Will trawlers disappear?

[backinblue]

My comments are based on my working experience as a professional forester, with over 20 years experience. I worked in Woods Buffalo National Forest, Alberta (Canada), Clearwater National Forest, Idaho and Georgia Forestry Commission, GA.
What happened after I retired, no idea. I do know we bent over backwards to maintain or improve water quality.
Then add in site reclamation and replanting as necessary.
I guess we will just have to agree to disagree.

I am not saying that I agree or disagree with you, just would rather not get into a debate here about Trump and what he is or is not to blame for. In many elections, there never seemed to be much a difference between the candidates. In this election, there are stark differences in policy and the direction they want to take the country in. I would hope that's what voters focus on and vote for rather than a personality contest as many of our elections end up being.

 

[OldDan1943]

And boats aren't really efficient fuel OR time wise. But who cares?
I can enjoy my boat by traveling an eighth of a mile, enjoy a drink watching the sunset and return. Fuel doesn't matter.

I agree. Boating is supposed to be fun. If the weather turns bad then, boating can be very 'interesting'.

 

[backinblue]

Freight shipped by boat is efficient, but that's different than pleasure boating.

 

[psneeld]

The posts about efficiency...in my case was to point out the thread that boats had to be light to be efficient is just one tiny bit of perception.


That not all of us agree that light boats are the key to efficiency.

 

[Hippocampus]

Think efficiency needs defining.
If you use your vessel for long range cruising and are on it for long periods of time then efficiency means how much energy does it take to move a pound of payload a given distance.
Compare a 55000lb N40 to a 58’artnautica. Fuel burn is about the same at 2.3nm per gal. Payload the same as well. But running at a S/L of 1.2 to 1.3 the 58’ “ultralight” (not really as dry wt. about the same as the 40’ boat) the Artnautica is more efficient. Here sog comes into play.
Both carry the same amount.
Both burn the same per mile.
One goes much faster doing it.
Narrow, long boats compared to beamy short boats have a greater hull speed at the same engine HP, better prismatic coefficient and when comparing equal displacement/payload nearly the same or in weather less total drag and resistance.
Talking about light v heavy in isolation not considering the totality of the design misses a lot of the science and art of naval architecture. The more extreme example would be to compare monos to multihulls. Or FD hulls over 70’ with bulbous bows. Or wave piercing bows on faster craft but still operating in full displacement mode.
That’s the problem talking about any boat. Be it a kayak or a VLCC. Any one feature doesn’t describe the boat. It’s the totality and how they work together or not for the intended use. Reminds me of the blind men and the elephant.

 

[Nomad Willy]

Freight shipped by boat is efficient, but that's different than pleasure boating.

Yes and the Wheatties go to Alaska via barge and tug. The barges are FD vessels. Most that have gone any distance up the PNW "Inside passage" will have seen several to many. Most (including me are amazed at how fast they go). 16 to 18 knots actually. So they run right past our trawlers. WLL is golden.

That would indicate my 30' Willard w a 27.5' WL is very inefficient. Hmmm

 

[Nomad Willy]

Hippo,
Weight is paramount in power required.
If I was to have a list of various FD trawlers (or other FD vessels) and asked how much power would be required for each vessel I could come amazingly close just knowing their displacement. It's typically about 4hp per ton of displacement.

Given a specific WLL and displacement and probably a picture to indicate general hull type a fairly accurate estimation of power required can be made very easily.

So perhaps weight is the most influential element predicting efficiency.

 

[psneeld]

Depending on what "efficiency" one is talking about...otherwise weight only matters for one or several parameters of efficiency.

 

[Peter B]

I would like Art to define and explain this 'Full-Cycle, Carbon Neutral fuels'' thing he places so much emphasis on for future efficiency while also helping reverse the CO2 build-up. I get the 'carbon neutral', but the 'full cycle' aspect escapes me...

