Mainship 390 gph?

I'm shopping for a live aboard trawler. Mainship 390 looks gorgeous, but I'm a little concerned about operating expense. At displacement speed of about 8 knots with a 300 ho engine, what should I figure for gph?

I'd been looking at Taiwan trawlers from the 1980's with Lehman 120 hp engines. But a Mainship 390, from the 2000's *is in my price range. A marine mechanic told me that modern engines are much more efficient than the older ones.


A newer, better built boat has obvious attraction, but the 1980's stuff seems to get 1.5 to 2 gph at displacement speed (7-8 knots). Do I get close in the 390?


Jeff Wolf

Wolfie wrote:"But a Mainship 390, from the 2000's *is in my price range.....

Click to expand...

To my way of thinking, this is a no brainer. If you can afford the newer boat, go for
it and don't worry about the fuel consumption. You will be glad you did.


*


-- Edited by SeaHorse II on Wednesday 8th of December 2010 05:57:37 PM

SeaHorse II wrote:


Wolfie wrote:"But a Mainship 390, from the 2000's *is in my price range.....

Click to expand...

To my way of thinking, this is a no brainer. If you can afford the newer boat, go for
it and don't worry about the fuel consumption. You will be glad you did.


*


-- Edited by SeaHorse II on Wednesday 8th of December 2010 05:57:37 PM
I*agree.

*In answer to your question the answer is no.* But then again you won't keep it at 7 kts either.* I know what you are going to say but it won't happen.* So*5 gph is closer to what it is going to take but that is closer to 9 kts which is about*2 mpg.* 2 MPG is pretty good for a boat.

Yes I agree that you will get about 2 nmpg probably a bit better at 7.5/8 knots with the 390. You should be able to cruise faster at times if required, say around 10 knots.
I have a 40 Albin single 120 lehman and get about 3.5 nmpg but at 7 knots, but top speed is only 8+.
There are tons of 390s out there and it's a buyer's market.
There is also a Mainship group in Yahoo. I suggest you join (free) and ask some questions. You might even find one for sale there.
Happy hunting.

My 2003 390 has a 370 Yanmar. I cruise at about 1900 rpm which gives me about 8.5 kts. GPH burn is about 4.5. I have run at 1500 rpm and 7 kts and gotten about 3 GPH burn
John

Johnma, what will your boat do at 2800RPMs??? Don't forget to run that Yanmar a little harder every now and then. That engine does not get into the boost until around 2400RPMs.

Thanks to all for your info. Coming from a sailing background, traveling at a consistent 7 knots seems like warp speed!

As usual, I now find myself more confused than ever. It would have been sooo much simpler if everyone had said that the only option was high fuel consumption. But it's a glorious confusion - right where I should be at this point in the process.


Work break at Xmas allows me to begin sorting and tossing "stuff" collected over several decades. Call in some realtors in January to figure out what needs to be done to get the house read to sell this spring. Been in the house for 10 years with a miniscule mortgage - a deal should be doable.


Time to spend some cold Chicago winter nights in contemplation. I'm sure I'll be on this board with more questions.


Hope to see you on the water sometime next summer!


Jeff Wolf

Johma's numbers answer your question.* Your numbers will be his numbers, or close enough, since he is referencing the same hull.* The difference in engines is not materially relevant.

Jeff, DavidM is probably correct on the CAT model.* If so, you might want to check out www.boatdiesel.com to get acquainted with some of the issues with that particular effort by CAT, as fuel consumption is a separate, if related issue to durability.* My understanding is that the 3116/3126 CAT was a transition engine between old technology and new technology that met emissions requirments.* Seems like a lot of problems with that model, but perhaps David can comment.

In 1999 Mainship transitioned from the Cat 3116 to the 3126. In 2000/2001, maybe 2002 *they used Cummins 6BTA at 315/330 hp. After that they went Yanmar.
Nothing wrong with a turbochrged diesel. Maintained reasonably a Cummins should last 8-10,000 hours.
Not too faimilar with Cat and Yan.
In any marine engine it's the externals that see*raw water that will get you.

Great summary, DavidM, thank you.

