Tugboat - EPA/California Engine Requirements

I hear lots of talk about Tier 1,2,3,4 and what is required when and where. I hear that certain Tier requirements compel or discourage rebuilding and repowering. Or that Tier requirements compel or discourage new builds.

I hear that under 800 HP per engine has lower requirements.

I hear that certain boats cannot be bid for jobs in California because they are not Tier 3 or 4. Yet, there seems to be no shortage of older Detroit Deisel powered tugboats, that must be Tier Zero, working in California.

Can anyone point me to a plain English explanation of the practical affects of these emission requirements for tugs.

Tier zero boats working in california are few and far between. Maybe a handful of offshore boats and the way they get away with it is their minimal amount of time in port.

This may clarify things if you have a few hours to kill Oceangoing Vessels & Harbor Craft | California Air Resources Board

I’m sorry, but that is not helpful. If I were going to study for a PhD, I’d pick a more interesting and profitable topic.

All of the 71 and 92 series engines are under 800 hp, and the EPA applies less stringent requirements for them. I don’t know about California. I happened to see a boat in California awhile ago that I know has two cycle Detroit 16V-149T engines.

I asked if a particular 1990s vintage boat with good clean running 3500 series Cats was being bid out for a particular job in California. I was told no “because it’s not Tier 4.” A boat (from a different company) that got the job has 1990’s vintage EMDs. Seems like someone either does not understand what is required, or how to get away with breaking the rules in California.

I have heard it said that old engines cannot be replaced because of the high cost of Tier 3 engines. I have heard it said that good used 2000’s era engines cannot be removed from a boat that should be scrapped and reinstalled in a new boat.

I hear talk about certain yards having an inventory keels that we’re built before a certain date. I hear that it maybe necessary to “rebuild” on old keels.

Have any of the magazines published a four page article that might shed light on this topic.


What I do know is there are no ship assist tugs from SF to SD that don’t have at least tier 2 engines…and most are tier 3 at least.
I am not positive what being carb compliant entails. I do know there is a way to make/modify old two stroke emds for example, carb compliant.
I do know there are loopholes depending on how many hours you may run in port/inshore with non carb compliant engines.
At one time, the state was assisting with the cost of repowering. Not sure if this program is still going on. Lots of vessels got engines for free and only had to pay for the installation.

I am going to assume that the handful of tugs running around with non compliant engines are doing construction/dredging support, but that is soley based on what i have seen.

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That makes sense.

Everybody has been flooding the market with new tractor tugs for ship docking, but I think that boom is over.

There does not seem to be much money being spent to replace older tugs in sectors other than ship docking and oil transport. Still a lot of boats from the 60’s, 70’s, and 80’s.

For convential tugs it’s mostly coastwise linehaul towing, or inside bunkering, dredging, construction, stone, sand and gravel, scrap steel, logs, and so on. Quite a few small construction and misc. tugs.

EMD claims their current 710 engines are Tier 4. Those probably have electronic injectors among other major changes.

I forget what the kit is called, but EMD has an upgrade kit for the 645 engines that I think makes them Tier 2. Other than improved injectors, I’m not sure what’s in the kit. Maybe more emissions friendly power packs.

I have seen truck engines with urea injection exhaust systems, but I have not seen that on a boat.

The Aiviq had such exhaust treatment in order to fulfill the permit requirements of drilling in Alaska.

The EMD 710 engines have a SCR (urea injection) system to make them Tier 4 compliant.

Edit: If I remember correctly the Nordica and Fennica, vessels Shell had chartered also had a SCR system in place.

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What is that EMD 645 upgrade kit called, and what’s in it?


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That helpful. Thanks.

An overhaul plus new injectors,camshafts and a four pass aftercooler brings the EMD 645 up to Tier 2 which compliant with both EPA and California.

I believe GE is using a urea injection also to get tier 4 compliant.

The fuel tenders on the Rhine sell the stuff, but I have no idea to whom.