Understanding Engine HP??? Caterpillar vs Ford Lehman?

My boat has 'rolling chocks' and experiences easily 50% less roll since fitting. I wonder why so many discount the benefits of these simple additions without trying them for themselves and seeing with their own eyes. Almost any mug can easily make and fit them. I did.

bogranjac1 said:

My boat has 'rolling chocks' and experiences easily 50% less roll since fitting. I wonder why so many discount the benefits of these simple additions without trying them for themselves and seeing with their own eyes. Almost any mug can easily make and fit them. I did.

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I'm sure you and AusCan are right.
When I had the option to have them added in Ireland for the more than reasonable price of $2500 while having my bottom redone, I debated doing it.
I also wanted the boat to be able to sit more upright if in a drying harbor.
Certainly a lot of European work boats have them.

Alas, in the limited time i had to make a decision, I opted against, because:

1. I knew and accepted how the boat handled. The devil i know was better ...

2. If they had no downside, then why didn't James Krogen put them on the boat in the first place?

3. It certainly wasn't going to add to my fuel efficiency. How much it would hurt was a significant issue. Even 10% would be unacceptable to me.
If I knew the number was only 1% , i would have done it, but not unknowing.

3. $2500

"Yes, but at slower speeds The SD will use similar fuel as the FD hull."

The SD hull would take 10% to 15% more energy to push at displacement speeds if both hulls had the same displacement.
The 2 engines or bigger single is also less efficient , by at least 5%.

The fuel burn increase is not noticed as the SD boat is usually built far lighter so it can be pushed on top of the water.

The SD boaters claim they can outrun the storms , so light construction is OK.

YRMV

kchace said:

The Mainship has the 380hp so they can say it has a top speed of 16kts which sounds really great. The reality is that the fuel mileage at 16kts is so poor that nobody except the rich would run it at that speed for any length of time. We're talking .7mpg vs 2-3mpg. If one only runs a few miles to the sand bar and back, 16kts is great. For anybody doing long range cruising, the .7mpg is prohibitive.

The KK has a much more realistic HP that is very adequate for the type of use the boat was intended.

Keep in mind that most trawlers in the 4x' range need only about 60hp to run at 6-8mph which is the speed range that most are run at.

Ken

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I thought I'd chime in on this thread since I have a mainship 400, albeit with twins, so it is a faster boat and perhaps a bit more efficient at higher speeds. Though at WOT our boat will run 19 knots, it's really pushing it to do that. It's much happier at around 15 knots. Sixteen knots is possible but is above the sweet spot. At 2800-2900 rpm we get about 1.2 nmpg. Not great, but much better than .7, and not some crazy fuel burn that only the super wealthy can afford.


That said, I think the general info in this thread is quite accurate as to the differences between HP and SD vs FD. I agree with most everything said here.


As far as motion goes, our old boat, a 1973 Gulfstar 36, was a round chine boat built on a sailboat hull. Our main issue with it was how much it rolled, it was not a comfortable boat in any sea over two feet. It would roll the gunnels under in a 5' beam sea. The hard chine Mainship is much, much more stable at slow speeds in bigish seas. I've never seen the "snap roll" thing with our boat that often gets quoted, though admittedly, I've never had it out in anything bigger than about 6-7' and that was mostly on the stern. My feeling is that what keeps Mainships and their ilk from being ocean crossers is their build quality and lack of range rather than the comfort/safety aspect of the shape of their hull. A friend has a 70' American Yacht sportfish (lucky dude) that they use to fish all over the world. They have taken it through the Panama Canal twice and it has been to the Galapagos. It's a hard chine boat. Big engines, big fuel tanks, big budget.



To me safety encompasses many things. Perhaps a rolly boat isn't going to capsize, but if it makes it so hard to move around that you almost have to crawl and it is rolling the dishes out of the sink (actually happened on our Gulfstar) it doesn't seem very safe to me.

Dougcole said:

I thought I'd chime in on this thread since I have a mainship 400, albeit with twins, so it is a faster boat and perhaps a bit more efficient at higher speeds. Though at WOT our boat will run 19 knots, it's really pushing it to do that. It's much happier at around 15 knots. Sixteen knots is possible but is above the sweet spot. At 2800-2900 rpm we get about 1.2 nmpg. Not great, but much better than .7, and not some crazy fuel burn that only the super wealthy can afford.