I have a 3306, which certainly qualifies as a low revving, high torque, last longer than the owner (at least me) type diesel engine.* It provides just over 18 hp/gallon of fuel, is designed to survive long periods of idling (developed for north slope oil development applications where shutting down an engine means not starting it again), and is relatively smooth at most rpm levels.* 50,000 hours have been achieved, with 30,000 hours the norm, or so I have been told.

I had read about a great many problems with the 3116/3126 engines, so enquired with our local dealer (NC Machinery) what the source of the issues was, and passed on the service manager's observations.* It sounded like there were a lot of expensive failures at relatively low hours, and CAT has tried to address the special requirements of these engines with special lubrication formulations.* I don't know much about them other than what was passed onto me by the dealer and what I have read, but based on that, I would be wary of taking on the responsibility of maintaining one.

Thanks for the info!

John,
at 2500 rpm's my 390 does 10 kts. On the Mainship board there has been a lot of discussion about the best speed to run the Yanmars. users and mechanics alike have chimed in on this point and the answers are all over the place. the Yanmar dealer mechanics that have given their opinion say you can run at the lower speed as long as you run to 2400-2500 rpm's for 5 minutes every few hours, and thats what i do.
John

Also, I forgot to mention, the 390 won't plane. Trying to go any more than 10 kts just pushes the stern hard into the water. The swim platform looks like its molded in and about 12" of it is below the water line. Its actually bolted on and glassed over. Trying to get up on plane puts a lot of sress on the platform. I'm told that the twin engine boats can get over the hump and do 16-17 kts. For them, once on plane, I don't think the platform's in the water.

If you do buy one of these, they're great boats, but make sure the platform has access ports. that means that the factory repair was performed to fix water leaking into the platform. it's hollow and between 2' to 2-1/2' deep. if the access port is big enough you can store fenders inside
John

Thanks John!!! My wife and I have always been huge fans of the 350/390. Still just a tad out of our comfortable price range....which is certainly a testament to them holding their value. You still don't see many(if at all) below 100k and it has been holding like that....well since their inception obviously. There was a twin Yanmar(230hp per)version that just sold around....super cherry boat. We really would have loved to have that boat. She went for right around $120k....which I think is a fantastic deal. Anyway, enjoy!!!

At 7 knots I get about 2.3 nmpg.* 2002 Mainship 390, 370 hp Yanmar


-- Edited by volboater on Tuesday 13th of September 2011 07:07:22 PM

My 98 350 has twin Yanmar 4LH DTE 170 HP engines. Sooo, it would not be very relevant to the discussion of single engine 350/390s. But, I cruise at about 1800 to 2000 RPM which does 9 MPH and burns a around 3.8 GPH. WOT at 3300 RPM she'll do 17 MPH on a pseudo plane. I don't know how much fuel she burns at WOT, prolly a lot.

Hi all, I'm new to the forum today, and I have a question I hope someone can help with.

My wife and I are looking at trawlers and one that we really like is the Mainship 390 with a single diesel engine. There is a 1999 review of the boat from Boating magazine posted at boatdiesel.com. The article includes extensive fuel-burn testing.

What got my attention is that the boat tested at 0.8 GPH turning 1200rpm and 8.5kts, yielding 10.6 nautical miles per gallon. This is exactly what we're looking for, but is it really true? Has anyone seen this kind of efficiency from the 390 single?

Here is the published test:

http://boatdiesel.com/Boats/Mainshi...at-Test-Report.cfm?PDFID=3983819201331&Page=5

Thanks in advance!

Riverguy said:

Hi all, I'm new to the forum today, and I have a question I hope someone can help with.

My wife and I are looking at trawlers and one that we really like is the Mainship 390 with a single diesel engine. There is a 1999 review of the boat from Boating magazine posted at boatdiesel.com. The article includes extensive fuel-burn testing.

What got my attention is that the boat tested at 0.8 GPH turning 1200rpm and 8.5kts, yielding 10.6 nautical miles per gallon. This is exactly what we're looking for, but is it really true? Has anyone seen this kind of efficiency from the 390 single?

Click to expand...

Good luck with that number. If it were true you probably couldn't find one on the market. Read the comments above, those are realistic.

