Looking to buy Mainship 390, Single engine... Advise?

I'm currently in the market for a 1997-2005 model year Mainship 390. I want a single engine. Looking at Yanmars 300-380 hp. Any experience or advise would be appreciated before I pull the trigger..

In a couple of years that's my retirement boat of choice. Stairway to awesome flybridge, lower helm with door, 2nd stateroom, single engine. Yanmar would be my first choice too, but I wouldn't pass on a Cat powered boat if the boat and deal were right.

I'll be paying attention

I have a single screw Cummins 330hp in my '01 390. Great boat, no issue with the Commins 6bta

I forgot they had Cummins too, 6BT great engine.

Vulcanbike said:

I have a single screw Cummins 330hp in my '01 390. Great boat, no issue with the Commins 6bta

Click to expand...

Welcome to the forum! We love a 390 as well. The stairs are the big item for us as the ladder is hard for the grand kids, but they have many more nice features as well. Good luck with your hunt.

How does the single perform for you?

We have a '99 350. They were re-badged 390 in 2000. We have friends with an 390 as well. Minor differences. The guest stateroom is a double in the 350 and twins in the 390. The 350 has a weird 'desk' area beside the couch which we use as an end table.

We have a single Yanmar, which replaced the Cat 3116 that was there before.

I would suggest a bow thruster if you go with a single. I would love to add a stern thruster.

I believe all the single engine 350/390's had a bow thruster standard

Shrew said:

I would suggest a bow thruster if you go with a single. .

Click to expand...

we have a 2003 390 with a single 370 Yanmar. Love the boat
John

We used to charter a 2000-ish 390 with a single cat 3208 in the SF Bay Area and delta. A bow thruster is a must have IMO. We found the master stateroom extremely noisy due to wavelet slap, which drives me nuts. Ended up using the fold out couch in the salon, which we really liked for a number of reasons.. closer to the coffee, easier to do quick visual anchor watches, quiet, and so on. A good honest boat and we liked the overall design with nice sized aft deck and big flying bridge.

Chartered a 390 with twin Yanmars out of Oxnard once for a day trip to the channel islands... faster and handled better but way too tight an ER for me.

Looking for Mainship

I tell you, it's not easy to find one that's been properly maintained. Everyone wants to defer the scheduled maintenance to the "New" prospective owner....

Look for the Yanmar 6ly 370-ish hp or Cummins 6BTA 330 or 370. Avoid the 6LY2 420 or 440. Cat 3116 or 3126 ok, but not the preferred engine. Avoid twins on this boat. Make sure you can get to the critical parts of the gennie and that it is not all rusted up.

It doesn't help that the gennie is in the bilge.... on most mainship 390's...

why avoid twins ?

Benthic2 said:

why avoid twins ?

Click to expand...

Too much of a cram fit. Can't get to some important engine bits.

that makes sense...thanks

Ski in NC said:

Avoid the 6LY2 420 or 440.

Click to expand...

I had eliminated the 390 from my search earlier because it was too slow, but recently heard about the 440s. Darn I was hoping those would give me the speed I want while still maintaining some engine room space. Just curious what the problems are with those engines?

BD

BDofMSP said:

I had eliminated the 390 from my search earlier because it was too slow, but recently heard about the 440s. Darn I was hoping those would give me the speed I want while still maintaining some engine room space. Just curious what the problems are with those engines?

BD

Click to expand...

8-9 kts is not for everyone. The 'enjoy the journey' is a mindset. You'll appreciate it when you see how little you spend on fuel.

Thanks and that will be a mindset that I fully enjoy - when I'm retired. I simply do not have that luxury today. I don't live on the water - I'm 4 hours without traffic - 5 on summer weekends - from the boat. My cruising grounds are isolated. "Nearby" destinations are 75 - 100 miles away. At 15 or 18 knots I can realistically travel somewhere and return (with safety margin) in a 3 day weekend. At 7 or 8 I simply can't.

They put the 440 in there so that people could do that. I was simply wondering what it is about that engine that would lead Ski to conclude that. I highly respect his opinion.

Which is the most desired boat , the 39 ft or the 400 mainship?