That said, I think the general info in this thread is quite accurate as to the differences between HP and SD vs FD. I agree with most everything said here.


As far as motion goes, our old boat, a 1973 Gulfstar 36, was a round chine boat built on a sailboat hull. Our main issue with it was how much it rolled, it was not a comfortable boat in any sea over two feet. It would roll the gunnels under in a 5' beam sea. The hard chine Mainship is much, much more stable at slow speeds in bigish seas. I've never seen the "snap roll" thing with our boat that often gets quoted, though admittedly, I've never had it out in anything bigger than about 6-7' and that was mostly on the stern. My feeling is that what keeps Mainships and their ilk from being ocean crossers is their build quality and lack of range rather than the comfort/safety aspect of the shape of their hull. A friend has a 70' American Yacht sportfish (lucky dude) that they use to fish all over the world. They have taken it through the Panama Canal twice and it has been to the Galapagos. It's a hard chine boat. Big engines, big fuel tanks, big budget.



To me safety encompasses many things. Perhaps a rolly boat isn't going to capsize, but if it makes it so hard to move around that you almost have to crawl and it is rolling the dishes out of the sink (actually happened on our Gulfstar) it doesn't seem very safe to me.

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Sorry if my post seemed insulting to your boat, it was not intended that way. I like the Mainships and almost bought one. I did generalize somewhat regarding MPG but have read many Mainship tests and while they're often reported to get about 1 to 1.x mpg at approximately hull speeds, I believe the fuel usage at higher speeds would be cost prohibitive for some folks. My whole point was that while a higher hp engine and higher top speed sounds good, in reality the fuel required for the higher speeds will turn some people off.



Ken

Maybe this should be in a different thread, but I've a comment on the "cost of speed". I've calculated this for several vehicles, including my Nordic Tugs trawler. Here's the jist of it: If you are going a given speed and burning a given amount of fuel, how much would it cost if I changed the speed a little. Cost is in term of dollars per hour saved. In other words, what would it cost to get there an hour sooner? It is essentially the slope of the speed and fuel consumption lines. For my Nodic Tugs 32 at 1200 rpm and 6.8 kts it is $2 per hour. At 1300 and 7.4 kts it is $10 per hour. At the very top end, at 2500rpm and 16.2 kts it is $36 per hour saved. I would very much like any information anyone has on a similar boat, hopefully including actual fuel consumption data. My information is from a sheet I found on the boat, source and accuracy unknown. Thanks in advance.

garycasey said:

Maybe this should be in a different thread, but I've a comment on the "cost of speed". I've calculated this for several vehicles, including my Nordic Tugs trawler. Here's the jist of it: If you are going a given speed and burning a given amount of fuel, how much would it cost if I changed the speed a little. Cost is in term of dollars per hour saved. In other words, what would it cost to get there an hour sooner? It is essentially the slope of the speed and fuel consumption lines. For my Nodic Tugs 32 at 1200 rpm and 6.8 kts it is $2 per hour. At 1300 and 7.4 kts it is $10 per hour. At the very top end, at 2500rpm and 16.2 kts it is $36 per hour saved. I would very much like any information anyone has on a similar boat, hopefully including actual fuel consumption data. My information is from a sheet I found on the boat, source and accuracy unknown. Thanks in advance.

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The offset is cost of slow or value of time. To some, getting to a destination and having more time there isn't important. A day on the water is a day on the water. To others, it's very important. To a family boating on the weekend, it's priceless. To someone with 2 weeks vacation with their family it's of tremendous value. Looking at the above, I'd never use per hour savings as that assumes you're not intending to go as far. Rather I'd use the amount saved per mile. Ultimately you'd end up with something more like this, just arbitrary numbers I'm using.

10 knots, 5 gph, $4 diesel, cost per mile $2
15 knots, 15 gph, cost per mile $4
20 knots, 30 gph, cost per mile $6

So per 1000 miles,
Cost at 10 knots $2000, 100 hours
Cost at 15 knots $4000, 67 hours
Cost at 20 knots $6000, 50 hours

Cost 15 knots cost $2000 extra, saves 33 hours.
20 knots cost $4000 extra, saves 50 hours.

If you were financially analyzing it then is the value of 33 hours as much as $2000, $61 per hour. Is 50 hours worth $4000, $80 per hour.

Not to the casual boater who isn't in a hurry. However, to the doctor spending his only two weeks of the year with his family, definitely is.

