80 hp vs 130 hp

I just read the entire thread, to this point it has more bouncing around then the last week of the final four.

You guys crack me up, seems like a bit of ADHD going on here.

NO 80 HP on each side is not to little hp on a FDH trawler of 40 LWL. Hull speed will be met at less then 75% power and really what more do you need?

There are times when more power is not needed just as there times when you don't need more fuel (you are on fire).

I'm starting to think-very scary. If you have a 4cly 200 cubic inch engine and the max RPM is 2000RPM. Each rpm burns 200 cubic inches of fuel/air mixture at whatever the compression ratio is. But, you could figure your fuel burn per rpm with a few calculations. My head is spinning!! Anyway, my boat is way over powered (165hp). I cruise at 1800 rpm. Max rpm is 3400. Very quite-speed 7 to 8 knts depending on conditions. Fuel burn??? Haven't refilled the tanks yet.LOL

"Each rpm burns 200 cubic inches of fuel/air mixture at whatever the compression ratio is."

With a 2 stroke ,yes , with a 4 stroke its half , as no fuel is injected for the exhaust stroke.

If your boat is displacement probably 1 GPH is about right at about 5K

If you run 35K itb will be 35GPH (not likely)

200CI would be close to 60-75HP 4 to 6 GPH if run on the pin.

Actually, my boat was built by Nunes Brothers in Sausalito, CA. It is a Geary design and very similar to a Blanchard 36 scaled to 90%.

Since my boat is from 1936, I would say that Yellow Cedar looks like my boat

Engine output power varies with engine rpms. The maximum rated power is normally determined by governor settings. As a result of new emission standards, many engine manufacturers have derated their engines to lower "maximum" power by simply changing governor settings resulting in lower maximum rpms. Maximum rated power really has very little meaning EXCEPT when you are trying to fit the correct prop and want the boat's power curve to intersect the engine power curve at maximum rated rpms.

Finally, running at 85% of engine output power only happens near the WOT. It simply isn't possible at lower throttle settings unless you are tied to the dock (look at typical power curves for boats - they normally don't hit 85% until more than 90% of rated maximum rpms). As far as what power output to run at goes, it really doesn't matter as long as you run at a high enough load to fully warm the engine up.

Tdunn,
There was talk of running 85% of rated rpm as a good ballpark max continuous power setting. Of course most engines have specifications that call out what that rpm is. And I assume it's assuming the engine is propped to rated rpm. Either that or it's stated in the specifications. And you're right 85% output will be over 90% rpm.

So from what you're saying it looks like a Tier ll engine is created by just injecting less fuel. That was common in the 50s with DD. But that was just by changing injector nozzles and I think you're talking about less fuel delivered .. not just a smaller orifice. But my knowledge if fuel injection is limited.

But actually the thread question here is re matching boats to power .. not engines to max continuous output.

FF if Tdnn's boat is actually FD fuel burn at 5 knots would be considerably to much less than 1 gph IMO. Probably half that.

TDunn said:

As far as what power output to run at goes, it really doesn't matter as long as you run at a high enough load to fully warm the engine up.

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Soooo True!

With nearly any engine in nearly any vehicle... boats, cars, trucks... running at full operating temp with variety of loads is critical for long periods at any speeds. Too hot or too cool can really mess with engineered specs for the motor's internal metal-parts-expansion qualities. Once warm and under load, regarding what rpm/hp-level to run at depends on the load carried, conditions experienced, and fuel economy desired. That said - there is always a max and min rpm that each engine has been engineered to not exceed on either end of the spectrum. And, some engines' increased performance paraphernalia require occasional blasts into higher rpm for raised accessory product temps to keep things clean/performing-best.

Biglia II 40' one single engine 200 days to round the world at an average seep of 7,1 kts .
Zeilhelden.nl is de nationale galerij van Nederlandse en Vlaamse zeilhelden
Some people ask about go faster (some wrotte 12 or above) but we are on "Trawler Forum" or speed boat forum ?

In 1936 Arielle 13m displacement boat one 50 hp engine cross the Atlantique @ 7,5 kts average speed .

I read also than a biger engine who work only at 25% will have a longuer life than one smaller engine who working at 65%.... I am not sure of that (unfortunatly because our too big engines always working at very light even less than 25% if we are below 10kts on both engines)

A colleague had two "small" engines 2X85 cv on a 18m boat with a displacement of 42 T and he cross 4 time north Atlantique.