Baker said:

Thanks John!!! My wife and I have always been huge fans of the 350/390. Still just a tad out of our comfortable price range....which is certainly a testament to them holding their value. You still don't see many(if at all) below 100k and it has been holding like that....well since their inception obviously. There was a twin Yanmar(230hp per)version that just sold around....super cherry boat. We really would have loved to have that boat. She went for right around $120k....which I think is a fantastic deal. Anyway, enjoy!!!

Click to expand...

Are you sure of this? There are quite a few mainships on the market, and it has been my recent experience that they are selling well below the asking price. We bought our boat at 45% less than asking. We had cash and found the right situation.

You could do the same.

Doug

jleonard said:

Good luck with that number. If it were true you probably couldn't find one on the market. Read the comments above, those are realistic.

Click to expand...

Thanks jleonard. The author of that article with the MS390 fuel-burn testiing is Capt. Bill Pike of Power&Motoryacht magazine. He has a stellar reputation and I'm guessing he has as much experience as most of us here combined.

Here's his website:

EASY DOES IT

Hard to believe he just fabricated a bunch of phony test data.

Nonetheless, 10.6 nmpg at 8.5kts is hard to believe.

Just curious, how do most folks here determine fuel burn? Floscan?

Riverguy said:

Just curious, how do most folks here determine fuel burn? Floscan?

Click to expand...

Yes....I do.

[QUOTE
Just curious, how do most folks here determine fuel burn? Floscan?[/QUOTE]

I calculate only after a long trip of several days and after I know I have previously topped off the tanks and have confidence I have a good handle on how much fuel I've used. That number will include everything...genny time, idle time, etc.
My recent nunber was based on a summer long cruise up thru the Trent Severn, Georgian bay, etc totalling 327 engine hours and 607 gallons of fuel, and I calculated 1.85 gal per hour with my Lehman 120 which seems to coincide fairly well with what I have seen others post.
(I could be off a little bit but who really cares?)
It's not a "true" representation of what the main engine burns, but tells me what I'll use with the way I boat.

Do you know if this is true of the 2002 390? (about the platform having access points)

Dougcole said:

Are you sure of this? There are quite a few mainships on the market, and it has been my recent experience that they are selling well below the asking price. We bought our boat at 45% less than asking. We had cash and found the right situation.

You could do the same.

Doug

Click to expand...

Check the date of that post....over 2 years old!...

390 Fuel burn

Riverguy said:

Hi all, I'm new to the forum today, and I have a question I hope someone can help with.

My wife and I are looking at trawlers and one that we really like is the Mainship 390 with a single diesel engine. There is a 1999 review of the boat from Boating magazine posted at boatdiesel.com. The article includes extensive fuel-burn testing.

What got my attention is that the boat tested at 0.8 GPH turning 1200rpm and 8.5kts, yielding 10.6 nautical miles per gallon. This is exactly what we're looking for, but is it really true? Has anyone seen this kind of efficiency from the 390 single?

Here is the published test:

http://boatdiesel.com/Boats/Mainshi...at-Test-Report.cfm?PDFID=3983819201331&Page=5

Thanks in advance!

Click to expand...

I get that or better as long as the current is swift and I leave the Main Engine off and don't put too much load on the generator.

2002 Mainship 390 Single Yanmar 370hp

volboater said:

I get that or better as long as the current is swift and I leave the Main Engine off and don't put too much load on the generator.

2002 Mainship 390 Single Yanmar 370hp

Click to expand...

No doubt. I'd like to see that. 1200 RPMs and 8.5 knots. I don't think so!!!

If fuel consumption is a concern, start looking at displacement boats. At that size you can easily hit 8kts at 1.5 - 1.6 gph.

That Mainship 390 should easily be in the 2-3 gph at just under hull speed, around 7-7.5kts.

It's a strange hullshape with built in hook and a not very streamlined keel. The hook will force bow down in the semiplaning regime, which is sorta nice, but the keel causes bad turbulence into prop making it very loud back there when running "fast". Not very efficient up there. Hard to decide whether to call it "semi-planing" or "semi-plowing".

But down around hull speed, it should get about the same speed vs burn rate as anything else in that size and weight class. Regardless of engine. Trawlers in the 35-40' range running just under hull speed seem pretty consistent in the 2-4nmpg range.

That 0.8gph at 1200 and 8.5kts is pure BS!!