Considering a Mainship 390 single vs twin. Would welcome any experience and thoughts about the both boat and the engine options. Biggest concerns are performance, handling and maintenance accessibility. Fuel usage is less important as we would have less than 100 hrs use per season. How does the boat handle with a single and a bow thruster vs a twin without the thruster? Boat will be used in sheltered Chesapeake bay. Thank you all.
Mainship 390 opinions?
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Comodave
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We looked at a 390. We didn’t buy it mostly because it wasn’t quite big enough. If we were going to buy one we probably would have gone with a single due to access for maintenance. Just get a thruster or two and you will be fine. We like the boat just make sure it has had the swim platform reworked.
caltexflanc
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Do some searching on this forum, there are a number of threads on these boats (and the 350 predecessor which is essentially the same except how they measured it). One was about the single vs twin versions, both of which I have had the opportunity to run, and commented on.
Keysdisease
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I do not have a 390, it is on my short list for my next boat. I owned an original 34MKI for 11 years and was a vendor to Luhrs/Mainship.
The 390 could be said to be the boat that boaters designed. Mainship actually asked groups of Mainship owners what improvements they would like to see and incorporated many of them into the 390. The door by the lower helm, stairs instead of a ladder, transom door, keep the bridge extension over cockpit, 2nd cabin, 2 door head, windlass, power connections at both ends, and several other features.
The early models suffered from "squatting" and the bustle (hull extension/swim platform) was added to add buoyancy and lift. As mentioned this needed to be re-worked after the fact but in reality the problem is minor.
The bustle does effect handling, but not to a large degree. Having the rudder a few feet further forward of the transom than originally designed slows response some.
Mainship did opt for good to best accessories. SeaStar steering, Vacu-Flush head, Rule pumps, etc.
I would prefer the single over twins. All single's came with thrusters, and coming from a single without thruster the slow speed handling is not a problem. Access and maintenance costs being the main reasons for this choice.
The generator under the cockpit is a mixed blessing. It's far from the forward cabin, but shoehorned under the cockpit with no room for an enclosure and some difficulty to access.
Performance: At trawler speeds 390's handle like most semi-displacement boats. For your use you will probably not encounter following or aft quartering seas which toss this hull type around pretty good.
Handling: If you are proficient with boats this size you will have no issues with a single with thruster. If you are new to this type it won't take you long, and the lower helm makes single/short handling easier than models without a lower station.
As you are aware, accessibility is much better on the singles. It's a bit cramped, but on boats this size it always is.
Many tweaks were made in, I believe beginning in 2003. Stainless rails instead of aluminum, the platform was fixed, a few other items.
The engine choices are all good. Most will have CAT, Cummins or Yanmar. I believe there are some with Volvo. The CAT 3126 is an "improved" 3116. The Cummins 6BT is Bulletproof, the Yanmar 370 probably is the "fastest' of the singles, but none of the single models like to plane all day. All will provide good service if maintained.
Overall I really like the 390. I think the Salon/Galley is a bit smallish for a boat this size, but other than that it ticks all the boxes for me.
$0.02
The 390 could be said to be the boat that boaters designed. Mainship actually asked groups of Mainship owners what improvements they would like to see and incorporated many of them into the 390. The door by the lower helm, stairs instead of a ladder, transom door, keep the bridge extension over cockpit, 2nd cabin, 2 door head, windlass, power connections at both ends, and several other features.
The early models suffered from "squatting" and the bustle (hull extension/swim platform) was added to add buoyancy and lift. As mentioned this needed to be re-worked after the fact but in reality the problem is minor.
The bustle does effect handling, but not to a large degree. Having the rudder a few feet further forward of the transom than originally designed slows response some.
Mainship did opt for good to best accessories. SeaStar steering, Vacu-Flush head, Rule pumps, etc.
I would prefer the single over twins. All single's came with thrusters, and coming from a single without thruster the slow speed handling is not a problem. Access and maintenance costs being the main reasons for this choice.
The generator under the cockpit is a mixed blessing. It's far from the forward cabin, but shoehorned under the cockpit with no room for an enclosure and some difficulty to access.
Performance: At trawler speeds 390's handle like most semi-displacement boats. For your use you will probably not encounter following or aft quartering seas which toss this hull type around pretty good.
Handling: If you are proficient with boats this size you will have no issues with a single with thruster. If you are new to this type it won't take you long, and the lower helm makes single/short handling easier than models without a lower station.
