246 gas to diesel

[Steve74]

What would be involved besides the obvious engine, tranny, and prop replacement. Would i need to install a larger shaft or modify the stringers/supports for the engine due the the increased weight and torque? I like the Cummins 220hp Diamond Series 220B.

Thanks
Steve

[Scratcher]

There is a good chance you'll need to re-shaft, although you may be able to go to a stronger shaft material (monel?) and still be able to use your existing shaft log and cutlass bearing.

Return lines for the fuel tanks will be needed.

You will probably need a new gear.

You'll definately want new engine mounts, but may well be able to use the existing bed.

Check clearances, diesels tend to be higher and longer than gas, so you may need to cut out more area and or need a new engine cover or modify your existing.

New instrument panel.

You'll have to check the thru-hull cooling water intake size, it may need to be increased depending on engine specs.

The exhaust outlet in the transom may/will probably need to be larger.

The rest of the exhaust system will probably need to be changed (diesels use high-temp hose and don't tolerate much backpressure.

I'm sure I've missed a couple of items, but thats a start anyway.

One of the first things you should look at is the prop. It doesn't make sense to put a larger/more powerful engine in if you are going to find yourself limited by clearances to a prop that won't complement the power plant.

[Mistress]

Is that a 6bt 5.9l 6 cyl? Prolly better off looking at the HO 4 bangers (cummins, Yanmar, etc). Easier fit, lighter and more similar rpm range lessening the requirements for gear, shaft, prop changes.

My 6bt has a 1-1/4" shaft...newer ones have 1-1/2". 3.5- 4" exhaust, 1-1/4" water intake. Fuel return lines required.

[Steve74]

Thanks for the replys. I know it wasn't going to be easy. I guess the tanks have to be cleaned too which means cutting the deck. Probably be better to just buy a boat with a diesel.

[Damon]

I believe "Fisherofmen" did this conversion on his former 246.

[Mistress]

Since you have MPI...you may have return lines already. Ya...need to get the gas out. I don't know what tank access is.

[MC]

Steve-

I reasearched this when looking at boats last fall/late summer. It can be done, just budget $25k. You should be all right with the stringger set up (just as long as they are in good shape), you may have to modify them, but be ready to replace everything else- gauges, fuely system (at least washing out). You MIGHT be OK with the shaft, but installers are going to recommend you replace the shaft and just add it to the budget.

$25k to decrease your fuel consumption about 20% (at most) does not make a lot of sence to me. Also, diesel's are great until they need service or break. Man are parts expensive and diesel mechanics charge a premium.

I think I figured out that I'd have to run about 800 hours (with out any major service issues) before I "broke even" (that was when Diesel was about .50 cheaper a gallon).

I could find all my paperwork, but never made sense. Fun to think about though.

Take a look at the Shamrock web site under the 246 adventure, I believe they had performance numbers between the gas and diesel versions of that boat. If I recall, there was very little difference in fuel consumption for the diesel upgrade. I'd assume, since the 246 open is a much lighter boat, the numbers would be even better for our boats.

[Mistress]

Steve-

I reasearched this when looking at boats last fall/late summer. It can be done, just budget $25k. You should be all right with the stringger set up (just as long as they are in good shape), you may have to modify them, but be ready to replace everything else- gauges, fuely system (at least washing out). You MIGHT be OK with the shaft, but installers are going to recommend you replace the shaft and just add it to the budget.

$25k to decrease your fuel consumption about 20% (at most) does not make a lot of sence to me. Also, diesel's are great until they need service or break. Man are parts expensive and diesel mechanics charge a premium.

I think I figured out that I'd have to run about 800 hours (with out any major service issues) before I "broke even" (that was when Diesel was about .50 cheaper a gallon).

I could find all my paperwork, but never made sense. Fun to think about though.

Take a look at the Shamrock web site under the 246 adventure, I believe they had performance numbers between the gas and diesel versions of that boat. If I recall, there was very little difference in fuel consumption for the diesel upgrade. I'd assume, since the 246 open is a much lighter boat, the numbers would be even better for our boats.

