And is there such a thing as too much power?

Oh Kean Sean, Founder and Managing Director of Pen Marine, recounted a humourous story to the team recently. Many years ago, he was out at sea with a few friends and the boat they were taking was so underpowered, he said with a chuckle, that the few of them had to stand at the bow just to get her to plane and get moving. Although this rarely happens anymore in the modern age of boating, it is a poignant reminder that power matters on a yacht. Too little or too much, and boating won’t be pleasurable at all. There certainly is a sweet spot in terms of power, and five factors will determine the answer to the question of just how much power does your boat need.

Size matters

Just like you can’t (or shouldn’t) put a Ferrari V8 into a Honda Jazz, small boats do not have the real estate to mount large engines, nor are their hulls made to withstand the stronger forces. Some boats have a capacity plate, and all have the capacity limit in the owner’s manual so consult that handy document first before doing anything. This factor puts a cap to the upper power limit of the vessel, and going beyond it is highly dangerous.

The golden ratio

Like the opening analogy, there is also a lower limit to how little power the boat can have, and it is in relation to the weight of the vessel. Boat Trader blog offers a general ratio that we believe to be highly useful – you should have between 40 – 25 pounds (20 – 12 kg for the rest of the civilized world) for every horsepower you have. The range is quite big, as this is relative to water conditions and hull design. In other words, it means that a boat weighing 7000 kg (like the Jeanneau Cap Camarat 12.5 WA) should have something between 350 hp and 600 hp.

Bear in mind that adding a motor or engine also adds weight to the yacht. That’s why sometimes having a single engine with 300 hp may produce better results than adding 2 with 200 hp each.

Always think in terms of range

Unlike cars, yachts can’t just refuel wherever they like. Fuel consumption, and the range of the vessel, is affected by the output of the engine, although this is not always the case. Revving the daylights out of a smaller engine will always consume more fuel than a bigger engine running in the creamy sweet spot of its rev range. However, it does provide another parameter when deciding how much horsepower is needed. For example, Yamaha’s V6 outboard with 250 horses is rated to 89.9 litres per hour (lph), while the 300 hp variant is rated at 98.3 lph. With this information and the maximum fuel capacity, you’ll be able to estimate how long and far you can travel.

Boat usage

The primary use of the boat will tell you how much power you need for it. If she is a casual coastal cruiser, she will need less power than a focused-fisher. Also, don’t underestimate the power needs of a boat used for recreational watersports. Bringing gear along puts additional weight onto the boat, and pulling water skiers and wakeboarders will add a surprising amount of drag.

How many people on board?

It goes without saying that the more people you have on board, the heavier the boat. If all the kids have flown the nest and she only serves you and the missus, you won’t need as much power as a boat that caters to the entire family. Having a realistic expectation on this will help you make a choice.

Bonus : extenuating circumstances

While the other five factors provide a general guideline in the horsepower decision-making process, special circumstances abound and it’s impossible to plan for them all, although it certainly helps to try. For example, the seas where the yacht is used also plays a part in deciding. Rougher seas with unpredictable weather require more horses to tame the former and outrun the latter. Certain countries have regulations on overpowered crafts, which may prevent your vessel from visiting if it has given too much talent.

The theory behind getting the right horsepower for the yacht is useful, but nothing really beats getting onto a boat, taking her out, and then feeling the variables for yourself. Sometimes the idea of having all that punch is great, but after heading out to sea you’ll find that you’d rather have less wind in your hair and face. Other times, with the winds and currents against you, you may come to appreciate having a few extra horses at the back of the boat. Also, don’t stress out too much about it and enjoy the process of discovery. As always, we’re here and would be glad to point you in the right direction too.