Repowering from Gas to Deisel

This may be a stupid question but I could not find a thread on this subject. I came across a possible steal on a late 90's Carver 370 Sundeck that I can pick up for a song. Problem is it has twin crusader 454 gas engines. I worry about gas fumes in this kind of boat. My questions are:

A: Is it practical to switch from gas to deisel? Are fuel tanks, lines, etc interchangeable?

B: Is there a rule of thumb on cost?

C: Who does this kind of work? Any boat yard or are there "specialists" that I would need to seek out.

Thanks guys.

I had a marina neighbor who pulled twin (350) Crusaders out of a 30 ft SeaRay sedan bridge and repowered with twin Yanmar 4 cyls. This was in 1998 and it cost him around 30K and he did all the labor himself.
He envisioned running up and down the ICW from Ct to Fl every year for a few years. He did it once and decided it was not for him. Outside of that he used the boat maybe 75 to 100 hours a year.
He changed a lot of stuff to do the conversion. He kept his fuel tanks, but had to re-plumb them, had to re-plumb his exhausts, wiring changes, lots of stuff to change over.
He also had to mess with his props several times to get them correct.
Bottom line is he did not use the boat anywhere near enough to justify the cost of conversion.

If it were me, I wouldn't bother. You would be way better off getting it for a steal and investing a good deal less money fixing it up as a gasser than you would trying to make it something it wasn't meant to be. Heck, I'd venture a guess that you could totally repower the boat for less than the purchase price of one diesel replacement engine.

Gas-powered boats are very safe. You just have to be aware of things that can cause problems. Things that should become automatic in a short time. There is no reason to fear gas boats at all. Give them a healthy bit of respect and they will treat you as well as a diesel, but for far less money.

Tom-

Agree with Tom many many expensive things to change out in such a conversion. You will never pay for it in fuel savings nor get much of it back when you sell / trade. In the process, on a boat that age, you will expose and have access to many other things (unrelated to the engine swap) that you will want to change out "while your at it" thus ruining any budget you may have made for the swap.

Question C is the key question in my opinion. If you are not capable of doing the work yourself and have the time to complete it would never pencil out. Add $40 to $60K to the price of the boat and ask yourself if it's still a great price. Personally I'd just enjoy the boat as a gasser.

Having said that, there is nothing rational about boat ownership in the first place. So if you have the cash and desire to spend that kind of money with no possibility of a return on investment, why not? It would be far cheaper to buy a diesel boat in the first place though.

Besides being gas powered is there anything wrong with the current 454's? Does the boat need a re-power?

Don't know where you are located but here in Florida you can buy 415 hp increased fuel economy 7.4s for around $2800 per plus labor..

Pluto:

Let me answer your questions first and then follow up with some advice about practicality:

A. You can reuse fuel tanks, lines, etc but you will probably have to add Racor fuel filters and a return diesel line for each engine.

B. One of the most economical diesels is the factory remanned Cummins 370 hp 6BTA. These cost in the low $20Ks each and will cost another $10K or so each to install depending on reuse of prop shafts, props, tranny, etc. So a ball park would be near $100K for two.

C. First decide on the engine and then talk to the dealer of those engines about doing the work. A boat yard can do it as well if they have good diesel mechanics on the payroll. But these guys are mostly good for oil and filter changes, not something as sophisticated as a repower job.

Is it practical? Well think about the benefits to be derived from spending close to $100K vs about half of that for new gassers. Safety, fuel consumption and maybe resale value are the main benefits. It will take more than 1000 hours of operation to repay the fuel cost savings.

David

Pluto, if you're not interested in this boat please PM me the details if it's located near Florida.

David Marchand

Also, the Carver may require additional added stringer strength to handle right sized diesels having greater mass and higher torque. The most satisfactory gas to diesel repowers tend to be on vessels where access is very good and brand name carries some catchet, such as Bertram, Tiara and Hatteras. Several Tolly 44s have been gas to diesel repowers, made simpler by virtue of the boat being made to accept gas 454s, DD 8.2s or Cat 3208s. Check out boatdiesel.com and their writeups of a few repowers.

BTW - saving money, being frugal and boating do not go well together. To really save, buy a well maintained trailer boat that can do it all. Today's high HP outboards are game changers. In the PNW you can choose between many different Al 26 footers that will get you quickly to most fun places. Or if in FL go with a spiffy 30' Trophy.

Also, be very careful of hurricane boats being sold as "good." Lots of deals going on today with last fall's East Coast derelicts flooding the US market according to Boat US

Do the math. It's always the money. If you replace engines that combined burn 12 GPH with diesels that burn 7 GPH you might not live long enough for the break even. I'm using guesstimates here but look at real figures before you jump.