Le journal en Français - The sailing igloo

In my mind "trawler " or "passagemakers" means navigation under the hull speed and displacement or semi displacement boat .
An d to much power is not necessary for example we have 2X215 hp and it is far too much.
It is a mistake i try to eplain why we do this "mistake" here :
Motorisation - Trawler long-cours

The next one will have 2X130 hp or even 1 X 250 hp, because if we take a look of the Perkins HP/propeller curve of the 130 hp and the 215 hp
At 1500 rpm (good for noise vibration etc )
The 130 hp atmo : 27 hp and 6,10 lt per hour = 0,226lt/hp
The 215 hp turbo : 54 hp and 8,92lt per hour = 0,165lt/hp

A big difference in consomption ! And just at 1500 rpm at this speed the turbo don't give the best..

TDunn said:

... As a result of new emission standards, many engine manufacturers have derated their engines to lower "maximum" power by simply changing governor settings resulting in lower maximum rpms. ...

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JD downrated the nominally 85-hp 4045 to 80 hp for emission compliance in my instance.

Sadly no engine , boat , gearing , prop can be optimized with a HP/prop curve.

What is required is a BMEP graph (AKA a fuel map) for that engine , as loaded,,, M1-M4 as required..

Eng mfg do not usually part with these .

A workaround can be to see if the engine is strong enough to be used for a generator , then sometimes the BMEP is shown for noisemaker mfgs..

BruceK said:

And, called an otter board because??? Nothing too fanciful please.

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I've heard the term before. I grew up on commercial shrimp boats (trawlers). I've always assumed it was due to a similarity to the boards we used to stretch otter (and other) hides on for drying. However every person I've ever known who actually used them calls them doors or boards. And those other terms that were quoted I've never heard (bobbins etc). Lead (the metal) line, mud roller, cork line, tickle chain, mouth, throat, tail, bag, skirt, etc are terms used along the Gulf of Mexico. Other regions obviously have their own vernacular.
And that is the perspective of someone looking from the inside out. Not a tourist or dictionary compiler.

Oh yeah. A "trawler" doesn't relate to a specific boat in the fishing realm. It just signifies that it uses a trawl. Putt-putts, jon boats, skiffs, luggers, double-riggers can all be "trawlers", or skimmers, butterfliers, seiners, longliners, etc. Or they could be bass boats, houseboats, yachts, cruisers, passage-makers, etc.

So the trawler term being applied to a pleasure boat is really irrespective of how its used. It is just a marketing ploy.

Kinda like a person with a Honda Civic Si telling a person with a Z06 Corvette about his "sports car".

Quote:
Originally Posted by TDunn View Post
... As a result of new emission standards, many engine manufacturers have derated their engines to lower "maximum" power by simply changing governor settings resulting in lower maximum rpms. ...

Mark wrote:
JD downrated the nominally 85-hp 4045 to 80 hp for emission compliance in my instance.

Governor's are limiting devices so I'm thinking Marks engine is only limited at max throttle and fuel injected below max is unaffected and just like the original engine that is not emission controlled. Is that right?

Eric:

Well yes and no. First I think that this subthread re emissions has it backwards. JD (and others) didn't "downrate" the engine to meet emissions regs. They made modifications like changing the timing, injectors, etc. to meet the regs and that resulted in slightly less horsepower.

That reduced horsepower is probably across the board. If you compare the before and after power curves, I will bet you see that the after one is lower throughout the rpm range. So it is not "just like the original non emissions controlled engine" below 80 hp.

But the difference is probably meaningless. If you subscribe to the correct propping philosophy you will probably have to run a very slightly lower pitched prop to hit the rated rpm while producing 5 less hp. Your top speed will be very slightly reduced. If you needed 50 hp before to cruise at your desired speed, you will have to goose the rpm up a fraction more to get that same hp/speed. And I suspect that your fuel consumption will be a tiny but unmeasurable amount more at that speed.

David

twiisted71 said:

So the trawler term being applied to a pleasure boat is really irrespective of how its used. It is just a marketing ploy.

Kinda like a person with a Honda Civic Si telling a person with a Z06 Corvette about his "sports car".

Click to expand...

Interestingly, the company that created the Grand Banks line of boats, American Marine, never used the term trawler to describe their boats. (Grand Banks Llc does today for marketing reasons).