Don't forget the inherent value added with diesel power. I know you aren't considering the swap to sell it...but if so eventually...diesel powered Shammies fly off the shelves at a premium. The increased range can be a factor too. If you do a lot of trolling...they'll do much better than 20% better than gas..at cruise, that's probably about right. At idle..diesel damn near makes fuel. Don't forget the inherently safer fuel too.

Between 2 diesel pick-ups over 15 years and a diesel boat..I've never found upkeep especially expensive. Not much to do but keep fresh filters in 'em and always monitor for clean, dry fuel. No spark plugs, ignition parts, routine manifold changes, etc. I hear the Yanmar filters are quite dear, but the Cummins filters are quite reasonable. Yes..internal parts on both get pricey in relation to gassers. The diesel motors are much better marinized. The exhaust manifolds are made to last for quite a few years without the capability of killing your engine (my Cummins anyways).

[MC]

Forgot to add-

Give the guys over at Mastry a call www.mastry.com. They are really good about giving you some information to think about. They might have been involved in the orignial installment of these boats when they were built in Cape Coral back in 2000. If not, they probably know who was and direct you to someone who can give you specifics.

As Mistress pointed out, resale definately will help out, but you might be better selling your current boat and looking for a boat that had an original diesel. I always had a concern about boats that were repowered with significantly different equipment.

Might make better sense than doing a repower on a 246 open and looking to sell it in the short term.

Rick gave me some great advise- buy a diesel because you want a diesel. The potential operating savings should not be the major reason for the purchase/modification.

[Mistress]

I can't disagree with any of that...providing your current engine is sound. Trying to find a diesel 246 might be difficult though. The sales volume of gassers is MUCH higher, due to cost of entry. The bigger the boat..the more likliehood of finding diesel.

It will take me many years to amortize the diesel in my truck based on my limited mileage useage....but the comparative ease at which it does the job asked of it (rolling at 22,000 lbs) is worth it to me. Plus I love diesel clatter in trucks and boats. ;-)

[Eyekymo]

Here you go;

http://adcache.boattraderonline.com/6/7/0/68296170.htm

I've been there several times, looking at different boats, they are usually a little tired, but this is a way good price. Most gas jobs cost more than this.

Mike

[Eyekymo]

Mistress,

You're right about it taking a while to realize the initial investment. Even with the miles we put on my trucks, the seven grand add, coupled with the fact that they're getting more for diesel than for gas, makes you seriously question why. I just put a Banks system in my boat hauler, and that made it all clear again.:twisted:
Steve, is there something wrong with your present power, or are you looking to save on gas? I like the diesel option alot, but it'll take you a long time to break even. Depending on how much you use your boat, maybe forever.

Mike

[Mistress]

What boat hauler you got? What's under the hood?

Here...diesel is about the same price as regular now. Got above premium for awhile here. Over the 15 years I've been diesel...I'd say it averages the price of mid-grade with less fluctuation than gas...until last Fall.

At the marinas..the diesel is usually a bit cheaper han regular gas.

[Eyekymo]

Mistress,

It's an Excursion, 2000. I put the kit on a couple of mos. ago, right after she hit 100,000 mi. It's got the 7.3, like my other three. I've had 6.9s, but not the 6.0. My brother is a Ford mech, and he has voiced his reservations about that motor enough for me to listen. Especially since Ford is already replacing it with something a little bigger.
With respect to diesel pricing, it's about .20 a gal. higher than reg. right now. Normal, for the last two years, anyway. Before that, it was about .20 a gal. cheaper. Before they started dying it, it was about half of the cost of gas. Here, it goes up every Thursday night, at least .15, and comes back down on Monday, at some point. Yes, we live in a fair and equitable world. There is no smiley for puke!
I always wondered why there is no marinization of the 7.3. It seems like a viable choice.

Mike

[Mistress]

The only Ford diesel I've seen in a boat was a 6.9. Not sure what the marinization was like. I know the early 6.0's were fragile...I think they've worked mosty the bugs out, but I'm still a bit leary too.

My Dodge 3500 has the 24v Cummins 5.9, DD1 injectors & DD fueling/timing box. Estimate about 325 hp at the wheels with about 700 torque. The one time I actually drove it empty it felt like a 426 hemi. Hit the peddle at 60 and you were shoved into the seat and up to 90 in short order. With the camper weight at 13K...feels like a hopped up Peterbilt. Add the Mack behind and she's finally working a bit, but not sweating. All smiles.