My advice is to go with the newer more fuel efficient gas engines. Those and new props and you're probably done. Resale of the boat with diesels won't justify the change and as mentioned above, going to heavier diesels could screw up a well planing boat. I've seen that happen and then the fuel curve that the pro said is out the window.

Do the math. Stick with Gas. Do the math, Stick with Gas!!

CaptHead has very sound advice here, I think. While many people have converted gas boats to diesel, particularly Tollycrafts here in the PNW, the big question is always if the gain is worth the cost. For some boats and for some people, it is. For others it's not.

In this case, especially as it's a Carver, I would think the ultimate cost would never be recouped in the value of the boat in both dollars and intangible value.

Were this me, I would never consider a gas cruising boat in the first place and so would keep looking until I found what I wanted in a diesel boat.

As it's not me but you, only you can judge the suitability of this particular boat to what you want to do with it, how this boat fits your financial requirements, and so forth.

If you were talking about a high-quality vessel like a larger gas Tollycraft, which is an outstanding boat in terms of quality and construction to begin with, the cost to convert it to diesel may be well worth it, particularly if you intend to keep and use the boat a lot and for a long time. I doubt you would ever recoup your cost investment even with a Tollycraft, but you can't really put a price on the added value, safety, ejoyment, pride of ownership, etc., etc., etc. of the now-diesel-powered boat to you.

But since the boat you are considering is not something like a Tollycraft, and if you decide you absolutely must have this particular boat, I would strongly second CatpHead's suggestion to stick with the boat's as-built gas engines. In my opinion this particular brand is not worth throwing that much money at in the form of a diesel swap out of one gas engine, let alone two.

Thank you all for the reality check. I may have gotten a bit carried away with some bad information i recieved about the boat. The wife really liked the modern features and creature comforts, however its all about the mission. Doing the loop and Bahamas would be doable with the existing power. I am learning as I go. Thank you for letting me bounce ideas off you all.

Pluto said:

Thank you all for the reality check. I may have gotten a bit carried away with some bad information i recieved about the boat. The wife really liked the modern features and creature comforts, however its all about the mission. Doing the loop and Bahamas would be doable with the existing power. I am learning as I go. Thank you for letting me bounce ideas off you all.

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We looked at a Carver, actually put one under contract. Just not aggressive enough for what we desire.

I agree with the consensus. There's not a darned thing wrong with gas engines in a Motor Cruiser like Carver, and if you do the research, you'll find that at least one 370 did end up with a twin diesel conversion. After the conversion, it was left to wallow in a slip, and was picked-up by a infatuated Broker over on the Gulf Coast, FL. He spent a lot of time and trouble making it a good boat, but all the bread was spent for the diesel conversion before he ever got to it. He had it for about a year, I think. Maybe it wasn't the boat he had hoped.

Economically, you`re better off fixing the gassers or changing boats than converting to diesel.
The cost reminds me of a comment by the producer of "Raise the Titanic":
"Would have been cheaper to lower the Atlantic"(or words to that effect).

There are diesel Carvers. They are usually in the 200-250 HP range, smaller displacement to make up for the weight difference. And they do command a much higher price tag.

Marin said:

If you were talking about a high-quality vessel like a larger gas Tollycraft, which is an outstanding boat in terms of quality and construction to begin with, the cost to convert it to diesel may be well worth it, particularly if you intend to keep and use the boat a lot and for a long time. I doubt you would ever recoup your cost investment even with a Tollycraft,

But since the boat you are considering is not something like a Tollycraft,

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OMG - Marin – OMG: I cut your post up to leave only the pro Tollycraft sentences that so much OMG me – So again, I have to say, OMG!!! This proves every one of us have chance to be saved! And, that even includes you and me... even with the way our minds work, at times so diametrically opposite... LOL and OMG!!

Pluto – Marin, Capthead, sunchaser... and many others have hit nails on the head with their posts. If you want a diesel powered boat then it is best to find one that is already a diesel, there are plenty in today’s soft market that can be purchased at a reasonable price and that are in good condition. If you get a gas powered boat that is in good condition just learn-very-well how to use it without blowing yourself up. Well equipped, good condition gas boats have great systems aboard to make sure there will be no fire or explosion... but... You DO NEED To Know How TO STAY SAFE when using a gasoline powered craft! Any smart and experienced gas boat owner or licensed Captain can explain the way to take care of your gasoline fuel and leave you with written instructions to use and memorize until all the precautions become 2nd nature to you. As Marin mentioned – Even changing Tollycraft to diesel will mean you are very unlikely to regain your investment. A friend changed a gas powered Tolly tri cabin to diesel a couple years ago and his bill was broaching $100K. He loves his Tolly (as most of we Tolly owners do!) and had the capital to have all the work done by others. Once he got into the project there were many other items that ended up being replaced too. “Pleasure Boating” should be only for adventure and excitement that feeds a boat owner’s enjoyment; and not to create a financial collar around anyone’s neck – at least that’s how I see it!

