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View Full Version : 200 hp inboard vs 200 hp 4stroke outboard



KOLSON
11-11-2007, 04:39 PM
What do you think gets better fuel economy? With all the talk about 4 strokes I wonder if inboards are still more fuel efficient. Just curious.

messi
11-11-2007, 06:19 PM
All I know is I can buy a lot of inboards for what that 4 stroke transom hanger costs!

So the break even point is how many hours?

sleather
11-11-2007, 06:54 PM
So the break even point is how many hours?

I know MOST of us aren't going to live "that" long!:shock:

If the WELL runs dry, they're both doomed!

Billy The Kid
11-11-2007, 08:11 PM
The 4 stroke outboard would be more efficent b/c it weighs less than the 4 stroke inboard. The weight savings would translate into better fuel economy.

The cost savings on the inboard engine's initial purchase price and later the replacement cost make a good argument to stick with the inboard.

-Brad

sleather
11-11-2007, 08:51 PM
Not to disagree, but I think the weight differential is minimal.
Has anyone actually weighed the "complete" drive-train on their Shammy w/ a 200hp V8?
My guess, 687#:mrgreen:

Honda, Suzuki, & Yamaha 200's all come in @ ~580# w/o prop.---As per 2007 brochures.
There's also a heavier steering system and perhaps an "off-shore" bracket.

The difference in fuel consumption is a function of the "high-tech" computerized FI systems on the OB's which many(myself included)don't trust! Give me a carb, @ sea any day(something I understand)!

The true "roadtest" would be a 2007 Shamrock EFI vs a comparable outboard! OOPS, ALL DIESEL NOW!

KOLSON
11-11-2007, 09:35 PM
What does everybody burn at cruise? I've got a 20 walkthrough and I've heard some burn 10gph and some burn 7gph at cruise. would a 4 stroke on a 20 foot hull get better economy? would it burn 5gph or more? Gas out here is getting spendy. Just for argument sake.

Esmeralda
11-11-2007, 09:55 PM
Provide the math, Sleather. We want to see.

sleather
11-11-2007, 10:12 PM
Just for comparisons sake. On my Arima(present boat)site most guys w/ 19' & 21's(very similar hull to the 20) are running 130hp Hondas(somewhat underpowered). I've got a 150 Evinrude(had a 175) They ALL talk mpg.

Their #'s ~4.5mpg @ 25mph cruise ~5.6gph(those MAY be older motors, old Arimas are still around)
The best I heard was 5mpg for a 140m trip in perfect conditions.(new 130 EFI Honda)

Mine is ~3.8mpg @ 28mph cruise ~7.4gph(2000-FI-2stroke) 3mpg used to be a 2stroke standard.

It ALL depends on the "accuracy of the data", who's talkin' & the sea conditions.

If somebody wants to buy me a NEW 200hp-4stroke Honda,
I'll have ALL the data you can swallow by next week!!!!!LOL

Poke around THT, there's got to be some more data there!

Esmeralda
11-11-2007, 10:37 PM
The question was breakeven point on the two engines' costs to push our boats.

You are wrong about the fossil fuel supply running out before we all pass, and I want you to provide the math on that, too.

sleather
11-11-2007, 11:04 PM
The question was breakeven point on the two engines' costs to push our boats.

I'm really sorry to hear that yours broke! Glad you're SAFE!

I don't think there IS a break-even point, based on the relative costs! I agree w/ messi!

I'm calm!

Esmeralda
11-11-2007, 11:15 PM
Well, you stated the math would surprise.

SCOOTER
11-11-2007, 11:30 PM
Not to disagree, but I think the weight differential is minimal.
Has anyone actually weighed the "complete" drive-train on their Shammy w/ a 200hp V8?
My guess, 687#:mrgreen:

Honda, Suzuki, & Yamaha 200's all come in @ ~580# w/o prop.---As per 2007 brochures.
There's also a heavier steering system and perhaps an "off-shore" bracket.

