Cat or Cummins power?

kevin27

kevin27

Well-Known Member
Aug 8, 2007
1,040
Winter Garden, FL
Boat Info
2017 Scout 175 sportfish.
2002 Crownline 202 LPX
Engines
Yamaha 90hp
Mercruiser 350mag mpi
Looking for opinions and experience with these two engines. Which one would you buy?
Boat weighs around 18k-19k.
Option 1: 375hp Cat 3208TA
Option 2: 330hp Cummins 6-BTA 5.9 Liter
Thanks for any info you can pass on.
 
I don't know anything about Cummins ( but i do know Cummins makes fine products) but those Cats are among the best, bulletproof diesels ever made. They are the diesel equivalent of the car and truck GM carbureted 350v8 made for 50 years. Millions were made (in addition to their popularity in boats, there are far more of them in dump trucks, loaders, bulldozers etc), not pretty, not high tech, not sexy, but just go and go and go and go...

They have almost 2 cubic inches displacement per horsepower so they don't work as hard to make this power. That's one of the reasons they last, and even a doctor can do regular maintenance and minor repairs.
 
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Both good, reliable power plants with ample parts and mechanics who know how to work on them at least in most parts of the country. My observation from boats in our marina is that the 3208's smoke-up quite a bit more than the cummins when starting them up but that only lasts a few moments. I also think the cummins run a bit quieter than the cat. The 3208 I believe has more torque and a lower power/RPM curve but the 6BTA is more fuel efficient. I think a rebuilt 3208 would be cost more than a similarly rebuilt 6BTA. Not sure I can weigh-in on which I would take over the two without more details.
 
This is good stuff please keep it coming.
 
What hull are the engines in. The 3208 is a work horse high torque engine. The 330 hp 6BTA is not. At a 300 hp rating, the 6BTA can easily be overloaded in 42-44 ft Sundancer. To get desired speeds, people tend to run the 6BTA at close to max rated cruise and that could easily mean problems for owners down the road. Cat engines are not that sensitive to the hull they are in and the 3208 will run forever as long as you don;t over heat or continually overload it.

I have friends who have a custom charter boat in Florida with 3208's...last May when I saw him, he has 17,000 hours on his engines with no major repairs......a couple of alternators, one fuel pump, a few injectors and just annual maintenance. We also have friends with 300hp B Cummins in a 440DA, and another with a 370DB both with around 1000 hours, and they both have had to rebuild engines. This is a universe of 3 boats so it certainly isn't statistically meaningful........just examples.
 
Regardless of engine make, the most important thing is where they taken care of by PO. This also includes did the PO overheat them or overload them? Answer we simply don't have.

Example: Boat A with 375 HP cats but was run on the pins with very little maintenance done and no records at all. Boat B with 330 HP Cummins, run at 80% max load, aftercoolers and heat exchangers were cleaned every 2 years, all maintenance records available including periodic checks of entire seawater system. Which would you want now?

With all things being equal thought, I would take the engine make that has better service in your area and are reliable. If you are a hand on guys and plan on doing that yourself, and again all else was equal, I would lean towards the higher horsepower Cats but there are many many things to consider when purchasing a boat, power plant aside.
 
The boat in question is 1987 thru 1995 Tiara 3600 convertable.
The cat power has around 1850 hours and looks to be maintained average condition. Don't really know without survey.
The cummins has around 900 hours and have not seen the boat yet so dont know condition.
 
What would you guys say your average anual maintenance cost run with you diesels? Compaired to strendrive config (bravo 3) would it be the same or more in cost per year?
 
I've had my boat for two years now and have put ~250 hours on it. Other than an oil change (25 gallons of oil with the genset) and filters (buy them online, not from CAT) and impellers on both engines and the genset, that's it. I don't have exact numbers but I'd say 25 gallons of oil would be around $500 (Costco price on Delo 400), plus about $40 for filters. CAT impellers are either solid gold or gold plated and are just over $250 each, so I buy Sherwood impellers (same impeller!) for about half that from one of several sources.

