Most repeat boat buyers know that new boat dealers often direct them to a boat that's in stock, rather than one that specifically meets the customer's needs or the one they walked into the showroom to see. Because of the Great Recession nearly all boat dealers are carrying far fewer boats in inventory than ever before. That's why you need to figure out before you get into the showroom how much horsepower and which brand engine you want in your new boat.
Selecting the brand of boat is only half the sportboat-buying exercise. The engine selection, both in terms of brand and horsepower, are also critical -- maybe even more so. Then, there is the lower unit to think about.
Check Point #2: Engine Horsepower and Engine Selection
The displacement of sterndrive diesel engines ranges from 3.0 L to 8.2 L.
A. Match Horsepower to Your Application
The engine is the most important component in your boat. Some people think the right engine and drive unit are even more important than the brand of boat itself. Indeed, many owners report that the only real trouble they have with their boat involves the engine. Also, if the engine selected cannot meet the requirements of the mission of the owner, then the boat's performance will be disappointing.
Engines are expensive and for that reason it is important that consumers know how much power and torque are needed for the intended application.
B. Compare Boats with the Same Engine Horsepower
When comparing boats make sure you are comparing apples-to-apples when it comes to the engines. Each boat builder has its own "target market" for each model it builds and do not necessarily equipment the same size boats with the same horsepower. However, most builders offer options in horsepower selection so consumers can usually compare boat pricing apples-to-apples as far as the engines are concerned.
Engine companies generally know what their competitors are charging builders for like products and as a result their pricing tends to be competitive for the base engine. However, do not assume that all builders have the same charge for the engines they install. Every builder has its own pricing policy and strategy for both engines and high-tech add-ons.
C. Engine Brand Selection
Corporate cultures, testing procedures, design and engineering, warranties and the customer service of engine makers are not all the same. We urge consumers to find out as much as they can about the engine models contemplated. Read the fine print of the warranty and compare them just as you would the warranties of the boat brands you are considering.
Be advised that many boat brands owned by the Brunswick Corp. offer only engines built by its divisions and affiliates, with only a few exceptions. Other boat builders also often have exclusive arrangements with certain engine brands for a variety of reasons. In all cases consumers should inquire from the dealer what engines are available for any boat model.
Sterndrive Engines. Virtually all sterndrive boats built in the U.S., and most in the world, are powered by either Volvo Penta or MerCruiser engines. Both of these companies marinize light truck engine blocks, called Vortec engines, that they buy from General Motors. They are currently available in the following sizes: 3.0 L, 4.3 L, 5.0 L, 5.7 L, 6.0 L, 6.2 L and 8.2 L. Horsepower ranges from 135-hp to 430-hp.
While the basic Vortec blocks are the same, the marinization procedures, equipment, materials, and systems added to the block by Volvo Penta and MerCruiser are not the same, and consumers would be wise to investigate the relative merits of both brands before buying. There are some important differences between the brands.
The Duoprop was invented by Volvo Penta, followed a couple years later by MerCruiser’s Bravo III.
Outboard Engines. There are five major outboard engine brands on the market: Evinrude, Honda, Mercury, Suzuki, and Yamaha. Horsepower ranges from 2-hp to 350-hp. Outboard engines also come in both 2-stroke and 4-stroke versions. Evinrude, Mercury and Yamaha offer both 2-stroke and 4-stroke outboards. Honda and Suzuki offer only 4-stroke motors.
Because of a number of factors, 2-stroke and 4-stroke engines are generally considered to be better for different applications, so again, match the stroke to the application. At one time 4-stroke engines were more fuel efficient than most 2-stroke engines, but that distinction has largely been eliminated by high-tech advancements in 2-stroke engines and today other considerations usually weigh more heavily on model selection.
Diesel Engines. There are numerous diesel engine brands on the marine market and horsepower ranges from double digits to quadruple digits. Most of these are marinized versions of commercial engines, but a few have been specifically designed for marine applications. Today, diesel engines available from the 7 major marine diesel brands are 4-stroke and virtually all are turbocharged. The horsepower-to-weight ratio of these engines is important when comparing them, along with the ease of adding joystick maneuvering applications.
Gas Inboard Engines. Gas inboard engines with conventional straight shafts are used extensively in specialized ski boats and in cruising boats in the 30' to 45' range, as well as in some specialized applications. There are several companies that marinize the same Vortec blocks used in sterndrive engines. Again, each company has its own unique approach to that process and consumers should educate themselves on the features and benefits of the brands available.
D. Lower Unit Selection
Sterndrives. The lower units offered by both Volvo Penta and MerCruiser come in several different configurations in both single and dual-prop drives. Like the engines, it is important to match the lower unit type and design to your application. Your boat dealer is best equipped to do that for you. Again, when comparing pricing make sure it is apples-to-apples on the lower unit as well. Sterndrive propulsion is usually more efficient than straight-shaft inboard propulsion.
Sterndrives models are available for both gas and diesel engines.
Top speed during our test of this 25' tri-toon was 45.2 mph. The time to plane was a remarkable 2.5 seconds. Test power was the Evinrude E-TEC 250 H.O..
Straight Shaft. There was a time when virtually all inboard-powered boats had straight-shaft drives for gas or diesel engines. Because of the down angle of these shafts they are inherently somewhat less than optimally efficient. In some applications builders and transmission makers have been able to lower that angle to a little as 6-degrees. For the early part of the 2000s joystick low-speed maneuvering was only possible with pod drive systems, but today new generations of joystick software is available from most engine companies that allows joystick docking with straight shift engines (even single engine drives) and a bow thruster.
V-Drives. These drives are a variation of a straight-shaft design. The difference is that the engines (both gas and diesel) have their fly wheel facing forward and are coupled with a V-drive marine gear that permits an aft-facing shaft. Current generations of V-drives have proved reliable and we are told by the engine makers that only about 5% of the engine's horsepower is lost in the gearing. V-drives permit the engine to be placed further aft in the boat than it would have been with straight shafts.
Pod Drives. Pod drive lower units swivel under the boat and an be directed pretty much anywhere the engine maker desires. IPS pod drives are forward-facing and Zeus pod drives made by ZF and Mercury have aft-facing props. Our testing has shown that both brands of pods are considerably more fuel efficient at mid-range cruising speeds than are straight-shaft drives in the same boats.
Because of the machinery involved pod drives are considerably more expensive than straight-shaft drives, however they have other advantages such as permitting the engines to be placed further aft in cruising boats thus opening up more of the boat for accommodations and more positive control at low speeds.
Yanmar is the most recent entry into the diesel-powered sterndrive market. Here you see its Z350 dual-prop stern drive.
Next Week: Buying Check List #3