What’s not to like about Diesels!

I don't think I would have bought a non trailer boat if I couldn't have got one with a diesel. Fuel prices in NZ are probably irrelavant to most of the members on this forum so I won't go there. Suffice to say, I have been very pleasantly surprised by the fuel economy and the double dipping affect of paying less for the fuel you do use. I guess we are quite lucky down under in being able to order these smaller Sea Rays with diesels factory fitted. I think Sea Ray exports these to Europe too. Another member on this forum (Melida from Turkey) has a 280 DA with a Volvo Penta KAD300 also. I know a big block V8 sounds nice but frankly I love the sound and smell of a diesel first thing in the morning and, they are reassuring when at sea. The only problem with being spoilt by a small boat with a diesel is that the next boat has got to be bigger and have twin diesels, and that aint happening anytime soon!


Terry
 
Most of the Sea Rays here in Europe are diesel because of price of fuel and because nobody seems to be confident in carrying aboard big quantities of gas. Outboard are popular though and more so since the new four strokes… me? I like a burbling gas V8 for sure (I’m a car nuts) but my CATs do have a nice low reassuring burbling voice I love!
 
fwebster said:
To give you the numbers to finish the calculation, the Caterpillars were burning a little less than 18 GPH at 2200 rpm................
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That is total for both engines right? Mine running at 4000 burns 14 to 15 per for a grand total of 30 GPH. Although I did somewhere around 24 to 26 as a total for the entire 470 mile trip. But then again for the big part of the trip I could not run anywhere near that fast, ocean was not playing nice.
 
I'm sorry......I should have mentioned that since I know it is hard to comprehend that a big boat can be that efficient..........it is 18 gph total.

As an interesting aside, we have not refueled in a few weeks because we needed to change a fuel sender. During this same period of time, the BP Vessels of Opportunity, the CG and the local Emergency Management folks have camped on our boating area. They have essentially closed my access to the Gulf, so for the last 10 hours of running time I have been in no wake or in crowded conditions which means "go slow". For most of the 10 hours, I have been at 1500 rpm or below with most of the time at about 12 kts @ 1450 to 1500 rpm. On that 10 hours, I averaged 5.5 GPH total.

Pat of what you learn about owning diesels is that you will use your boat more because the fuel and maintenance costs are not always on your mind as a sunk cost.
 
One thing not to like in my area is the accessability to a certified marine diesel mechanic. (CAT or Cummins) The closest one is about 2-1/2 hours away (by land)....not like you'll need them frequently...you hope. I'm not sure if you want a dozer or 10 wheeler tech working on your floating diesel.
 
Stray Cat said:
My jaw just hit my keyboard/////////mmmmmmmmmnnncccccccc
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I know! That’s what I mean, I had a boat following me for over 400 miles that was much bigger, wider, faster, and getting much better fuel economy! I thinking what am I doing; I got to get me one of those!

Bill is in the market!
 
I keep very accurate 'average' GPH and MPG records for my 410DA with CAT 3126TA. When I show people my 'average' (I don't have fuel flow meters) they don't believe. I show them the receipts for the fuel fills and they still don't believe me.

My cruise speed is 21-23 knots.

On 'average' my MPG is ~1.1 sMPG....I won't even print my 'average' GPH....you probably won't believe me anyway.......
 
Wow, I had no idea they would burn so much less. Of course the upfront costs are significantly more too.

Pay me now, or pay me later......................I am paying with each tank unfortunately.
 
:smt009Unfortunately....Even though I'm on a relatively large lake...no diesel filling stations and not many mechanics I bet. I've only seen and heard of 1 boat on the lake and he has to have it trucked in...
 
I am with you Bill. Next boat thanks to all the folks on here is my next sea ray will be a 450 or 460 thanks to Frank... Now he has me looking for a 500!!!!

Really the budget is more in the 450 range...


Can't wait for diesels!!!!!
 
On balance, diesel doesn't really make sense where we boat for the following reasons:

1. In a good season, we may put 50 hours a year on the boat. Even boating in May and October can be iffy, weatherwise.
2. The regular mechanics in this area aren't terribly knowledgeable working on them. To get a "good" diesel mechanic here, you have to send for someone 100 miles away and often are waiting a long time for service.
3. Marinas here don't tend to keep a lot of diesel engine parts/service items in stock, while common gas engine parts are easy to find without a wait.
4. Only about 50% of the marinas around here stock diesel fuel. Those that do don't seem to sell a ton of it, which makes me wonder how fresh the fuel is.