Coming from my background, I can't stop valuing my time highly. I'm use to thinking that way.

kchace said:

I did generalize somewhat regarding MPG but have read many Mainship tests and while they're often reported to get about 1 to 1.x mpg at approximately hull speeds, I believe the fuel usage at higher speeds would be cost prohibitive for some folks.

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Seems low, to me. We can push close to 2 NMPG at about 7 kts, closer to 3 at 6.5 kts... although that's using nominal Cummins figures, not measured fuel flow.

-Chris

ranger42c said:

Seems low, to me. We can push close to 2 NMPG at about 7 kts, closer to 3 at 6.5 kts... although that's using nominal Cummins figures, not measured fuel flow.

-Chris

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I would have no idea but this is what I read in 2 different tests.

FF said:

For cheap travel the full displacement boat run at about the SQ RT of the WL (not hull speed) only takes about 3 HP per ton of displacement .

2240lbs per displacement ton. Hull speed can be 5HP per ton or more.

So a 44,800 boat will need only 20HP in the water , to cruise , a bit over a gallon an hour.

Larger engines are installed so alternators , bilge pumps and other goodies can be engine driven.

As non industrial engines are peak rated , not cont rated.

,A cruiser can be fitted with an engine rated with over "100" hp , although in most cases it uses 2 or 3GPH , or 30 -55HP long term.

IF the eng. mfg. has a table of rpm/hp ratings from M1 to M4 it is usually an industrial engine.

IF not the engine will be OK of only loaded to 1 hp for every e CI of displacement , or so.

Good hunting.

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Trick will be getting a decent engine.
I doubt a 1.9 litre 75hp yanmar or similar will do as well as a 7 litre 5lw Gardner for example

garycasey said:

Maybe this should be in a different thread, but I've a comment on the "cost of speed". I've calculated this for several vehicles, including my Nordic Tugs trawler. Here's the jist of it: If you are going a given speed and burning a given amount of fuel, how much would it cost if I changed the speed a little. Cost is in term of dollars per hour saved. In other words, what would it cost to get there an hour sooner? It is essentially the slope of the speed and fuel consumption lines. For my Nodic Tugs 32 at 1200 rpm and 6.8 kts it is $2 per hour. At 1300 and 7.4 kts it is $10 per hour. At the very top end, at 2500rpm and 16.2 kts it is $36 per hour saved. I would very much like any information anyone has on a similar boat, hopefully including actual fuel consumption data. My information is from a sheet I found on the boat, source and accuracy unknown. Thanks in advance.

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Hi,

here's the NT 37 information, all the tanks full of 5 people and all the goods in the long journey involved. Wind front, wave 1-2 "feet. Speed ​​GPS and fuel consumption Cummins computer which proved to be really accurate.


I am sorry fuel is litres/hour 1 gal is 3,8 litres

NBs

Chris,
Using your numbers (6.5kts@3mpg and 7kts @2mpg) I come up with the number of $45 per hour. That is, it costs $45 for every hour saved going 7kts instead of 6, all assuming $3/gal for fuel. That sounds fairly expensive for going 7kts instead of 6. And BandB said his boat costs $61 at 15kts and $80 at 20. I think, given different boats and unknown accuracy of the numbers, it all comes down to about the same thing. And I've done the calculation for other things. My sailboat was about $5/hr at 6.5 kts, a fairly efficient car is about $20/hr at 70mph, and my airplane was about $200/hr at 165 kts. Does everyone take this into account when driving/flying/boating? It's probably in the back of our minds, but I find it useful to put it into numbers. If I have a real need to get from here to Frankfort in a day, then I'll be willing to spend $15 an hour or more. If my destination is not so far, then I might cruise at $6/hr. The $200/hr in my airplane convinced me to cruise more for efficiency than speed. But then my time probably isn't worth as much as others. However, time always has a value.

