Basic Trawler questions

Greetings boating experts!

I am a lifetime sailor but this summer my family chartered a 40' trawler for a week, traveled 250 miles, and absolutely loved it. *It was this exact boat, fwiw:


http://www.yachtworld.com/boats/2004/Mariner-Orient-38-Double-Cabin-2003884


While our charter experience has given me the bug/itch/whatever-you-call-it, the*likelihood*of actually buying a trawler is slim but I do enjoy browsing the classifieds and have some questions if you will have the patience to help educate me:


1. *This particular vessel has a single 220 Cummins and one of the shocks for me was fuel efficiency. *We only burned on the order of 100 gallons and that was running the generator most of the time. *I was expecting much worse over 250 miles and 6 days. *In fact I still wonder if they somehow accidentally under-filled it upon returning although that seems unlikely and I'm sure not going to inquire. *Now I did generally run on the slower end of stated cruising speed and worked pretty hard to find the "sweet spot" each day based on tides/winds - which generally was somewhere in the 1600 to 1700 rpm and 8 knot range. *I never went over 2000 at all and never cruised higher than 1800. *Remember I come from sailing - 8 knots is fine with me. * *So finally my question (remember I thanked you in advance for your patience): *Is this typical efficiency for a single screw?


2. How different is fuel efficiency for a*similarly sized*2-engine boat than this single screw? *Say a 40' marine trader for example. *Is it much worse? *Slightly worse? *Somehow (I dream) about the same?


3. I see in some classified boat pictures a picture of some structure on the forward deck that is usually centered right in front of the front windows - it's about 6" to 12" tall and a flatish A-Frame such that if you're standing on the bow pulpit looking back, it looks like a flat A-frame house - only it's about 8" tall and maybe 20" x 20" base. *It is sometimes covered with a protective canvas. *What is this? *A/C possibly?


4. I saw in one boat picture a large bag (looks about like a sail bag to me - big enough for a working jib or small genoa) from which a rope comes out of the tied up end that is tied off to the rear fly bridge stanchions. *What is this likely to be? *Some kind of emergency inflatable vessel? *It is not a dinghy I know that for sure. *Bag is probably 3' high by 18" diameter with the open end on top.


5. This trawler we chartered had nice c-shaped dinghy mounting things (ha) that flipped up/down on the swim platform making it very convenient to pull it out and store it vertically on the swim platform. *Great, but we fish and swim a lot and need that space for something other than dinghy toting. *I see some boats for sale that show a dinghy living on the rear deck. *Presumably, there is some hoisting system they use with the mast/boom for this arrangement? *Is that typically a manual system or a power winch type? *And either way, is it easy or cumbersome compared to what we had - the two swinging C-clip things for dinghy on the swim platform? *Assume an avon-type inflatable dinghy.


Thanks so much in advance for any guidance! *I have to say I've been dreaming about trawlers since our trip. *I hope winter gets here soon to distract me. *A ski trip should do it - I think I can hold out.

My what interesting questions!* I just bought a trawler a couple of weeks ago after years of sailing and can't answer most of your questions but I look forward to seeing the replies.*

I believe the answer to # 3 is a dog house hatch.*

# 5 the hoists I generally see are manual though I have seen some power ones.* The sound of the guy across the dock from my running his power one Sunday morning brought me up on deck to see who was making that gawd awful racket.

I wonder if #4 is a whole lotta line?* Maybe they are somewhere with tall locks that they need a lot of line for?* that is PURE speculation on my part.* One of our friends has a HUGE spindle of line mounted (somewhere, I forget exactly where) on his boat for tying up to moorings or what not.

ok I am ready to read others anwers...* I feel like this is a trivia game.

Scott,

I run a 34' trawler with a 120 Lehman, and I burn about 2 1/2 gph at 1700 rpm, which normally equates to about 8 knots. *This means, under good conditions, that I'm getting about 3.6 miles for every gallon burned.


The newer engine you were using is undoubtedly more efficient than mine, and with a heavier boat, it seems you got about 2.5 miles for every gallon burned. When you factor in the genset, you actually got better mileage than even 2.5!