The difference in fuel consumption is a function of the "high-tech" computerized FI systems on the OB's which many(myself included)don't trust! Give me a carb, @ sea any day(something I understand)!

The true "roadtest" would be a 2007 Shamrock EFI vs a comparable outboard! OOPS, ALL DIESEL NOW!

Has to be more than 687 lbs.

302 base engine = 480 lbs.
3" exhaust manifolds & risers = 140 lbs
Borg Warner Velvet Drive 1:1 = 95 lbs

Bell housing, damper plate, engine & transmission mounts, trans cooler & lines, raw water pump & bracket, alternator & bracket, pulleys & belts, fuel pump, water & exhaust hoses & starter = 75 lbs (min)

Coupler, propshaft & prop = ?

oceannavagator
11-12-2007, 12:42 PM
Brand new 250 hp merc= $17000.00 bucks
Brand new 250 hp Indmar with velvet drive, prop, shaft, and steering set up
= $10,000 more or less.
$7000.00 of 3.25 gasoline= 2153 gallons = 6500 miles at 3 mpg.
I personaly don't know how they even can sell outboards above 100 horse power. :confused:
Plus the fact is that the weight of the outboard is in the wrong place for the seaworthyness factor.
O.N.
ps. I just had a friend buy a 32 thousand dollar truck cause it got 5 miles per gallon better mileage than his paid for american truck. He didn't do the math either. You can wear out 3 trucks with 32,000 dollars worth of fuel.

cyacht
11-12-2007, 04:48 PM
Tough to compare.
GPH might be better, but you'll be traveling a good bit faster, so the MPG's kindof even things out.
The Yamaha F250's burn about 9-10 gallons per hour @ cruise.
250hp of 22' inboard equals a relatively slow boat.
250hp on the back of a 22' hustles.

BUT, I fished the 36 this weekend (triple 250's) and it was pretty rough in the Bay on saturday. She requires a good bit of "helm input" to maintain a steady line during a slow troll.
Well, long & short, an inexperienced helmsman ended up running over one of our lines. About 50' of 30# test & a brand new fancy umbrella rig ended up very fouled around the prop.
Let me tell you how fun it was hanging off the back of that boat in seas breaking over the bow while I try to cut that mess off! Then, those beefy dam engines are so close together that when the driver went to starboard, my knee got crushed between the 2 engines. No permanent damage, but sore & bruised.
I think the outs have a place, I like to go fast, but dear gawd I hate fiishing around them.

L.A. z GATOR
11-12-2007, 05:08 PM
I would guess that the most fuel efficient setup between the two would be the outboard. However, if you mate the inboard to a jackshaft, you have a contender for efficiency.

Most overall economic package is still the straight inboard. I would guess the break even point is equal to about 3 inboard motor replacements or 6000 hours ????
This would make for an interesting study and article, but most Boat magazines get too much adverising dollars from outboard manufacturers for the truth to be revealed.
Does anybody stop to think about how us boaters get caught up in the marketing frenzy? I think us Shamrockers are in it at just a fraction of the multiple outboard CC guys. The marketing gurus in this industry have most people thinking that you can't catch fish unless you have a XXXX CC with 4 outboards and tow it with a 60,000 duelly diesel. Nothing is rational after a while.

jon
11-12-2007, 05:14 PM
Horsepower is horsepower. 250 OB horsepower = 250 inboard horsepower, whether it's gas, diesel, electric, or windmill. The same boat should go the same speed, with equivalent HP. The only variation could be in the way the HP rating is calculated, whether it's a continous rating or intermittent, as far as how long you can use the rated HP safely. Also, inboards are generally rated before the trans, while OB's may be rated at the shaft.

grreatdog
11-12-2007, 05:26 PM
Inboards are less efficient than outboards and I/O's due to the shaft angle. Plus an inboard typically had more drag. So it isn't a one to one comparison in terms of hull speed generated for any given horsepower. An outboard or I/O is trimmed to the most efficient prop angle for any given conditions. But an inboard is always going to waste some thrust pushing upwards no matter where you set the tabs.

