By David Rowland
Buying an engine or generator set used to involve a visit to a local engine dealer. The dealer would assist in selecting an engine or genset appropriate for the application. A model would be selected, a price negotiated, and a sale was made. The internet has somewhat changed the marketplace.
Propulsion engine selection for a fishing vessel can be a complex process. There are sometimes dozens of factors involved to get the job done right. Powering up a new hull is usually easier. The boatbuilder will have recommendations for horsepower, type of cooling, transmission ratios, shaft size, and propeller size based on the designer’s calculations. The engine bed can be set up for the selected engine as the boat is being built.
A repower project can be much more complex in nature. Generally, older engines are less efficient than the newer engines, particularly the new electronic engines. Considerations for selecting an engine might be the size of the proposed engine compared to the old engine, to minimize adjustments to the engine bed, exhaust system, shaft coupling, and controls.
Reducing power might be an option. I know of a Bristol Bay gillnet boat that was purchased by a fisherman in S.E. Alaska. His fishery was much more relaxed than the often-aggressive ways of the Bristol Bay fisheries. The run to his fishing grounds was also short, so high horsepower and speed were not needed. The fisherman replaced his old 425 HP fuel guzzling hot rod engine with a more sedate and economical 175 HP engine, saving a tremendous amount of fuel with little difference in travel times.
A new engine might require relocation of the exhaust piping, and possibly resizing the piping. It is important to check with the engine seller for piping requirements to avoid damaging an engine by restricting exhaust flow. I’ve often heard complaints about relocating and resizing exhaust systems. Either make the adjustments, or overhaul the old engine.
Most engine manufacturers have drawings available showing the dimensions of their engines. It’s not a bad idea to secure a copy when considering a new engine. A newer engine might, for instance, have a deeper oil pan than the engine being replaced. Or, the pan’s oil sump might be located differently from the old engine. In smaller vessels, this can be a major issue if the engine can’t be mounted properly on the engine bed and be lined up with the propeller shaft. Sometimes selection of the marine transmission can help mitigate these difficulties, as some gearboxes have less or greater offsets of the output flange that connects to the propeller shaft. Length and width of the engine are also major considerations.
If planning to use a marine transmission from a previous engine, great care must be taken to assure the gear will fit the flywheel housing of the new engine. If there is a difference in engine horsepower output, compared to the old engine, it would be wise to check with the marine transmission distributor, or engine seller, to verify the old gearbox will work with the new engine. If the gearbox can be used, it would be a good idea to install a new coupling on the transmission. Many times, over the past thirty years, I’ve seen old couplings fail when installed on a new engine. Saving a few dollars on the repower can cost big dollars if a failure happens during an opening.
Cooling is another issue to be considered. Many of the newer engines, starting at about 300 HP, may require two cooling circuits – one for the engine block, and one for the aftercooler, if so equipped. Trying to cheat by plumbing the two circuits into one keel cooler can cause overheating problems. Check with the engine seller for manufacturer recommendations. If the engine is heat exchanger cooled, larger through-hull fittings may be required to provide adequate water flow for cooling.
Engine manufacturers are becoming fussier about warranties. Most require an inspection of the engine installation and a sea-trial to be performed to assure proper application. The newer electronic engines will likely require a trained technician equipped with electronic equipment to monitor engine performance. This can be an issue if the repower is done at a remote location. Cost of transportation, lodging and food for the technician should be considered when purchasing an engine. Most importantly, I’ve heard the statement made that if the warranty wasn’t registered when the engine was new, there is no warranty.
Selecting a generator set can have similar complications. On a boat, where space is usually at a premium, trying to tuck a new generator set into the space held by an older set can be a challenge. Again, exhaust piping can also be an issue. Re-routing an exhaust system is almost a given factor. It’s important there be no backpressure due to an undersized exhaust system.
Moving a generator set into an engine compartment can prove to be challenging. I’ve seen fishermen practically disassemble an engine – removing manifolds, alternator, oil pan, and sometimes even the flywheel housing in order to move the equipment through a small hatch. If removing parts is a necessity, make sure any gaskets needed for re-assembly are on hand to avoid unnecessary delays in completing the job and going fishing.
Logistics is another major consideration for budgeting an engine or generator set purchase. Many motor freight carriers are prepared to greatly reduce your bank balance if you don’t take care to check shipping costs prior to making a purchase.
Freight companies charge by weight, according to a tariff they have filed with the government. The classification of the freight determines the amount charged per hundredweight. The greater the value of the goods shipped will mean a higher freight rate. Freight companies generally give frequent shippers a discount based on the volume of goods shipped. The person sending a single shipment may get little or no discount from the carrier’s freight rate.
Recently, I received a shipment of engine parts from Chicago. The freight rate, before discount, was $330.81 per hundredweight. While I received a good discount, the one-time shipper might pay an exorbitant freight bill. Freight companies have also been known to change the classification of goods shipped to enable charging higher freight rates. On a recent shipment of a marine engine to Georgia, the carrier attempted to change the classification from class 85 – normal for diesel engines – to class 125. This change nearly tripled the transportation costs resulting in a successful fight to get it reduced.
If purchasing a new engine from a distant seller, ask the seller to get a written freight quote before purchasing to avoid surprises. If purchasing a used engine, or if the new engine seller doesn’t wish to handle freight arrangements, a freight broker can be contacted on the internet. Have the weight and dimensions handy, as that will determine the rate. Freight brokers can sometimes save as much as 50 percent over trucking company rates.
Remember, though, if purchasing an engine or generator set from a distant seller, service after the sale may be just as distant.