 

[BruceK]

I would like Art to define and explain this 'Full-Cycle, Carbon Neutral fuels'' thing he places so much emphasis on for future efficiency while also helping reverse the CO2 build-up. I get the 'carbon neutral', but the 'full cycle' aspect escapes me...

Example of full cycle:

 

[Hippocampus]

NW you’re right of course but at the same displacement (Weight) different hull shapes require different amounts of propulsive force. Surely you’d agree even if wetted surface (also determined by displacement) is the same waterline (lwl) matters as well as parasitic drag. It’s harder to push a box through the water than a pencil. So yes weight is important and determines several other parameters but even inside your post you must agree a fair hull not producing turbulence, it’s diagonals, it’s rocker, it’s gyradius, it’s expected speed of operation, it’s stern, stem and appendages all effect how much power is required. Now add in non calm waters and further differences appear.
Simple example. Centerboard or lifting keel sail boat. Both are much faster going downwind with keel retracted. Displacement didn’t change wetted surface did as did parasitic drag and turbulence. Or a barge v a hard chine hull. Both could be the same weight and wetted surface and LWL but the barge takes more HP to drive through the water. Particularly if the bow and stern are straight verticals so it’s just a box. Usually beamy boats are less efficient. Naval architects do earn their keep.

 

[Nomad Willy]

Hipp,
Yup many variables. And did I mention variables?
But the biggie, once you’re past displacement is wave making resistance and skin friction resistance. Canoes don’t have much wave making resistance but plenty of skin friction. And if in their design speed (2 Maybe 3 knots) the total resistance is very low. But total power is the arms of the paddler. Also low.
But w SD trawlers at hull speed (too fast for a FD boat) the shape of the stern is the Big apple. If a boat is to have a design speed of 2 knots above hull speed less rocker would be ideal whereas at hull speed (previously mentioned) noticeably more rocker is ideal. One knot below hull speed and plenty of rocker is ideal ... for a FD boat. So much so that all or nearly all of the transom will be out of the water at rest. So the stern dictates the performance after one gets past displacement and general dimensions.
Hipp I think most all barges have rounder chines. So the term “box” is mostly the sled ends and the soft chines make it into a crude/very basic boat/ship form.

 

[Peter B]

Hipp,
Yup many variables.
But the biggie, once you’re past displacement is wave making resistance and skin friction resistance.

Yup. Word on the street was that in the finals of the Fremantle Americas Cup in West Australia in 1986, big bad Dennis Connor was able to bring his Stars and Stripes, which up to then had been a bit of a dog in performance terms, up to being competitive - albeit in the more extreme conditions that just happened along for the finals - by having the boat skinned with a special layer of 3M material that mimicked the friction reducing effect of a shark's skin. KZ7, NZ's challenger, (the plastic fantastic), thrashed Stars & Stripes in every other weather state. It appeared to make a difference. He won, and went on to retain the cup. Sadly, Aussies defender was never in it. They all had winged keels by then.

 

[Art]

I would like Art to define and explain this 'Full-Cycle, Carbon Neutral fuels'' thing he places so much emphasis on for future efficiency while also helping reverse the CO2 build-up. I get the 'carbon neutral', but the 'full cycle' aspect escapes me...

Peter - Full Cycle; in the aspect of using atmospheric airborne CO2 for producing liquid hydrocarbon fuels:

1. Pull CO2 out of atmosphere

2. Reconstitute the CO2 into gasoline, diesel jet and other fuels

3. Burn reconstituted CO2 fuel in reciprocating engines and other liquid fuel using engines - therefore placing the CO2 back into atmosphere

4. Again pull the CO2 out of atmosphere

Repeating step #'s 1 - 4 again and again = Full-Cycle, Carbon Neutral liquid fuels

Refined Crude Oil = Non-Cycle, Carbon Positive liquid fuels

 

[Peter B]

Wow. Thanks Art. Sounds good. I just hope it's not one of those, "if it sounds too good to be true..." We all know how that goes. However, I know you are confident, so please keep us posted.