[Damon]

Mistress,

I always wondered why there is no marinization of the 7.3. It seems like a viable choice.

You'll never see it.....

Due to the lack of good fuel economy and longevity of the 7.3, any company that chooses to marinize these motors would be making a poor investment.

That's why you don't see them in boats today.......

[Mistress]

Boy...I dunno. The 7.3 holds up in pick-ups pretty damn good in my experience, with fuel mileage being close to the 24v Cummins. Granted..marine use is much tougher and my modestly hot-rodded 24v Cummins will run circles around a stock 7.3 powerstroke.

[Eyekymo]

That 5.9 is a good motor. Heavy as hell, for a pickup, or a small boat, but gobs of torque, and long lived. Remember John 33 whatever? He sure liked them.
Damon, why would you say that about the 7.3? Both the 6.9, and 7.3 have went over 300,000 in my trucks, with nothing but starters. a very proven motor, in my book. Same with the 5.9s. Ford was using them in the mid 80s, and there are still some floating around from back then. Both proven powerplants.

Mike

[Mistress]

About the only early death I've heard on the 6.9 and 7.3 was due to cavitation from the outside of the cylinders...permeating the cylinder walls. Using a "fully formulated" coolant or coolant additive was supposed to remedy that pretty well. Again..this is just trucks.

The 7.3 powerstroke and the Cummins 5.9 24v were rated for avg 250k before by JD Powers before significant work required. I know we've all heard of a few Cummins 12v's going 1 million miles too though. A friend got 15,000 hours out of a 6bt Cummins in his boat. Not commercial..but used VERY often. Rating is 6000.

[Eyekymo]

The cummins is my pick for the future boat. No doubt about it. The higher rpm on the yanmar concerns me. The 5.9 just keeps plugin' along. I'm looking at a pilot house with that power plant, we'll see.

Mike

[Mistress]

Given a choice...I think I'd choose the Cummins too.

Ohhh...that's right...I already did...LMAO

a 270 5.9 bta would be kinda nice though.

[Steve74]

My current engine has been great and was thinking more towards the future. I pull the boat with a Dodge Cummins and just have a thing for diesels.

I like the longevity and the safety of diesel, plus i would like to extend my range. I'll probably wait till my current engine give me problems before deciding what to do, but just wanted to see what my options are. Thanks for all your replies.

Steve

[Mistress]

oh Steve...had you asked a question?...LOL Sorry for the threadjack.

The wider rpm range of the HO engines can be a practical advantage...though you'll always give up something in the longevity dept for it.

[ryanbr]

This may be a little late but Ill try anyway. The dilemma hinges on usage, the more you use it the more it makes sense. Yanmar usually make the most sense because everything comes fitted from the factory all in one box. You will have to do the modifications and dont skimp. Do it right the first time. A diesel has only one exhaust so youll have to plug one hole. The shaft is usually larger and the props entirely different. If you like the boat and plan on keeping it diesel is the way to go. The fuel is usually more like 60% of a comparable gas engine, having run similar boats with a gas and diesel. Most everybody I've known that went to diesel has to pinch themselves the first few times they fill up. Keep in mind that diesels like to be run-the more the better. And fuel doesnt store well. !!!!!Dont try to push it either like you did that gas engine. People that push it get 2000 hrs on an engine, those that dont may get 6 or 7 thou or more. Good luck

[Eyekymo]

Why do diesels have only one exhaust?

Mike

[ryanbr]

Most diesels are in-line and not v in configuration. This is a different animal. It takes a little getting used to, but there is not much to piddle with. You must must must keep the fuel,air,and oil clean. I recommend the largest Ray-cor fuel/water separator you can fit. It needs the glass bowl so you can see when to drain the water. One problem with the yanmar in a 'rock. You need to fabricate a new exhaust riser. The engine exhaust sits low in a Shamrock and needs a taller riser to keep water from backing into the turbo. Most people dont know this until their turbo freezes up-nobody will tell you this. But dont let that scare you. This happens because the Yanmar is usually a lighter,smaller 4 cyl engine, instead of the larger 6 cyl cummins. Both are very good engins.