Diesel Repower of an Old Gasser

rondds

rondds

Well-Known Member
Oct 3, 2006
8,859
Jersey Shore
Boat Info
2001 380DA
Engines
Merc 8.1s (2008)...Hurth ZF 63 V-drives...WB 7.0 BCGD (2013), Garmin 8208 & 740 MFDs, GMR 24xHD dome
it's raining here, the boat is laid up for the winter and i'm bored. so i got to thinking. if you had an old boat that needed new engines because of age/hours or whatever, and you wanted to keep the boat, what would you do? so i started cruising the internet checking out the marine diesel websites (yanmar, cummins/merc, volvo penta, man, perkins, etc).

i am not looking to repower (less than 400 hours on my 7.4L FWC), but if i were, what would a job like that cost, soup to nuts? i like the yanmar 6LPA-STP, which they are currently powering the new silverton 36 convertible (slightly longer and a bit heavier dry than my boat). let's assume the fuel tanks are satisfactory and not in need of replacement - i'm not sure about instrumentation and throttle/controls - would they have to go? i'm also aware that the genny would have to be replaced too, but let's forget that for now.

i had seen an article in power & motoryacht where they repowered an old Viking sportfish (mid 80s vintage, 40' i think) and i seem to remember something >$100k for the job, which was done right here in Forked River NJ.
 
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I seriously considered repowering my gas 390EC before we sold her. I worked with Mastry Engine Center in Fla for the quote and while they are competent and do good work, the money made no sense on that particular boat. The turn key $ was in the $75K area.

Things I had not considered changing had to be changed. Generator, generator panel and wiring, props, shafts, transmissions (the 7.4's were counter-rotating and diesels are not), add fuel return system, primary 12V service upgrade.....bigger batteries, no quote was given for the panel since some stuff would work and some would not and that that would not would need changing at the time of installation.

Would I ever re-power a boat?........certainly. In fact, I'm working on a deal for a Correct Craft Fish Nautique that I will re-power, probably with a single 6BTA Cummins if I can buy the boat. I don't think that an older Sea Ray is a very good platform for re-powering. It just doesn't make sense to spend $75K re-powering a $60K boat and end up with a $80K boat. You'd be better of to sell your older Sea Ray and buy a newer one equipped the way you want it......and that is precisely what we did.
 
frank
as ever, you make a very good point. there's no way i'd ever get near the investment back at resale. dlesels are certainly a selling point that would make my boat more desirable than a sistership powered with gas. but if you are talking about dollars and cents, where are you going to get a 35+ foot sedan bridge (any make), powered with diesel, for $75K+ (the cost of the "upgrade")? you could probably find another older diesel powered boat for that price, but then you are right back where you started, but, worse yet, you really dont know what you're getting (used boat, someone else's headache, etc). this size boat is difficult a class to find with diesels, since it is on the cusp of being too heavy for gas and too costly to purchase with diesel. and i do NOT want anything larger (a early '00s 400DB would be nice, but it's more boat than i need).

if money was no object, you are absolutely correct - buy something newer (or brand new for that matter) powered the way you want. but i figure that after about 3 years of enjoyment, that boat would depreciate the amount of money i could have spent on the repower.

bottom line is it is still an old boat; but, if the boat is otherwise "perfect," do i make a compelling argument??

you have answered my question as to cost of this type of job. out of curiosity, what engines were you looking at? was that ballpark price including a genny repower and trannys/shafts/props? can ONE of the trannys be utilized or are the ratios likely to be different?

interestingly, according to the spec sheet in the archive section of SRs website, this boat was offered back in 1989 with twin TAM D41A-MS4s (200hp). i've NEVER seen one in 4 years of receiving email updates from yachtworld on all new listings the come up nationwide.

http://www.searay.com/Archives_Manuals/Sea_Ray_Archives/1989/26-35%20feet/340DB_SS.pdf
 
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You going to do some fishing Frank? I never thought you would put fish on a boat you owned....
 
Gary,

If you noticed, he's putting in a "harmonically challenged" diesel....I hear they attract more fish due to the way they wiggle the teaser bates when trolling...