Cjsangster said:

Which is the most desired boat , the 39 ft or the 400 mainship?

Click to expand...

Which one best suits your tastes, needs and wants? That's the one you go for.

I definitely prefer the 400 but it's generally far more expensive than the 39. 39 is more realistic for my budget.

I'll probably end up with a sedan cruiser but I'm trying to keep my options open.

BDofMSP said:

Thanks and that will be a mindset that I fully enjoy - when I'm retired. I simply do not have that luxury today. I don't live on the water - I'm 4 hours without traffic - 5 on summer weekends - from the boat. My cruising grounds are isolated. "Nearby" destinations are 75 - 100 miles away. At 15 or 18 knots I can realistically travel somewhere and return (with safety margin) in a 3 day weekend. At 7 or 8 I simply can't.

They put the 440 in there so that people could do that. I was simply wondering what it is about that engine that would lead Ski to conclude that. I highly respect his opinion.

Click to expand...

You'd be better off with a Sportfish or an express. You're not going to get close to 18k with a trawler.

Neither sportfish nor express cruisers meet my criteria. I'm primarily looking at Sedan cruisers - Ocean Alexander 42 Sedan is top on my list for example. But from a layout perspective there's no important difference between the OA and the Mainship. They both have two cabins, a salon, a cockpit, and a large flybridge. I wasn't considering a Mainship with a semi-displacement hull a "trawler". It's just a boat that is styled like a trawler.

I'm aware of the typical performance of these models, and 18 WOT is what Powerboat Guide provides as a guide for the 390 with twin Yanmar 230s, so I think one can "get close to 18k with a trawler" - at least a semi displacement one like this. My question was not whether I could reach that speed with the single 440. My question was why Ski made the comment to "avoid the 440". Perhaps I should just PM him instead. I just thought others might be interested in the rationale too.

Please consider keeping it in the forum. Others can benefit. No offense was intended. An innocent comment with limited information.

BDofMSP said:

Thanks and that will be a mindset that I fully enjoy - when I'm retired. I simply do not have that luxury today. I don't live on the water - I'm 4 hours without traffic - 5 on summer weekends - from the boat. My cruising grounds are isolated. "Nearby" destinations are 75 - 100 miles away. At 15 or 18 knots I can realistically travel somewhere and return (with safety margin) in a 3 day weekend. At 7 or 8 I simply can't.

They put the 440 in there so that people could do that. I was simply wondering what it is about that engine that would lead Ski to conclude that. I highly respect his opinion.

Click to expand...

Here's my basis for not recommending the 420/440 6LY2 series:

The 6ly (up to 370hp) is about 5.2liter at 3300rpm. It has dry cylinder liners that can be replaced.

The 6ly2 (up to 440hp) is nearly the same engine, but bored out to 5.8liter without replaceable cylinder liners. The bores are hardened so engine can not be bored oversize should a piston/cylinder failure occur. Should that happen, block replacement ($$$$) is required.

Both are very well made engines and if not overloaded have a good reputation. But there is a liability of a low probability 6ly2 failure that that could bite you for big bucks.

If the 6ly can give you the cruise speed you want without pushing it too hard, I'd go that route. Should be able to make 3350-3400 full power and cruise ok at 2900.

If the 6ly needs to work too hard for desired speed, it may be preferable to go 6ly2 as with the larger displacement it would not need to work too hard.

Guess I am not condemning the 6ly2, just that if the ly can do it, it is preferred.

That makes a lot of sense, and is a great insight. Perfect example of why I stick with this forum year after year. Thanks Ski!
BD

BDofMSP said:

I'm aware of the typical performance of these models, and 18 WOT is what Powerboat Guide provides as a guide for the 390 with twin Yanmar 230s

Click to expand...

You might want to talk to owners of the model to get some real-world information. For example, while my 34T will do 16 knots at WOT it is not happy there--twitchy with a propensity to bow-steer.

Good advice. If I decide to add this boat to my list I'll definitely have to do that. I've recently reviewed several other threads here on these boats and I'm beginning to see that this is probably not a good candidate to fill my needs though.

We bought a 2001 390 this year. A well maintained 390 is a lot of boat for the money.