Changes to the classic Mainship 34T

We've been looking at a few different MY and Trawler designs and we keep going back to the Mainship 34T. Built from '77 through '88 or so, there seems to be 3 different versions. I understand the early ones had 165hp and they upgraded that to 200hp at some point. There were changes made to the layout and cockpit as well.
Is there a definitive list of changes made to these boats by year? It would be good to educate ourselves on what to expect from a particular vintage as we look.

First the model 34T was used to designate the new 34' trawler built from 2005 to about 2007 when they redid the interior and gave it a new designation.


The main difference among the three versions of the classic 34 was the upper deck extension covering the lower cockpit. On the first version it extended all the way back to near the transom. On the second it essentially went away. On the third it came back but only went about 2/3 of the first version. I like the first the best and many do.


I am sure there were other details that also changed among the three.


David

Perkins engine went through a pretty good revolution. Ending in the Range 4. The most notable innovation was the “manicooler”.
This very expensive casting provided three important tasks
Intake manifold
Exhaust manifold
Heat exchanger

The unit was really impressive and IMO a great move forward. However, Saber bought Perkins at a key point in the number of manufacturer units and decided to discontinue a 30+ year old design. The result was there was not enough demand to create an aftermarket “manicooler”.

The engine will run 10-12 thousand hour before a major overhaul. The Range 4 manicooler needs creative thinking to either work around or back up.
I would buy another without hesitation. Knowing that today’s epoxy products (read Marine Tex) properly used will repair these units indefinitely.

I think there is some confusion about the model. The 34T is the new model in the 2000s. The original 34 from the 70s and 80s was built in 3 versions. The first had an extended hardtop. Then there was a model with an extended cockpit. And a model with the larger salon without the extended hardtop. I don’t know the years each was built. Powerboat Guide does address the different models I believe.

the 3 models of the 34 classic are the MK I, II, III. The main difference is the overhang over the cockpit and the ratio between the cockpit and salon. The III also did away with the bulkhead between salon and galley, and added a door to the swim platform. Many prefer the I, or the III version. The II as I'm told, was designed to accommodate easier fishing from the cockpit. Personally, I like the MK III, for the reasons above, but you might want to look at each for your preference.

Dcbeach said:

Perkins engine went through a pretty good revolution. Ending in the Range 4. The most notable innovation was the “manicooler”.
This very expensive casting provided three important tasks
Intake manifold
Exhaust manifold
Heat exchanger

The unit was really impressive and IMO a great move forward. .

Click to expand...

This is the first time in decades I've heard anyone express love for the manicooler. Twenty years ago when the manicooler was shelved it allowed Perkins to use jacket water on the exhaust manifold, have separate engine and transmission HXers and a separate after cooler for the turbo versions. Cat played a large role in modernizing the Perkins cooling systems to a industry standard and trouble free design.

The early Mainships were called "Nantucket". There was a Model I, II, III.
(it was never called "Mark I' etc.)
The 77 thru 80 boats used the old Perkins T6.354 rated at 160 hp. Some of these were reverse rotation engines. I had one and it was a PIA to get some parts for.
The exceptions were there were w few built with a Mitsubishi 6 cyl diesel at 200 hp, and a few had the International V-8 "bus" diesel.
In 1980 they changed to the T6.3544 or "Range 4" model rated at either 165 or 200 hp.
There were a few rated at 240 hp.
In 1985 ish they started putting in the V-8 Detroit diesel that was rated at 220 hp(I believe).
Model Is and IIs were built thru 1982, then the model III started in 1983 thru 86 or 87. Then they moved from NJ to FL and destroyed the old molds.

The raw water cooled exhaust manifolds were a big disaster in my opinion. I had one and know many that also had them. They would fail (leak) internally OR externally. If it failed internally, it took out the engine before anyone could stop it. That happened in about 30% of the failures that I knew about.

I thought the "Nantucket" models were the 36 and maybe the 40?

And the first one wasn't really called the I -- was only called the Mainship 34 -- until after the II and III came around??