As you are aware, accessibility is much better on the singles. It's a bit cramped, but on boats this size it always is.
Many tweaks were made in, I believe beginning in 2003. Stainless rails instead of aluminum, the platform was fixed, a few other items.
The engine choices are all good. Most will have CAT, Cummins or Yanmar. I believe there are some with Volvo. The CAT 3126 is an "improved" 3116. The Cummins 6BT is Bulletproof, the Yanmar 370 probably is the "fastest' of the singles, but none of the single models like to plane all day. All will provide good service if maintained.
Overall I really like the 390. I think the Salon/Galley is a bit smallish for a boat this size, but other than that it ticks all the boxes for me.
$0.02
Byekurman
Veteran Member
I have only recently taking possession my 2003 mainship 390. I gave significant consideration toward one engine or two. My research indicated to me that the Yanmar 370 single engine what's my best choice. After looking at this boat with twin engines it became apparent that the engine room was extremely crowded. The single-engine boat has drive shaft and prop protected within a cut out of the bottom hull. This is a benefit when getting into a grounding condition. I think only the rudder is exposed. With the two engine option the running gear for both engines is fully exposed. This equates to more drag and more maintenance. The performance of two engines versus one engine seemed insignificant to me except for fuel consumption. I think the 390 is a great couples boat with room for an additional couple on occasion. My fuel consumption at 7-8 kts. was about 2 gallons per hour at 1800 RPMs. My top speed what's 14 knots. For me very adequate. Hope this helps. My boat is in Urbanna Virginia on the Chesapeake.
Thank you all.
I guess I currently lean toward twins as I don't want to send the whole day at 8 ktns ( can do that with a sailboat) nor do I want to squat at higher speeds pushing tsnamis across the bay.
How well does single or twin plane?
My idea speed would be 12 to 15 knts.
I guess I currently lean toward twins as I don't want to send the whole day at 8 ktns ( can do that with a sailboat) nor do I want to squat at higher speeds pushing tsnamis across the bay.
How well does single or twin plane?
My idea speed would be 12 to 15 knts.
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firehoser75
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I have no first hand experience with a Mainship and am not an expert on hull design. However, my Nordic Tug is a semi-displacement style hull (so at least similar to a Mainship). I would guess that a Mainship would perform somewhat like a NT in this area (except no twins on Nordics). At 7-9 knots the boat performs well with a relatively small(ish) wake and achieves good fuel economy. Above those speeds, fuel consumption goes way up for what to me are small gains in speed with an ever increasing wake with a top speed of 15-17 knots (greatly depending on boat loading, propping, etc.) then throwing a large wake.
The engine room would be crowded with twins, and access for routine maintenance and repair could be very difficult. If you had a single with both bow and stern thrusters (I only have bow) docking and close quarter handling should be quite easy with a single.
At 7-8 knots we burn about 2 gallons per hour; at 11 knots we burn 11 gallons per hour; and at WOT 17 gallons per hour. So to gain about 3 knots of speed we increase fuel burn by 9 gallons per hour (over 4 times the rate). Not worth it in my opinion and the boat "feels" way more comfortable at 8 knots. However, it is nice to have the option of increasing speed when circumstances suggest that will help boat handling (eg. matching wave speed in following seas).
Anyway, different boat, but I think, same idea. Just some "food for thought".
The engine room would be crowded with twins, and access for routine maintenance and repair could be very difficult. If you had a single with both bow and stern thrusters (I only have bow) docking and close quarter handling should be quite easy with a single.
At 7-8 knots we burn about 2 gallons per hour; at 11 knots we burn 11 gallons per hour; and at WOT 17 gallons per hour. So to gain about 3 knots of speed we increase fuel burn by 9 gallons per hour (over 4 times the rate). Not worth it in my opinion and the boat "feels" way more comfortable at 8 knots. However, it is nice to have the option of increasing speed when circumstances suggest that will help boat handling (eg. matching wave speed in following seas).
Anyway, different boat, but I think, same idea. Just some "food for thought".
ranger58sb
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Indeed. Wider beam, too. When we first started shopping for our "next boat" after our 34 Mk III, the 350 offered pretty much everything we identified as " could be a great evolutionary improvement." We didn't care much about the second cabin, but it seemed logical other 34 owners might well have suggested that.
