Power choice Poll

[Willallison]

depends what kind of gallons you use! Imperial or US...... I used 1 gallon = 4.54609 Litres.

more to come........

[Portager]

That is the correct conversion for liters to Imperial gallons, however all my data was in US gallons. To compare my data to yours you need to multiply by 1.201 so 0.065 X 1.201 = 0.078 US gal/HP/hr.

Cheers;
Mike Schooley

[Portager]

I calculated the weight of O-1 with the following propulsion options; Mercury Optimax 150 , Mercury Mercruiser 135 stern drive, Yanmar 4 LHA-HTA inboard, Yanmar 4LHA-HTA surface, Steyr inboard, Steyr surface drive. I set the empty weight of O-1 with the Mercury Optimax to 5,000 and increase it for the other options by my best estimate of the engine and drive weight difference. I calculated the fuel required to obtain a 300 NMi range with a 20% reserve for each engine/drive option based on the specific fuel consumption and the drive efficiency (I assumed the surface drive was 10% more efficient and the inboard 5% less efficient than the outboard and stern drives).

If the Excel spread sheet that I saves as a web page shows up, you will see that the fuel requirements in gallons were highest for the Mercury Optimax 107.4, followed by the Steyr inboard 105.4, Mercruiser 135 stern drive 98.8, Yanmar 4LHA-HTA inboard 97.8, Steyr surface drive 90.2 & Yanmar 4 LHA-HTA surface 83.9.

The interesting thing is when I calculated the weight of the fuel, the order changes because of the higher density of diesel fuel. The lowest fuel weight is Mercruiser 135 stern drive at 593 lbs, followed by Yanmar 4 LHA-HTA surface drive at 595 lbs., Steyr surface drive at 641 lbs., Mercury Optimax at 644 lbs., Yanmar 4LHA-HTA inboard 695 lbs., and the highest was the Steyr inboard 748.

When I calculated the fully loaded weight the lowest was Mercury Optimax at 5,644 lbs., Mercruiser 135 stern drive at 5800 lbs, Steyr surface drive at 5,993 lbs., Steyr inboard 6,100 lbs., Yanmar 4 LHA-HTA surface drive at 6,275 lbs. and Yanmar 4LHA-HTA inboard 6,374 lbs.

So even though the diesels save fuel in gallons they do not save weight for a boat of this range. If you increase range the Yanmar surface drive eventually becomes the lightest weight but not until 2,400 NMi.

Next I calculated the fuel usage pre 100 hours assuming $1.20 US per gallon for gas (petrol) and $1.10 per gallon for diesel. I estimated the acquisition cost of each propulsion option (I need an estimate of the installation cost), subtracted the Optimax outboard and divided by the fuel savings per hr to get the hours to break even. The Steyr surface drive broke even in 214 hours of use followed by the Yanmar surface drive at 270, Steyr inboard at 290 and then the Yanmar inboard at 398. Note that these break even times do not take into account the value of money i.e. the interest you would pay on the investment until you get it back at the fuel pump so these numbers are optimistic.

Assuming 100 hr use per year and 10% interest, the break even period becomes Steyr surface drive 2.51 years followed by the Yanmar surface drive at 4, Steyr inboard at 4.63 and then the Yanmar inboard at 8.71.

Now I think the analysis is almost complete (we should try and estimate the difference in the cost of maintenance per hr and per year). I personally was surprised that the diesels were not lighter that the gas engines at O-1's range and I was also surprised at how soon the Steyr engine reached the break even point. This is partially due to the fact that the Steyr dealer quoted me a very good discount on the Steyr engine, but I expect this discount to be available for a number of years until the market figures out what a value the Steyr is.

I hope this analysis was as informative to some of you as it was to me.

I really hope the spread sheet comes through. I will make explaining an analysis much easier. P.S. It was a no go on the spread sheet. I'll have to find another way.

