Re-engine Marina Trader 34DC

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sailtones

Veteran Member
Joined
Jan 22, 2013
Messages
98
Location
Montenegro
Vessel Name
Nostra Signora
Vessel Make
Marine Trader CHB 34DC
Hi Everyone,
Has anyone ever considered or actually re-engined an MT34DC?
I have 2 x 130hp Volvo Pentas, both 44 years old, which are scheduled to come out of the boat for a major overhaul.
The boat feels significantly overpowered with these large engines, and the engine room is quite cramped.
While they're out, I’m contemplating replacing them with something more suitable.
I’d appreciate any thoughts or advice on this.
Cheers,
Tony
 
If I were going to go through a re-power, I'd look at putting in two Beta Marine engines:


Now, whether it's worth it or not to repower, is another question. Maybe yes, maybe no. By the time you put you buy engines, transmissions (if yours are not compatible or in good shape), possible new sized drive shafts and props . . . . you're probably into $30k, plus install.
If your boat is your dream boat, it is otherwise set up exactly the way you want it, and you plan on keeping for many more years, go for it!
 
I repowered my boat, going from a Cummins 6CTA 450 HP to a John Deere 4045 132 HP. In my case the Cummins was worth most of the cost of the new engine, and I was able to reuse the transmission and drive shaft, only replacing the propeller.

My situation was certainly unusual and doing much of the work myself kept the cost reasonable. As far as the economics are concerned, I saved far more in fuel costs than the engine swap cost, but that's based on 6,000 engine hours and 39,000 miles. Most won't do 25% of that in ownership of their vessel.

Other costs involve exhaust system, engine beds and motor mounts, gauge panels and engine controls. Some calculation should be made for weight reduction as engines can also effect ballasting of the vessel.

I also like and recommend the Beta Marine power plants with Kubota engines.

If you want more information on my engine swap, here is the thread covering it:


Ted
 
You could not get more reliable engines that the John Deere or the Kubota. There is a reason these engines are used by most generator manufacturers
 
Repowering is rarely cost effective. Purchasing the new engines is at best only half the cost of the job. People rarely understand how expensive it is to relocate motor mounts for proper engine alignment. Then there is transmissions, even if they match are they geared properly? Next is the expense of designing a proper exhaust system. Since you are stepping down shafts won’t be an issue but props might need replacing

First, find out what a rebuild is going to cost. Then compare that to the cost of the new engines doubled.
 
We have put many hours on Kubota diesels over the years in our excavation equipment. Flawless…. Likewise have a 1999 4045 (non turbo 81hp) in a Deere skid steer loader; over 8000h and still fires right up down to -10c. No need to use glow plugs unless colder….

I am in the process of repowering a 26’ Tollycraft with a 48hp 2.5l diesel. It is a Chinese ‘knockoff’ from a unfinished sailboat repower project so basically new…

I will start with this power unit, BUT am fabricating the engine beds & sub frame to allow an easy swap to Beta (my top pick for this project) if the need arises. Boat is on a trailer at home and I have excavators for lifting…

I am doing all the fabrication/welding etc myself so not a terribly expensive project…also quite a bit of room in the open cockpit. The engine compartment also has a good amount of working room for a small 4 cylinder diesel; making the job somewhat easier.
 
Repowering is rarely cost effective. Purchasing the new engines is at best only half the cost of the job. People rarely understand how expensive it is to relocate motor mounts for proper engine alignment. Then there is transmissions, even if they match are they geared properly? Next is the expense of designing a proper exhaust system. Since you are stepping down shafts won’t be an issue but props might need replacing

First, find out what a rebuild is going to cost. Then compare that to the cost of the new engines doubled.
When did boating become cost effective? If you need to repower do something that suits your style. On a 34 if it were me I would think seriously about going to one engine.
Another option would be to go with twin Betas and use feathering props. I betcha you’d end up running with one engine most of the time.
 
As I reread the post, are your plans to replace the two Volvo gassers with the single diesel?
 
Hi Troy. First, I see the engines are being pulled for major overhauls. Those are big heavy engines and take up a lot of space in a small engine room. I have a trailerable sportfishing boat from 1979 with one of those 130hp Volvo-Penta diesel engines. It is the original engine and has only 1900 hours, so it doesn't get used often. But when it does, it gets run hard because it is underpowered for that boat with full fuel, full bait tank, gear, fishermen and the desire to get out and back quickly. I have it's 200hp big brother ready to replace it. The 130hp volvo is otherwise a great engine and parts, though they are expensive, are available.

I took a look at MT34DC specs and it appears yours is a simi-displacement hull and some were equipped with performance doubles to allow for higher 13-14knot speeds when desired and lower 7knot economical cruise speeds tread off.

I did an engine swap on my other boat which is a 33,000lbs 40' full displacement trawler. The old engine was an obscure obsolete unit from a Ford/Fiat partnership that didn't last long in the US, so parts were nearly impossible to find. The engine was near end of life, so I installed a Cummins with great parts availability. I did 95 percent of the work myself, but it was still an expensive endeavor. Like the others have already said, conversion work is expensive with stringer, exhaust and raw water intake modifications.
 

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