If it's diesel you want, then buy a diesel boat.

If you can live with gas and the lower entry price, but a gasser.

I'd never buy one planning to change it to another unless I just needed the practice changing engines...which I don't.

Art-- As I believe I've said before, I'm not a fan of Tollycraft's for aesthetic reasons. I just don't care for the look of them. But that's got nothing to do with their quality or how well they're made. If one likes that type of boat, I think they are some of the best cruisers out there, particularly if one can find a diesel or diesel conversion.

There are, orthere used to be, a number of Canadians who kept their boats in the Point Roberts marina to avoid Canadian fees. Several of them have or had larger Tollycrafts-- 40+ footers-- all of them diesel, and they were outstanding examples of the type. Beautifully kept up boats and used a lot, too.

They had to restrict their boating to US waters as they told me that if they took their boats into Canadian waters they would instantly be liable for all the back registration, tax, etc. fees they hadn't paid over the years. This was assuming anyone would bother to catch them and enforce the law.

But I've never hesitated to recommend looking at diesel-powered Tollycrafts to people I've encountered who say they're looking for a cruiser-style boat. If the Tollycraft styling is what one likes I dont' think there's a better-built production boat out there. Second-best might be Uniflite.

This prohibition-era, previously-movie-director-owned boat was originally gas-powered. Now diesel-powered because suitable engines are now available.

Marin said:

Art-- If the Tollycraft styling is what one likes I dont' think there's a better-built production boat out there. Second-best might be Uniflite.

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I've owned a classic Uni; twin screw V-drive, 1973 FB sedan fisher. I do feel Tollycraft boats are (were) better built than Uniflite... but only by a little. Hatteras built (builds) some real nice cruisers too. GB is of course an iconic brand and very well built also, although I really don't like their exterior design looks and particularly their lack of bow flare. Different strokes...Different folks!

We have done some gas to diesel re powers in the past, About 15 years ago going from twin 454s to 4 LH Yanmars was very popular, Marcus @ TAD in White marsh VA has a good deal on rebuilt 210 & 250 B series Cummings , You will need a gen set also, Some of the Carvers had the same Diesel engine package from the factory, I think a 100k may be on the high side, In this economy if you shop you should be able to cut the labor down to 12k and 30k in engines & parts, Most of the yards in NC were slow this past winter, But spring is here now so the deals will be a lot harder to find, I would think that one of the main deciding points would be the condition of the installed machinery for a start then a cost of repair / replace vs Diesel re power. Craig

Art said:

GB is of course an iconic brand and very well built also, although I really don't like their exterior design looks and particularly their lack of bow flare. Different strokes...Different folks!

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I'm not a big fan of GB's design aesthetically, either, and yes, the lack of bow flare makes for a VERY wet boat.

I forgot about Hatteras. From everything I'm given to understand another excellent boat although I have only ever seen one (that I know of), a pretty big one a couple of docks over from us. The same guy who got American Marine into fiberglass with their Grand Banks line (and built the molds and personally supervised the layup of every GB hull for the first year) also helped Hatteras get started in fiberglass.

Marin said:

I'm not a big fan of GB's design aesthetically, either, and yes, the lack of bow flare makes for a VERY wet boat.

I forgot about Hatteras. From everything I'm given to understand another excellent boat although I have only ever seen one (that I know of), a pretty big one a couple of docks over from us. The same guy who got American Marine into fiberglass with their Grand Banks line (and built the molds and personally supervised the layup of every GB hull for the first year) also helped Hatteras get started in fiberglass.