We even took the big dogs aboard a new one at one of the early Trawler Fests (by broker invitation) because we wanted to be sure the Pretty Good Pyrenees and his only slightly smaller Golden Receiver brother could make it up and down the stairs easily. (Piece o' cake.)
Were it me, I'd have preferred the single, and would have added a bow thruster (I don't remember those being standard). Could have lived with twins.
We ended up going a different direction at the time, mostly because the 350 was too new for our budget... but if our wallet had cooperated, we'd have been all over one of those.
-Chris
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Keysdisease
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Not having one but having the slightly smaller and older sister, I can say that up to about 10 knots (9 to 9.5 was our sweet spot) the bow rise is manageable, the wake larger but reasonable. In the MKI's the minimum plane speed w 200HP and medium load is 13.5 knots in smooth conditions. At that speed a turn or wake brings you off plane. At 15 knots she stays on plane nicely up to a light chop.
Anything between 10 and 14 is not a good idea. Engine working very hard, enormous wake, lots of bow rise, the transition hump is not somewhere to spend any time in on a planing or semi-displacement hull.
Anyone else have similar experience, or perhaps 390 experience?
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ranger58sb
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In between depends on the boat... but in many cases 8-ish is below maximum theoretical hull speed, 14-15-or-higher is usually getting on toward planing... and in between you're just using a lot of extra horsepower to push water... very inefficient. The actual speeds vary from boat to boat, of course, but generally there's slow, expensive, and planing... in that order.
We had an "experimental" boat in between our 34 and the current one. That one was an attempt to see if an express boat -- no flybridge but also no ladder -- would be a better fit. Not. Good boat, just not our solution.
Back to a bridge boat, this time with stairs... that had been invented in the meantime in boats like the 350 plus our current boat and a very few others. Took a while for some of those to age into our budget range.
-Chris
firehoser75
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Reread post #7. Nordics and Mainships will not be thaaaat much different. At 8 knots we get (single Cummins 6BTA) 2 gallons per hour. After 8 knots, fuel burn starts to go up a lot for little gain in speed. At 11 knots we increase burn to 11 gallons per hour!!!! and just push a lot of water.
If you want more speed, maybe a Mainship is not the right boat for you. What about a Sea Ray or other boat designed to plane?? Why try to make a boat do something it is not really very good at when there are others that are meant for it?
Phyrcooler
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My experience was with my 390 with twin 240hp Yanmars. As others have noted, at or below hull speed is comfortable and economical. 8 - 8.5 kts was a comfortable cruise speed for both vessel movement and sound volumes. Above this, she started to push a lot of water as she worked to get out of the hole. At around 2600 - 2750 rpm she was up on top and running at 11 - 12 kts. This was my fast, long range cruising speed and burned fuel at or just below 1mpg. We always drove from the flybridge. Noise in cabin at this or higher speeds was loud. (No carpet). Top speed was around 3300 - 3400 rpm and normally around 16.5 - 17 kts. Occasionally I saw 18kts, but this was on a calm, fairly flat day with isinglass sections all open. (Boat had full canvas - which creates additional windage, compared to none, or a simple Bimini.) Note, that was at full throttle, and not continuous duty rated at full throttle.
Other folks have relayed that the single was not as fast and trying to plane was not worth the fuel burn. It all depends on your needs. If you’re going to do your own maintenance/repairs, you can work around the big single. You‘ll curse the twins! (Remote oil filter for starboard engine recommended!) Maneuvering with the twins was simple and well controlled.
The salon is a bit small - but that allowed full walk around side decks. She can serve as a full timer, or a weekend fishing/diving/relaxing cruiser. They are a pretty good all around boat. We sold ours to go back to sailing.
Other folks have relayed that the single was not as fast and trying to plane was not worth the fuel burn. It all depends on your needs. If you’re going to do your own maintenance/repairs, you can work around the big single. You‘ll curse the twins! (Remote oil filter for starboard engine recommended!) Maneuvering with the twins was simple and well controlled.
The salon is a bit small - but that allowed full walk around side decks. She can serve as a full timer, or a weekend fishing/diving/relaxing cruiser. They are a pretty good all around boat. We sold ours to go back to sailing.
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I have a 350 Single with a bow thruster. This is the exact same boat as the 390, just slightly older (before the rebadging). I wouldn't say one is better or worse than the other, just different.
twins have higher cruising and top speed
Single reverses to Stbd. Twins you can reverse straight or use prop walk to choose the direction that you reverse.