I'm slowly built up a supply of belts and hoses in case we're out somewhere and something breaks. They ain't cheap, but if I can buy them when I want, and buy them online they're a lot cheaper than what CAT wants for them.

I did have an issue with the Westerbeke genset. It would run for a few minutes but then quit. I hired a guy who owns a diesel truck mobile business to diagnose and fix it. Before we were done he removed the injectors and had them tested and cleaned, then found the problem was a leaking hose that was allowing air to get into the genset. Before that was all done it cost me about $1900.

Other than that, there haven't been any engine or genset related problems or maintenance costs. So I've probably spent $3,000 total in maintenance costs and repairs, but for 250 hours of use that figures out to only about $12 per engine hour.

Now if we talk about fuel costs for those 250 hours that's a whole different ball game and involves quite a few more boat bucks!
 
2years ownership as of last weekend and me doing all the labor approx 250 hours use
Changed oil 3 times now so 4 gallons each x 2 x3 = 24 plus 4 gallons total for transmission and genset = 28 gallons at $16 each for Rotella 40wt is $448

12 total oil filters. Don't remember price, we'll say $20 each equal $160

4 fuel filters at $20 each is $80

Changed stock air filter to a walker unit $100 each. = $200

2 alternators at$189 each is $378

2 impellers at $91 each is $182

About $150 for zincs

This weekend I'm going to Rydlyme the seawater side of the cooling system, then pull and clean the air side of the aftercoolers.
Total cost of this is around $250 including some of the onetime costs of pumps, hoses, etc to pump the rydlyme thru the system

Nothing broke, never had to call mechanic or fix major problem.

Total engine specific cost is $1848 divided by 250 is $7.79an hour
 
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Here kitty, kitty, kitty. The CAT's will not do you wrong. Cummins makes a good product and may be quieter but the CAT's are pretty bullet proof. As with any engine, there is always a chance for failure but the CAT's have phenomenal torque and are soooo easy to maintain. I would like to know the vintage and boat model these are in...
 
If you had said you were looking at a Tiara Open like trit21's, then the 6BTA would be perfect, but the Convertible is a lot heavier boat and I would urge some caution since toy probably need the torque Cat engines provide. But, most of us have limited experience with 20 year old Tiara's. Decide for yourself after sea trialing both of them and you decide, then be sure to have either Cat or Cummins survey the engines in whatever you decide.
 
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I don't much about the Tiara 3600 Convertible but if you are looking for a cruising boat, up on plane and running as opposed to idling, then I would have to agree with more horsepower/torque and the Cats. I have Cummins 370HP in mine and she screams right along so I would think with a heavier boat, and less power (Cummins) it will not act as mine does. Will the Cats, hard to tell. If you can talk to some other owners maybe you can get an insight. I will send a PM with more information on that.
 
Kevin, you have no room left for private messages. I have some info if you need it, please let me know and I will PM you when you have room available. Don't think everyone here wants to hear about Tiara's.
 
OK cleared my pm. Sorry have not looked at them in a while.
 
Cant say much for the typical Cummins other than; 1..they keep things simple (a good thing), 2.. they don't run alot of oil pressure and need to turn higher rpms to get into big horse power (not a good combo).

As far as the 3208 Cat; 1.. Holds lots of coolant in the block, manifolds and turbo (a good thing), 2.. valve lash can loosen up if they don't get enough load or run at too high rpms for too long (not a maintaince free area).
 
My cats suck ass!! With 800 hrs I have had to rebuild both of them over the last 4 years to the tune of over $50,000. Moisture caused my valve seats to rot. Despite being very proactive with my servicing they have cost me big time. When I asked cat for help they basicly told me to go **** myself. I will never buy a boat with cats again.... never
 
Good thread. I like my 8.1's but have definitely spent large money on them, mainly due to an irresponsible PO, on items missed during survey. I had been out of boating for many years, before jumping back in 1 1/2 yes agp. If there is a next boat in my future, it will have diesels. I spent thousands of hours on fishing boats with diesels in high school and college, and do not remember a single breakdown. I believe those were cats, but don't remember for sure. Tiara makes a nice boat, and we have quite a few in our marina. I am interested to hear more on how this goes.
 
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