ken
11-12-2007, 07:50 PM
For what that outboard costs and the length of timeit will last I think a diesel would cost almost the same,But that's just what I think, Ken

redneck7
11-12-2007, 11:11 PM
Horsepower is horsepower. 250 OB horsepower = 250 inboard horsepower, whether it's gas, diesel, electric, or windmill. The same boat should go the same speed, with equivalent HP. The only variation could be in the way the HP rating is calculated, whether it's a continous rating or intermittent, as far as how long you can use the rated HP safely. Also, inboards are generally rated before the trans, while OB's may be rated at the shaft.

Indeed horsepower is horsepower, but the variable you're forgetting (which Greatdog already mentioned) is that it's HOW the horsepower gets USED that changes. Efficiency is the name of the game in figuring out which one will burn more gas. My lifted Suburban burns more gas with it's TBI 350 than a stock 2 door Tahoe with the same TBI 350 because it's pushing more...OR, a Corvette with nice sticky tires gets more MPG than the same Corvette that's always burning rubber with crappy tires.

On a boat with hull shape/size held constant it'd come down to prop slip and power loss between the crank and the prop.

jon
11-13-2007, 11:50 AM
One of the boating mags recently did a test of single versus twin versus triple OB's for both speed and fuel economy. Surprisingly, The same HP (total) had all three setups give virtually the same top speed and fuel economy!!
Point is, the three bottoms sticking into the water had no measurable reduction due to the increasd drag over the single.
I agree the angled prop of an inboard wastes significant power trying to raise the boat rather than drive it forward, but an outboard has to turn its power 90 degrees to get to the prop, also a huge power drain.
Maybe Volvo's new IPS and Cummins new drive will eliminate shaft angle loss, but they have two 90 degree turns to get to the wheel. Their manueverability looks awesome, though.

oceannavagator
11-13-2007, 04:06 PM
After three pages of posts people are still advocating putting $50,000.00 dollars into 3 outboards on the back of a boat right where you have to fish. You really have to hand it to advertising companys. Is there drag on an inboard shaft and strut? Yes but if you think the lower unit is invisible to the water flow you are wishfully thinking. Most boats are outboards because it makes them cheap to manufacture and ship and if the maker isn't liable for the engine or fuel tank installation so much the better.
I don't like fishing around an obstruction as big as a refrigerator with a built in line cutter 3 feet behind the transom any more than I like spending 15 large every 2000 engine hours for an engine. Compared to Outboards, an inboard's fuel is free for the first 4000 hours.
O.N. :confused: :confused:

grreatdog
11-13-2007, 04:27 PM
I don't think anyone here is advocating for triple outboards. We all have inboards for pretty much the same reasons. Pointing out differences between drive systems is not exactly the same as advocating for them.

I know that a 250 outboard is going to be faster than a 250 inboard on the same hull. But I also know that I don't want the outboard for all the reasons we are already familiar with.

SCOOTER
11-13-2007, 05:11 PM
Not to stir the S-pot, but if you wanna see something eat the horsepower up, couple your inboard or outboard to a jet drive.

Capt JR
11-13-2007, 07:09 PM
OK I will say it:
Inboards have lower of center of gravity=superior righting moment at sea and safety while on the trailer

Inboards have superior fore after movement do to distribution of weight.

Inboards equal fishability (said before, but worth saying again)

Inboards can be maintained by most shadetree wannabees.

Inboards can be modified to needs easier (ie larger alternators, carbs, etc.)

Inboards SOUND great.

I agree that the VOLVO IPS is probably the most significant development in the past twenty years since the VOLVO jackshaft. It is the future for boats with no shoal water issues. However, the jackshaft arrangement found in the Carolina Classic 25 is the most efficient motor/transmission combination on the market. They can vector their thrust like an outboard and use thrust to control pitch (trim) plus the counter rotating props are far more efficient. The Carolina Classic 25 can get double of what we get in MPG and almost twice the cruising speed for the same HP.

