Powercat Trawlers

RickB · Dec 12, 2013

FF said:
...60 HP from a 150-300 P engine is not efficient , even with a modern electronic injection engine.

Using a Cummins 6BT5.9-M as an example, at full rated power of 210HP its BSFC (pounds of fuel burned to produce one hp for one hour) is 0.397.

At a moderate output of 120HP it will burn the same amount to produce one horsepower ... 0.397 pounds.

If you pull the throttle back to 60HP, that engine will burn 0.385 pounds of fuel to produce each horsepower.

It is more fuel efficient at 60HP than at its rated maximum power output and a moderate "cruising" power.

While that particular BSFC relationship may not apply to every engine, in every installation, it shows very clearly that the statement you keep making about "low efficiency" at less than some arbitrary high power output is incorrect. It is misleading, and it is based on docktalk and rumor.

brian eiland · Dec 12, 2013

Here is a Passagemaker mag boat review (nice pics also of quality built interior):

http://www.journeycatamarans.com/wp-content/uploads/2012/11/JourneyCat.pdf

....excerpt...
THE TEST
Underway, the twin 220hp
Cummins QSD diesels turning 20
x 20 x 4 props through Seatorque
drive shafts produced a smooth and
quiet ride at the lower helm. New
21 x 19 x 5 Michigan Wheel M500
series props are planned for hull
number one, adding about 30 percent
more surface area and an anticipated
increase in economy and performance.

Beginning with hull number two,
standard 260hp Yanmar 6BY diesels
spinning 24-inch diameter props will
be standard propulsion, adding 40
more horsepower and blade area, and
reducing weight by 100 lb. per engine

brian eiland · Dec 12, 2013

RickB said:
Using a Cummins 6BT5.9-M as an example, at full rated power of 210HP its BSFC (pounds of fuel burned to produce one hp for one hour) is 0.397.

At a moderate output of 120HP it will burn the same amount to produce one horsepower ... 0.397 pounds.

If you pull the throttle back to 60HP, that engine will burn 0.385 pounds of fuel to produce each horsepower.

It is more fuel efficient at 60HP than at its rated maximum power output and a moderate "cruising" power.

While that particular BSFC relationship may not apply to every engine, in every installation, it shows very clearly that the statement you keep making about "low efficiency" at less than some arbitrary high power output is incorrect. It is misleading, and it is based on docktalk and rumor.

So you are saying that if you pull back the throttle and cut the RPM's of the engine significantly, you will save almost no fuel??

Just the greatly reduced volumetric intake would seem to counter this??

RickB · Dec 12, 2013

No. There is a big difference between BSFC and fuel consumption. BSFC is how much fuel an engine burns to produce one horsepower for one hour. Fuel consumption is how much the engine burns in one hour.

Most engines are have the lowest BSFC at some power level other than the lowest or the highest, that range is where they are most efficient at converting fuel to power. That doesn't necessarily mean that the system in which they are installed is most efficient at that point however.

rjtrane · Dec 12, 2013

Rock is right. The fuel/Hp curve on modern diesels is a shallow curve with the most efficient RPMs towards the center - the least efficient at the ends both high and low.

If one is designing a boat where maximum efficiency is an important goal, then engine choice would take into consideration using the RPMs at cruise where the motor is delivering the maximum HP per unit of fuel. Since this part of the curve is towards the center, then there would always be plenty of HP in reserve.

brian eiland · Dec 12, 2013

...but we are talking 'efficiency' here , not lowest fuel consumption ....correct?

Daddyo · Dec 13, 2013

Deltaville, VA June '13. First boat I saw after tossing the lines headed solo for Maine

Sorry the pics are grainy but it was about 5 am I think.

Parmenter · Dec 13, 2013

Daddyo said:
Deltaville, VA June '13. First boat I saw after tossing the lines headed solo for Maine Sorry the pics are grainy but it was about 5 am I think.

Nacelle appears to be shocking overkill.
I have delivered similar sized powercats before without anything even remotely like that.

I also have my worries about the bluff wall of metal at the front, especially if you were to encounter seas that required such a large nacelle

harbor950 · Dec 13, 2013

Daddyo said:
Deltaville, VA June '13. First boat I saw after tossing the lines headed solo for Maine

I was curious. It has a site: FAQs About the Boat

Said to be a 12 Knot Crowther built by AF Theriault. Interesting url, BigDumBoat.

markpierce · Dec 13, 2013

The Coot is the antithesis of all of this. Fat, heavy, and plowing the water, burning 2-minus gallons an hour going six knots using a fraction of its 80 horsepower.

232323232%7Ffp734%3A3%3Enu%3D3363%3E33%3A%3E57%3B%3EWSNRCG%3D394%3A9%3A67%3B%3A336nu0mrj

RickB · Dec 13, 2013

brian eiland said:
...but we are talking 'efficiency' here , not lowest fuel consumption ....correct?

Correct? Who knows?

What kind of efficiency are you talking about?

Fuel efficiency?
Transport efficiency?
Engine efficiency?
Propulsion efficiency?

You guys appear to be trying to measure some undefined parameter without a real gauge or even a common vocabulary.

I'm waiting for someone to come up with an equation to describe how much elbow room each angel has when dancing on the head of a pin. That would probably have more practical application.

RT Firefly · Dec 13, 2013

Greetings,
Mr. Rick B. Here ya go....

healhustler · Dec 13, 2013

Daddyo said:
Deltaville, VA June '13. First boat I saw after tossing the lines headed solo for Maine Sorry the pics are grainy but it was about 5 am I think.