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I've been keeping my eye on a 60's twin screw 41' Hatteras sport fisher for a few years. This Hatt was originally owned by CG. 95 they repowered w/ brand new Detroit 6V53T for her sale on public boater market. Fellow purchased her and used for a few years fishing, unfortunately debilitating item befell him. So... since bout 2001 she's been a dock queen w/ just over 700 hrs on her 1995 New Detroit engines. Owner has kept her paid up and 6 month bottom cleaning, zinc changed. The boat's been for sale since 2009. I called him then, his price was way too high, I had a tour of the boat by an attendant of his. Interior was pretty good condition, engines pristine, exterior basically OK. Since then the price has dropped way down and a low ball offer by some other buyer was accepted, but the deal fell through when buyer placed too many stipulations on the owner. Sooo... I recently stopped by to walk the finger docks next to her. Man, in three years weather really has taken its toll on the wide open to the elements exterior. Much refinishing is now required on entire top section and bridge enclosure canvas has gone bad. Hull needs painting too and swim step needs repair. I'd only take this Hatt at fire sale bargan price - if at all. That's the way of so many boats that have become dock fixtures for one of many reasons during the last 10 +/- years. One HUGE reason is fuel costs. Many boat owners simply can't afford to often spend hundreds of $$$ for a relatively short cruise.

Unfortunate power-boat-user market, with no end in sight for increasing fuel costs!!

Doing the loop and Bahamas would be doable with the existing power.

A HUGE portion of the loop is in Canada and limited to 5 or 6 mph (10 klicks)

So the fuel burn will be almost as good as most diesels at the same speed.

Gas is only expensive IF you actually use the HP , want to cruise at 20K, 1/2 mpg with luck.

Cruise at 6K , and enjoy the quiet.

A good auto pilot is required for slow cruise as the rudders are probably small to enable plaining.

YOU CAN NOT AFFORD an engine swop if you can not do the work.

FF said:

Doing the loop and Bahamas would be doable with the existing power.

A HUGE portion of the loop is in Canada and limited to 5 or 6 mph (10 klicks)

So the fuel burn will be almost as good as most diesels at the same speed.

Gas is only expensive IF you actually use the HP , want to cruise at 20K, 1/2 mpg with luck.

Cruise at 6K , and enjoy the quiet.

A good auto pilot is required for slow cruise as the rudders are probably small to enable plaining.

YOU CAN NOT AFFORD an engine swop if you can not do the work.

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Ditto!

Uniflites are 25 cents on the dollar here. The blister problem coupled with our warmer water destroyed their value. I've seen them with blisters all the way up to the gunwales and in the yard they can get deep into the glass. The fix is very expensive and you'll never recoup the cost at your selling.

To the contrary, the boat in the slip next to me is a Uni and he has zero blisters and has owned it about 12 years now. I like the lines of that boat too.

When I was a manager at a dealership the should I buy diesel question always came up. For the customer who trades every four to six years and has under 100K on the odometer, I always said no. The reason is the upgrade cost of the diesel option at that time was around 3,000. The fuel costs are about the same so the only benefit is the MPG savings. At best that would be, and we are speaking about a 1 ton truck mostly, going from 14 MPG on a gas to 18 MPG on diesel. That 4 MPG savings doesn't compute for a 3000 price increase. AND, I'm not talking about resale value which for diesels is lower so the actual swing might be 4500. You would have to own it over ten years and drive it over 600,000 miles to see daylight, which you can with a diesel truck.

Boating is a different scenario. Fuel costs for diesel is lower due to the tax savings. We don't pay road tax on diesel fuel but we pay them on gas. Therefore, the fuel savings costs are far greater owning a diesel powered vessel. That Uni next to me has twin Chrysler 440's. They idle at 12 GPH and WOT IS 36 GPH each engine. Gasoline at the fuel dock is around 4.80 a gallon and diesel 3.60. He spends $350.00 to go to Catalina for a weekend in fuel.

My twin diesel 42' GB will burn 22 gallons for that trip to and from. That's under $80.00 for me.

I'd look at the numbers and do what Marin said. Find a good diesel powered boat and have fun cruising the Bahamas.

One last thing about Gasoline. The USG and the EPA is ruining gasoline's power by adding ethanol. It takes 1.5 gallons of ethanol to equal a gallon of unleaded regular gasoline. When you dilute gasoline with 10% ethanol you lose power and that means MPG. Ethanol eats rubber and some plastics. It's very corrosive and it absorbs water. The Boat US group is fighting right now to stop E15 from happening. That will cause even more damage to gasoline powered engines. Keep in mind, boat engines work much harder than car engines and with all that stress adding more ethanol shortens the life of that engine.

I'm predicting a bad future for gas powered boats, especially for brokers and sellers.

Tens of thousands of gas powered, new and old, large cruisers, houseboats, pontoon boats, ski boats and fishing boats cruise the inland and near shore waters of the US. Many more than diesels. There are reasons for this:

• Lower front end costs
• Lighter
• Acceptable fuel burn for weekenders
• Easy to repair

Now if it weren't for that darned E10/15-----------