So why do boat builders use outboards? Easy, you do not have to design around the power, simply make your transom stronger. I saw a Grady White with twin Yamaha 350's this summer. Does anyone want to do the math on what the fulcrum point force would be on that motor with a 30" shaft. Someone needs to figure the added weight on the transom reinforcement along with the weight of the motors if you would like to get a true weight comparison. Shoot the transom of our boats are the lightest part of the boat.

Man I love these winter threads, makes me think. Keep it up boys. Capt JR

PS If you are in the North Myrtle Beach Area the Saturday after Thanksgiving, go to the ICW to watch the boat parade. I will be the smallest in the fleet again.

MAC
11-14-2007, 08:28 PM
Like Capt JR said,

My inboard sounds really cool.....

I love the sound of the gurgling at idle..........

Sounds like an adventure.....

skipm
11-15-2007, 03:22 PM
My friend has a 25 Steiger pilothouse with honda 225 gets 2 mpg , my 26 210 Cummins getes 3 mpg. No comparison in ride especially rough seas.

cyacht
11-16-2007, 09:04 AM
My theory as to why the outboards have gotten so big is simply speed.
The advent of the mechanically sound & efficient outboard (as compared to how they used to be) has had a direct impact on the explosion in recreational offshore fishing.
Granted, alot of the people buying these boats are cammode captains (most of their time wrapped up in offshore fishing is spent in the pages of Marlin magazine), but they want the ability. I hear it all the time.

I agree that an inboard is a logical choice, but most recreational captains generally pick their weather, and have a limited amount of time. So when they go, they want to get there and get home in a hurry.

So, I'm going to play devils' advocate, and say that although I love inboards, I generally fish outboards alot more, and I do enjoy the advantages that they give.
3 oclock in the afternoon, and I suddenly get some time to fish, I grab a 24' bay boat w/ a 250 on the back. I can cover alot of water in those last couple hours of daylight.

The ASA tourney I fished has designated marina's you can leave & return to.
A 50 MPH cruise speed means I can run long distances to find big fish. Being able to carry 6 head means you share the fuel bill.
This also means I can fish longer, and haul azz for the scales.

Could I afford to run a twin outboard boat of my own? Hell no.
Even if I ran charters on it, I couldn't.
But I can run charters on a 22-24' outboard and make a good go of it, based on the fact that I can cover alot of spots quickly and efficiently.

There are lots of logical arguments for both camps, and working both side of the fence, I've heard a bunch of them.
I'm very lucky in that I get to enjoy the best of both worlds, or as I mentioned earlier w/ my prop wrap adventure this past weekend, the worst.

Capt JR
11-16-2007, 06:13 PM
The reps for Yamaha said that Grady-White came to them because the triple engines needed for the 30'+ hulls were too stressful for their transoms. Why? Well the center engine (say a 250) would need a very long shaft to overcome the extreme deadrise on those hulls. The long shaft length make for two very bad side effects. The first is draft. Since the cavitation plate must be below the deadrise it adds 17" to the minimum draft. Secondly that long shaft make for an awesome lever (awesomely bad in this case). That long shaft with 250 HP at the end of it makes for one heck of a crow bar at the transom.

Both of these issues hurt the otherwise great design of power cats that use outboards of any HP. Long live the heavy iron. Capt JR

Esmeralda
11-18-2007, 10:29 PM
OK I will say it:
Inboards have lower of center of gravity=superior righting moment at sea and safety while on the trailer...
That's a good point about safety on the trailer. I did not think about that.

skipm
12-08-2007, 10:13 AM
I have a 210 diesel cummins gets 3 mpg on a 7800 lb 26' boat , my friend has a 200 hp honda on a 25' Steiger gets 2 mpg.

Quik Fix
12-08-2007, 07:17 PM
I had 250 hp Yamaha on a Grady. 2MPG. 240 hp Indmar in my 26 Shamrock, 2.2 mpg