Diesel VS Petrol: Which Is The Better Engine For Tenders?

Diesel or petrol? This is the dilemma faced by large yachts when choosing the right type of engine for yacht tenders. Nigel Upton from Superyacht Tenders is here to cover some of the deciding factors when it comes to the type of engine and drive to consider when ordering a new tender. Also, he’ll talk you through what new advances in the market place are influencing decisions.

Diesel

Inboard diesel engines are generally the most popular unit when it comes to yacht tenders for a variety of reasons: 

• Not reliant on carrying additional petrol onboard the mothership as they can refuel using the main diesel deposit. Meaning that yachts that may be cruising in more remote areas do not need to carry 1000’s of litres of petrol onboard or have to source locations for refuelling access which may be limited or simply not available. 
• A diesel engined inboard enables a much lower profile boat as the engine sits inside the boat rather than on the transom – like with an outboard.
• Much lower fuel consumption offering better range between refills. For example, a well publicised test with comparable 9m boats, one fitted with twin 200hp outboards and the other with twin 220hp inboards. At 30 knots the outboard vessel burned 100L per hour compared to just over 50L per hour for the sterndrive. That’s 50% better fuel efficiency at 30kts – a significant difference, especially over a longer period.
• Inboards can be coupled to a variety of drive options these being shaft drive, v-drive, z-drive, jet drive, IPS, surface drive and stern  drive. These can be normally aspirated, turbocharged or supercharged.
• Engines can be positioned centrally with jet drives and aft with outdrives meaning that the design and layout of boats can be changed.  
• In harsh marine environments and in the event of being submerged and having salt water ingress it will be the diesel engine that proves the more robust over the petrol engine. Diesel engines are known for their longevity. A well-maintained inboard diesel engine typically lasts around 5,000 to 6,000 hours without a major overhaul far outweighing the 2000hrs as typically seen seen with some of the outboards. 
• The new generation of diesel engines are lighter and more powerful and environmentally friendly than previously. 

Petrol

If a yacht chooses the petrol option it will almost certainly be outboard powered. On very few occasions will an inboard petrol engine be specified with the exception of some of the dedicated ski and wakeboard boats. 

So do petrol outboards still have a place onboard yachts? Petrol outboards still prove a popular choice for many yachts. Outboard power does come with some significant advantages:

• An outboard unit is cheaper to buy and easier to service and run. New outboards generally offer superb reliability if  maintained and serviced correctly.  
• Outboards are lighter, provide improved acceleration, higher top speeds and overall performance in most cases than their diesel counterparts.  
• Traditionally you would be limited to a maximum of twin inboards on a typical yacht tender. It is now commonplace to see outboard powered boats with 4 or more engines fitted. This may seem excessive to some but for a true performance oriented petrol head its just the combination they are looking for. 
• Outboard manufacturers are now producing 600hp V12 units offering huge performance in a relatively compact package.
• Petrol Outboards engines have the uniqueness of requiring less amounts of air for fuel combustion to happen. Meaning that they release significantly less amounts of air pollutants than diesel engines. 

Diesel Outboards

Another option that has gained in popularity over the last few years are diesel outboards. The main factor is the vastly improved fuel economy but the downsides are the high costs compared to  petrol versions, the overall weight, and the lack of performance. 

They are beneficial if you are doing very high hours, as the fuel consumption is much better. BUT, this only translates to a saving if doing lots of hours, as the purchase cost in the first place is so high.

Electric Tenders

Are the advances in electric power now influencing the tender market? Options are still rather limited at this stage. No one has truly produced anything that stands out as leading the way in the yacht tender sector. 

In reality due to weight, power produced and the range limitations available the only tenders that may be useful are the smaller electric powered 6-8m passenger tenders that don’t need to reach high speeds or cover long distances between charges, it seems that 2hrs usage between charges is around the maximum to expect. This is suitable for some, but with a busy charter yacht and a full guest itinerary, this may not prove to be a feasible option. However, there is a lot of work going on behind the scenes and continuous development so the electric tender may well prevail in the future. 

Diesel VS Petrol. What’s The Verdict?

Petrol and diesel options are still in widespread use. They are chosen depending on the yacht’s itinerary, cruising areas, designated usage, owners preferences, and logistics. 

An inboard diesel will always prevail when the garage or deck storage heights are limited, or a yacht that frequently operates in locations with limited access to petrol. 

However, an outboard powered tender will work perfectly well if it’s being operated in the Med or Carribean. For example, with plentiful locations for refuelling access and no storage restraints. There may never be a definitive answer to the petrol vs. diesel marine engine debate – a growing number of new build tenders can be optioned with either diesel or petrol engine options. 

Diesel will always end up being the more economical choice in terms of usage. Overall, from a large yacht perspective, it is easier and safer to store onboard. 

Both types of engines have advanced significantly over the years and it will be interesting to see what the future has in store.

Superyacht Tenders is the place to go for your next tender.

Email: info@superyachttenders.net

Phone: (London) +44 7756 867 806 OR (Barcelona) +34 659 556 991

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