Cheers;
Mike Schooley

[Nomad]

How much was that Steyr quote could give me an approx. ??

[Portager]

Approximately $11,438 for engine and transmission.

Cheers;
Mike Schooley

[Nomad]

How many Hp for 11ish?

[Nomad]

Are they planing on large engines in the near future?

[Nomad]

4 more days.......................

[Portager]

Currently Steyr's largest engine is 240 HP. I don't know if Steyr is planning any larger engines in the future, but I don't think so. The dealer told me that their current engine was the result of a joint venture between Ford and somebody who I forgot to develop a light weight diesel engine in the 1970's. When diesel cars declined in the 80's Ford dropped out of the joint venture and it ultimately became the Steyr diesel.

They have an inline 4 and a V6, maybe they have a V8 up their sleeve?

Cheers;
Mike Schooley

[Nomad]

Thanks Mike Just checking to see what you know because Steyr will not E-mail me back. I have asked about dealership/manuf. setups etc. Kinda weird

[duluthboats]

We really could use a few more votes here people. We are at a virtual tie. Come on, how about a dozen or so of you lurkers out there choose your preference for O-1’s power. It only takes two clicks of you mouse.
Gary

[tom28571]

One item that has a large effect on my choice of an outboard is maintenance and repair service. I know that diesels have the great reputation for reliability but I hear of far more problems with repair from friends with diesels than with outboards. I'm not talking specifically about the engines but about the availability of good service. When I have a problem with my outboard I can take it to the dealer who has "factory trained" service people to work on it. Yeah, they can screw up too, but at least they have access to expertise and a wealth of information. Each engine is a complete identical system under the hood which helps with the service..

[Willallison]

Its taken me some time - and I still haven't found the article I was after - but here are some interesting numbers to consider. Look out Mike - here it comes!!

If the diesel is at an 18 degree down angle then the horizontal thrust vector is cos(18) = 0.95 or you loose 5%.

If we can accept that the efficiencies inherent in a sterndrive are similar to those of an outboard, then these are clearly not born out by reality. "Motorboat & Yachting" recently did a comparison on two 40-odd foot Sealines. One powered by 2x 260hp Volvo sterndrives, the other with 2x 420 hp inboards. The outdrive's managed a top of 31 knots. The inboards - with 38% more power managed just 32.
From another test ........the gains in efficiency can be astonishing. Take the Princess V42. Powered by a pair of 480hp Volvo TAMD74P inboard diesels, this 9.5 tonne boat has a top speed around 37 knots. But the same boat can reach close to 36 knots fitted with a pair of comparatively tiddly 260hp KAD44's driving through Volvo's highly efficient Duoprop outdrive legs.
Using the elementary designers formula that states: Speed = Efficiency x sq.rt (hp / displacement) the outdrive powered boat is about 30% more efficient - a startling improvement over conventional props

Now this tells us a number of things. One is that whilst one can't argue with Mike's mathematical case for the diesel inboard, in practice the numbers simply don't stack up. And whilst this isn't a direct comparison between inboards and outboards, it clearly demonstrates that both sterndrive and outboards (with their similar drivelines) will overwhelmingly outperform a similarly powered shaft driven boat. Further, it shows that should we decide not to go for outboards, then we should certainly consider alternatives to conventional shafts. Their greates assest - simplicity and longevity when submerged - is only applicable to boats left in the water for extended periods.
Now I know that I carry just a smidgen of bias towards outboards , but if forced to choose an alternative - for this style of boat - then a shaft driven inboard would be well and truely at the bottom of my list.

[Nomad]

Come on someone either needs to vote or change their vote....................

[Jeff]

After all the discussion I had a feeling that this one would come out close.

If only there were a surface-drive or inboard hybrid like the trimax drives or BPM or Arneson's or PowerVent Drives without such a steep pricetag that would make thigns more interesting, but I fear our budget (like in reality) makes it a difficult decision.

--who me using this as an excuse to play with the new photo gallery?