Ron:

If you "NEEDED" to repower and "LOVED" the boat, then you could probably justify the cost, if to no one else, then yourself. At that point you would only have to justify the difference between a straight forward repower and the diesel (dare I say) upgraded repower. You would certainly recoup some of that difference at resale and at the pump. But I would doubt you would ever recoup the full monetary value unless you kept the boat for MANY years an MANY hours. However, you would also gain the added around-the-dock handling, the grin-factor extra speed and the on-the-hook safety of less CO when running your genie.
 
Ron,

We were looking at 315 hp Yanmar 6 cylinders. If you are going to change transmissions then you should do it with gears that are best suited for your power and hull and the Borg Warners were questionable. Besides, if you are going to spend this kind of money, then do it right with gears that are mated to the transmission and will hold up under the added torque of diesels.

The TAMD41's were not popular in the US due to cost....almost all were sold in Europe.

I had the same situation with the 390EC....the boat was in perfect condition and suited us very well. Even at that it made no sense to repower at those costs when newer better equipped boats were available.

The 340/345 DB's are stern heavy and are not good performers......I'm sorry, I know you own one, but facts are facts. I'd consider this approach: I'd sell the 340DB, look for a 370DB with 300hp Cummins 6BTA's and you would get about a 7-8 year newer boat with lots of improvements, a little but not a lot more space and you wouldn't spend as much as a re-power. The 370DB with Cummins is a good performer and is fuel efficient.

Gary,

That is why I'm looking for a Fish Nautique....it is real hard to fish a Sundancer without destroying the cockpit. I'm going to Awlgrip the outside and have the inside sprayed with polyurethane bed-liner stuff and just hose her off.
 
I had a '93 370DB with gas power. The hull and boat were great, but it was way underpowered. I, too, checked with Mastry Engine center and had a $75-$80k ballpark for Yanmar 315HP. I couldn't justify the investment. I ended up selling that boat for $5k more than I paid for it and moved up a bit. The 370DB hull really likes the 23-25kt speed, but it required 3600RPM to do that with the gassers. And they liked about 40GPH to do that.
 
frank - dont worry, i'm not offended at all!:smt001 i'm well aware of the weight problem my boat has and how it affects it's run angle. i CANNOT realistically run with all my sundancer buddies (at 23 knots) - the extra fuel consumption just does NOT justify the extra couple of knots), so it really isnt practical to push her that much. my signature pic below shows typical cruising - 3250rpm, 19mph, FULL FUEL).

i actually forgot abt the mid-90s vintage 370DB. you've mentioned this boat before in our past conversations. exactly what makes this boat a better package (other than available diesels). it weighs less than mine by 2000lbs, it's two inches narrower and about a foot and a half longer. i would imagine it's got the same degree of rear end sag on plane as mine (as do all bridge searays). i can certainly understand what pirate said about being underpowered with gas, but other than propulsion, why would it be an improvement over my old tub? pirate please chime in as well!
 
We loved our 370DB. There is a 340DB down the dock from us now. The 370DB had a larger cockpit and bridge area than the 340, but the interior was similar. We put almost 2000 hours on that boat. I've never been aboard the 340DB underway. By the time we were looking to move on, our current engines were pretty tired and, as I said, I could not justify the diesel re-power. We sold that boat and a 340DA we kept in FL and consolidated to one boat that we take back and forth. Our fuel burn in $$ is considerably less moving the 480DB at 26kts than our 370DB at 18kts. The new owner of my former 370DB repowered with 8.1 Horizons. It's a while different boat with those engines. Much stronger throughout cruise range, much more efficient, etc.
 
speak of the devil! you think this guy will get his price???? i'll tell you one thing - with these yanmars you can now stand between the engines. i can barely get my forearm btwn my big blox! reason enough to repower right there!