IntoTheBlue
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The Mainship 390 was our first "Trawler", and actually was our introduction boat into boating trawler style. It was a great boat and we really enjoyed it. (The only reason we sold it was because of a bridge we had to get under to leave from our dock)
My boat had a single Yanmar 315 HP engine. With this the cruising speed was between 9-10 knots. Handling with the bow thruster was great, as the boat has a full keel, which kept it steady in reverse. The boat did not handle well in following seas. So, if your only concern is handling and not cruising speed, I would suggest the single. I believe that around 2002 (year of my boat) that Mainship did offer the Yanmar 440 HP engine.
Enjoy!
My boat had a single Yanmar 315 HP engine. With this the cruising speed was between 9-10 knots. Handling with the bow thruster was great, as the boat has a full keel, which kept it steady in reverse. The boat did not handle well in following seas. So, if your only concern is handling and not cruising speed, I would suggest the single. I believe that around 2002 (year of my boat) that Mainship did offer the Yanmar 440 HP engine.
Enjoy!
Salish Nomad
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I prefer a single. Bow thruster is nice to have, but not a deal breaker. I have never considered adding a stern thruster.
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DrissZougari
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I have 1999 MS390 with single Cat. 3116 that I have been enjoying with my wife and Dog. At 7-9 knots the boat performs well with a relatively small wake and achieves a very good fuel economy. Above those speeds, fuel consumption goes out off the window for small gain in speed.
If you are looking for a planning hull, then you are looking in the wrong Forum as they are called Trawlers for a reason.
good luck,
If you are looking for a planning hull, then you are looking in the wrong Forum as they are called Trawlers for a reason.
good luck,
Cartouche
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390 is a great boat Stay away from the Cat engines Re work of the swim platform is not as arduous as people stay top literally unscrews around edge and silicone bead at transom cuts easily with a knife then she is ready to dig out I installed two hatches to allow for storage in the Swim platform Gas Propane etc. Single Yanmar is the best all boats come with a Bow thruster and handle well, for two they are ideal. for the money they are great boats and great for inland cruising. Sorry don't know why some pics are rotated
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firehoser75
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Edward,
Great idea on putting a couple of hatches in the swim platform to use the space as storage. However, very bad idea to put gasoline or propane in that space. This would be especially true if you have ANY potential ignition sources in that same space like batteries or chargers or electric motors (like a stern thruster)! Never store flammables whose gases are heavier than air in an enclosed space. Say BOOM. All such storage (if enclosed) must have vents from the bottom of the space, and with a swim grid, this is not possible. Even with no ignition sources readily available, it is not a good idea
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Edward,
Great idea on putting a couple of hatches in the swim platform to use the space as storage. However, very bad idea to put gasoline or propane in that space. This would be especially true if you have ANY potential ignition sources in that same space like batteries or chargers or electric motors (like a stern thruster)! Never store flammables whose gases are heavier than air in an enclosed space. Say BOOM. All such storage (if enclosed) must have vents from the bottom of the space, and with a swim grid, this is not possible. Even with no ignition sources readily available, it is not a good idea
The space is isolated from the bilge. Unless there is a stern thruster or a bilge pump installed, there are no ignition sources.
firehoser75
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Shrew,
That is all well and good, and much better than if there were ignition sources in the same space, but it is still not a good idea to store flammables in a non-vented space!! Under the right conditions, it does not take much to "set it off". Any spark including static electricity. That is why propane requires a "special" locker with venting at the bottom!
It is your boat, and do what you want, but I am just giving warning to anyone who will listen, it can be very dangerous, but yes, some "get lucky" and "get away with it", however, that does not make it safe or a good idea.
Use the space to store "other" non explosive items.
That is all well and good, and much better than if there were ignition sources in the same space, but it is still not a good idea to store flammables in a non-vented space!! Under the right conditions, it does not take much to "set it off". Any spark including static electricity. That is why propane requires a "special" locker with venting at the bottom!
It is your boat, and do what you want, but I am just giving warning to anyone who will listen, it can be very dangerous, but yes, some "get lucky" and "get away with it", however, that does not make it safe or a good idea.
Use the space to store "other" non explosive items.
Maybe picking nits but … The Chesapeake is relatively safe but can make you wish you never said this. Don't bet your life on "sheltered water".
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