Regarding the discussion of a large engine running at "low" rpm compared to a small engine running faster, I suspect the fuel consumption could be a toss-up. A large-diameter prop running slower should be more efficient than a smaller one. A large single engine should be more efficient than two smaller engines. In the end you pays your money and takes your choice.

garycasey said:

Chris,
Using your numbers (6.5kts@3mpg and 7kts @2mpg) I come up with the number of $45 per hour. That is, it costs $45 for every hour saved going 7kts instead of 6, all assuming $3/gal for fuel. That sounds fairly expensive for going 7kts instead of 6. And BandB said his boat costs $61 at 15kts and $80 at 20. I think, given different boats and unknown accuracy of the numbers, it all comes down to about the same thing. And I've done the calculation for other things. My sailboat was about $5/hr at 6.5 kts, a fairly efficient car is about $20/hr at 70mph, and my airplane was about $200/hr at 165 kts. Does everyone take this into account when driving/flying/boating? It's probably in the back of our minds, but I find it useful to put it into numbers. If I have a real need to get from here to Frankfort in a day, then I'll be willing to spend $15 an hour or more. If my destination is not so far, then I might cruise at $6/hr. The $200/hr in my airplane convinced me to cruise more for efficiency than speed. But then my time probably isn't worth as much as others. However, time always has a value.

.

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And using cost per hour assumes hours are of no value. I greatly prefer using cost per mile. Even then I look at cost in terms of dollars and time. Neither dollars nor time are limitless or infinite in nature. Both are important.

Cost of diesel is different in every market- need to state that cost so people can adjust one persons reality with their own cost- thus gallons burned per hour is better to go by.

"I doubt a 1.9 litre 75hp yanmar or similar will do as well as a 7 litre 5lw Gardner for example"

The simple method of finding a suitable engine would be to only look at those with M1 to M4 ratings.

That will select out the taxi, farm implement and lawn equipment based engines. .

Back in the day Detroit made 2-3-6-12-16 cylinder engines , made the selection a snap.

Today I would look for a mechanically injected engine with no turbo.

Might cost a bit more in fuel every 1,000 hours , but no $$$$$ computer $1,000 injectors or turbo to service.

I prefer to pay at the pump, rather than at the parts counter.

Well, that was sort of my point. Neither dollars nor time are infinite. Therefore, whether out in the open or not, we all compare the relative value of our time and the dollar. For some, $1000 of operating cost is virtually meaningless, while for others it might be felt to be huge. For some an hour saved is not worth much, while for others it apparently has a virtually infinite value. Basing a decision strictly on cost per mile ignores the value of time - and vice versa. My technique of calculating the ratio of incremental time to incremental cost gives a rational way to decide on cruising speed. That's what I was getting at. For each his own.

Thank you very much. I'll put it into my spreadsheet and publish the results.

Thanks to "North Baltic Sea" for providing data. From the looks of it, the behavior of the SD hull is pretty typical, I would think. It is obvious that one would be strongly tempted to cruise at 8kts or less, or if in a hurry, go to 14 kts. Any other speed is very expensive per hour saved. Looks like I'm not smart enough to insert the chart, so I'll put the calculated data below. Again, this is the cost per hour saved of going at a given speed compared to a little slower.
SPEED(KTS) INCREMENTAL COST PER HOUR SAVED(USD/hr at $3.55/gal)
6.8 3.91
7.4 20.85
8.1 35.78
8.7 81.49
9.4 83.02
11.3 12.87
13.5 12.32
14.7 85.49
15.4 249.83

garycasey said:

Thanks to "North Baltic Sea" for providing data. From the looks of it, the behavior of the SD hull is pretty typical, I would think. It is obvious that one would be strongly tempted to cruise at 8kts or less, or if in a hurry, go to 14 kts. Any other speed is very expensive per hour saved. Looks like I'm not smart enough to insert the chart, so I'll put the calculated data below. Again, this is the cost per hour saved of going at a given speed compared to a little slower.
SPEED(KTS) INCREMENTAL COST PER HOUR SAVED(USD/hr at $3.55/gal)
6.8 3.91
7.4 20.85
8.1 35.78
8.7 81.49
9.4 83.02
11.3 12.87
13.5 12.32
14.7 85.49
15.4 249.83

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Hi, I find it wise to look for a sweet spots and save money and latex emissions at the same time. Here gallon costs 6.5-7 $ and our standard of living index is roughly the same as US. Often, time is not as important when I'm at sea enjoying vacation days.

An interesting idea really is to turn consumption into price and see real savings in cash.

NBs

HP

I have a Grand Banks 36 with a single Ford Lehman 120. Honestly, I think the boat is underpowered in terms of cruising speed, fighting wind and currents etc. But I really like that boat so I deal with this. If speed is important to you then consider the semi displacement boat with the greater hp. If you are comfortable with 6-8 kts in good conditions and somewhat less in rougher conditions but prefer the Kady, then go there. Price, boat condition, personal preferences are all important considerations. Just be brutally honest with yourself regarding what is important to you and how you will use the boat and buy the boat that best fits that profile. Good luck!