http://www.boats.com/listing/boat_details.jsp?entityid=17184811&searchtype=buy&searchid=1&back=%2Flisting%2Fcache%2Flisting_search_results.jsp%3FSearch.x%3D53%26searchtype%3Dbuy%26fromYear%3D1989%26hmid%3D0%26sm%3D3%26enid%3D0%26toYear%3D1989%26currencyid%3D100%26luom%3D126%26toLength%3D34%26fromLength%3D34%26ftid%3D0%26ps%3D100%26ic%3Dtrue%26sfm%3Dfalse%26Search.y%3D8%26man%3Dsearay%26slim%3Dquick%26psdistance%3D1%26pszipcode%3D07733%26searchPage%3D%252Flisting%252Fcache%252Fadvanced_search.jsp&rev_srh=%2Flisting%2Fcache%2Fadvanced_search.jsp%3Fsearchtype%3Dbuy%26fromYear%3D1989%26uom%3D126%26sm%3D3%26duom%3D126%26wuom%3D126%26toYear%3D1989%26luom%3D126%26toLength%3D34%26currencyid%3D100%26ps%3D100%26fromLength%3D34%26sfm%3Dfalse%26ic%3Dtrue%26man%3Dsearay%26slim%3Dquick%26psdistance%3D1%26pszipcode%3D07733%26ps%3D100%26clk_srcrvs_nav&srh_prev=true&srh_next=true
 
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This past summer we met an owner of a 42 foor SeaRay that repowered with twin Yanmars and a new gen set. Cost was 120. He said it all works well but a new boat would have cost less. The Yanmars came with transmissions. Worked looked very good.
 
We have a friend who owned a 38 foot aft cabin Bertram bought new with 454s and used for 20 years. The old gassers were pretty well worn out and he repowered the boat and installed a new genny, all diesel. I don't know what it cost although the admiral said they bought the boat again. Apparently the repower cost was the same as the boat purchase price 20 years earlier. They used the boat for another five years and then retired from boating. A person from New Zeland was in Michigan on business and decided to buy the boat. She paid them a bit more than the cost of the repower and shipped the boat down under in a big shipping container. There are probably only a handful or two of builders where the equation works this way. Most production boats are well depreciated by the time they need repowering and a switch from gas to diesel makes no sense.
 
i really dont know what my boat cost back in 1989 (> $100K?), but i guess it was more than $75K. a diesel repower today would cost $75K (which is more than i paid for the boat in 2004). i'd be fairly confident that in 3 years, if i sold, i'd be able to get approximately what the repower cost. if i sell it in three years, unrepowered, with, say, 550 hours, maybe i'd get $30K. i guess, having bought the boat used, which allowed the first owner(s) to take the brunt of the depreciation, repowering as the third owner wouldnt sting as much at resale. :huh:
 
Am I the only one who finds it amusing how we all become "fiscally responsible" on repowering a boat versus all the other things we spend on it over it's lifetime? This hobby is the most obscene irresponsible expense that is tied to emotion anyone could have.


Repower away.....
 
no THAT'S what i'm talkin' 'bout!!:smt038

a boat is the worst investment you could make - why not make it even worse-er-er!?
 
Ron... 30K for your boat in a few years.... I doubt that very much. That is unless GAS goes to $5 per gallon. Then we'd all be sitting at the docks with our "dock queen yachts".

No one answered your question regarding the difference between the 370DB and the 340 DB performance wise.... I would be very interested as to why the 37 is a better boat considering the facts you stated. Any takers?
 
Ron,

Did you see the 340 last year that some guy added 4 ft. to the cockpit to end up with 38 ft. and repowered with big diesels? He was at about $150K a year ago.....but it was one really neat boat and the work appeared to have been very well done.

The 370DB with 300hp Cummins isn't the usual DB. There is enough weight forward and enough torque to drive bigger props so the boat runs much flatter and the stern does not seem to dig in nearly as much as with gas engines.
 
frank
i VIVIDLY remember the boat. he wanted an awful lot of money for that boat and i wonder what he actually got. but that boat struck me as ABOVE AND BEYOND reasonable in the "modifications/customizations" department. slicing a boat open to get a larger cockpit is over the top, much more over the top than a "simple" repower. it's all a pipe dream anyway - but it's fun to talk about it :grin:
 
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