You’re in the market for a new boat, you know where you’re going to keep it so you know the general size and draft constraints. You’ve thought about how you will primarily use the boat—now you’re down to the final details before you buy. What are your preferences for powering the boat, inboard or outboard power?
Clearly, from 30-40 feet and up, inboards are the choice. A boat that size needs an inboard because of its deeper draft and electrical requirements. Below 30 feet, particularly if you have draft limitations or expect to keep the boat on a trailer, outboards are a good choice. Also, if you plan to go gunk-holing or would like to drive the boat up on a beach, kicking up the engine is a nice option. The only time that inboards are good in shallow draft situations is when you have jet drives.
So size, draft requirements, and what you plan to do with the boat are some of the considerations in your decision, but you still aren’t sure. What else should you consider?
One big difference is fuel type. Outboards run on gas; inboards are predominately diesel-powered. Oh, you can find gas inboards, but for safety reasons I would go with a diesel inboard every time. (Two exceptions for a gas inboard would be if you are considering a power-driven Formula-type race boat for performance reasons, or an older used boat because it is cheaper.)
Another consideration is power and torque vs. speed. Power and torque are two strengths of diesel inboards. And while there are some very fast turbo-diesel inboard boats, speed is generally the domain of gas outboards.
Finally, there are maintenance, dependability, and cost issues. A few years ago, I would’ve said that diesel inboards were more likely to be yard-maintained by a professional mechanic and hence would be more costly to own than an outboard; with today’s sophisticated outboards, that is almost reversed. Simple diesels are easy to work on and very dependable, even if you have to be a contortionist to shoe-horn yourself around a tight engine compartment. Modern computer-controlled outboards—particularly the large ones— need technicians with the right training and tools to work on them.
If you do have to replace or upgrade an engine or prop, it is easier with an outboard. And on a smaller boat, having outboards will give you more space for you and your guests.
Editor’s Note: To help with your next decision, read Do You Need a Surveyor?