I think you need to look at with Cat engine. 3208, 3116,3126. Some are better than others. KK boats I think are superior to Mainship.

jefndeb said:

But what I am confused about is the Mainship has a single Cat 380 HP diesel but the Kadey has a single Ford Lehman 135 HP...

What am i missing?? Why does the slightly smaller boat have so much more HP? Is it because is newer and engines are more advanced?

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I believe that Cat engine 3208? is 210HP normally aspirated, 380HP on turbochargers. When I was researching the 3208 engine I found that the time before overhaul was 30,000. Fantastic! I thought.

But then I noticed it was 30,000 gal, not hrs. At the rate they were using fuel with 380HP then, that engine may be past its MTBO already...

Sometimes I think this power to speed talk misses the more dominating element or variable. WEIGHT

Even FD hulls are directly affected by their weight. Double the weight ... need to double the power ... to maintain the same speed .. typically and at typical speeds.

FD boats suffer from their extra weight as typically they weigh considerably more that SD or Planing boat. My gen 1 25 Albin weighed 1/4 what my W30 does. Both FD hulls but the Albin should get along with 1/4 the power. But as I said in another post it depends on the speed.

But if you dream of pushing the hull speed element w a SD hull you can. Unlike the FD hull where you can’t. However at a bit over hull speed weight becomes even a greater limitation than it is for a FD boat at lower speeds. Most skippers here w SD boats probably cruise a little over hull speed to a knot or two. I don’t know the weight/power ratio here but I suspect that to gain 10% speed w a SD hull running 1/2 a knot over hull speed one would need considerably more than 10% more power.

So I’m think’in the average rec trawler running at a typical speed will find that weight is a more limiting factor for speed than power.

It all boils down to your age.
Are you still working ? Then you probably want to rush down to your boat at 80 mph, jump on board and whizz down the coast, whizz back to the marina, jump in your car and rush home at 80 mph= Planing, Semi planing hull.
If your retired then comfort rules OK. Your cute enough to have made enough money to buy the boat, you want to make your money stretch as far as you can and you've got time on your hands to enjoy every day as you wish= displacement hull.

The Ford Lehman was a very good engine. The Super Lehman 135 is the same as a Lehman. 120 and the Super Lehman 90 is the same a Lehman 80. The only problem with those Lehmans is getting parts as they went out of business many years ago. I had a Crosby tug with a 80 that needed work. I re powered it with a 90. Most of the time I ran it at 1750 RPM s. Also had a Lehman 120 with a Warner 73 and 3-1 reduction. If you don't run them at. 2600 but rather 1750 those will last for a very long time. Also had the 120 rebuilt where it ran like new. The red work boat was re powered with a JD.

I have never had a problem getting parts for my Lehman 120’s. American Diesel has everything you need for your Lehman’s. I get 4gph @ 1800 rpm 8-9 knots. Love this boat.

MOJO (www.mvmojo.com) displaces about 80,000 lbs. Her hull speed is ~9.3 kts. Cruising speed is 7.5 kts and at that pace she burns 2.7 gallons per hour. She has a 250 hp Cummins but only needs about 60 hp to push her at 7.5 kts. She'll make hull speed, but will be burning in excess of 10 gph. So, at $3.00/gallon for diesel, at a cruise speed of 7.5 kts it will take 13.3 hours to run 100 nm and she'll use ~36 gal for a cost of $108. Kick her up to 9 kts and the time will be cut to 11.1 hours but she'll consume 111 gallons costing $333. Saving that 2.2 hours per 100 nm will cost an additional $225 in fuel! Like the old saying goes, "Speed is just a matter of money"!

Yes, that is true. Bob worked at Ford Lehman in Linden NJ. There was also a former Lehman employee who sold Ford parts but I am not sure is he is still business. That business is in North Jersey. As a note. Probably half of the employees at Ford Lehman, Linden NJ were former sea scouts.

If the FD boat has an autopilot, using it removes some of the need for speed.

This little tug was purchased by Massachusetts Marine as a training tool. I owned it from 1984 to 2000 when the school obtained it. The tug has a small 90 Ford Lehman diesel with a Paragon 1.97-1 gear. The tug has a 22 x 16 inch prop. The school tows a 38 foot barge as the schools training. The engine was installed in 1984 and they tell me that the engine is still going strong.