:20 PM
Yep, I agree, wetted surface is a HUGE factor. I've never seen a BF 200, but I'd guess there is very little of the hull in the water at top speed. What is the top speed of a BF 200 with trim all the way down?


Agreed. Wetted surface is a HUGE factor when considering trim!!
:D:D:D

MIskier
02-11-2011, 05:33 PM
Slow day at work! Any thoughts out there on the age old outboard vs I/O vs inboard debate? Co-worker says outboard has the least power loss of all boat motors I disagree, my thought is my inboard has no real change in direction therefore less chance of loss of power? Prove one of us right so I can get on with my life! Thanks TB

The whole story isnt just the drive train loss. In that respect the Inboard has the upperhand. But due to the shaft angle in relation to the hull there are effiency losses there, and along with the OB's ability to trim it wins the speed competition.

03geetee
02-11-2011, 05:39 PM
The biggest question is which boat gets the most chicks, I would say the inboard.

Woooot!

JTR

CantRepeat
02-11-2011, 06:43 PM
Agreed. Wetted surface is a HUGE factor when considering trim!!
:D:D:D

I like where this is headed! :D

thatsmrmastercraft
02-11-2011, 06:49 PM
The biggest question is which boat gets the most chicks, I would say the inboard.

Woooot!

JTR

Finally someone who understands. :D