1.*Is this typical efficiency for a single screw? *In my estimation, yes. *Trawlers are very fuel efficient; hence many of we 'ex-sailors' love them.


2. How different is fuel efficiency for a*similarly sized*2-engine boat than this single screw? *You'll have to have someone else weigh in that runs twins. *Marin would be a good choice as he has lots of miles under his keel and runs twins. *My answer would only be what I've heard, and not*definitive. I know the fuel*usage*isn't doubled.


3 & 4 I will defer to others, as I haven't a clue without seeing a picture.


5. A boat my size (34') doesn't have enough room to store a dingy on board neatly, but larger boats do indeed store them on the aft cabin, aft deck, or even on the*fly bridge. *Normally you'd use the mast boom or other method to raise and lower the boat. *A friend of mine, with a 50' Marine Trader, stores his dingy on the fly bridge and has an electric davit to lower his inflatable. *There are manual and electric devices out there; just a matter of how large your checkbook is.


Personally, I have my dingy on the system you describe; on the swim step.


Others will have more info for you, but I'd like to welcome to "the dark side" (boating). *A ski trip may help, but we've got you now!


Welcome aboard,




Mike
Brookings, Oregon

nm


-- Edited by one wolf on Monday 20th of September 2010 07:49:31 PM

Here's another one - canvas covered a-frame shaped thing on the deck. *Maybe it's just a hatch lol. *I haven't seen one on a sailboat shaped like that but I'm new to trawlers, who knows.

I'm a new member here as well, bitten by the trawler bug landlocked in NJ!* To answer what those two tems are:

first it is a Doghouse Hatch as Pineapple Girl said, a very traditional design element that was used in "olden days" to keep the waves from crashing through flat hatch covers and to provide weather protected ventilation on the lee-side of the boat.

the second item appears to be a fender covered in a sack to prevent UV damage.

Could the second item be a "lifesling"? Those usually have a rope attached to the railing they hang from. The rope goes into the bag and attaches to the open "U" shaped lifesling.

Fuel economy is directly related to the size of the wave that you make. At 8 knots, my 44000 lb 44 foot trawler gets slightly better than 2 mpg. Doesn't matter whether its one or two engines.

The first item to be identified is definitely a hatch. Mine have gratings of SS wire over the glass, and are varnished teak. The covers are to keep the teak looking good, protection from the sun.

Dinghy storage varies with the availability of space, the weight of the dinghy and its motor, and the preferences of the owner. Just about as many permutations as boats.

We have a DC electric powered mast and a boom to lift the dink up on to the roof.* So lifting the dink up on to the deck is pushing a up/down button.* The winches cast 70 bucks are Harbor Freight Tool.* We also have a steady sail that*is used mostly at anchor to keep the bow into the wind and prevent swinging.* We also have a square front hatch but solid teak wood so not canvas cover.* We are 58 ft, 43 ton, single DD 671 and get 2 miles per gallon.***

What other questions do you have?*


-- Edited by Phil Fill on Monday 20th of September 2010 09:00:01 PM

-- Edited by Phil Fill on Monday 20th of September 2010 09:01:05 PM

one wolf,The difference in efficiency with single and twin screw is fly stuff.*I think twins are more efficient but I think over 50% of Trawler Formers think a single is.*To be meaningful comparing twins and singles one must compare same boats with same total power. The most efficient boat is a full displacement hulled boat and there are very few of them. Your choices are much broader w semi-displacement and the increased fuel consumption is small stuff compared to total boating costs. Twins are more expensive (probably 20% to maintain and 35% to buy new) and are generally better but if one goes aground or runs into things that can damage a propeller the vulnerability of the props on a twin can cost you in various ways.
The "A frame thing" is simply a skylight window on the cabin top.

koliver wrote:
Fuel economy is directly related to the size of the wave that you make. At 8 knots, my 44000 lb 44 foot trawler gets slightly better than 2 mpg. Doesn't matter whether its one or two engines.

Click to expand...

Thanks - very helpful info. *What RPMs are your twins running at 8 knots?