Looks more like in the tradition of Pacific Expedition or Trawlercat Marine designs, both below. Huge hulls. My interest in cats are more along these industrial styles, even though I don't consider them attractive. I too, am puzzled about the bluff bow.

Photo 1, Pacific Expedition, Photo 2, Trawlercat Marine

brian eiland · Dec 13, 2013

Daddyo said:
Deltaville, VA June '13. First boat I saw after tossing the lines headed solo for Maine Sorry the pics are grainy but it was about 5 am I think.

http://www.trawlerforum.com/forums/showpost.php?p=198529&postcount=127

Butte ugly as well

BruceK · Dec 13, 2013

I hoped Healhustlers pics in #133 above were photoshopped, seems they are not. Maybe something was cut down the midline and a beam extension inserted in-between. Why do some cat designers use a school bus as their inspiration?

Parmenter · Dec 14, 2013

healhustler said:
Looks more like in the tradition of Pacific Expedition or Trawlercat Marine designs, both below. Huge hulls. My interest in cats are more along these industrial styles, even though I don't consider them attractive. I too, am puzzled about the bluff bow.

Photo 1, Pacific Expedition, Photo 2, Trawlercat Marine

Pretty sure I read in the blurb once that they to are a crowther, all I can say is I hope it was Brett and not the legend, his father Loch who penned it.
And if it was Brett, that would go a way's to explaining why there is no Crowther designs anymore.

Heres something similar in steel

Steel Workcat 55' “Stay Calm” | Commercial vessels | Boat Sales Tasmania

markpierce · Dec 14, 2013

Something?? What the hell is that??

Northern Spy · Dec 14, 2013

healhustler said:
Looks more like in the tradition of Pacific Expedition or Trawlercat Marine designs, both below. Huge hulls. My interest in cats are more along these industrial styles, even though I don't consider them attractive. I too, am puzzled about the bluff bow.

Photo 1, Pacific Expedition, Photo 2, Trawlercat Marine

That thing looks like it's made out of Lego.

Tidahapah · Dec 14, 2013

Bluff bows, Sharp Shooter is one of 2 (Straight Shooter) that I did a bit of work on.
Both were tuna long liners, Economic, ugly but bloody terrific work platforms and comfortable so less fatigue for the crew working long hours.

Can't recall the builder/designer from down south in NSW but I did approach him re design for a smaller version when I was going thru my cat phase.

Off Duty · Dec 14, 2013

I find something rather ruggedly beautiful about "Sharp Shooter" pictured above. Then again, I drive an old FJ62 Landcruiser and love the 80-90's Suburban's, so maybe that's it?

Daddyo · Dec 14, 2013

I like it

brian eiland · Dec 14, 2013

How many 'yacht' owners really want the looks of a fully commercial vessel?

psneeld · Dec 14, 2013

brian eiland said:
How many 'yacht' owners really want the looks of a fully commercial vessel?

depends...the boating community is pretty varied in personalities.

I prefer workboat over yachtie...that way I don't feel as guilty about "less than perfect" any part of the boat...gives me more leisure time than slaving over details.

brian eiland · Dec 14, 2013

Sorry, probably should have utilized a different word than 'yacht'. I wasn't referring to the high gloss yacht style as a preference over commercial.

healhustler · Dec 14, 2013

BruceK said:
I hoped Healhustlers pics in #133 above were photoshopped, seems they are not. Why do some cat designers use a school bus as their inspiration?

I can clearly understand your Photoshop suspicions when it comes to boats of this sort. Of course, a less rugged but equally impressive profile is in the Krogen Mana-Cat

N4712 · Dec 14, 2013

healhustler said:
I can clearly understand your Photoshop suspicions when it comes to boats of this sort. Of course, a less rugged but equally impressive profile is in the Krogen Mana-Cat

hollywood8118 · Dec 14, 2013

brian eiland said:
How many 'yacht' owners really want the looks of a fully commercial vessel?

look at those fugly Dashew oversize beer cans...

People buy them and pay through the nose for them...

HOLLYWOOD

Maltese52 · Dec 14, 2013

I think the Commercial/Yachty look appeals to a lot of people cause it makes you look serious and bad @ss... at the same time...

More than that though its tells people you are not a cookie cutter boat person, more of a MAD MAX type of boater...
There is always something cool about a boat that exudes that look. In my opinion.

I was very close to painting our hulls a Greyish Awlgrip Color but ended up going with Matterhorn because it has enough of a hint of grey for the very reason of wanting to make the boat look more aggressive

I think the Cabinhouse along with the reverse bows does that enough...

Maltese Catamarans MP52-Trawler

Nomad Willy · Dec 14, 2013

I like the reverse stem rake but that "T" shaped thing dosn't do your boat any favors. I thought at first it was a construction brace of some sort but it's looking more like it's actually part of the boat. THAT"S what you should paint light grey in hopes that it will visually disappear. I'm hoping the T bar is a functioning prototype for a nice white carbon fiber unit shaped like an airplane wing w a curved shape like the camber in cabin tops.

Designing a cat must be very challenging regarding structural integrity. I designed and built a boat that wasn't very good looking but it was just a prototype.

Thinking about the reverse stem rake again it may or even probably would be just as good looking as the usual positive rake of most boats. I think you like it to have an out of the box look.

N4712 · Dec 14, 2013

I agree with manyboats, I thought that's was a jig for bulkhead alignment or something. Looking closer and seeing that it's a part of the boat, wow that's about as butt ugly as, well I don't know anything butt ugly enough to compare it to. I would rip that thing off. Sorry. Also where does the windlass go?

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