If you own a model that can be pushed around adequately with gas motors, the "economics of diesel" argument doesn't really hold up as well here as a location with a 12-month boating season where you can rack up many more hours. If I were operating a boat much larger/heavier than this, I would prefer the torque of diesel motors, of course...
 
Just reminded myself of another big advantage to big torque diesels.....the ability to run slow and maintain plane.

Three years ago, coming up the Hellaware, I was running with a gas 390DA. The wave heights were 4-6...occasionally larger....and the period was ....'one after the other'. I was able to slow down real nice to take the peaks....the gasser....not so lucky. I stayed with him just to stay with him, but I could have slowed down even more.

Big torque, big wheels, more control.....
 
osd9 said:
Just reminded myself of another big advantage to big torque diesels.....the ability to run slow and maintain plane.

Three years ago, coming up the Hellaware, I was running with a gas 390DA. The wave heights were 4-6...occasionally larger....and the period was ....'one after the other'. I was able to slow down real nice to take the peaks....the gasser....not so lucky. I stayed with him just to stay with him, but I could have slowed down even more.

Big torque, big wheels, more control.....
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I agree with Dominic. Of course the real answer is depends on how a boat is used, but if you plan traveling often enough you need the best rig. I've been in situations when I would like to go slower to keep the ride smooth and keep the boat on plane. The more I travel the more I might have this need, although my 320 so far gives me what I need.
 
osd9 said:
Just reminded myself of another big advantage to big torque diesels.....the ability to run slow and maintain plane.

Three years ago, coming up the Hellaware, I was running with a gas 390DA. The wave heights were 4-6...occasionally larger....and the period was ....'one after the other'. I was able to slow down real nice to take the peaks....the gasser....not so lucky. I stayed with him just to stay with him, but I could have slowed down even more.

Big torque, big wheels, more control.....
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Sure good have used that last Friday on the Ocean..... Man did we take a beat down!
 
Bridog said:
How about nasty black smoke? That's about all I could come up with. ;)
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If you like diesels you’re going to love the new SCR (Selective Catalytic Reduction) engines.

Marine SCR technology

SCR works by injecting urea into the hot exhaust stream where the urea decomposes to ammonia. The ammonia enters a catalyst where it reacts with nitrogen oxide (NOx) in the exhaust and reduces it to pure nitrogen. NOx emissions can be reduced by as much as 90%

The up side of this is an expected 10-20% increase in power due to emissions being treated outside the engine by a converter. The engine will not be choked down by current emission components within the induction system and valve train. The urea is a fluid that will be added via a second tank. The consumption is small in relation to fuel used and the added HP will more than pay for the increase cost of buying the Urea.

More power, less emissions and longer engine service life.
As you said, What’s not to like.
 
I enjoy reading this and would love to pilot a diesel boat one day.
One point that always made me wonder was the claim that a diesel boat can stay on plane at a lower speed. Could someone explain this better? To me a boat is going to plane at a certain speed regardless of the power pushing it. Yes a gas motor may take more power/time to reach plane but just because a diesel has more torque shouldn't mean that the boat will necessarily plane at a lower speed. It seems contradictory also due to a diesel boat weighing more which should actually mean it will take more speed to lift it up on plane.
Ok explain away...
 
You're right about the Hull being the limiting factor....you won't get a 410DA to plane at 10 knots....not gonna happen.

But, start by understanding that motors don't move boats, Props move boats.

Motors, of course, are what turns the trans that turns the props that moves the boat.

In all planing hull boats, designing the props/motors/trans to work together is a compromise. You have to be able to spin the prop fast enough to get the boat on plane and then once on plane, be able keep the boat there and move it at a reasonable speed.

That said, with gas motors, there is less torque to start with, so in order to spin the props fast enough to get on plane, you can either cut out pitch (which will kill your cruise speed) or increase gear ratios in the trans.....like putting your ten speed bike in first gear....more teeth, higher gear ratio....again...designers have to find the happy compromise.

With Torquey diesel motors, you spin a higher ptiched prop through lower gear ratios to get the boat on plane.....like starting off ten speed bike in 5th gear or so....so the boat actually gets on plane at lower RPMs and will cruise faster at planning RPMs.

Again, the Hull will determine the lowest speed it can hold plane, but the motor has to be able to spin the prop to keep it there.

I hope I explained that right.....:smt101
 
I just cruised in some rough seas, I held plane at 14.5 knots. Don't ask my why cause I don't know. Sure beats getting pounded to death. Only burned 100 gallons from Norwalk to barnegate.
 
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