So you are suggesting that the length, beam, draft, hull shape, and weight are the influencing factors to fuel efficiency, not size or numbers of engine. *Assuming this is the case, then why would anybody want twins over single other than the ability to limp in if one quits of course... *For inland boaters, maintaining two engines sure seems like a high price to pay just to know you have a spare if one quits in the middle of the lake.


Thanks again for all the replies!

Best guess on #4: sea anchor.

Wolf

Some years ago PMM had an ariticle on an NT 50 single and an identical twin. Fuel economy was about a 15 - 20% difference, favoring the single. Not much difference in purchase cost. There are many older singles to choose from under 40 feet, not too many over 45 feet. My 55,000 lb trawler gets 1.5 nmpg at 8 knots with twins running at 1750 RPM. The only single I'd consider for the type of cruising I do would require a decent get home option, which is essentially another engine and drive train - such as with Nordhavn or Selene. Those are very expensive vessels.

For* low price and lots of space in a newer boat,*consider a reasonably new Carver, Bayliner or Searay. twin of course.

koliver wrote:Fuel economy is directly related to the size of the wave that you make. At 8 knots, my 44000 lb 44 foot trawler gets slightly better than 2 mpg. Doesn't matter whether its one or two engines

Click to expand...

I for one am one of those people who DO BELIEVE that a single engine displacement hull is more fuel and dollar efficient than a twin setup. I just have returned today from a 200 mile trip that I calculated my fuel very carefully, 60,000 lbs, 48' displacement hull single, naturally aspirated John Deere with 2100 hours. 1700 rpm in flat water = 7.9 kts @ 2.3 gph = 3.43 mpg.* The twin suffers a loss in efficiency due to parasitic drag ( two shafts/rudders/struts....and friction caused buy two engines full of whirling gizmo's vs. one.* I am not debating the safety issues... just the fuel and cost issue.* Need to put a lot of horsepower to the water with shallow draft? twins win. Look at all freighters and tankers... they are singles for a reason... cost per mile..
HOLLYWOOD

*

Hollywood, it is not just a belief...it is a FACT!!!

And I think it's not John. But anyone that's interested in the OPINIONS expressed previously on this twin v/s single business can go look in the archives to see all the OPINIONS we expressed in the past. Unless yo'all want to throw all those tomatoes all over again. There's just way too many variables to ever say (objectively) yea or nay.

"1700 rpm in flat water = 7.9 kts @ 2.3 gph = 3.43 mpg"

2,3 gph is at most 50 hp.

Great if the Deere is the 4 cyl 80 hp model, but some harder running at times should be done if its one of the 6 cylinder marinizations.

There are too many very COST efficient +45' trawler twins out there*which muddles the economy discussion.*Economy is more than gph and the number of fuel filters per year. It includes the purchase cost*and resale value too* -- a 50' newer single is*costly to OWN. Just look at the very expensive Selene, Nordhavn, Krogen and*Tugs. Not to mention the plethora of one of a kind steel single engine trawlers that frequent the used boat market.

There are some that read* this forum that own vessels over 45' such as*Offshore, Fleming, Tollycraft, Ocean Alexander, DeFever, Grand Banks, Albin et al. I'm one. I gladly pay the extra $1000 to $2000 per year in fuel, impellers*and filters to be on this list. Unfortunately I don't have the extra $100,000 per year of interest and insurance*payments*to get the big Selene, Watson*or Nordhavn of my dreams.

Last but not least, if life were all about the cheapest way to do something, we would not own any boats nor pay taxes. We'd all be on Obama care railing against those rich*guys..

An interesting test would be to find one of the very few Krogen 42's that were made with twin engines and compare their fuel use / mileage to the standard 42. Think I'll pop over and send a note to the Krogen group.

Eric, I will ask you a very theoretical question...one we can't prove right now.

If we had 2 50 hp Yanmars and one 100hp Yanmar and ran them at 2000RPMs with no load. Do you think the fuel burn would be the same? Or better for either example? And why. Under load?

Also Keith, for it to be a proper comparison the total horsepower would have to be the same.

You can't compare at no load. Useless information.

