A U.S. district judge recently certified a national class-action lawsuit brought by a Detroit businessman against Illinois-based Caterpillar Inc. over diesel engines the company makes for large yachts.

The suit brought by James Jaikins against the company potentially affects more than 7,000 Caterpillar marine engines produced since 1996. Damages could easily exceed $100 million, lawyers say.

The boat industry and boat safety is not regulated in the same way automotive safety is, "this is a major consumer protection case," said the attorney representing Jaikins.

The suit alleges certain Caterpillar engines contain defective aftercoolers — components that cool air inside the engine. The defect allows water to enter the engines and mix with fumes, resulting in severe corrosion and engine failure, sometimes involving the engine exploding, the suit alleges.

The main focus of the suit is the Caterpillar 3196, which the company has described as the ideal engine for yachts 40 to 60 feet long. Jaikins alleges some versions of another Caterpillar yacht engine, the C-12, contain similar aftercoolers and could also be affected.

Though Caterpillar denies the aftercoolers are defective, officials have acknowledged problems with the engines in testimony and documents produced as evidence. A Caterpillar official testified in a deposition that of about 4,600 Caterpillar 3196 engines put on the market, more than 4,400 had warranty claims related to their aftercoolers.

Another company document introduced as evidence refers to an 80-90 percent engine failure rate. Caterpillar sent out notices alerting dealers to "a potential situation (involving) entry of water through the engine's aftercooler," but never launched a recall, according to evidence produced in the lawsuit.

Caterpillar argues the high number of warranty claims is a result of Caterpillar asking dealers to invite owners to bring their yachts in for inspection even if they weren't having problems.

Jaikins' Riviera 48 yacht contained two Caterpillar 3196 engines when a 2003 engine explosion and failure caused the construction company owner to be nearly stranded between Florida and the Bahamas, Jaikins alleges in the lawsuit.

When Jaikins started talking to other boat owners, he found his experience was not unique. He alleges problems with the engines are the subject of widespread "dock talk" and are documented on Internet forums.

Caterpillar says in court pleadings that many factors, including lax maintenance, can contribute to engine problems Jaikins and other boat owners describe.

A company lawyer told U.S. District Judge Arthur J. Tarnow, who certified the suit's class-action status, that Caterpillar has evidence Jaikins was overloading his engines, resulting in engine damage.

Eight versions of the aftercooler were used in the 3196 and C-12 engines cited, so Jaikins cannot claim to represent boat owners that had engines with aftercoolers different from those that were in his boat, the company argues.

Also, Jaikins received three new replacement engines, one 3196 and two C-12s, all paid for by Caterpillar, so he has already been compensated for damages, the company argues.