Diesel Conversion

andy k

andy k

Active Member
Feb 7, 2009
505
Lake Erie
Boat Info
40.3
Engines
Yanmar
I am thinking of buying an older boat, like an 1989 340 DB and renovating it completely. I would like to know how much it would cost to convert the gas engines to diesel engines. What is all involved? About how many hours are involved per engine if I decide to have a mechanic do it? Also how much would a generator cost? My goal is to be at 80k into a boat, so if I spend 30k on the boat and spend 15 on interior and exterior, is 35k enough room for a diesel conversion. or am I just wasting my money :smt021
 
You will be wasting your money in my view. You will be better off buying a boat that better meets your specs than trying to convert. People seem to underestimate the work involved in doing a diesel conversion. No offense intended, but if you are serious about taking on a project like this, I would buy a brand such as Bertram, Hatteras or another known for durability and seakeeping . Properly done, these old boats command a premium when you sell them. You will recover more of your depreciation than if you refit and old SR.
 
sbw1 said:
You will be wasting your money in my view. You will be better off buying a boat that better meets your specs than trying to convert. People seem to underestimate the work involved in doing a diesel conversion. No offense intended, but if you are serious about taking on a project like this, I would buy a brand such as Bertram, Hatteras or another known for durability and seakeeping . Properly done, these old boats command a premium when you sell them. You will recover more of your depreciation than if you refit and old SR.
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+1,

I recall reading an article in Motor Boating last year on the economics of diesel re-powering. As I recall, the numbers outlined were in the $ 100,000 to 175,000 range for engines, transmissions, fuel tanks and instrumentation. I know my neighbor's insurance company paid over 50K just to replace the Yanmar diesel on his Mainship two years ago.

Henry
 
Thanks for the advice, It sound really expensive. I am a freshwater boater and I am affraid to buy a salt water boat as I see what salt does to vehicles on the road in winter up here. When looking for a diesel boat in salt water, what should I consider, and what should I avoid. Thanks for the advice
 
andy k said:
Thanks for the advice, It sound really expensive. I am a freshwater boater and I am affraid to buy a salt water boat as I see what salt does to vehicles on the road in winter up here. When looking for a diesel boat in salt water, what should I consider, and what should I avoid. Thanks for the advice
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Basically the same thing you would look at in freshwater but make sure that you are dilligent about any corrosion issues and make sure you have some sort of maintenance history (which I would want on any boat Fresh or Salt).

After you have done that have her surveyed and see if thats the boat for you.
 
As others have said, a diesel conversion is expensive. I priced it out on a 390EC a few years ago and it was north of $80K for 6 cylinder diesels.

Why so expensive? Considering that you must replace fuel lines and add a fuel return system, purge existing tanks of fuel, change transmissions, increase shaft sizes, replace props, perhaps struts too, replace the generator with a diesel one, change instrumentation or at least tacks and all engine senders,.....and the list just seems to go on forever.

If I were going to get into a major repower like this, I wouldn't do it in a low demand boat like a 340DB, but would pick something like a 31 Bertram.

Buying someone else repower project has some potential, but that also comes with some potential pitfalls as well. Somneone repowered a 340 Sedan back in the early 90's with 6BTA Cummins and the boat was so stern heavy it wouldn't perform. It eventually sold to someone else who added 4-5 ft to the cockpit to change the running angle. I saw it in So Fla in about 1998 and it was a cool looking 340, now 390ish and was a diver's dream boat with that much cockpit. I hate to think what the repower and boat stretching costs totaled when it was all done.
 
It cost some one I know 100,000 to repower a SeaRay like mine including replacing the generator. Think of all the gas he could have purchase. In my opinion it does not make economic sence. As to salt water damage my boat has been in salt water since new and the only work I have done is risers on the 454s and replace the end caps on the generator manifold. If you keep the zincs up I think you will be fine. Get a good engine survey including the manifolds.
 
Friends of mine have been hunting for 30-something Bertrams. There are some really nice examples out there. An interesting twist to the older Berts, (and Hatts for that matter) is that they had horrible interiors. Ugly laminates and cheap materials that had to have been behind the times before they left the factory. In contrast, those boats tend to have timeless, stout designs and great build quality. That makes them great candidates for renovations, so it's not hard to find updated examples.

We've come across very few diesel-powered examples, but I agree with the above: if you're going to convert, convert a classic.
 
fwebster said:
Buying someone else repower project has some potential, but that also comes with some potential pitfalls as well. Somneone repowered a 340 Sedan back in the early 90's with 6BTA Cummins and the boat was so stern heavy it wouldn't perform. It eventually sold to someone else who added 4-5 ft to the cockpit to change the running angle. I saw it in So Fla in about 1998 and it was a cool looking 340, now 390ish and was a diver's dream boat with that much cockpit. I hate to think what the repower and boat stretching costs totaled when it was all done.
Click to expand...

Check out the first link I posted. It is that boat.
 
You are right.......that is it!

But the last time I saw it she was a pretty bare bones boat. It looks like someone has continued spending re-fit $ on it since then. I see all new vinyl, teak/holley sole, new electronic, etc, etc,, and I have to say that the current asking $ might make her a decent value today.
 
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fwebster said:
Buying someone else repower project has some potential, but that also comes with some potential pitfalls as well. Somneone repowered a 340 Sedan back in the early 90's with 6BTA Cummins and the boat was so stern heavy it wouldn't perform. It eventually sold to someone else who added 4-5 ft to the cockpit to change the running angle. I saw it in So Fla in about 1998 and it was a cool looking 340, now 390ish and was a diver's dream boat with that much cockpit. I hate to think what the repower and boat stretching costs totaled when it was all done.
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I don't see the extra 5' in the cockpit. It looks like there is about 5' from the cabin door to the transom. I owned an express version of this boat and the lines and length look unaltered. Maybe it's the pic.
 
While looking at YW the other day a saw there were quite a few 90's 370db's in Brittish Columbia with diesels.
 
sbw1 said:
I don't see the extra 5' in the cockpit. It looks like there is about 5' from the cabin door to the transom. I owned an express version of this boat and the lines and length look unaltered. Maybe it's the pic.
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Totally different boat than the express 340.
 
andy k said:
I am thinking of buying an older boat, like an 1989 340 DB and renovating it completely. I would like to know how much it would cost to convert the gas engines to diesel engines. What is all involved? About how many hours are involved per engine if I decide to have a mechanic do it? Also how much would a generator cost? My goal is to be at 80k into a boat, so if I spend 30k on the boat and spend 15 on interior and exterior, is 35k enough room for a diesel conversion. or am I just wasting my money :smt021
Click to expand...

A diesel conversion will cost $60-80K. You will have to install new engines, transmissions, shafts, struts, props, fuel tank, fuel lines, batteries, engine electrical system, and gauges/controls. You also will probably need to modify the engine bed to support the weight of the diesels and accomodate the new engine mount pattern. Do yourself a favor and look for a diesel boat that passes an engine survey.
 
Carver370 said:
Totally different boat than the express 340.
Click to expand...

I understand that but it looks like there is about 5 feet from the cabin door to the transom. Are you saying that prior to adding the 5 feet, it was designed with the transom at the door? It doesn't seem logical.
 
Look how much shorter it used to be

2090014_1.jpg
 
Look at the photo posted of the standard 340DB that Carver370 posted..........

now look at photo #32 in the yachtworld listing for the altered '88 340DB.

If you can't see the difference; we propably can't help you.
 
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