They need to be compared at some horsepower level. With that kind of comparison you can take the data from a manufacturer's chart and it would be meaningful.

In the past I have compared Cummins engines models*using Cummins data charts and the larger hp engines get better economy at the lower hp levels.

For example a Cummins 6bt 220 at 1600 rpm produces 155 hp using 3.5 gph
A Cummins 6bta 270 at 1400 rpm produces 155 hp using 2.9 gph. (data taken from mechanical enignes circa 2002)

*

*

Some good thoughts this time around.sunchaser,
Earlier some were alluding that the charm of a Nordic Tug was'nt worth paying for. Hogwash! These boats of ours are YACHTS and "charming" should be one of the very most important elements of desirability. Well worth paying for as it gives us satisfaction and that should be at least close to the bottom line.
John,Keith,
"Also Keith, for it to be a proper comparison the total horsepower would have to be the same." Yes. AND the engines would need to be VERY similar in type and design. Not a GB 36/42 w a 240 hp electronic and turbocharged state of the art modern engine compared to 2 old 120 Lehmans. The 50/100hp Yanmar question w no load is an interesting question but I don't see the point in it. If both engines had the same displacement per hp, ran at the same engine speed (rpm), had the same type on combustion chamber, had the same type of injection system, developed the same torque at the same rpm, developed their power at the same rpm, had the same exhaust back pressure, weren't widely different in bore/stroke relationship................... This is just off the top of my head. Perhaps if Ford had made a 165 cu in 3 cyl version of the 120hp/380 cu in we could come close to a good comparison but that wouldn't be ideal either as each engine would have half as many and twice as many cylinders per cu in. With same displacement and other things being equal (and of course they never are) the engine w fewer cylinders will be most efficient. REmember the economy car contest a week ago? The winning car had one cylinder and this was not a mini * * *..it was a 4 passenger car. "Do you think the fuel burn would be the same? Or better for either example? And why. Under load?"
This is a very big question with many more variables than above but the answer to "under load" is meaningful to us. If an engine is propped right and has the appropriate propeller and reduction gear ratio one can use the "specific fuel consumption" figures provided by the engine manufacturer to predict fuel burn. One can see at what rpm the engine is most efficient too and one would want to cruise if efficiency was most important. There are variables here too as the engine marineizers and installers can induce variables like exhaust system back pressure, cooling fans or no fans v/s water pumps. One can shoot from the hip and come surprisingly close on older NA engines by figuring 20 hp per gallon per hour (I think I've got that right). FF will correct me if not.
Does this raise more questions than answers? I will say this to your question John. If both engines were basically the same regarding the variables above and their torque max was at 2000 rpm and the engine load was the same the fuel consumption would be the same plus or minus very small fly stuff.

Right on Eric, charming is what it is all about, for some of us anyway.* The bottom line in this whole single vs twin thing to me is, I don't care about an extra few tenths of a GPH. I want a charming, safe, reliable, fairly new, high quality, seaworthy boat with a good pedigree that helps resale. And the*BIGGEST I can afford to own and operate!!

My study of Cummins b series shows the 6 cyl engines as more effificient that the 4 cyl even though they have more jugs.


-- Edited by jleonard on Wednesday 22nd of September 2010 12:32:07 PM

sunchaser wrote:

Right on Eric, charming is what it is all about, for some of us anyway.* The bottom line in this whole single vs twin thing to me is, I don't care about an extra few tenths of a GPH. I want a charming, safe, reliable, fairly new, high quality, seaworthy boat with a good pedigree that helps resale. And the*BIGGEST I can afford to own and operate!!

Click to expand...

I made the mistake of going to a Seattle Boats Afloat show this past weekend.* This is my new dream boat (and, unfortuantely will likely remain a dream).
http://www.seaspirityachts.com/passagemaker60.shtml

Besides the superb layout, fittings, etc, the boat has the nicest ass-end I've ever seen.*

Single engine with the get-home-system being either of the two generators which can turn the main shaft hydraulically.* Range up to 7,000 nms!

So, if about 2 million of you would just send me a dollar each....