 

[FF]

"1. Pull CO2 out of atmosphere."

I have read this could be done by grinding iron ore tailings very fine and spreading them in the ocean.

This is supposed to cause a bloom and when the organisms die they take the CO2 to the bottom.

No idea how one would "recapture " the CO2

 

[Hippocampus]

NW we’re on the same page. Seems we’re using different terminology to talk about the same variables. It’s instructive to read the appendix in the new Beebe and look at actual nm per g. They’re listed by LOA not LWL but it does allow comparisons. Would offer that fins v fish, genset dependency seem to have as much effect as design elements. Wonder why fin manufacturers don’t report some measure of their impact on efficiency? Wonder if the new designs stated to decrease roll at anchor have more or less impact?
Sailboats have sugar scoops which add to LWL and decrease exit turbulence but the stern platforms on trawlers are often above the static waterline with transverse slotted boards. Would think it would be low lying fruit to change platform design to improve stern performance. Don’t understand why that’s not done?

 

[psneeld]

..............

 

[Hippocampus]

Agreed but many don’t

 

[psneeld]

Because of tradeoffs that a few feet of WLL do not make it worth it.

 

[OldDan1943]

So you are suggesting, canoe sterns improve fuel efficiency?
I really dont know.

 

[Hippocampus]

My understanding is they don’t and the splitting the seas when running down wind is a fallacy as well. Apparently it’s more complicated than it would first appear.

 

[Art]

Wow. Thanks Art. Sounds good. I just hope it's not one of those, "if it sounds too good to be true..." We all know how that goes. However, I know you are confident, so please keep us posted.

Pete

There are many peaks and valleys to this endeavor. Have I PM'd you my business signature / web link?

Cheers!

Art

 

[Nomad Willy]

Go for it Peter

 

[Nomad Willy]

So you are suggesting, canoe sterns improve fuel efficiency?
I really dont know.

Canoe sterns are identifying the sides of the hull. The Bartender has a canoe stern but if it’s efficient at all it’s due to it’s lightweight. It’s a planing hull.

Efficiency comes from the bottom. If the after-plane of the bottom curves up to the transom such that displacement at the transom is much less then you have a SD hull. More efficient but only at a certain speed.

But Dan most canoe stern boats also have the bottom that curves up at the stern. So canoe stern boats are more efficient but not necessarily because of their canoe stern. And most canoe stern boats curve in at the sides AND up from the hull bottom. But usually it’s the bottom curve that makes them more efficient.

 

[OldDan1943]

Canoe sterns are identifying the sides of the hull. The Bartender has a canoe stern but if it’s efficient at all it’s due to it’s lightweight. It’s a planing hull.

Efficiency comes from the bottom. If the after-plane of the bottom curves up to the transom such that displacement at the transom is much less then you have a SD hull. More efficient but only at a certain speed.

But Dan most canoe stern boats also have the bottom that curves up at the stern. So canoe stern boats are more efficient but not necessarily because of their canoe stern. And most canoe stern boats curve in at the sides AND up from the hull bottom. But usually it’s the bottom curve that makes them more efficient.

Is it correct to say, canoe stern do not like following seas?

 

[psneeld]

I have no direct experience...but owners say they do and in parts of the world where breaking waves are the norm to coming home (inlets or surf) canoe and dory stern evolved for some reason.

 

[socalrider]

I remember an interview with Bob Perry, probably the most prolific modern designer of canoe stern sailing vessels (Baba, Valiant, etc.), where he basically said he designed them because people like the way they look.

 

[OldDan1943]

I remember an interview with Bob Perry, probably the most prolific modern designer of canoe stern sailing vessels (Baba, Valiant, etc.), where he basically said he designed them because people like the way they look.

Ah ha, a very good reason too!!

 

[psneeld]

But long after they were prevalent in workboats that evolved in certain locations and surf zones that operators felt they helped.


I think most of the USCG surf boats have some sort of rounded stern.