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How to evaluate the weight of boats in relation to the power of the engines

A guide:

 It is very important to pay attention to the weight / engine ratio when buying a boat and especially when considering a larger vessel, such as over 40 feet and in flybridges in particular. A boat needs to have excellent propulsion. More importantly, I would say, more power is better than less and this will change the fuel consumption and effort when the boat goes into planing mode and maintain planing at a moderate speed.

Several factors will influence this step. The manufacturer’s design is important with regards to the weight distribution, location of the fuel tanks, location of the engines, generator, in short the configuration of the various systems that are on board.

Also, if the boat has a hardtop, there will also be a parachute effect caused by the angle of the boat, which will require even more power from the engines.

THE EXAMINATION

Let’s take a look at seven popular boats sold in North America:

The Searay 510 Flybridge (with shafts)

The Prestige 520 Flybridge (with PODS)

The Carver C52 Command Bridge (with shafts),

The Tiara 53 Flybridge (with PODS)

Azimut 53 Flybridge (with shafts)

The Cruisers Yachts 54 Flybridge (with PODS)

The Sunseeker Manhattan 52 Fly (with shafts)

Technical data for theSearay 510 Flybridge:

 

Dry weight is 46,500 lbs with two Cummins QSC 8.3L engines (2 x 601 hp). LOA: 50.10 ft, beam: 15.4 ft. Possible option to have a propulsion with ZEUS PODS. Possible option to have 2 x Cummins QSM 715 HO with shafts, but very rare on the market)

Technical data for the Prestige 520 Flybridge:

Dry weight is 31,084 lbs with two standard Volvo IPS 600 engines (2 x 435 hp) Presently theonly engine option. However, the manufacturer mentions that the new 2021 models will be with Volvo IPS 650 (2 x 480 hp). We do not have a performance test with these engines. The LOA: 52.9 ft and the beam: 14.9 ft.

Technical data for the Carver C52 Flybridge:

Dry weight is 42,000 lbs with two Cummins QSB 6.7 480 HP but it is rare that this engine isinstalled as it is underpowered for the weight), for comparison, let’s use the optional engine, 2 x cummins 8.3L (600), which will add approximately 1500 lbs to the dry weight, bringing it to 43,500 lbs. Also total into consideration the “unknown” weight of the hardtop. In summary : Carver C52 Command Bridge, dry weight 43,500 lbs, 2 x Cummins 8.3L engines (2 x 600 hp), LOA: 51.10 ft and beam: 15.8 ft

Technical data for the Tiara 53 Flybridge:

Dry weight of 51,300 lbs with two Volvo IPS 950 (2 x 750 hp) engines LOA: 54.6, beam: 15.11 ft

Technical data for the AZimut 53 Flybridge:

Dry weight of 48,501 lbs with two Caterpillar C12 ACERT engines (2 x 715 hp) LOA: 54.9, beam: 16.2 ft

Technical data for Cruisers Yachts 54 Flybridge:

Dry weight of 45,900 with two Volvo IPS engines 950 (2 x 750 hp) LOA: 53.4 ft, beam: 15.6 ft

Technical data for Sunseeker Manhattan 52 Flybridge:

Dry weight of 59,524 with two Volvo D11-725 engines (2 x 725 hp) LOA: 52.6 ft, beam: 16.0 ft

 

COMPARISON:

The Searay 510 Flybridge (for the test) equipped with two Cummins 600 engines (shafts) has a top speed of 27.3 kn with a fuel consumption of 65.6 GPH.

The Prestige 520 Flybridge is equipped with two Volvo IPS 600 engines (2 x 435 hp) for models before 2021 which offers a very modest performance. They consumes little fuel but the maximum speed is very limited, 25 kn for a consumption of 44.5 GPH (gallons per hour).

The Carver C52 Command Bridge has a top speed of 29 kn and consumes 64 GPH

The Cruisers Yachts 54 has a top speed of 36 kn and then consumes 75.5 GPH but at a speed of 28 kn, it consumes 57.5 GPH

The Azimut 53 Flybridge has a top speed of 32.7 kn and consumes 63.2 GPH. Several Azimut 53s are also equipped with MAN R6-730 engines which can then exceed 33 kn.

The Tiara 53 fly has a top speed of 38 kn and consumes 75 GPH but at a speed of 28 kn, will consumes 56 GPH. The Tiara has a fairly significant weight, in fact the Tiara has an dry weight of more than 7,800 lbs than the Carver C52 but boasts a top speed much higher than that of the Carver C52. If the Tiara 53 goes at a speed of 28 kn, it consumes less fuel than the lighter Carver C52.

The Sunseeker Manhattan 52 Flybridge has a very reasonable top speed of 31 kn, especially considering its dry weight which is double the Prestige 520 Fly. It then consumes 70.3 GPH. This model can also be fitted with two Volvo IPS 950 engines. All this to show you that the power to weight ratio is very important to consider when buying a boat.

 

In summary: (click on the image to enlarge) Here is a graph comparing the 7 boats.

 ANALYSIS

Of course, many boaters will say that they never go to top speed but I remind you that you still need power to remain at cruising speed ​​and also to get the boat to plan especially with a hardtop roof and a fairly heavy dinghy on the hydraulic platform.

Regarding the Tiara, it is possible to order the boat with CAT C12.9 engines and shafts, which makes the boat heavier but with a considerable gain in power. Indeed, the engine then offers 2 x 1000 hp with shafts. With this much power you no longer have to worry about performance, the number of passengers on board or fuel levels.

The boat, its design, its structure must be able to accept this power. In short, do your homework before buying a yacht over one ($) million, everything needs to be consistent. Often manufacturers offer small engines in order to maintain a better selling price, so assess the situation, check the internet discussion forums for the boat you are looking to purchase, always take into consideration engine power / weight ratio of the boat.

A powerful engine, always promotes better fuel consumption at moderate speeds. Of course, at top speed the engines will consume more, but it is the captain who is in control.

CONCLUSION

The objective of this article is not to favor one model over another as boat tests are sometimes very fluctuating, it would be necessary that the seven boats be tested at the same time and especially with the same navigation conditions, fuel and water levels, passengers on board etc.

The important thing is to note that there are major differences between the models and that we must consider these facts according to the preferred mode of navigation. Also, one should never forget the resale value. In addition, the weight of the so-called “heavy” boat also influences the comfort in navigation mode in, say, unpleasant waves.

Of course, the purchase price has to be taken into account, but this exercise did not want to distract the reader from anything other than weight versus engine. There are some very interesting deals on all of these models on the used market. Do not hesitate to contact us if you have any comments or suggestions for articles, the brokers at Ita Yachts Canada are at your service.

N.B. Data and statistics were obtained from different websites: respective manufacturers, Boattest.com website and powerandmotoryacht.com

 
 
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