Our '87 III had the DD 8.2T (marinized by Johnson & Towers), I think 220-hp sounds like what I remember... apparently not a popular engine in the grand scheme of boat diesels, but we had good luck with ours. We couldn't live without the transom door, given the big dogs we had at the time...

-Chris

It was a 34 Nantucket. The
Others were also Nantuckets. However the 36 sedan was never called a Nantucket fromwhat I remember. Perhaps because it had a planing hull.

Mainship 34 I: 1978 -1982
Mainship 34 II: 1980 -1982
Mainship 34 III: 1983 -1988

The Powerboat Guide lists it as the 'Diesel Cruiser', but mentions it is often referred to as the 34T. I've heard them commonly referred to as MKI; MKII; MKIII.

Powerboat Guide also lists the 36 as the Nantucket, no mention of this designation for the 34.

https://www.denisonyachtsales.com/p...nship-34_III-boat-description-yacht-research/

I cant speak to much on the engine changes over the years but below are some brochures that show the "Type I, II and III" - essentially as others mentioned the "I" had a large cockpit over hang, the "II" no over hang and the "III" a small over hang. I could be wrong but my sense of it was they swung the design pendulum to much toward a sport fish design with the "II" and the "III" was a correction on that. I dont think they made many of the "II"'s. I know a few owners of the "III" and they love that model.

I dont know much about the "II" or "III" as I own a "I"

They did make some design changes to the 'I" over the years that aren't a big deal but if someone was shopping for one might be good to be aware of;

The first "I"'s came out with this unusual cross bunk V berth set up - my best guess is the 1978's had that then they changed it to a traditional V berth set up in 1979. (the traditional V berth set up is superior imho, unless you have a couple of young kids that would fight if put in the same bunk!)

The early "I"'s had molded side seats on the fly bridge - they were actually part of the entire fly bridge mold. Again a guess, but around 1979 they changed that to where the seats are a removable type back to back set up. I have often wondered why they did this, and my only guess is that it was an effort to reduce weight. I removed my fly bridge once (I have the molded seats) and was shocked how much it weighed. My boat can ROLL given the right circumstances and especially at anchor if given the right waves on the beam.

Brochure for Type I and II

Brochure for Type I

Article and picture of the III

I have a III. As I understand it the I has a longer cabin/shorter cockpit. The II had a short cabin/big cockpit. The III was a 'happy' median.. It split the difference. I has the long overhang. II no overhang. And the III a short overhang. Another difference on the III is the side decks and transom is stepped down and lower than the I and II. I and II have side fuel tanks, the III has 1 tank under the cockpit.

Solly said:

I and II have side fuel tanks, the III has 1 tank under the cockpit.

Click to expand...

My '84 MK III still had the two side fuel tanks... If the sole tank is under the cockpit, does it block access to the stuffing box, steering gear and all the other assorted "stuff" under the cockpit?

Ken, The tank is pretty far forward. Stuffing box is a bear to get to but do able. Everything else is clear.

All great info, and exactly what I need to know when looking at ads for these boats.
They seem to be a cheap and cheerful option for cruising the bay and close coastal waters
A coworker knows someone that had a 34 classic and mentioned the handling in a following sea. It might not be something I'd notice since I spent alot of time sailing lightweight trailerable sailboats.

The engine options are not so much of a concern anymore. Because of the age of the boats, 1978 to 1983, few still have the original engine. My 1978 Mk1 has a Volvo TAMD40A of about 135 HP. I have seen 34s with Cummins engines and Perkins engines, and I am sure there are others. My Volvo is a sweet engine. I love the Perkins NA 6-354, it is bullet proof.


The packing box is in a tight situation but is accessible if you are limber and stand on your head. I changed the packing two months ago, in the water, with no problems in less than 15 minutes. After taking two hours to slack off the jamb nut.....LOL



I dont know about other engines, but my Volvo backs to Port. This is different than my Gulfstar that has a Perkins 4-108 and backed to Starboard. My BR 44 had a Perkins 6-354 and backed to Port. Lots of possibilities if the engine is not original and most are not.