*

Eric, one thing you are missing is that we are likely trying to power the same boat. So your "same RPM" comment doesn't apply. In reality, the same boats, one with single and one with twins, the one with the twins will likely have more horsepower. Now you run both of those same boats at the same speed(theoretically using the same horsepower since we assume all other things being equal), and you will likely have a higher fuel burn with the twins. There are inefficiencies that are compounded by two engines. Mainly drag caused by the components on the engine....pumps...alternators etc. Even if we cut an engine in half and had two "half engines" that equaled the one single engine with all thins equal, I still think you would suffer this added drag due to the accessories. But back to reality, that is usually not how it turns out. You end up with more total horsepower in the twin boat.

There are a lot of theoretical "in a vacuum" type scenarios. In reality, the way manufacturers power boats, the single is gonna burn less fuel for a given speed in a given boat.

It is always fun to read these debates... single vs. twin......
everyone of us has an opinion... usually related to the boat they already own!
what kind of a moron would I be if I ranted in favor of a twin vs the single ... when I own a single!.*** I for one... and I think Delfin will chime in.... just do a happy dance around my engine room with all the extra room afforded by my single.... why dance? ... because I can!
HOLLYWOOD

Not all singles have good ERs. Some Selenes and*Nordhavns are quite cramped. I was looking at a Nordhavn 62 a few weeks ago - not a good single ER.

Jay,Variables variables variables. If you looked at the specific fuel consumption for 100 engines you'd prolly find that fewer cylinders = more efficiency.
Tonic,
I did just the same thing several years ago when the Seasprit 60 was the Ocean Queen 58 or some such thing. A dreamship to be sure. Does it still have the beautiful VG Douglas Fir interior? I don't really like big boats but was completly Ga Ga over this one. Looked at the ads in the magazines and it was just another boat but to see the real thing!!! This boat is more than charm.
John,
I'm not missing that at all. It's an assumption if you want apples and apples you must have the same load on the engines and the same boat, at the same speed would come close enough * *..I think. As I say * * .... they (the twin and single being compared) must have very close to the same power or the comparison is'nt valid.*I mean within about 5%. Drag from auxiliary equipment would probably be FAPP the same as water pumps, gear boxes ect will be half size on the smaller engines.
SO * ... if you want to say the average boat w twin engines is less efficient than the average boat w one engine * * ..I'll throw you the blue ribbon. I thought the discussion was what is more efficient * *twins or singles? In other words which configuration is more efficient. To that I will say the twin is more likely more efficient but by a small margin.
Sunchaser,
Most trawlers are semi-displacement and that tells us that most trawlermen feel as you do. Low fuel burn is not the holly grail as most trawlers are SD BUT most trawler owners didn't buy the boat new. If you can afford a new Nordic Tug the fuel burn is fly stuff. But if you want to do Passagemaking with your trawler, range is no longer fly stuff. To some degree trawlermen see their trawler as a passagemaker and like to brag about their range even though they never go that far. My boat has a range of 6 or 700 miles * ....
ridiculous for a 30' boat. I understand someone took a W30 to Hawaii but why should the rest of us have to deal w those big fuel tanks? Anyway * * ...if fuel burn and efficiency was the most important thing most all of us would have full displacement trawlers. Right now I'd like to have an 8 knot boat that burned 2 gph * *..twice my current burn.
Hollywood,
I hope you don't think I'm ranting as that would mean I've been called a moron.

My name is John....and I am a moron.....

Eric....to be continued!!!!

Tonic wrote:


sunchaser wrote:

Click to expand...

I made the mistake of going to a Seattle Boats Afloat show this past weekend.* This is my new dream boat (and, unfortuantely will likely remain a dream).
http://www.seaspirityachts.com/passagemaker60.shtml

Besides the superb layout, fittings, etc, the boat has the nicest ass-end I've ever seen.*

Single engine with the get-home-system being either of the two generators which can turn the main shaft hydraulically.* Range up to 7,000 nms!

So, if about 2 million of you would just send me a dollar each....

*

Yeeeaaaah.* Mind if I dream along with you Tonic?* That's one fine vessel all right.

*