But American Marine always referred to their Grand Banks boats as "diesel cruisers." Which, of course, is exactly what they are.

David thanks and that makes loads of sense. It may even help explain why my S4L2 Mitsu has Three different hp ratings. Westerbeke 44hp, Vetus 42hp and Klassen 37hp.

Marin,
"diesel" isn't even necessary. They were "Heavy Cruisers" in the 50s and are Heavy Cruiser's now. I agree "Trawler" should have been left to our fishing cousin's but since 98% of "trawlers" are pleasureboats the meaning has been changed. I was trying to explain what kind of boat Willy was and they (female) said "you mean a trawler?". Trawler as per fishing boats is obscure now so there's no need to point out the true meaning of Trawler when the true meaning is history. The true meaning now is "slow heavy pleasure powerboat".

manyboats said:

David thanks and that makes loads of sense. It may even help explain why my S4L2 Mitsu has Three different hp ratings. Westerbeke 44hp, Vetus 42hp and Klassen 37hp.

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Actually I don't think the hp variation is emissions related. In fact Tier 1 did not apply to under 50 hp diesels. Don't know about Tier 2+.

I think that the variations in published hp are more in the rating standards. For example there are two fuel temperature specs that are used to rate diesels. The colder one (60 deg F or the C equivalent) makes more power than the warmer one. Also the rating might include or exclude a raw water pump which would not be used in an automotive or industrial design.

Small volume marinizers like Klassen probably use the base engine's rating data. Westerbeke and Vetus may do their own ratings.

All of these can change the hp rating for exactly the same engine.

David

80 HP 4 cyl Sabre has served this boat for 30 years. Never felt deprived.

Thanks David. Most of the small Klassen's are on gen sets. Very few for propulsion.
Yes i think the 37hp rating is straight from the industrial line. Never seen anything but 37hp from Mitsu. Westerbroke and Vetus propagate the 42 and 44hp numbers.

Salty Dog,
You have a very slick FD hull so you may not work the Sabre very hard. The Sabre may be smoother than the Lehman .. do you think?

Eric- Based on the set of manuals that came with our boat, some Sabres are the same base Ford of England diesel that Lehman used. I'm not sure why we have a Sabre manual on our boat along with the Lehman operations manual and Lehman and Ford parts and shop manuals, but it shows the same engine.

Hi Marin,
Yup I know that. I had a 120 Sabre in my Sumner Craft. Great engine. I think it had a SS exhaust manifold. And it wasn't a typical 380 Ford. It got sent back to England to get blueprinted. Was very smooth but noisy compared to my Willy and Mitsu. Bigger engine more noise of course but there was more to it. I had to choose between the Willard and Sumnercraft. If we hadn't been going to Alaska I probably woulda kept the Sumnercraft. It was a 29' express. It drew 3' and it's engine was inside the keel w a horizontal prop shaft. It was kinda like a big torpedo w a boat on top. Composit construction w fir planks inside and FG on either side. A 1961 boat. Amazing boat.

manyboats said:

Hi Marin,
Yup I know that. I had a 120 Sabre in my Sumner Craft. Great engine. I think it had a SS exhaust manifold. And it wasn't a typical 380 Ford. It got sent back to England to get blueprinted. Was very smooth but noisy compared to my Willy and Mitsu. Bigger engine more noise of course but there was more to it. I had to choose between the Willard and Sumnercraft. If we hadn't been going to Alaska I probably woulda kept the Sumnercraft. It was a 29' express. It drew 3' and it's engine was inside the keel w a horizontal prop shaft. It was kinda like a big torpedo w a boat on top. Composit construction w fir planks inside and FG on either side. A 1961 boat. Amazing boat.

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Hi Eric

You have pictures of that Sumnercraft? Sounds interesting.

Art

Art,
Sure wish that I did. I have print photos somewhere but nothing digital.

The hull cross section looked a bit like a wine glass w a fat stem (wide enough to accommodate the engine) and almost pointed at the base (keel). The valve cover gasket was about level w the WL. She turned very flat and sharp. Had a rudder almost as big as my Willard. Compared to other boats she was very easily driven at the difficult speed of about 12 knts. Very level running too. Soft chines much like a lobsterboat down to 8" below the WL. The construction was called "compoglass". Douglas Fir planking w FG on both sides. Light and strong. If I ever come up w pics I'll post them on Interesting Boats.